# EVComponents or PingBattery?



## Indubitably (Jan 8, 2010)

Update:

After poking around on the EV components website I noticed that thundersky 40ah LiFeYPO4 primatic cells are $44. I'm guessing I would need about 15 of them in series to get the 48v I want, which would set me back $660, and I'd need a bms, but even so it would double the capacity of my pack for about the same price. It almost seems too good to be true though, am I missing something, or does it just make way more sense to go with a pack made from these thunder sky batteries?


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## dimitri (May 16, 2008)

Pay attention to max continuous discharge rates. Cylindrical cells have much higher rate , that is why they cost more, but you may or may not need it. What's max current your controller can dish out? Do you know from similar conversions how much current they use during heavy acceleration?

Also, prismatic cells tend to have larger volume, make sure you can fit them on your bike.

With 40 AH TS cells, you would not want to exceed 120 Amps ( 3C rate ) even during heavy acceleration if you want them to last long.

Hope this helps


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## Indubitably (Jan 8, 2010)

Well I would be using a 1000w 48v motor, so I'm guessing that I would be using a little over 20amps constant if I was moving at full tilt. I'm really not sure how high the current draw would spike though.

It looks like they have a "10 to 17 volt" 20 ah battery for $120 as well for that matter, which might workout to be better solusion, cut down on costs and take up up less space. I'm guessing I would need 3 or 4 of these.


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## dimitri (May 16, 2008)

Indubitably said:


> Well I would be using a 1000w 48v motor, so I'm guessing that I would be using a little over 20amps constant if I was moving at full tilt. I'm really not sure how high the current draw would spike though.
> 
> It looks like they have a "10 to 17 volt" 20 ah battery for $120 as well for that matter, which might workout to be better solusion, cut down on costs and take up up less space. I'm guessing I would need 3 or 4 of these.


I would be very careful with those batteries, I don't think they are meant for traction use, they have strange discharge specs, seems to be 1C only and they state LP, not LFP, although they also state LiFePo4, which is confusing. Check with EV Components to make sure its good for your needs before you buy.

What motor controller will you be using? What max current specs does it have? Motor ratings tend to be continuous and can be several times more during short acceleration bursts.


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## jondoh (Sep 8, 2008)

Firstly, I'd like to point out that a "small" controller will put out 20 amps-- and probably a few more under hard acceleration. If you're looking for a little performance, you'll probably want a 30 amp controller and size your battery for approximately 50 amps under hard acceleration.

The thing with ping is that it's a good battery and you'll get good support from him, but unless his batteries have improved, i'd be a little leery of pulling 50 amps out of his pack. 

I like the idea of using 40ah TS or SE cells. The problem here is that they're pretty bulky and a bit costly.

Cylindrical cells are good too but you still get the occasional bad one and they're a little pricey as well.

I have given some thought of putting together a LiPo pack. I understand that there is a fire danger but for a small EV (like electric bike) it does very well for cost, performance, and weight. 

eight of these:
http://hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9176

some monitors and the right chargers would make for [email protected] ah
weigh about 15 lbs
have 20C (or 400 amps) performance
cost is about $600 probably for all the parts and pieces and shipping


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## Indubitably (Jan 8, 2010)

Ok, well it looks like TS has a model that is intended to be a replacement for lead acid starter batteries with much higher discharge impulse ratings. The LP12V20AH has a max charge rating of 20amps continuous with 50 amp spikes, and max discharge of 20amps with 200amp spikes. It does cost more though, I'd be looking at 480 for 4 of them, and it would only be a 20ah pack, but it sounds like these batteries might work better. I don't know though, it almost seems like with the cost of the 40ah batteries I should just live with a poor acceleration curve so I can get the better range per dolar.


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## Indubitably (Jan 8, 2010)

Ok, upon closer inspection and poking around to get more information on what the discharge specs actually mean, the 40ah thundersky cells seem like they would work just fine.

