# Has anyone tried Solar Power?



## Ziggythewiz (May 16, 2010)

My car uses 10-20% of the power used by my home. Unless you're just driving too far it shouldn't be the majority of your power consumption.


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## sirwattsalot (Aug 27, 2012)

I average 60 miles each day for work which is part of the problem. Solar panels on the car does not seem to be practical. The typical solar home will use much less energy than the average home to stay off of the grid. Everything is relative to the energy available, not just the cost. Large commercial projects to set up solar and wind are being protested by people who want more oil and coal. They don't seem to understand that the world is past peak energy production because energy comes mainly from oil and coal.


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## PStechPaul (May 1, 2012)

Tesla now has at least six solar powered charging stations for their Model S, and they are free:
http://inhabitat.com/tesla-unveils-six-free-solar-powered-superchargers-in-california/
http://www.renewableenergyworld.com...0000-chargers-for-model-s-drivers-in-highways

You may also consider residential geothermal:
http://www.scientificamerican.com/article.cfm?id=earth-talks-geothermal
http://www.residentialgeothermal.ca/
http://www.waterfurnace.com/residential.aspx
http://en.wikipedia.org/wiki/Geothermal_electricity


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## nat_ster (Oct 19, 2012)

To The OP

You and I are almost in the same boat. At this time I live off the reliability of the grid, but can supply as much as I use. Because my source is wind, I'm only generating 60% of the time. 

Soon I want to move where there is no grid to connect to. I don't yet have a EV, but when I build one, it will be one of the biggest consumers of electricity in my home. Same as you, all my light is L.E.D, heat is wood/electric, cooking is electric ect.

To anyone not reading this right.

The OP Is Not Installing Solar Panels On Their EV.

So learn to read, and quit your judgmental BS. Unless your EV is powered by a clean electricity source, you are a hypocrite.

Sorry, but it really gets to me every time some one scoffs at alternative electricity sources for charging a EV. 

Nat


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## Ziggythewiz (May 16, 2010)

nat_ster said:


> The OP Is Not Installing Solar Panels On Their EV.
> 
> So learn to read, and quit your judgmental BS. Unless your EV is powered by a clean electricity source, you are a hypocrite.


Not sure who you're arguing with/attacking.


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## nat_ster (Oct 19, 2012)

Ziggythewiz said:


> Not sure who you're arguing with/attacking.


No one, just making a opinionated statement.

Nat


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## RE Farmer (Aug 8, 2009)

Yes, I'm planing to use PV/Wind to charge my car. I've already reduced my consumption ~2/3 by changing to CFL and LED lighting, added insulation and solar thermal radiant heating.

My question at this point is charging directly from these renewable sources w/o going through an inverter and wasting energy converting to AC then back to DC for the charge. If I have PV panels that have a nominal 60V output, do I just hook up two panels in series to charge a 120V pack?


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## ricklearned (Mar 3, 2012)

Yes I have solar panels on my home and they cover all my electrical needs.


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## La Dignidad (Nov 9, 2012)

I've been living off the grid for 4 years now with only a relatively small solar power system of 1.08 Kw (6 X 180 watts). In SE Colorado, where I live, I can usually get about 6-7 KwHr/day. I have no backup, no wind, no generator. I have a TV, stereo, lights, large refrigerator, guitar amp, microwave, toaster, power tools, etc. I've never ran out of electricity. I've always had lots of extra power, especially during the day when the sun is shining. I am now buying a different house where I plan on installing 10, 200 watt panels which will give me about 12-14 Kw/Hrs/day, more than enough for my house and an EV car.

During the day the panels are producing much more power than I am using and, after charging the house batteries, which is finished by mid-morning, the electricity being produced is just being wasted. This could easily be used to charge the batteries in an EV car. The trick to living on solar power is to use the energy when it is available, not just when it is convenient for you.

I am retired and am planning on building an EV conversion pretty soon. I live in a small town and I figure that I could go without driving every third day or so while the sun charges my car. I can plan my driving so that I take care of social, shopping, entertainment, and other needs in an efficient manner. I won't usually have to drive more than 5-10 miles in any day and often less than that. So I could easily drive most of the time using no carbon fuel at all in my house or my car. The only time I would have to buy diesel is if I drive long distance to visit family or friends in another town or state and then I would just start up my VW Passat TDI which gets 45 miles to the gallon.

So - the question is not whether or not you can charge an EV car with solar. The question is whether or not you can adjust to using solar.


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## nat_ster (Oct 19, 2012)

Getting back to the OP's original goal of charging their EV batteries directly from the solar panels.....

What the OP and I both need is a charge controller with MPPT, set up for charging li-ion batteries. If we were wanting to use lead acid batteries, it would be simple, as there are already many charge controllers on the market to do this.

We are just trying to avoid the losses, cost, and reliability of having more devices in the system than necessary. 

I don't know about the OP, but I also intend to use Li-ion batteries to power my home when i move off grid.

Off to read for a few more hours......

Nat


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## Sunking (Aug 10, 2009)

nat_ster said:


> I don't know about the OP, but I also intend to use Li-ion batteries to power my home when i move off grid.


Well Nat not so sure that is a good idea or not. I have been design/building off-grid solar battery systems for just over 10 years now professionally and would not recommend that for two reasons.

1. Other than Hobby RC models there are no commercial MPPT charge controllers for lithium chemistry so you are looking at a very expensive custom design. 

2. Really not cost effective compared to other battery chemistry and cycle life. Based on 20% DOD/day you can buy Rolls 5000 Series FLA batteries. At 20% DOD will give you roughly 4000 to 5000 charge/discharge cycles or realistically about 7 to 10 years battery life. Minimum capacity with Lithium batteries is 3-day reserve capacity to get you through a couple of cloudy days. A 3 day lithium cost more than a 5 day FLA and only last 2 to 4 years.


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## nat_ster (Oct 19, 2012)

Great info. Thanks. Things are starting to make sense now on why there is no controller on the market for Li-ion chemistry.

With that info, I now realize that the only place I need Li-ion batteries is in mobile application's where size, weight, and quick discharge/charge are needed. 

EV, power tools, ect.

Nat


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## Sunking (Aug 10, 2009)

nat_ster said:


> Great info. Thanks. Things are starting to make sense now on why there is no controller on the market for Li-ion chemistry.


Pretty simple really, no demand for them yet. That is not to say there are some out there that do have lithium batteries because there is. Those folks either took a commercial CC and modified it, custom designed one, or out of ignorance used a standard controller for LA batteries without realizing the consequences and economics of their decision. 

Some day they will be available but it will not happen until lithium batteries are price competitive to LA and last as long. That has not happened yet.


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## sirwattsalot (Aug 27, 2012)

Fantastic! I think I can do this as well but I live in Michigan which is not the best state for solar energy. I must conserve energy to make it work. There will not be a 72 inch TV running in the living room. The car runs on 57 K watts peak which is not as much as some.


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## EVEngineeer (Apr 11, 2012)

In the original post, they mentioned using LED bulbs. I know LED bulbs use much less energy, but am I the only one who is concerned that my light bulbs do not contain, lead and arsenic?


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## Ziggythewiz (May 16, 2010)

Would you rather that lead and arsenic be in the ground or in your lightbulb?


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## sirwattsalot (Aug 27, 2012)

At home the lead batteries are best and most cost effective. In a car, the lighter the better.


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## sirwattsalot (Aug 27, 2012)

As far as LED bulbs go, the world is going lead free with most of it's electronics starting with Japan. At work we build almost everything with lead free materials. However, If you own anything electronic that was made before 1990, it is most likely full of lead tin solder. Unless your home if fairly new, the plumbing was put together with 50/50 lead tin and yet most of us survived it. LED's are not like nuclear waste or smog.


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## sirwattsalot (Aug 27, 2012)

There is no aurgument that Lithium batteries are better in a car, but the lithium batteries do not charge themselves. Electric cars use less energy than a gasoline burning monster and this is good, but the power grid is not up to what it needs to be before many of us drive electric. California has banned sales of some of the big screen TV sets to aviod the strain on the grid. The lights will go out if many people plug a car into the grid.


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## Siwastaja (Aug 1, 2012)

sirwattsalot said:


> There is no aurgument that Lithium batteries are better in a car, but the lithium batteries do not charge themselves. Electric cars use less energy than a gasoline burning monster and this is good, but the power grid is not up to what it needs to be before many of us drive electric. California has banned sales of some of the big screen TV sets to aviod the strain on the grid. The lights will go out if many people plug a car into the grid.


This is one of the most typical arguments made by anti-EV people, and it is not well supported. It has been shown countless of times that in _most_ locations, even changing _all _cars to electric in just one night would not pose a problem to the grid. Practically, in those locations where the grid is undersized and just on the brink of stop working at any time, this shouldn't be a problem either, because it is just impossible to produce such large number of EVs in short enough time. Upgrading the grid step by step over the years and decades comes naturally as some maintenance is needed anyway.

This is simply because the amount of electricity used in industry and households is just so vast. Electric traffic will be just a small percentage. Furthermore, the charging happens mostly at nighttime when the grid is less loaded. At most, the charging effect will _slightly_ offset the imbalance between day and night.


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## PStechPaul (May 1, 2012)

Actually, I think there may be a problem if people start getting EVs and using high power chargers. The usual "pole pig" is rated 25 kVA, and often serves five residences. So each home can use 5 kVA on average, which is just 220V at 23A. Most of these homes have at least 100A service, so if each one used the full capacity of the line, it would be a 4x overload. Normally, the duty cycle of high power appliances is very small, especially stoves and dryers, and even heating systems run about 25% duty cycle. But they can easily be 50 kVA, and the transformer is generally sized appropriately for such service (200A). Here is some discussion of the situation, mostly regarding large machine tools (also low duty cycle),without mentioning EV chargers.
http://www.practicalmachinist.com/v...erco-transformers-learned-somthin-new-103224/

Now consider the reasonable case of having five families get EVs with 10kWH battery packs and 3kW fast chargers. Their normal load could easily be 3000W each if they have electric heaters, which may run at 50% duty cycle on cold nights, so a "normal" average load of 7.5 kW. Add 5 fast chargers at 15 kW, and you are at 22.5 kW. It is still within its rating, but it's getting close. My own electric usage varies from about 500 to 1500 kWh/month or an average of 700-2000 watts. So I could easily add a 3 kW charger which might run 3-4 hours a night, which is an average of no more than 500 watts on a daily basis. 

So I can get 12 kWh for my car and be able to drive 30-40 miles a day and add maybe $50/month on my utility bill. Not bad. Not bad at all. But it will still take a long time to pay for a $10,000 electric conversion!


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## Ziggythewiz (May 16, 2010)

sirwattsalot said:


> California has banned sales of some of the big screen TV sets to aviod the strain on the grid.


California has banned big screen TVs because they want you to buy them in Oregon or Nevada.

People hanging on to an old CRT because they're not allowed to upgrade are using far more power than what is saved.

If everyone drove electric, the average EV would add 30% to the average home's energy use...at night, when it doesn't matter. It is not an issue. .

It will never be an issue aside from more areas needing to switch to load-based pricing.


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## nat_ster (Oct 19, 2012)

sirwattsalot said:


> California has banned sales of some of the big screen TV sets to avoid the strain on the grid.


This is just one more example of rules that are passed with no reality involved. 

If we were talking about the old tube, or the big screen projection TV's, this might help. However, the new plasma, and now LED big screens use less than a old incandescent light bulb did. 

What are they going to tell the Californian's next? Don't turn on the clothes dryer, or the electric cook range when you get home? 

Nat


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## RE Farmer (Aug 8, 2009)

nat_ster said:


> Getting back to the OP's original goal of charging their EV batteries directly from the solar panels.....
> 
> What the OP and I both need is a charge controller with MPPT, set up for charging li-ion batteries. If we were wanting to use lead acid batteries, it would be simple, as there are already many charge controllers on the market to do this.
> 
> ...


I'm with Nat and and the original question of looking to charge LiFePO4 cells directly from PV. 

SunKing, can you tell us how PbA charge controllers (CC) and/or MPPT charge home packs? What would I need to change to build a CC for LiFePO4?


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## onegreenev (May 18, 2012)

You could couple your mppt to the JLD 404 meter and use that to turn on the meter and turn it off. Just never let the pack go below 12 volts and you will always have power for your meter. You may need a good dc dc or just use a large 12 volt lithium battery and keep it charged up with another mppt charge controller. You don't really want to charge with straight power to the batteries. I think there will be plenty of old lithium cells that are still good and being used at low current levels they will most likely last for many years to come. Maybe even longer than your solar panels. That is what I am going to do. I will be testing the mppt charge controller I have with my panels and I will connect up my JDL 404 meter. I may actually use the JDL's brother the volt meter to turn on and off the contactors to the mppt. Reason is because it has a much finer voltage range to work with. The JDL 404 is good for checking amperage.


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## sirwattsalot (Aug 27, 2012)

This is a valid point. Charging the car during off peak hours works. Now getting people to do this is the hard part. When the car is out of juice how many people will wait until the Sun goes down?


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## EVEngineeer (Apr 11, 2012)

zsnemeth said:


> Than, DO NOT eat them!


If it goes into the ground and then contaminates the water, then it may get into your drinking water. 
But my real point to all this was a more realistic look at things. Like if the bulb breaks, very possible if you drop it, then the arsenic gets out and you breath it in.


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## onegreenev (May 18, 2012)

EVEngineeer said:


> If it goes into the ground and then contaminates the water, then it may get into your drinking water.
> But my real point to all this was a more realistic look at things. Like if the bulb breaks, very possible if you drop it, then the arsenic gets out and you breath it in.


I'd be more concerned about the plastics we use and hold our foods in. That includes all the cans and boxes where food directly contacts what you consume and drink. Bottled water is on the list. Might not be so healthy for you after all. Recycle #7 being on the bad list. I have my sugar in a #8 recycle plastic container. Time to ditch that for a nice glass container. Working on getting rid of much of the plastics we have around the house including clothing. 

The amounts of lead and arsenic in the lights is minute. Not saying its good. We do recycle all our lights and we have not busted a single one yet. 

Pete


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## EVEngineeer (Apr 11, 2012)

onegreenev said:


> I'd be more concerned about the plastics we use and hold our foods in. That includes all the cans and boxes where food directly contacts what you consume and drink. Bottled water is on the list. Might not be so healthy for you after all. Recycle #7 being on the bad list. I have my sugar in a #8 recycle plastic container. Time to ditch that for a nice glass container. Working on getting rid of much of the plastics we have around the house including clothing.
> 
> The amounts of lead and arsenic in the lights is minute. Not saying its good. We do recycle all our lights and we have not busted a single one yet.
> 
> Pete


Great answer  Thank you. I too am reducing the amount of plastic I use and I always try to recycle it. I use mostly #1 and #2. I sometimes use #5 like my Starbucks cups. I use #6 very little. I never use #7 or #8, trust me I check every time.


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## PStechPaul (May 1, 2012)

EVEngineeer said:


> If it goes into the ground and then contaminates the water, then it may get into your drinking water.
> But my real point to all this was a more realistic look at things. Like if the bulb breaks, very possible if you drop it, then the arsenic gets out and you breath it in.


I think most LED lamps are plastic and should not break like glass tungsten or CFLs (which contain some mercury, which is worse than lead and arsenic). The arsenic in LEDs is in the form of gallium arsenide, which is used to "dope" the silicon, so it is not in a form that is easily released to the environment, and the LED chip is sealed in plastic anyway. The only possible danger of inhalation or other toxicity may be if the LED burns up.

I am a strong environmentalist, but many of the laws, especially in CA, are not the right way to boost efficiency and lower per capita energy use. The proper way is to introduce fairly high taxes on the less efficient products, and also tax the energy itself, so that the newer ones become more cost-effective. Outright bans on things like incandescent lamps and drugs lead to hoarding and underground industries that fly under the radar and contribute more to crime and not so much to the economy and environmental health.


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## EVEngineeer (Apr 11, 2012)

Great informative answer. I did not know some of that. Can you please send me a link(s) to your facts, so I know that it is not rhetoric? Thank you.


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## PStechPaul (May 1, 2012)

There are various reports about the purported toxicity of LEDs, but here is one that seems more reasonable:
http://ledsmagazine.com/news/8/2/13

A more alarmist slant:
http://www.sciencedaily.com/releases/2011/02/110210124136.htm

My statements about using taxation rather than legislation and bans is an opinion, but one that is fairly well supported.
http://www.motherjones.com/environment/2012/06/soda-sugar-tax-richmond
http://www.slate.com/articles/busin...verages_is_a_better_more_effective_idea_.html
http://blogs.bostonmagazine.com/boston_daily/2012/11/15/brookline-banned-plastic-bags-tax-instead/


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## RE Farmer (Aug 8, 2009)

onegreenev said:


> You could couple your mppt to the JLD 404 meter and use that to turn on the meter and turn it off. ... That is what I am going to do. I will be testing the mppt charge controller I have with my panels and I will connect up my JDL 404 meter. I may actually use the JDL's brother the volt meter to turn on and off the contactors to the mppt. Reason is because it has a much finer voltage range to work with. The JDL 404 is good for checking amperage.


That's a good idea, Pete. I have a spare JLD404 I can use. I haven't bought my PV panels yet. What is the voltage of your panels and which MPPT are you using?


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## Sunking (Aug 10, 2009)

PStechPaul said:


> I am a strong environmentalist, but many of the laws, especially in CA, are not the right way to boost efficiency and lower per capita energy use. The proper way is to introduce fairly high taxes on the less efficient products, and also tax the energy itself, so that the newer ones become more cost-effective.


I cannot believe I actually just read this.


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## onegreenev (May 18, 2012)

RE Farmer said:


> That's a good idea, Pete. I have a spare JLD404 I can use. I haven't bought my PV panels yet. What is the voltage of your panels and which MPPT are you using?


I have a Xantrex C-40 Charge controller

http://www.ecodirect.com/Xantrex-C40-PWM-Charge-Controller-40-Amp-12-24-p/xantrex-trace-c40.htm

I purchased it before I got my Kyocera 200W panels. I have 4 70w panels and was going to do a demo using the Xantrex and use it to learn how to set up off grid power for the house in small scale first. 

My Kyocera panels produce 26.3 volts each. I have 30 of them. So I am not sure what charge controller I will use for those.


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## PStechPaul (May 1, 2012)

Sunking said:


> I cannot believe I actually just read this.


You read it right. I stand behind my assertions. There only need to be laws banning such things that directly harm the environment or infringe on the rights and freedoms that are supposedly guaranteed to all citizens. The government, and the people of, by, and for whom it serves, has no business limiting what a person does unless it adversely affects others. Inasmuch as inefficient light bulbs, cars, and TV sets use more energy than other more modern alternatives, it is perfectly reasonable to tax energy use, and in fact the reverse is "currently" true, since fossil fuel costs are heavily subsidized and we pay in money and blood to protect our preferred sources. 

Our government was formed with the assumption that people should accept personal responsibility for their actions, and it is not a valid function to protect people from themselves. We do have the duty to protect our resources from exploitation by greedy corporate interests, and also to regulate them so they do not cause harm to the environment. But the main issue is unsustainable escalating demand, which can be reduced by passing on the true cost in the form of taxation (and also by reversing the population explosion). 

Please enlighten me as to why you (apparently) oppose this idea, and instead want to make it illegal to manufacture, purchase, and use things that are not inherently dangerous to other people or the environment. I may choose to purchase a classic car or a high powered new sports car that gets 10 MPG, and as long as I pay for my extra fuel consumption, that should be my choice. If it emits a lot of pollution I would be expected to fix that or pay an appropriate tax which would limit my use, or pay taxes to subsidize fuel saving devices and sustainable energy research. 