The max continuous discharge rating on these is 3C, and correct me if I'm wrong here but for a 40ah battery, wouldn't that be 120amps? That seems to be well within my needs if I'm only going to be pulling 50amps from time to time under heavy acceleration. Standard discharge is .5c, or 20amps, which seems right in line with a 48v 1000 watt motor. I don't know what discharge issues people have been having with these large prismatic cells, but perhaps the new LiFeYPO4 chemistry has solved them. The pack is going to be big, but at 2.7 watt-hours per dolar I can find a way to live with bulky batteries.

Have I missed anything here? This seems like the right way to go but I'm pretty new to this stuff, and I don't want to drop 7 hundred on batteries that will wind up toast the first time I use them.


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## Amberwolf (May 29, 2009)

I have no direct experience with either battery, but until i hit severe money issues, I was going to go with some of those TS LiFePO4 40Ah cells for my own ebike (etrike, actually) project. Ended up that I must use the SLA I already have, which is much heavier and not nearly as much power.

The testbed bike I have now (CrazyBike2) draws around 10-20A normally cruising, and up to 50A short bursts for acceleration, with very occasional forays into the 70+A range if I'm loaded with cargo, so it's probably similar to what you expect in power usage. Around 35Wh/mile, when loaded down, and about 30 without cargo. 

Ping batteries are what I wanted to go with a couple of years ago, but have never had the money for one. There are people on Endless Sphere ebike forums that have used Ping batteries for quite a long time successfully, and others that have had problems from various causes. Some of the causes have been mechanical construction issues in the pack itself, where tabs rip loose from cells. Some were BMS board failures, some were cell failures, some charger failures.

EDIT (ADDED): Forgot to mention that Ping has generally seemed to take care of the problems, but remember that you're dealing with shipping to/from China, so it will get expensive to ship and it will take a long time. I gather some repairs can take months because of shipping. 

The main thing I see about Pings is that they generally aren't recommended to run beyond a 1C rate. So if you need 50A, get a 50A Ping, to be sure you won't have problems with the BMS or the cells. 

Personally, I'd always like to size my pack so that I am drawing an average of 0.5C or less from it, if I had a choice. I don't have that choice, so I am drawing around 1C from my SLA pack, and that's going to shorten it's life a lot, I'm sure.
________
Web Shows


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## Indubitably (Jan 8, 2010)

Thanks for all the info guys, I just bit the bullet and ordered 16 of them from evcomponents for $704.

Dimitri: It probably seems like I ignored your comments because I didn't notice them until after I posted some of my replies, but your advice was actually quite helpfull in my decision to go with the 40ah batteries instead of those shifty looking 20ah models.

Amberwolf: Thanks for the detailed response your post actually answered a lot of questions I had about what kind of range and power draws I could expect which made the decision a lot easier.

Jondoh: I may have decided not to go with the cylindrical cells, but your post did pretty much force me to figure out exactly what various discharge ratings meant in order to make my final decision, so the input was definitely appreciated.

At any rate, I will let everyone know how it turns out... in a couple of months when the batteries get here. I guess that is the price you pay though, for 3 watt-hours per dolar I can be a little patient.

In the mean time I need to decide on a motor (I have a bike with a 20 inch wheel so, so I'm guessing not just any hub motor would be wound for the 30mph I want, and I'm still a little iffy on chain drive systems), and I need to put together a 16 channel BMS setup, so any further comments would certainly be appreciated.


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## dtbaker (Jan 5, 2008)

dimitri said:


> With 40 AH TS cells, you would not want to exceed 120 Amps ( 3C rate ) even during heavy acceleration if you want them to last long.


Talk a little more about the 3C limitation.... how long do you think TS cells can take 3C without damage? 5C ? and on what do you base your opinion?

I am thinking that with TS 100aH cells (in a car) I might pull 300a for 30 seconds while accelerating, but would rarely hold over 200a for any length of time since I am not doing long stretches of highway. If the battery output should be limited, I may just go with the less expensive controller like a Curtis 1221 rather than something that would suck the life out the batteries....