It should also be my choice if I wish to grow, purchase, or consume substances that may possibly be harmful to myself, but I may be rightly expected to pay taxes to cover increased health care costs or sign a waiver to be excluded from such public benefits. The only laws that impose criminal punishment should be based on actual or reasonably expected harm to others, which would include distribution to minors or operating a motor vehicle under the influence. The war on drugs (and other victimless "crimes") is a sham and a dismal failure, and is a major reason for economic decline. 

Now, please provide your reasons for a different viewpoint.


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## onegreenev (May 18, 2012)

onegreenev said:


> I have a Xantrex C-40 Charge controller
> 
> http://www.ecodirect.com/Xantrex-C40-PWM-Charge-Controller-40-Amp-12-24-p/xantrex-trace-c40.htm
> 
> ...


Missouri Wind and Solar has a bunch of good DIY stuff. Well priced too. I am sure you could configure a setup to work with lithium cells. 

http://www.mwands.com


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## onegreenev (May 18, 2012)

> The only laws that impose criminal punishment should be based on actual or reasonably expected harm to others, which would include distribution to minors or operating a motor vehicle under the influence. The war on drugs (and other victimless "crimes") is a sham and a dismal failure, and is a major reason for economic decline.


It is reasonably expected that anyone using or distributing DRUGS will harm or put in harms way, others. Sorry but I don't favor myself accepting that as victimless. 

As for a major economic decline? WTF are you thinking. How do you come up with that? You on the page that drugs should be main stream business? Think that anyone under the influence is really thinking rationally?


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## nat_ster (Oct 19, 2012)

Hey fellow members, can we take the chit chat to a dedicated thread please.

A few of us here are just at our learning stages. That and others in the future that read this thread have the right to read relevant information on the original topic.

Please for the sake of learning.

Nat


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## PStechPaul (May 1, 2012)

So, I would assume that you are in favor of prohibition of alcohol and nicotine? Both are much more harmful and addictive than marijuana and even reasonable amounts of barbiturates and opiates. If I want to grow some pot plants and have a smoke or some Alice B. Toklas brownies, and share them with adult friends, should I be considered a felon? Would occasional use of opium be any more evidence of probablility of doing harm than people who have three-martini lunches and get boozed up at happy hours? 

The reason drugs like nicotine (and caffeine) are tolerated and legal is because they tend to make people more productive which is approved by the Puritan work ethic. Cocaine also has this effect but was made illegal because of overuse, and now their are many more addicts and abusers than when it was legal 100 years ago. The waste of money and lives on futile attempts at "drug enforcement" has only driven up the price and turned addicts into career criminals, and dealers into a multi-billion dollar business where the money flows out of the US.

At least there is some indication of reason in the recent rulings decriminalizing the possession, use, and sale of marijuana, for medical or even recreational use, and I think the federal laws will be changed as well during this administration. Occasional pot use does not automatically make someone dangerous to others, and even driving under its influence is very likely less likely to cause horrific accidents. Psychoactive drugs and depressants such as heroin are more likely to create a perpetual feeling of euphoria and obvious inability to do useful work, but it would be much cheaper for society to allow the use of such drugs than to drive addicts to often violent crime and imprisonment. It is really a medical and moral problem, and prohibition and criminalization of anything that is needed to support an addiction will never work except in a totalitarian fascist state, which will also infringe on all other freedoms we enjoy.

Ron Paul also understood this:
http://www.washingtonpost.com/blogs/the-fix/wp/2012/11/14/ron-pauls-farewell-speech-video/

*PS: Sorry for the off-topic comments. But the discussion of overzealous government regulations and laws with respect to environmental issues is relevant. Solar energy and other sustainable technologies will become much more competitive if fossil fuels are properly taxed to reflect the true costs.*


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## onegreenev (May 18, 2012)

PStechPaul said:


> So, I would assume that you are in favor of prohibition of alcohol and nicotine? Both are much more harmful and addictive than marijuana and even reasonable amounts of barbiturates and opiates. If I want to grow some pot plants and have a smoke or some Alice B. Toklas brownies, and share them with adult friends, should I be considered a felon? Would occasional use of opium be any more evidence of probablility of doing harm than people who have three-martini lunches and get boozed up at happy hours?
> 
> The reason drugs like nicotine (and caffeine) are tolerated and legal is because they tend to make people more productive which is approved by the Puritan work ethic. Cocaine also has this effect but was made illegal because of overuse, and now their are many more addicts and abusers than when it was legal 100 years ago. The waste of money and lives on futile attempts at "drug enforcement" has only driven up the price and turned addicts into career criminals, and dealers into a multi-billion dollar business where the money flows out of the US.
> 
> ...



I suppose it is out of personal experience you have this top advisory knowledge, right? If you or your adult buddies get in the car and I happen to be on the road and they do some stupid stunt on the road and put my life in danger then yes you are a criminal. I deal with that crap every day. Drunks, druggies and plain stupid people. All in a hurry to get no where fast. Put my life in danger because of your stupid actions I hope your not near me when I get out of my vehicle. That is if I can get out of my vehicle. 

You sure pot is less harmful? You truly jest. Oh it is natural right? So it reasons it must be safe to use. Right? Hope you have not used it the day you need a procedure in the hospital that requires pain killers or sedatives that put you out or nearly so. People who self medicate and self doctor themselves usually have no clue as to what they are doing. Self medicate and you risk much. 

We have idiots that do this over at the hospital all the time in front of the ER then go drive away. I see it daily. What friggin idiots. 

I quite drinking because it just did nothing for me and I quite smoking pot because after years it just put me to sleep and fogged my head. Cleared up about 6 months later. It will put you into a stupid stupor for much longer than you think. Thinking rationally, nope. 

So what changed for me? I woke up. I quit the crap and saw a clear different world much better than one where your in a chronic state of stupor. 

You are deceived.


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## onegreenev (May 18, 2012)

nat_ster said:


> Hey fellow members, can we take the chit chat to a dedicated thread please.
> 
> A few of us here are just at our learning stages. That and others in the future that read this thread have the right to read relevant information on the original topic.
> 
> ...


We could but this is the fun of the forums. All newbees must dig for pertinent information. It is there but you must dig. I did. Built 2 and working on number 3. 

Threads do go off topic pretty easy due to the passionate nature of men and testosterone. 

Deal


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## Duncan (Dec 8, 2008)

onegreenev said:


> We could but this is the fun of the forums.
> 
> Threads do go off topic pretty easy due to the passionate nature of men and testosterone.
> 
> Deal


And that is the reason while the fantasy of a polite armed society is just a fantasy!

Curse you testosterone!


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## EVEngineeer (Apr 11, 2012)

onegreenev said:


> We could but this is the fun of the forums. All newbees must dig for pertinent information. It is there but you must dig. I did. Built 2 and working on number 3.
> 
> Threads do go off topic pretty easy due to the passionate nature of men and testosterone.
> 
> Deal


hahahaha, it's also a pain to switch to a different thread just for this.


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## Ziggythewiz (May 16, 2010)

nat_ster said:


> A few of us here are just at our learning stages. That and others in the future that read this thread have the right to read relevant information on the original topic.


If there was a specific question presented by the thread that hasn't been addressed, please repeat it.



onegreenev said:


> I quit the crap and saw a clear different world much better than one where your in a chronic state of stupor.


Chronic state of stupor could be a viable coping mechanism for a while...say 4 years...


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## aeroscott (Jan 5, 2008)

The extra cost of lithium's is offset somewhat by the greater charge efficiency . If LA is 80% and Lith is 100% it would take 20% more power to cover this loss , plus 4%( of base #) to add for the loss incurred when the 20% was added , Every time I add power I lose 20% of what I added ( but this gets smaller in watts ) . In sum I need about 25% bigger system for La then lithium . Been thinking of how nice 25% more power would be for my system .


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## Ziggythewiz (May 16, 2010)

aeroscott said:


> In sum I need about 25% bigger system for La then lithium .


+20% for long life DOD of lead (50%) vs lithium (70%).

Lead's good for stationary applications now, but in 5 years tired lithium packs from EVs will need begin to need good homes.


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## aeroscott (Jan 5, 2008)

Ziggythewiz said:


> +20% for long life DOD of lead (50%) vs lithium (70%).
> 
> Lead's good for stationary applications now, but in 5 years tired lithium packs from EVs will need begin to need good homes.


 I'm talking about charge efficiency not battery capacity usage .


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## Ziggythewiz (May 16, 2010)

Yes, just another reason lead has to be oversized vs lithium.

Also, if there's no sun for a few days the lithium wouldn't care while lead really likes to be topped off daily.


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## aeroscott (Jan 5, 2008)

As La ages it gets less efficient in charge acceptance . My old La's are getting bad , mybe 50% charge acceptance .


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## aeroscott (Jan 5, 2008)

Ziggythewiz said:


> Yes, just another reason lead has to be oversized vs lithium.
> 
> Also, if there's no sun for a few days the lithium wouldn't care while lead really likes to be topped off daily.


 Yes , If discharged for long time ( any time does damage) the charge acceptance efficiency and capacity are damaged .


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## nat_ster (Oct 19, 2012)

Wow

Reading some of the debates on here that have nothing to do with the topic I find vary useful. 

Quite often there are trolls on every forum. Some try to push buttons to get people to react. Sometimes even non trolls will deliberately try to get someone to react, so they can mentally profile the other person.

What I have read and observed in this thread alone gives the whole EV community a bad rap. Peoples real, true colors coming out to shine. 

I won't name any names, or direct this to anyone. However, there are two people on here that are ready for the psychiatric ward. Then they could be force fed the drugs that they are so against.

Thank you to the members that contributed to the knowledge base without the mental instability's.