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## dimitri (May 16, 2008)

dtbaker said:


> Talk a little more about the 3C limitation.... how long do you think TS cells can take 3C without damage? 5C ? and on what do you base your opinion?
> 
> I am thinking that with TS 100aH cells (in a car) I might pull 300a for 30 seconds while accelerating, but would rarely hold over 200a for any length of time since I am not doing long stretches of highway. If the battery output should be limited, I may just go with the less expensive controller like a Curtis 1221 rather than something that would suck the life out the batteries....


Dan,

this is very subjective and I am afraid it may cause a lot of debates. TS datasheets claim 3C continuous load, so its expected for people to size the pack to pull 3C regularly, which is how I sized my pack. After a year of use several of my cells clearly show signs of degraded performance at 3C load ( deep voltage sag ), especially at low temps. Other cells seem to be doing fine. Even cells that sag deep at 3C are doing good at 1C and 2C. I don't know how long these cells will last, but I have my eye on replacing at least 2 cells this year.

Here is the subjective part. Do I judge TS cells entirely based on 10% of their cells being sub par quality? Maybe I just got few defective cells. I don't know if my experience is a rule or exception to the rule. Also, recent addition of Yittrium to TS cells may be an improvement, we just don't know yet.

Personally I think 100AH size is too small for a car with less than 50 cells ( i.e. DC conversion with less than 200V ). I would go for 160AH if I were you.

If I was to redo my pack today, I would go for 180AH-200AH and I would add few more cells for higher voltage, but my car is not very light at 3200lb and we tend to drive pretty aggressively, especially my lead foot better half


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## dtbaker (Jan 5, 2008)

dimitri said:


> Personally I think 100AH size is too small for a car with less than 50 cells ( i.e. DC conversion with less than 200V ). I would go for 160AH if I were you.


I am tempted, and probably have room, but keep coming back to what I NEED.... I am looking at 38 cells for 120v nominal in a Suzuki Swift (1900# ICE curb weight, and 2490# with 96v worth of 8v floodies). Use is mostly 35-45mph urban, with a few stretches of 50-55, and some 25mph as well. even with 96v lead the only time I pull 300+amps with the curtis 1221 is accel from a stop. so...... I am thinking the 100ah cells will probably be fine in my case. BUT now I am also thinking it would be counterproductive to upgrade controller to a 1231 or Zilla which I was considering.


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## dimitri (May 16, 2008)

dtbaker said:


> I am tempted, and probably have room, but keep coming back to what I NEED.... I am looking at 38 cells for 120v nominal in a Suzuki Swift (1900# ICE curb weight, and 2490# with 96v worth of 8v floodies). Use is mostly 35-45mph urban, with a few stretches of 50-55, and some 25mph as well. even with 96v lead the only time I pull 300+amps with the curtis 1221 is accel from a stop. so...... I am thinking the 100ah cells will probably be fine in my case. BUT now I am also thinking it would be counterproductive to upgrade controller to a 1231 or Zilla which I was considering.


If you are OK with performance you have now, perhaps you will be OK with 100AH cells, as long as you don't get any defective cells.

Zilla will definitely make it easier to suck the life out of the battery .


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## TheSGC (Nov 15, 2007)

dimitri said:


> If you are OK with performance you have now, perhaps you will be OK with 100AH cells, as long as you don't get any defective cells.
> 
> Zilla will definitely make it easier to suck the life out of the battery .


Amen. I have my Zilla set so far back it's funny. I can bring my 12 volt floodies down to 9.2 volts/batt if I dont limit my battery AMPs. I have my battery AMPs limited to 250, but I am betting it's still too much for my 125Ah batteries. I usually cruise around 75-85 battery AMPs.


I have been thinking about going to Lithium, but I don't have the budget for it. My next pack will probably be 8 volt floodies as I only need 20 miles of range, but batteries that will take a constant 140 AMPs drain and not cry too much.


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## Amberwolf (May 29, 2009)

Indubitably said:


> In the mean time I need to decide on a motor (I have a bike with a 20 inch wheel so, so I'm guessing not just any hub motor would be wound for the 30mph I want, and I'm still a little iffy on chain drive systems), and I need to put together a 16 channel BMS setup, so any further comments would certainly be appreciated.


There is a BMS by Goodrum/Fechter over at TPPacks you could use, it is modular up to 24 cells. If you want details about it, it's creation thread is over on Endless Sphere. 

For the motor, I don't know specifically which brand/model you want, but you could have one rewound for the speed you're after. Not sure of the cost for that kind of thing, but you could check with Karma on ES, he does hub motor rewinding. 

As for chain drive systems, it depends on what you are after as to whether you would want one. If you think you will need a lot of lower-speed power, such as for hills, frequent stop/start traffic, etc, I would recommend a system that uses your regular bike drivetrain (or some other multi-speed method) to gear the motor down for low speeds, and back up for higher speeds. Even just a two speed transmission, like Thud's dog-clutch system on ES, would be better than trying to run the motor at lower speeds due to the much higher current flow at those motor speeds.

Bike hub motors are known to cook due to heat buildup, as they are enclosed and can't get rid of the heat from high-power use, which happens primarily at low speed / startups or on long hills. The motor only has so much thermal mass to absorb heat, and only so much of a thermal path to get rid of that heat, usually only thru the axle itself for direct conduction, and radiation/convection for the latter two. 

Sometimes it is hall sensors that fry, sometimes it is the actual windings that smoke their insulation off and then short, or the phase power wires going into it that melt their insulation. 

The latter can be fixed with silicone-sheathed wire, and the hall problem can be fixed by using a sensorless controller (but there aren't any really high-powered versions for ebikes yet, unlike the sensored versions of which there are several and more in development all the time).

But fixing the cooked-winding problem would pretty much require finding a way to get the heat out of the hub, and most of the methods to do that require it be moving pretty quickly, meaning going faster on the bike--at faster speeds, the heat isn't that big a problem usually so it would not help when it is needed most. Ventilating the hub is a bad idea because even a tiny bit of road grit gets in there between the magnets and stator and it can cause a jam directly if it's big enough, or if smaller could break a magnet piece loose that then causes the jam. When the motor jams, the wheel stops, and you get to greet the pavement in a spectacular manner, especially if it was a front-wheel hub. 
________
Babes Cams


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## Indubitably (Jan 8, 2010)

Well I guess if something seems too good to be true it probably is. I just got my invoice back from evcomponents and it looks like they've tacked on yet another "shipping charge", to my order. 

It started with a 10% charge for shipping and duties that came to about $70, which I didn't realise would not include domestic shipping untill I contacted evcomponents for a quote. Fair enough though, duties are already 5% of the cargo value, and if you read the fine print on their site they do specifiy "ocean" shipping and duties charge. I am then quoted a ground shipping cost of about $70, which is a little on the high side, it just so happens that I have shipped heavier and larger packages to washington for $40, so I know they are skimming a little off the top. I try to write it off as justifiable though, since it might cost them a little more for top notch insurance and special packaging to make absolutely sure the package is in good condition when it gets here.

Then the invoice comes, and the $70 ground shipping charge has almost doubled to $130. To top it all off there is a 3% charge if I want to pay with anything other than cold hard cash. All in all the batteries that were advertised at $44 each have bit by bit crept up to $58.20. At this point I'm starting to get a whiff of something foul, I expect these bait and switch tactics from cellphone companies and shady ebay dealers but this is not the sort of thing you expect from a reputable electronics distributor. I was tempted to just pull my order right then and there, the whole thing about charging extra for using a credit card or paypal just sent up red flags all over the place, and these kind of tactics are always a bit suspect, but I have sent an email to the guy that originally quoted me the $70 in order to give evcomponents an oportunity to defend themselves.