Nat


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## onegreenev (May 18, 2012)

Looks like a button was pushed.  Sent a PM and explained about gathering information from a forum. Not just this one but any that you want information from. Remember we are not all on the same page. We argue and banter but it is mostly go draw out information that would otherwise not be spoken or written. 

You are new here and we have been around quite some time. Don't take it personally. 

Pete


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## Sunking (Aug 10, 2009)

Ziggythewiz said:


> +20% for long life DOD of lead (50%) vs lithium (70%).
> 
> Lead's good for stationary applications now, but in 5 years tired lithium packs from EVs will need begin to need good homes.


Maybe I am getting off-track here, if so I apologize. 

Lithium chemistry is the only choice both economically and specific energy for an EV application. there is no doubt about it. 

However when it comes to off-grid solar battery applications for a home, or whatever stationary application you might have, a Flooded Lead Acid is the hands down winner in every category you can think of. I design Solar Battery systems for a living for telephone companies, home owners, and others who use telemetry in remote locations. The systems for the Telco at cell sites in remote locations demand a minimum of 6 Kwh/day for a single carrier and up to 20 Kwh/day for multicarrier with data. These guys have the big bucks and can aford anything but reliability and longevity are the most important factor. FLA not only is less expensive, but far more reliable in the long run.

The FLA batteries used in off-grid solar are the true deep cycle batteries. Not the hybrid types like those used in Golf Cart, Floor Machines, Fork Lifts, Marine, RV's, and EV's. Example of a hybrid all you are familiar with is the Trojan T-105. The true Deep Cycle FLA have fewer but but thicker and heavier plates. On the Flip Side of Trojan (I do not use them but to make the point) is the T-105-RE. Take note it has 5 more pounds of lead in them. The T-105-RE would be a poor choice between the two for an EV application because the T-105-RE has higher internal resistance than its older brother T-105 so it cannot deliver the same high current loads without voltage sag. But the T-105-RE has some 4000 cycles if only discharged to 20% DOD vs his brother @ less than 2000 cycles. 

One extremely important factor with a off-grid solar system is battery how many days of reserve capacity to cover you for cloudy days. Minimum recommendation when using FLA batteries is 5 days. This does two extremely important things:

1. It limits the daily use to 20% capacity which maximizes the battery cycle life.

2. In reality it gives you 2.5 days of cloud cover before you hit the magic 50% DOD which you never want to go below as this allows the lead sulfate crystals to harden on the plates, and once hardened off is extremely difficult to knock off and dissolve. Sulfated batteries accounts for 90% of premature LA battery failure, and 95% of all LA battery failures. Eventually with TLC your LA battery will fail from sulfated plates.

If I could use Lithium I would jump all over it, but I cannot, my clients would fire me and find someone else. The reasons I cannot are many.

1. To use lithium for a minimum of 3 day reserve for cloudy spells cost more than the 5 day FLA option.

2. No commercial Solar Charge controllers made for lithium yet. Would require very expensive custom build for 24 or 48 volt models. 

3. Cycle life. A quality FLA Rolls 5000 series discharged 20 %/day last 7 to 10 years or 4000 cycles. They even come with a 10 year warranty. No lithium I know of can do that for a competitive price.

4. Voltage discharge characteristic. LA is flatter and most equipment will shut off before a lithium is fully discharged.


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## PStechPaul (May 1, 2012)

That is excellent information about LA cells for stationary energy storage. What is the approximate cost per watt-hour for these? I have found that cheap LA batteries such as from Walmart and Tractor Supply are about $0.07/Wh and SLAs are about $0.16/Wh. LiFePO4 are about $0.42/Wh. The premium sealed LA batteries I've seen, such as the ones in SirWattsALot's Saturn, are closer to $0.50/Wh. I found some Trojan T-105-RE batteries for about $0.12/Wh:
http://www.altestore.com/store/Deep...25AH-20HR-Premium-Line-Flooded-Battery/p9403/


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## Sunking (Aug 10, 2009)

PStechPaul said:


> That is excellent information about LA cells for stationary energy storage. What is the approximate cost per watt-hour for these? I have found that cheap LA batteries such as from Walmart and Tractor Supply are about $0.07/Wh and SLAs are about $0.16/Wh. LiFePO4 are about $0.42/Wh. The premium sealed LA batteries I've seen, such as the ones in SirWattsALot's Saturn, are closer to $0.50/Wh. I found some Trojan T-105-RE batteries for about $0.12/Wh:
> http://www.altestore.com/store/Deep...25AH-20HR-Premium-Line-Flooded-Battery/p9403/


The T-105RE are in good supply and yes you can find them around $120/Kwh but keep in mind they are a 2/5 year warrant. To get something like a Rolls or Hup 10 year more like $200/Kwh with a 10 year warranty.


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## aeroscott (Jan 5, 2008)

just got a call from my buddy at the junk yard on Wednesday about 10 Marathon M12V155FT and 7 Acme T Range 12NDT190 . all are new ,6 months since manufacturer/ shipment . AGM ,telecom , about $.50/ pound , Marathon weight 117 lb. Acme's little heaver . this would be for solar system 2000 watts/ day . that's about $.03 / watt . 12.7 v for all except one @ 12.3v. I think I could a few years out of them . any thoughts ?


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## nat_ster (Oct 19, 2012)

I think I found what I was looking for.

http://www.diyelectriccar.com/forums/showthread.php/10kw-60a-diy-charger-open-source-59210p8.html

This is from post 80



valerun said:


> After talking to a couple of you offline, just  realized that my PFC stage can be easily used to boost the DC voltage to the same output value. Reading the datasheet for the ir1153 chip we are using, it is clear that the chip will force the input current track whatever input voltage. In the case of rectified AC input, this will result in half-sinusoidal current draw and hence the power factor correction. But in the case of DC, this will result just in a constant current draw but the booster will produce the same voltage.
> 
> So the charger design with PFC stage can be used for ANY type of input - universal AC or any DC input voltage within ~100-400V. Both limits are soft and can be changed by changing the values of the resistors on the PFC board.
> 
> ...


The best part is they can build it for us if we need here.

http://www.emotorwerks.com/cgi-bin/VMcharger_V9.pl

Nat


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## Elithion (Oct 6, 2009)

sirwattsalot said:


> Solar panels on the car does not seem to be practical.


\

It's *TOTALLY *impractical. That's why I went for it. ;-)

Solare panels fold into the bumper for driving. No charger, no AC power inlet.

73 miles per charge, 2~3 months / full charge (!)

Yet, it works for me, because I normally walk or bike.


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## Ziggythewiz (May 16, 2010)

I like how you don't need a parking space either.

If I could cover my roof/hood with 40% eff panels I'd never have to plug in. I suppose a luggage rack with fold outs could do it with today's 20% panels.


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## IamIan (Mar 29, 2009)

Sunking said:


> However when it comes to off-grid solar battery applications for a home, or whatever stationary application you might have, a Flooded Lead Acid is the hands down winner in every category you can think of.


I'm a bit curious.

How far apart are you expecting the two to be?

Allow me to explain that question a bit more:

Part 1: Size of comparable Battery Pack.
I mean you assume 20% DoD for the LA in order to get your ~4,000 Cycles over 7+ years... I've seen tests showing some LiFePO4 still retaining ~95% of their initial capacity after 1,000 cycles each at 100% DoD... this means that LiFePO4 pack at 100% DoD only needs to be 1/4 or 1/5 the Wh capacity size of your 20% DoD pack in order to have the same usable Discharge Wh ... so one could buy a smaller Wh rated battery pack that is more able to use a larger DoD window... and still get the same Wh of usable output... this reduces the size of the needed battery pack significantly... if you need to by a 100 kwh LA in order to get your 20kwh ( at 20% DoD ) usable output ... you only need to by about a 20-30kwh LiFePO4 for the same usable ~20kwh output... yes the kwh capacity of the battery pack can be different ... those are just an example of the concept.

Part 2: Cycle Efficiency
With a lower Cycle Efficiency the LA Battery Pack ... needs to have more Wh of energy put into it than a higher cycle efficiency type of battery pack does ... This means the LA battery pack needs to have a larger rated Solar Watts of charging system to feed it for a given amount of Wh of needed output ... the more cycle efficient battery pack thus also reduces it's cost due to needing to feed it less for a given Wh of output... if you need to feed 40kwh at ~50% cycle efficiency into the LA to be able to get 20kwh output ... you only need to feed in ~23kwh at ~87% efficiency for a LiFePO4 battery to get the same 20kwh output... yes both LA and LiFePO4 can both be higher than those % ... that's just an example of the concept.

Part 3: Self Discharge Rate
The LA as a higher self discharge rate ... which is just that much more Wh of energy that has to be pumped into it over time ... every year for those 7+ years ... the lower Self discharge rate battery needs a slightly smaller power power input sense less yearly energy is lost to self discharge... for every 1Wh of less self discharge that is 1 less Wh of needed yearly input for the same wh of output.

- - - - - 

I'm just curious how far apart you saw / see them to be? ... as I see some solid reasons to think that if the $/wh gap is not more than 10x ... LA doesn't look like a hands down winner and could be fairly close ... or getting fairly close... depending on the specifics of a given application.

The majority of off the shelf solar control electronics part being currently designed for LA chemical characteristics ... is 100% valid in itself ... but there are solutions to that ... if the gap is close enough to support such efforts.


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## sirwattsalot (Aug 27, 2012)

OK, I see how that could work. I have a slightly larger car to charge but a similar concept could work when parked at work. Very cool.


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## jeremyjs (Sep 22, 2010)

Sunking said:


> only last 2 to 4 years.


Why would that be? So long as the Lithium is sized properly and charged/discharged properly they should last many thousands of cycles or even 10's of thousands of cycles if treated similarly to the lead acid.