You know, I'd have had no problem with this situation if the cells were advertised at something like $56 each plus shipping in the first place, but the way this has been handled just plain makes it hard to trust them now. Hopefully this will all get cleared up.. but still, my confidence in evcomponents is to say the least a little shaken, I can't imagine how unsettling this would have been if I had ordered $7000 worth of batteries from them for an electic car conversion instead of $700 for an electric bike.


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## dtbaker (Jan 5, 2008)

Indubitably said:


> Well I guess if something seems too good to be true it probably is. I just got my invoice back from evcomponents and it looks like they've tacked on yet another "shipping charge", to my order.


I didn't get the feeling they were hiding anything....they showed +10%duty +shipping and disclosed that on the invoice. I can get that since people are getting different sizes and amounts the shipping would be really hard to calc automatically.

Charging to cover the cc fees is not unheard of, and when you are talking another 3% on a $4000 battery order, I welcome the opportunity to send them a check! 

So.... I for one will continue to think they are good guys, unless the delivery is a month late.


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## etischer (Jun 16, 2008)

Indubitably said:


> I am then quoted a ground shipping cost of about $70, which is a little on the high side, I try to write it off as justifiable though, since it might cost them a little more for top notch insurance and special packaging to make absolutely sure the package is in good condition when it gets here.


That being said, i was impressed with how my cells were packaged. Mine arrived FedEx Freight, not FedEx ground, this might explain the higher cost than you're used to.


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## dtbaker (Jan 5, 2008)

boy, those crates look almost nice enough to drop directly into a car!


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## EVComponents (Apr 20, 2009)

dtbaker said:


> boy, those crates look almost nice enough to drop directly into a car!


Those crates are needed to ship these cells via ground freight. They are using forklifts to move these around. Boxes get stabbed all the time. They need to be designed to take some abuse during shipping without the cells being damaged.

There is also a layer of styrofoam around the cells to provide extra padding/protection during transport.


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## Indubitably (Jan 8, 2010)

I'm not surprised at all by the $70 duties charge, they state that clearly on their web site. It would have been nice if they had just included it in the price of the battery, but I didn't think that in and of itself was terribly shifty. Actually, if they are having the cells crated up the $130 makes sense. For shipments much larger than 70 lbs there is really no other practical way you can do it. My problem was apparently just that my shipment was so small that it fell through the cracks. I'm sure if they were regularily shipping 50 lb packages they would have a system set up to take advantage of the fact that it costs so much less just to box it up in cardboard and styrofoam yourself then send it through the mail. It was more a question of the fact that a significant portion of the cost was not readily apparent untill the invoice came. I basically ordered a $44 battery and got billed for a $58 battery. 

The extra credit card charge was just something I'd never seen from someone unless they were trying to avoid a paper trail, but even if it wasn't anything sinister it was still another unexpected fee on top of the pile, which seemed suspect enough to warrant scrutiny. Really, I would have just much preffered that they be upfront about all these charges. Ideally if they were being absolutely honest it would be calculated into the cost of the battery, and then they could state why it cost that much in the fine print, rather than advertising a lower price then surreptitiously adding on fees as you go.

Let me be perfectly clear, evcomponents has done nothing that could be considered legally dubious during my interaction with them, nor to the best of my knowledge have they deliberately lied to me at any point, I merely take issue with the way in which their charges are presented. Like I say, I'm used to this kind of thing coming from cellphone companies and the like, no one is going to argue that verison or att&t aren't a legitimate bussiness, but I certainly don't consider them any more trust worthy when I get a bill that is comprised as much of roaming, overage charges, and taxes as it is the service they advertised at significantly lower price.


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## EVComponents (Apr 20, 2009)

Indubitably said:


> The extra credit card charge was just something I'd never seen from someone unless they were trying to avoid a paper trail, but even if it wasn't anything sinister it was still another unexpected fee on top of the pile, which seemed suspect enough to warrant scrutiny. Really, I would have just much preffered that they be upfront about all these charges. Ideally if they were being absolutely honest it would be calculated into the cost of the battery, and then they could state why it cost that much in the fine print, rather than advertising a lower price then surreptitiously adding on fees as you go.
> 
> Like I say, I'm used to this kind of thing coming from cellphone companies and the like, no one is going to argue that they aren't a legitimate bussiness, but I certainly don't consider them trust worthy.


Here is the problem we have with battery pricing on our website.
We have two types of customers. 
1) USA
2) The rest of the world.

For USA customers we import to our warehouse near Seattle, then we break up the container and ship to individuals via ground freight. So we paying the import duties, ocean shipping and port fees because we take possession of the cells.

For every other country in the world, we ship direct from China to their nearest port. We do not bill the customers for the duties of their country or the ground shipping from the port to their city. Those customers receive a seperate bill from the freight forwarding company.

The website software that our company is using does not have the flexibility to handle this. We have a new website under development that will have this flexibility in shipping quotes.

So with these two types of customers, it is difficult to have two seperate prices for every product that accounts for the differences in shipping already built into the price.

So we choose to post the prices for the cells FOB China. And we make it clear on the website that shipping is extra. We also make it clear on the website that USA customers will be charged for the duties, shipping, port fees. 

It is not a perfect solution. But if we want to provide these cells internationally, which we do, then we have to do it this way for now. We are working on a better solution so that the full shipping quote is displayed on the website. But it is not accurate yet.


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## Indubitably (Jan 8, 2010)

EVComponents said:


> It is not a perfect solution. But if we want to provide these cells internationally, which we do, then we have to do it this way for now. We are working on a better solution so that the full shipping quote is displayed on the website. But it is not accurate yet.


Well it sounds like you guys have been working on the implementation of measures that should eliminate these sorts of misunderstandings, so I have no doubt future customers of a similar disposition to myself will have no qualms ordering from you. I had for that matter just updated my post to reflect more accurately the nature of my discontent in this matter when you issued your response, so hopefully your current customers will not read any more suspicion into the matter than it is due.

It still seems however that it would be in the best interest of both your customers and evcomponents to establish an alternative means of domestic shipping for small orders. I realise that it is uncommon for diy ebike projects to employ large prismatic cells, but since these batteries are becoming more affordable and more accessible by the day, you may find your demand for such a service will increase significantly in the near future.


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## EVComponents (Apr 20, 2009)

Indubitably said:


> It still seems however that it would be in the best interest of both your customers and evcomponents to establish an alternative means of domestic shipping for small orders. I realise that it is uncommon for diy ebike projects to employ large prismatic cells, but since these batteries are becoming more affordable and more accessible by the day, you may find your demand for such a service will increase significantly in the near future.


Email me your invoice number and I will take another look at it. You might have been charged for a large format cell shipping. Let me see if there is another option for your specific product.

My email is [email protected]

Sorry if I missed a previous email from you.


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## Indubitably (Jan 8, 2010)

EVComponents said:


> Email me your invoice number and I will take another look at it. You might have been charged for a large format cell shipping. Let me see if there is another option for your specific product.
> 
> My email is [email protected]
> 
> Sorry if I missed a previous email from you.


Ok, email sent. If you do have a different proceedure for shipping small packages then it would indeed seem that this was for the most part just a missunderstanding. Hopefully we will get everything worked out, at which point I will be happy to report on my satisfaction with the manner in which evcomponents customer service addressed my concerns.


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## Indubitably (Jan 8, 2010)

With everything that has been going on with school I've barely had time to work on my project, but I just got a chance to finally take a look at the batteries I ordered, and I wanted to give everyone an update.