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## Sunking (Aug 10, 2009)

jeremyjs said:


> Why would that be? So long as the Lithium is sized properly and charged/discharged properly they should last many thousands of cycles or even 10's of thousands of cycles if treated


Please name one known Lithium battery that has that kind of cycle life and cost per watt hour. I know of none any where. Lithium batteries have not even been on the market long enough to get through those kind of cycles in real life application. 

Top of the line FLA like a Rolls 5000 Series you might get 5 to 7 years with TLC and maximum 20 to 30% DOD daily and full recharge each cycle. A Rolls 5000 series will cost you roughly $240/Kwh of capacity. At 7 year cycle life to 20% DOD means in 7 years your battery cost alone per Kwh = $240/510 Kwh = $$0.47 Kwh. In real life practice under less than ideal conditions around 5 years or $0.66/Kwh.

Where I live (TX) we pay around $0.082/Kwh for the first 2000 Kwh/month and drops to $0.08 Kwh for anything over 2000 Kwh/month. Rates are expected to drop in the next 3 years as they have for the last 5 years. Last thing I or really anyone else would want to do is go off-grid battery if they have commercial power. Who wants to pay 500 to 1000% more if they do not have too? 

FLA is less expensive than Lithium and last just as long if not longer. YOu get what you pay for.


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## jeremyjs (Sep 22, 2010)

Sunking said:


> Please name one known Lithium battery that has that kind of cycle life and cost per watt hour. I know of none any where. Lithium batteries have not even been on the market long enough to get through those kind of cycles in real life application.
> 
> Top of the line FLA like a Rolls 5000 Series you might get 5 to 7 years with TLC and maximum 20 to 30% DOD daily and full recharge each cycle. A Rolls 5000 series will cost you roughly $240/Kwh of capacity. At 7 year cycle life to 20% DOD means in 7 years your battery cost alone per Kwh = $240/510 Kwh = $$0.47 Kwh. In real life practice under less than ideal conditions around 5 years or $0.66/Kwh.
> 
> ...



maybe not the cost per watt hour. I never claimed that there was, but cycle life is easy. Here's an example. All LiFePO4 at different tempratures and DOD. here


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## onegreenev (May 18, 2012)

I have 730 cycles on my Leaf so far. Not full cycles but close. Freeway driven daily. Used as a solar back up these have the potential of lasting as long as or longer than the Solar Panels. Pretty good in my opinion. Hunting good used lithium cells for my back up.


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## Eric (Sep 9, 2012)

RE Farmer said:


> If I have PV panels that have a nominal 60V output, do I just hook up two panels in series to charge a 120V pack?


No because the voltage of the panels changes depending on temperature/amount of sunligt etc.


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## Caps18 (Jun 8, 2008)

Eric said:


> No because the voltage of the panels changes depending on temperature/amount of sunligt etc.


Shouldn't the solar charge controller handle that and reduce amps, but boost voltage to keep it in the correct range?

I ran the numbers and almost had to put 8 panels on my truck if the city had banned me from putting them on the roof.

1. It would have looked a little funny, but it would make a statement.
2. It is 400 lbs of panels, mounts, and inverter to carry around
3. I think I figured out I could have 4 along the top, and two on each side of the bed slide out when parked.

But, even in the ideal case, you can only make 1.8 kWh each hour, or enough for about 6 miles. It would take all day to recharge. But with Level 1 charging being 4 miles an hour and Level 2 being 9 miles and hour, I guess it isn't quite as far off as I had thought.


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## Sunking (Aug 10, 2009)

Caps18 said:


> Shouldn't the solar charge controller handle that and reduce amps, but boost voltage to keep it in the correct range?


No other way around. Depends if you use MPPT or PWM.

PWM is the simplest but pretty inefficient. With PWM Input Current = Output Current which makes them inefficient. Panel Vmp voltages have to be higher than the battery voltage. Rule of thumb when using PWM is for every 12 volts of battery you need 17 to 18 volts of Vmp Panel voltage. For a 60 volt battery around 70 volts with a PWM controller.

MPPT is a different animal as it is a power converter, but they only work in one direction, down (Buck Converter). MPPT is up to 98% conversion efficiency where as PWM is only 67% at best case. Output Current = Panel Wattage / Battery Voltage roughly minus conversion losses. What makes MPPT preferable over PWM other than efficiency it allows you to use much higher panel voltages and use much less expensive Grid Tied Panels. On a 12 volt battery you can use as much as 600 volts with a few MPPT Controllers. That means much much lower current between the panels and controller. For example you could use 5 - 200 watt Grid Panel all in series giving you roughly 150 Volts Vmp @ 6.67 amps Imp. On a 12 volt battery the output would be roughly 13 volts @ 80 amps assuming the battery and/or load demand current.


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## steven4601 (Nov 11, 2010)

@ Sunking,
Not that I care much about this thread, or its contents, but why does PWM have a certain efficiency.  ?

edit: I react because of the MSEE in your title...


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## Siwastaja (Aug 1, 2012)

He just doesn't understand what PWM means which is not surprising. Just ignore him like most do


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## onegreenev (May 18, 2012)

Siwastaja said:


> He just doesn't understand what PWM means which is not surprising. Just ignore him like most do


You know, sometimes the information found on the internet is not very clear for the question asked and I guarantee there are very many NON EE types on this forum and have no clue and don't even know how to ask the question. So rather than get pissy or what ever and ignore them, why not educate them or put them in the RIGHT direction for the answer. Remember they are not asking for an EE education but just a simple understanding. So if you can answer why the PWM is less efficient then the person will have a greater understanding. 

Pete 

I don't know either. So answering for one, will answer the question for many.


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## PStechPaul (May 1, 2012)

I was curious about the difference in these technologies, so I did a little research. I found this, which supports the contention that MPPT is more efficient than PWM, at least where sunlight is highly variable:
http://www.schams-solar.de/download/DESCRIPTION/comparison-mppt-pwm.pdf

Here is a simple explanation:
http://enersol.wordpress.com/2013/07/31/solar-panel-charge-controller/

It shows a very rough block diagram of a PWM circuit as using a transformer to provide the output voltage, while the MPPT is shown as a buck converter which uses an inductor. Since the transformer operates on voltage, the PWM can only adjust the pulse width of the primary from the solar panel, and thus when the waveform is in the OFF state, the voltage from the panel is not being utilized, and no current is being drawn which does not actually waste power in the usual sense as generating heat, but it simply underutilizing what is available.

The buck converter alternately stores energy in a series inductor and then transfers it to the load, and it can be adjusted so as to obtain maximum power from the solar panel (at the "sweet spot"), and the efficiency of the converter is limited only by the quality and size of the components, so it can achieve 97% efficiency or better.

It may be possible to get even better efficiency, or at least more flexibility, with a Cuk converter, which can operate in either buck or boost mode. Thus you can still get some useful output from a solar panel when the voltage drops below what is needed to charge the batteries:
http://en.wikipedia.org/wiki/Ćuk_converter
http://www.ijsrp.org/research-paper-1012/ijsrp-p1060.pdf


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## onegreenev (May 18, 2012)

My controller uses the boost method to boost the lower voltage of a DC source with an inductor and the computer in the controller to charge the higher voltage pack. Was designed to be used with solar or from a stationary DC source. Battery source or Solar source or DC generator source. I am working on using a small diesel engine to drive a DC generator to provide up to 30 volts and 400 amps. Boost that to 120 volts at a lower amperage. From a 48 volt battery source it works great. Hoping to implement this with the generator for a tow along charger when needed. Not as a charger to run while driving. Only while resting. Diesel will be set to run bio diesel or SVO.


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## IamIan (Mar 29, 2009)

onegreenev said:


> So if you can answer why the PWM is less efficient then the person will have a greater understanding.


Eloquence and conciseness are not among my strengths ... but ... here goes a ... extremely crude / basic Ian-ish version.

It isn't the circuit itself ... as much as the effects it has on what it is attached to.


More Detail Bellow:
- - - - - - - - - 
PWM = Pulse Width Modulation
(The Basics)

Switches the connection on and off very rapidly ... in order to achieve a net average level of Voltage and Current ... if for example you are zero amps for 1/2 the time and 60 amps for 1/2 the time ... your net average is ~30 Amps.

The number of times it is switched on / off per second is given by the operating frequency ... often in hz.

Because many switches have their least resistance in either the on or the off position ... they don't want the switch to stay for any length of time at any point in between on or off.

The Pulse refers to the period during which the switch is turned on.

By varying the width ( in relation to time ) of that pulse ... one is altering the ratio of on time vs off time ... so if the width of the pulse is changed so that ... it were off for 1/4 of the time and 60 amps for 3/4 of the time ... the net average would be ~45 Amps.

PWM circuits can themselves be built to operate at very high efficiencies.

- - - - - - - - - 

MPPT = Maximum Power Point Tracking
The Basics:

MPPT can use a variety of topologies ... even PWM ... the difference is that MPPT takes into account the known power curve characteristics of Silicon based PV panels.

Meaning ... As you move along a PV cell's power curve from Max Voltage @ Minimum Current ... to Max Current @ Minimum Voltage ... the maximum amount of power one gets is not at max voltage ... nor at max current ... Sense the energy rate per unit time is power ... it is the combination of the two ... the point at which a given panel is at it's maximum power point ... that that panel is operating at it's peak efficiency ( for those conditions ).

As the conditions of the panel change ... age , temperature , light frequency , etc ... the exact location of the maximum power point changes as well ... and it changes from panel to panel ... thus it is a moving target as the conditions change.

A MPPT device is usually designed to 'test' for the MPP ... it is not often given the data and sensors to calculate what it should be for a given panel under some given conditions ... instead it tweaks up and down ever so slightly ... if more means less total net power ... it does less ... if less means less total net power ... it does more ... back and forth back and forth all the time.

Sense MPPT devices are built for a niche that is specifically wanting that potential extra few % point of net system efficiency ... they as devices are often built to be more efficient themselves ... but that is not necessarily part of being MPPT platform itself ... just a byproduct of the market the MPPT devices are bought by.

- - - - - - - - - -

An analogy for an ICE is Torque and RPMs ... the ICE's peak efficiency is not at min or max RPM , nor is it at min or max Torque.

And be it PWM or MPPT ... might analogs to different kinds of transmissions ... that are changing the tire torque and RPMs to a different combination of torque and RPMs by the time the ICE sees it.

In that kind of analogy ... the PWM is a crude transmission that is shifted with no regard for the BSFC of that ICE it is attached to ... and the MPPT type of transmission is shifted in an effort to keep the ICE near it's peak efficiency and away from it's lowest efficiency states... 

So even if the 'transmissions' themselves are equally efficient ... the MPPT would still result in a higher net system efficiency.


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## onegreenev (May 18, 2012)

Thanks, I understood that. I had a basic understanding but that did help and I know it will help others. 

Thanks again. 

Pete


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## Eric (Sep 9, 2012)

Caps18 said:


> Shouldn't the solar charge controller handle that and reduce amps, but boost voltage to keep it in the correct range?


Yes it should but you didnt mention the use of a charge controller so i thought you just wanted to tie the panels to the batteries and go


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## MN Driver (Sep 29, 2009)

Sunking said:


> ...
> 2. No commercial Solar Charge controllers made for lithium yet. Would require very expensive custom build for 24 or 48 volt models.
> 
> 3. Cycle life. A quality FLA Rolls 5000 series discharged 20 %/day last 7 to 10 years or 4000 cycles. They even come with a 10 year warranty. No lithium I know of can do that for a competitive price.
> ...


I was looking at the SMA solar Twitter page as it was referenced on a solar PV blog and I decided to see what people are saying and I found this. ..so apparently SMA Sunny Island controllers can do it. Granted not too many details though in the whole 140 character limit but it appears its possible.
https://twitter.com/SMAsolar/status/364697340210184193

Regarding cycle life, I was at the MREA Energy Fair earlier this year and there was a guy talking about how he's been off-grid using solar for decades and he had plenty of complaints for the lifespan of his lead-acid packs ranging from 5-10 years each replacement. I'm pretty sure that after his numerous replacements that he would probably been better off if lithium cells at today's prices were available to him when he started.


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## IamIan (Mar 29, 2009)

MN Driver said:


> Regarding cycle life, I was at the MREA Energy Fair earlier this year and there was a guy talking about how he's been off-grid using solar for decades and he had plenty of complaints for the lifespan of his lead-acid packs ranging from 5-10 years each replacement. I'm pretty sure that after his numerous replacements that he would probably been better off if lithium cells at today's prices were available to him when he started.


Especially when those PbA are only lasting to around ~3,000 cycles with a ~20% DoD... 365day x 7yr = 2,555 cycles ... 365day x 10 yr = 3,650 cycles.

You can take the OEM A123 cycle tests with a grain of salt ... but they showed ~3,000 cycles at 100% DoD still having ~90% original capacity at a 1C Charge and 2C discharge.

Which means for roughly about the same number of cycles the PbA at just 20% DoD ... the PbA needs to buy 5x as much wh of batteries to get the same usable output as the A123 does at 100% DoD.

Haven't even yet added in the PbA additional $purchase $costs for lower cycle efficiency ... higher self discharge rate ... etc ... and the PbA already has to be 1/5 the $price just to break even.

That to me ... is a significant gap... especially after all those other negatives of PbA are added in as well.

And it explains why there are utility companies installing ... the grid scale A123 battery systems ... and I don't know of any PbA utility grid scale battery installations... despite many many PbA battery companies out there.


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## PStechPaul (May 1, 2012)

I may be a rare bird to consider lead acid instead of lithium, but there is some renewed interest in PbA and some newer technologies that make it more attractive, while lithium may be declining somewhat in light of the Dreamliner fires and other considerations:
http://www.designnews.com/author.as...ndustry_alt,bid_318,aid_262198&dfpLayout=blog

The author states that lithium battery systems are about $700/kWh while lead acid systems are about 1/7 that, or $100/kWh. That may be true if you consider the liquid cooling, special chargers, and BMS expense for production lithium packs. The costs I have seen for just the batteries are about $60/kWh for FLA, $150/kWh for AGM SLA, and $400/kWh for LiFePO4. LiIon might be about $300/kWh. 

Also consider the recycling aspect of lead-acid batteries. Lead is now up to almost $1/lb, so a 1.2 kWh battery that costs $80 and weighs 65 lb might fetch $30 or so as scrap value, which brings the cost down to about $40/kWh. Of course, if you run a lead-acid battery at 0.5-2C the effective capacity due to Peukert is about 50%, but that is still an equivalent cost of about $80/kWh. If the weight is not a major factor, as in stationary solar storage, the 5-10 year replacement may not be such a bad thing. Who knows if we will still be around ten years from now? And if lead-acid is affordable now, where lithium is not, then it may mean that one can start utilizing electric vehicle or home energy technology now, rather than wait until the money can be saved while wasting money in the interim. The choice may not be as clear-cut as it may seem. 

http://www.scrapmonster.com/news/us-used-lead-battery-price-at-median-44-centslb/1/6743


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## IamIan (Mar 29, 2009)

PStechPaul said:


> The author states that lithium battery systems are about $700/kWh while lead acid systems are about 1/7 that, or $100/kWh.
> 
> The choice may not be as clear-cut as it may seem.


This is the perspective I agree with ... not a one size fits all.

If a PbA system is cheap enough ... currently , based on battery characteristics ... I'd say if the PbA system is less than 1/10 the Li system $ , PbA wins the $ race ... if PbA is more than 1/5 the price of the Li $ , the Li wins the $ race ... and between 1/5 and 1/10 , will depend on the specific details exactly where the line is drawn and which wins the $ race.

Although not yet mentioned ... another niche for the mix would be the LSD NiMH ... Which kind of fall in the middle between PbA and Li in a allot of characteristics.


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## Duncan (Dec 8, 2008)

I don't think it is as close as all that

A given house/whatever will need a certain amount of storage

Say 100Kwhrs

For LeadAcid at 20% discharge I would need - 500Kwhrs battery
For Lithium at 80% discharge I would need - 125Kwhrs battery

So I need a battery four times as big to get half the life!

Then I need 25% more solar panels to make up for losses in charge/discharge

Then I need watering systems, acid storage..

Lithium Ion used in this configuration DOES NOT NEED fancy heating cooling systems, It will be used at a fractional C rating - so there will be no issues requiring cooling
As far as heating is concerned some cheap insulation and heat pads

(Fractional C rating because it is storing several days worth of power
5 days storage = 120hours therefore C = 1/120)

The temperature control is easy because it is a high mass low power (fractional C rating) 

PbA would have to more like 1/20th of the cost of Lithium to make it worth while


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## PStechPaul (May 1, 2012)

If a photovoltaic system is designed for 1/20 C or less, then the Peukert effect is negated, so the actual cost is 1/2 of what I estimated at 0.5-2C. And during the times of peak sunlight, the power from the solar cells will be either charging the batteries or providing power for air conditioning. At night, with LED lighting and judicious use of electric appliances, the drain should be rather low, unless you are charging an EV. Occasional discharge of a lead-acid system to 80% DOD does not cause a huge hit on lifetime. It is very much a judgment call based on many factors.


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## Duncan (Dec 8, 2008)

PStechPaul said:


> If a photovoltaic system is designed for 1/20 C or less, then the Peukert effect is negated, so the actual cost is 1/2 of what I estimated at 0.5-2C. And during the times of peak sunlight, the power from the solar cells will be either charging the batteries or providing power for air conditioning. At night, with LED lighting and judicious use of electric appliances, the drain should be rather low, unless you are charging an EV. Occasional discharge of a lead-acid system to 80% DOD does not cause a huge hit on lifetime. It is very much a judgment call based on many factors.


The problem is you must plan for year round,
In the winter you should plan for several days of low/no sun
This means that you need capacity for several days,
This is not "Occasional discharge" as it will be frequent in the winter
If you repeatably discharge a PbA to 80% it will not last very long.

Lithium is about $1.25/Ah or $0.4/watthour - $400/Kwhr
Lead would have to be $20/Kwhr before it would be worthwhile


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## PStechPaul (May 1, 2012)

According to the spec sheet for the UB12120 SLA batteries ($140/kWh) I have, lifetime will be about 1200 cycles for 30% DOD, 500 cycles for 50%, and 200 cycles at 100%. This is at about 80% of original capacity, but it quickly drops to 40% after 20-100 more cycles. Since the 80% discharge condition will occur mostly during winter and about once a week, there will be only about 25 such deep discharge events each year, assuming a 6 month winter. So it seems that it would not significantly affect the 5-10 year expected lifetime. They should last about 3 years if they are discharged 30% every day. Typical nighttime energy use should be only about 500 watts (1/100C) for 10 hours or 5 kWh, so a 50 kWh pack should only discharge 10%. This would correspond to four days of continuous discharge for 100% DOD.

If lithium batteries exhibit a similar life curve, then the 10% loss of capacity after 3000 cycles may correspond to a similar point for lead-acid at 1000 cycles. So it might not be a linear degradation but the edge of a steep curve which might mean dead batteries at 3600 cycles.


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## Duncan (Dec 8, 2008)

Hi Paul

Assume that you need the same size pack as you are discharging to 80% only 20 times during the winter

This means that the Lithium pack is only discharging 10% every day,

The life information I have seen is 3000 - 5000 cycles at 80%
at 10% I would expect a LOT more - say 12,000? cycles or
10 times as much as Lead!