First of all I should report that working with EVComponents was entirely satisfactory. There were some minor complications as a result of my having initially sent them a check from the wrong account, but the staff was both prompt and courteous in alerting me to the problem, and everything was sorted out after a call and a few emails. 

My concerns about shipping costs were likewise addressed in a timely and direct manner, and EVComponents was eventually able to make accommodations for my unusually small order. The cells none the less arrived packed in a crate with ample Styrofoam padding. It should theoretically have been possible to send my package in a cardboard box via standard parcel post, so I'm guessing that there is some reason why the cells need to be shipped in an upright position or crated for safety reasons and the like.

The cells all seemed to be in good working order and are all charged to 5.3v. I'm guessing its normal to ship the cells with this voltage, but I'm not sure whether or not charging them to 5.3v is standard operating procedure (if anyone knows more about this, any info would be appreciated). I won't really be able to say that they're all good until they're broken in and I've seen how they perform after a few discharge cycle. Unfortunately however, my BMS is still not ready yet, so you'll have to wait for the verdict on that. At any rate, I am certainly satisfied with my experience with EVComponents, and so far the ThunderSky cells do seem to have been a suitable choice for my project. 

The one issue I have with them is that they are indeed a bit on the bulky side. Its hard to really get a grip on just how unwieldy they are until you actually have a few in your hands. Not to mention that they need to be bound together in order to prevent swelling during charging, so mounting them is a bit reminiscent of the problems associated with trying to mount SLAs, but its nothing unreasonably problematic. You really can't beat the cost per watt-hour, so these are pretty minor complaints in the grand scheme of things.


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## frodus (Apr 12, 2008)

5.3V

are you joking? 

They should never be charged over 4.2V, as per the datasheet, and now its actually down to 4V......


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## EVComponents (Apr 20, 2009)

Typically cells ship at a voltage of between 3.2v to 3.3v.

Maybe it was a typo.


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## dtbaker (Jan 5, 2008)

Indubitably said:


> ...
> The cells all seemed to be in good working order and are all charged to 5.3v.


???? either you are dyslexic and/or need a new voltmeter? I'd expect them to be 3.2-3.3 v


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## Indubitably (Jan 8, 2010)

dtbaker said:


> ???? either you are dyslexic and/or need a new voltmeter? I'd expect them to be 3.2-3.3 v


I think you might be right about there being something wrong with the meter, because I got 5.3 for each and every one of them when I checked last night, and this morning they all read 4.2 which is in line with what every one seems to be saying they should be (I even connected 4 of them in series and got 21 volts, which is down to about 16 volts today).

Its a ten dollar meter, so I suppose I shouldn't be surprised when it goes haywire from time to time.

At any rate, I take it that they won't hold that charge of 4.2v for very long before settling at 3.2?


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## EVComponents (Apr 20, 2009)

dtbaker said:


> ???? either you are dyslexic and/or need a new voltmeter? I'd expect them to be 3.2-3.3 v


Come on guys. Go easy on him. We all make typos.


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## EVComponents (Apr 20, 2009)

Indubitably said:


> At any rate, I take it that they won't hold that charge of 4.2v for very long before settling at 3.2?


If the initial charge is 4.2 that is fine. But going forward you should limit your charge to between 3.6v or 3.8v maximum.

They should have shipped from the factory at between 3.2v to 3.3v. That is standard and has been very consistent for a long time.


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## Indubitably (Jan 8, 2010)

EVComponents said:


> If the initial charge is 4.2 that is fine. But going forward you should limit your charge to between 3.6v or 3.8v maximum.
> 
> They should have shipped from the factory at between 3.2v to 3.3v. That is standard and has been very consistent for a long time.


Yeah, I'm guessing there really is something wrong with the meter. At first I thought maybe I was just smoking something last night, but I just rechecked the cells and it seems like they're all between 4.6 and 4.7v, which sounds like it is exactly 1 volt higher than what you are saying it should be. I'm going to go ahead and pick up another meter just to be sure.