So for $140/Kwhr I can buy lead or for $400/Kwhr (less than 3 times as much)
I can buy lithium and get 10 times the life 
And I would need less Solar Panels because I lose the inefficient Charge/Discharge of lead

Not to mention;
The watering, 
The overcharging to stir up the electrolyte,
The corrosive atmosphere,


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## PStechPaul (May 1, 2012)

My $140/kWh was for small SLAs. FLAs are about $40/kWh if you factor in the recycling value. The other factor which is as yet unknown, for lithium, is long-term life, which is well known for lead. I have a 17 Ah SLA with a date code of 1999 and it still holds a charge, even though it has been abused by sitting outside for over a year without being charged. The lithium cells in common use today have not been around long enough to know what their actual lifetime might be, except by "accelerated life tests", which are not conclusive.

I agree that lithium is "the best" and wins hands down for electric cars, but for tractors and stationary photovoltaic systems there is still a strong case for lead, mostly on an economic basis. A 50 kWh lead battery bank costs about $2000 over a 5 year period, including recycling value, and since lead batteries can be obtained locally, there is little shipping cost involved. 

My SLA battery cost includes shipping, and I did not add recycling payback, and the price may be lower for larger batteries and higher quantities, so final cost may be $100/kWh. So a 50 kWh SLA pack might be $5000, which is still a small investment over 5 years for a 5 kW solar system that probably costs $10,000-$20,000 or more. 

A 50 kWh lithium system at $400/kWh would cost $20,000, and that assumes you can get the cells for that price including shipping. You also need to consider the extra cost of four times as many connections for 3V lithium compared to 12V lead, and also three times as many BMS modules if you choose to monitor and protect the cells automatically.

I don't have figures for the charge/discharge efficiency of lead, except for the Peukert factor which is negligible at 1/20 C or less as is the case for a solar installation. The charge would be about 1/10 C for 5 kW solar and I think the efficiency of lead is fairly good at that current. Shelf life of my SLAs is about 12 months at 20C (which is typical average for basement or a storage pit), which equates to a loss of 144 Wh/year where the actual annual usage at 1/100 C is 12.6 kWh, which appears to be about 1.14%.


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## IamIan (Mar 29, 2009)

PStechPaul said:


> but for tractors and stationary photovoltaic systems there is still a strong case for lead, mostly on an economic basis.


Only when the PbA system is significantly cheaper than the Li ... like ~1/10 the cost... not in the ~1/5 cost range that many are today.



PStechPaul said:


> So a 50 kWh SLA pack might be $5000,





PStechPaul said:


> A 50 kWh lithium system at $400/kWh would cost $20,000,


You seem to be forgetting to factor the DoD gap between the chemistries.

50kwh of SLA does not give the same usable wh as 50 kwh of Li does... they are not equal.

For around ~3,000 cycles SLA needs around ~20% DoD that 50kwh of SLA only gives you ~10kwh usable ... for around ~3,000 cycles the Li can do around ~100% DoD ... only have to buy ~10kwh for ~10kwh of usable.

Even at $400/kwh Li buys ~10kwh for ( ~$4,000 ) ... vs $100/kwh for SLA spends ~$5,000 to get the same usable ~10kwh for the same roughly ~3,000 cycles.



PStechPaul said:


> I don't have figures for the charge/discharge efficiency of lead,


Modern LiFePO4 is around ~95% cycle energy efficient.
From What I've read SLA is around ~80% cycle Energy efficient.

ie to get the same ~10kwh of usable energy out ... the SLA has to put ~15% more kwh of energy in.

- - - - - 

Then also factor in that the SLA has a higher self discharge rate ... ie another sink where the SLA has to have more kwh put into it , in order to get the same number of kwh out of it ... have to keep it charged ... so fight that higher self discharge rate all year long all the time.

- - - - - 

To me ... a 1/5 cost gap just isn't big enough to overcome the SLA batteries inferior performance characteristics... the system cost gap has to be closer to ~1/10 before it seems to me PbA has a good chance at a life cycle / long term economic argument.


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## PStechPaul (May 1, 2012)

I have found some references to lead-acid efficiency as about 75-85% so you are on target - at least for batteries used in deep cyclic applications such as EVs. Here are some articles:
http://evbatterymonitoring.com/WebHelp/Section_3.htm
http://www.solar-facts.com/batteries/battery-charging.php

Lead batteries in EVs mostly suffer from the Peukert effect, which reduces available energy to about 50% at 1C, and lead-acid battery packs in EVs tend to be smaller because of the prohibitive weight of a pack that would be used at an average of 1/20 C or less, as is the case for solar installations. Likewise for charging, a 20 kWh pack used for a daily commute of 40 miles R/T would need to be recharged with about 15 kWh overnight (8 hours), which would be about 1.9 kW or 1/10 C. But a lead-acid charger typically uses 0.2 C for the first 5 hours and then tapers down to 0.02 C. So the losses due to internal resistance and heating would be 4 times what they would be at 0.1 C. 

Solar installations usually operate in the *20%* (not 80% as I had mistakenly stated) DOD region most of the time, so the overall efficiency should take that into account. I will make sure to do some extensive testing when I get my 48V 4 SLA charger and BMS done. I've had some strange problems with the PIC I chose for the BMS, and I have finally been able to get it to work, so now progress can continue.


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## IamIan (Mar 29, 2009)

PStechPaul said:


> So the losses due to internal resistance and heating would be 4 times what they would be at 0.1 C.


Can you give more detail / explanation? ... I think I am missing some part of what you are describing.

The net amount of Energy losses due to internal resistance are not effected by rate ... 10W for 10 hours = 100Wh = 100W for 1 Hour ... the power loss changes ... Peukert usable capacity changes ... but not the net energy loss.



PStechPaul said:


> Solar installations usually operate in the 80% DOD region most of the time, so the overall efficiency should take that into account.


Should be taken into account , Agreed ... but that doesn't help the SLA Economic argument.

If you are operating in the ~80% DoD range ... instead of previously suggested ~20% DoD range ... that SERIOUSLY effects and reduces the PbA/SLA cycle life ... you won't get any where near ~3,000 Cycles at ~80% DoD ... This results in the SLA needing to be replaced more frequently than a LiFePO4 would getting the same %DoD cycles.

Using the "500 cycles for 50%, and 200 cycles at 100%" rate you listed previously to get to ~80% initial capacity ... and averaging in the middle to about ~350 cycles @ ~75% DoD .... that's only about ~1 year for the ~80% DoD you are expecting it to operate in most of the time , before you are down to ~80% of original capacity.

While ~80% DoD from a LiFePO4 system would give you more than ~3,000 cycles to the same ~80% Initial Capacity ... ie about ~8 years ... although the BMS can be reused ... the additional SLA battery packs bought (as they crap out every 1-2 years under 80% DoD operation ) would again create a significant performance gap ... one that needs a larger gap than a 1/5 SLA system $ in order for it to have a strong economic argument.



PStechPaul said:


> I will make sure to do some extensive testing when I get my 48V 4 SLA charger and BMS done. I've had some strange problems with the PIC I chose for the BMS, and I have finally been able to get it to work, so now progress can continue.


Best of luck ... if you need batteries ... SLA are a fine low initial cost way to get your foot in the door.

It is in the long term ... system operating life time ... that the performance characteristics of SLA create a significant cost gap being needed for them to break even economically ... ie SLA system has to be less than 1/5 the $ cost of the LiFEPO4 system to have a chance of the economic argument ... around ~1/10 the $Cost or less and SLA system is on more solid ground economically.


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## PStechPaul (May 1, 2012)

Oops, I really meant 20% DOD, or 80% of charge. 

As for the resistive losses, if a 100 Ah battery has 0.1 ohm internal resistance, charging at 10 amps causes 10 watts of power over 10 hours or 100 Wh energy loss. At 1 amp it causes 0.1 watts of power over 100 hours, or 10 Wh energy loss. For a 12V battery this is 1200 Wh so efficiency at 1/10 C is 92% and at 1/100 C it is 99%.

The SLA battery for my tractor seems to be a reasonable choice, since the weight is a benefit, and the cost will be about $400 for a 2.88 kWh pack that will provide 2 HP (1500W) for at least an hour, which should be all I need. And I will only use it maybe once or twice a week, so the batteries should last 5-10 years.

An equivalent lithium pack would cost $1152 if I could find 80 12 Ah cells for $14 each, including shipping. I could even use 8 Ah cells. But the smaller cells seem to be closer to $1/Wh so I would probably spend over $3000 for the pack, especially after making 80 connections and 80 BMS modules. The SLAs have simple quick-connect slip-on connections and I only need 20 of them and 20 BMS units.

Solar installations may do better with FLAs which may have lifespans similar to SLAs, and are about $0.06/Wh, and maybe less with recycling. So there might be a 10:1 cost factor for lithium vs lead.

I think it's important to look at all the factors involved before committing to a particular battery type, or putting off getting batteries because of the expense. The superiority of lithium for cars is pretty much unquestionable, but for occasional use in tractors, or long term low discharge use as in solar installations, I think lead is worth considering.


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## IamIan (Mar 29, 2009)

PStechPaul said:


> As for the resistive losses, if a 100 Ah battery has 0.1 ohm internal resistance, charging at 10 amps causes 10 watts of power over 10 hours or 100 Wh energy loss. At 1 amp it causes 0.1 watts of power over 100 hours, or 10 Wh energy loss. For a 12V battery this is 1200 Wh so efficiency at 1/10 C is 92% and at 1/100 C it is 99%.


It seems to me you are trying to directly apply things like Ohms Law to determine the electro-chemical cycle efficiency of chemical reactions ... and I have serious doubts about the validity of that approach.

Putting those doubts of mine about the method aside for the moment ... do you have some kind of tests by your or anybody ... that shows complete cycle , ie 100% DoD cycle at C/100 getting this claimed 99% energy ( not Ah ) efficiency from a SLA?