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## dtbaker (Jan 5, 2008)

EVComponents said:


> Come on guys. Go easy on him. We all make typos.


not trying to dis.... just sounds like the meter was wacky....


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## Indubitably (Jan 8, 2010)

Ok, so I was starting to think I was going nuts, because the voltage on the cells seemed to have mysteriously dropped over night, then I though maybe my meter was bad because it was reading voltages that seemed too high. Now I'm just confused, because I tested the meter out on a number of various different batteries and power supplies and it is consistently reading the correct voltage.

So, I decided to check the cells again, and now they're reading 3.5v, so the most reasonable conclusion seems to be that they are indeed steadily dropping in voltage. I can't for the life of me figure out why though. They sat in a box in my living room for what was probably more than 2 weeks without going flat, and they have not been subjected to a load of any kind since I took them out of the box last night.

At any rate, I'm going to keep an eye on them. Hopefully they settle down at some point, but either way this is a mystery I would like to solve.


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## Travdude (May 11, 2009)

Maybe your voltmeter was set on the wrong scale?

I have done that.


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## Indubitably (Jan 8, 2010)

Ok, so I kept an eye on the cells last night and the voltage was indeed gradually falling off. It seemed to stop at around 3.3 and it was still at that voltage when I woke up this morning. I had also noticed a curious "metallic" odor in the room since I moved the batteries in that seems to have mostly dissipated since last night. I can't say for sure that the batteries caused it, and when I inspected the batteries more closely none of them seemed to be producing any stronger of a scent than the rest of the room, so it is possible that its just a coincidence.

This whole thing just seems a bit odd. I've just plain never heard of anything like this happening with thundersky cells. If they work alright I suppose its no big deal, but I'm still curious as to what exactly could have caused it. Thinking back, I am fairly certain that the cells were indeed initially charged to 5.3v. I checked them multiple times to be certain because it quite frankly was not what I had expected to find. What strikes me as even more odd though is that they held that voltage the entire time they were in the box, and appear to have spontaneously begun dropping in voltage as soon as I took them out. Aside from the act of measuring the voltage, the only thing the cells have been exposed to is light, air, and perhaps a slight increase in temperature.

Its all really quite puzzling.

PS: It is also perhaps also worth noting that every battery I checked, dropped at the same rate. In other words, every time I checked, they were all within a tenth of a volt of each other.


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## Amberwolf (May 29, 2009)

It sounds much more likely that the meter itself is reading incorrectly. Perhaps it's own internal battery has a problem? Either was overcharged or is low?

EDIT (ADDED): Mostly I think this because if the cells were charged over 5V, they would have been that way for months, during shipping from China and then at EVC, then shipping to you, then sitting there for the two weeks (?) you had them. Then to suddenly drop that much *only during the days you are measuring them* would be highly unlikely. 
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## Indubitably (Jan 8, 2010)

Amberwolf said:


> It sounds much more likely that the meter itself is reading incorrectly. Perhaps it's own internal battery has a problem? Either was overcharged or is low?
> 
> EDIT (ADDED): Mostly I think this because if the cells were charged over 5V, they would have been that way for months, during shipping from China and then at EVC, then shipping to you, then sitting there for the two weeks (?) you had them. Then to suddenly drop that much *only during the days you are measuring them* would be highly unlikely.


Thats what I thought too, but I checked the meter and it seems to be working just fine on everything else. Not to mention that if the meter was causing it, you would expect the reading to continue dropping instead of stabilizing at 3.3 volts.

Hell, you would think that either it would hold the charge at 5.3v, or it wouldn't. As unlikely as it would seem though, apparently both are true. The batteries do seem to have held the charge at 5.3v then dropped to 3.3 after I measured them. It defies common sense, but that is none the less what the evidence keeps pointing to. I can't imagine what would have prompted this though, they were subjected to no obviously significant change in environment. They weren't left in the sun, or dropped, or even turned upside down, just taken out of the box and measured.


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