PStechPaul said:


> The SLA battery for my tractor seems to be a reasonable choice, since the weight is a benefit, and the cost will be about $400 for a 2.88 kWh pack that will provide 2 HP (1500W) for at least an hour, which should be all I need. And I will only use it maybe once or twice a week, so the batteries should last 5-10 years.
> 
> An equivalent lithium pack would cost $1152 if I could find 80 12 Ah cells for $14 each, including shipping. I could even use 8 Ah cells. But the smaller cells seem to be closer to $1/Wh so I would probably spend over $3000 for the pack, especially after making 80 connections and 80 BMS modules. The SLAs have simple quick-connect slip-on connections and I only need 20 of them and 20 BMS units.


I have no issue at all with the possibility of SLA being a better fit for some other application... if you change the context you change the results ... 1 or 2 times a week ( 50 - 100 times a year ) is vastly different than ~365 times a year.... etc.

The other error above ... is that you are still assuming the Li needs to have more Wh than the SLA to achieve the same wh of usage discharge ... this is not true... completely backwards.

Your 2,880 wh SLA discharging 1,500wh from it , is a ~52% DoD ... for 50~100 cycles per year ... 5-10 years ... your only expecting to use it for 250-1,000 or so cycles before needing to replace the SLA.

A LiFePO4 Battery doesn't need this same baby treatment ... LiFePO4 have done 3,000 cycles at to 90% original capacity from 100% DoD ... ie 2 or 3 times longer from the LiFePO4 before needing replacement ... and it only needs a little bit over the 1,500 wh to give your tractor the same 1 hour run time... not 80 cells 12Ah each ( ~3,000Wh ) you don't more wh than the SLA ... you need less.

Even if we conservatively use 45 of those 12Ah cells ... we still have ~1,800 wh of usable LiFePO4 Battery ... more than enough for your ~1,500 wh needs ... 45 cells at that $14 each is more like ~$630 for a liFePO4 Battery pack that is expected to last 2-3x longer than the $400 Lead... and need less energy to charge it due to higher cycle efficiency , and lower self discharge rates.

The two batteries you listed have a cost gap of about ~2.5:1 ... that's too small for the Lead acid to make up for all of it's weaker performance characteristics.

I'm not trying to convince you SLA is bad ... but I am trying to show you it is not the automatic winner in the economic side... cheap up front does not necessarily mean cheap in the long run.



PStechPaul said:


> Solar installations may do better with FLAs which may have lifespans similar to SLAs, and are about $0.06/Wh, and maybe less with recycling. So there might be a 10:1 cost factor for lithium vs lead.


$60/kwh for FLAs compared to the ~$354/kwh ( $14 , 3.3v , 12Ah ) you listed for Li above is a 6:1 cost ratio ... not 10:1 ... unless you are expecting the rest of the battery system for the Li to be so much more expensive than the FLAs system to make up the difference.

That 10:1 ratio I think the lead will be on much strong ground for trying to make a economic argument... more power to it.



PStechPaul said:


> I think it's important to look at all the factors involved before committing to a particular battery type, or putting off getting batteries because of the expense. The superiority of lithium for cars is pretty much unquestionable, but for occasional use in tractors, or long term low discharge use as in solar installations, I think lead is worth considering.


100% agree it is worth considering ... use the right tool for the right job... whatever that tool is for whatever job that is.

For example a fork lift ... or any other application where a reduced battery weight means you have to buy counter balance weight ... lighter would be bad in itself ... fork lift might not be designed to use counterbalance weight , which would mean reducing the rated capacity of the fork lift ... which might just not be viable for the production needs of the forklift.

Or if there is fixed ___$ to do the project ... weather it is better or not ... if the budget doesn't have the $ for it... than the budget doesn't have the $ for it... you make due with the budget you have.

etc .... etc.

Whatever is best ... is best ... whatever that is ... but be fair and accurate in the comparison.


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## PStechPaul (May 1, 2012)

Well, I did say that I could use 8 Ah LiFePO4 cells rather than 12 Ah for equivalence to lead, but such smaller cells are harder to get at a good price, and are usually about $1/Wh. I cannot use 45 LiFePO4 cells because that gives me only about 150 VDC and I need at least 200V at full discharge to meet the requirements of a 230V VFD. 300-350V would be even better, and ideally I'd like twice that so I can use a 460V VFD and drive a 208/230 VAC motor at 2x frequency with full torque and get double the HP. For that I would need 200 LiFePO4 cells at about 3 Ah, which gets into the 18650 or even AA cell range. I have considered this but from experience I don't trust the ratings of the cheap cells I've seen (and purchased) on eBay, and for the true Ah capacity the effective cost goes up to well over $1/Wh, and the high quality cells are about $1.50 to $2/Wh, which would make my pack about $3000-$4000.

The $60/kWh for FLAs could be offset by recycling, possibly returning as much as $20/kWh which brings total cost down to $40/kWh. And it is hard to get lithium cells for less than $400/kWh if shipping costs are factored in. Also, lead batteries are often manufactured in the US, or Mexico, which helps our balance of trade and provides jobs for American workers. And the recycling also provides local jobs. I have nothing against the Chinese, if they engage in fair trade practices, but we have seen where they have not. I can rely on a sustainable supply of lead batteries well into the foreseeable future, and about 95% of lead batteries are recyclable.

As for the charging efficiency of the SLA battery, my 0.1 ohm internal resistance was just a reasonable number used for example, although it seems about right for a 12 Ah battery that might be expected to provide 10C (120A) short circuit current. I realize that ohmic efficiency is not the same as overall charging efficiency, which is based on the chemical process, but slow charging allows more time for the reaction to equalize over the entire surface of the plates, while faster charging causes localized areas of higher activity. This is why it takes 2-3 hours for a charged battery to equalize and attain the normal voltage levels which can indicate SOC. 

With very low charge and discharge rates it seems to me that charging would be maximally efficient, and at 1/20 C the energy obtainable from discharge is according to the rated Ah specification. I don't know what the relative efficiencies of lead-acid vs lithium might be at such low levels, but I would think the losses would cause heating, unless they cause some non-reversible endothermic reaction that sucks the energy and refuses to release it. FLAs at high charge rates cause electrolysis of the water and hydrogen and oxygen gas which has a lot of energy, and is normally expelled to the atmosphere without recombining and creating the heat.


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## IamIan (Mar 29, 2009)

PStechPaul said:


> I cannot use 45 LiFePO4 cells because that gives me only about 150 VDC and I need at least 200V at full discharge to meet the requirements of a 230V VFD. 300-350V would be even better, and ideally I'd like twice that so I can use a 460V VFD and drive a 208/230 VAC motor at 2x frequency with full torque and get double the HP. For that I would need 200 LiFePO4 cells at about 3 Ah, which gets into the 18650 or even AA cell range. I have considered this but from experience I don't trust the ratings of the cheap cells I've seen (and purchased) on eBay, and for the true Ah capacity the effective cost goes up to well over $1/Wh, and the high quality cells are about $1.50 to $2/Wh, which would make my pack about $3000-$4000.


I was not aware of your voltage requirement... that's not inherently about the batteries themselves... and more about a specific other component issue... the cost options of that kind of high voltage system you want.

That does add another piece to consider ... but begs the question ... where are you getting a equally high voltage ~460V ~2.88kwh new SLA pack for $400 ?? Lead is lower voltage per cell ... you need about ~65% more lead cells than you would LiFePO4 cells for the same pack voltage ... which means more connections , etc.



PStechPaul said:


> The $60/kWh for FLAs could be offset by recycling, possibly returning as much as $20/kWh which brings total cost down to $40/kWh. And it is hard to get lithium cells for less than $400/kWh if shipping costs are factored in.


And I will still continue to agree that when you get the cost Ratio closer to 10:1 like that ... that it is then that the Lead is on stronger ground to make a economic argument... but not like some of the other examples of ~2.5:1 ratios.



PStechPaul said:


> Also, lead batteries are often manufactured in the US, or Mexico, which helps our balance of trade and provides jobs for American workers. And the recycling also provides local jobs. I have nothing against the Chinese, if they engage in fair trade practices, but we have seen where they have not.


This is a separate product criteria ... a 100% valid one ... but itself has nothing to do with the economic arguement of a given application ... it is more about the broader social/political land scape... and it blindly applies to any domestic product ... a Chinese SLA or FLA would suffer just as much as a LiFEPO4 would.



PStechPaul said:


> I can rely on a sustainable supply of lead batteries well into the foreseeable future, and about 95% of lead batteries are recyclable.


I see no reason to think that either type of chemistry will be going away any time soon.

LiFePO4 are also largely recyclable as well ... I will give the Lead batteries currently have a more convenient / established system for that in place ... and that matters ... but it is not that the Li is not recyclable.



PStechPaul said:


> I realize that ohmic efficiency is not the same as overall charging efficiency, which is based on the chemical process, but slow charging allows more time for the reaction to equalize over the entire surface of the plates, while faster charging causes localized areas of higher activity.


I agree.

But I personally prefer to refer to it as a gradient ... or diffusion ... not 'activity' ... the term 'activity' gives me a very different mental image ... the chemical reactions are quantized ... a molecule reacts or it doesn't in quantified steps.



PStechPaul said:


> With very low charge and discharge rates it seems to me that charging would be maximally efficient, and at 1/20 C the energy obtainable from discharge is according to the rated Ah specification. I don't know what the relative efficiencies of lead-acid vs lithium might be at such low levels, but I would think the losses would cause heating, unless they cause some non-reversible endothermic reaction that sucks the energy and refuses to release it. FLAs at high charge rates cause electrolysis of the water and hydrogen and oxygen gas which has a lot of energy, and is normally expelled to the atmosphere without recombining and creating the heat.


I agree ish.

I see the low charge rate being potentially able to be more net efficient because it is less likely to cause a gradient or absolute position ... that would be large enough for any one molecule to do a different kind of undesirable chemical reaction ... not that the slow desirable reaction itself is any more chemically efficient ... the chemical reaction of each molecule is quantized... more power flow means more individual molecules are reacting , not that any one of those molecules is reacting any faster , or differently ( just because of a higher or lower power rate by itself ).


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