# Newbie looking for advice



## Lionstrike (Oct 29, 2011)

Hello all,

I am considering building an electric car. I've built numerous electric bicycles, have two electric motorcycles (including one Vectrix), and well... I just love electric vehicle technology. I want off foreign oil dependence and to beat the rising costs at the pump. In short... I want off this ride.

So when it's reasonably warm in Pennsylvania, I can ride my electric bicycles and motorcycles. They're great. I love them to death. 

But in the winter... I am screwed. I'll freeze to death on my bikes, and if there's any... ANY ice out there, it's just out of the question entirely. But I want to be a four season EV enthusiast.

I thought about a car. I don't even mind not having heat or AC. But there are more problems than that.

I understand batteries have BAD voltage sag in the winter. Happens to my Vectrix too. Cold hurts the range HARD. My impression so far was to not even try it, especially with lead acid.

I also understand that lead acid batteries vent hydrogen gas when charging (even the sealed, AGM ones). That's a problem too. I work third shift and would have to charge while sleeping, so they'd be unattended. I have a condo and no garage so I'd have to open the trunk or something while charging. In the rain I have a serious problem. More than that, there are kids on my block. I don't want them ANYWHERE NEAR that battery pack and have no way of protecting them from it. Lithium would then be the only option, but there's no other way to say this than:

"OMG!!!! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"

That cost would take this project out of my range. The other option would be to lease a Smartcar ED for $139 a month which is a reasonable price to pay.

Another option still would be to invest in cold weather riding gear so that I can get more days in on my bikes, but all in all.... a car would be AWESOME.

Any advice for me? I like the idea of a car but it's got some real problems for me logistically. Thanks all.


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## Duncan (Dec 8, 2008)

First things

What do you need 
Range
Performance
Comfort

My car has limited range (20 miles) but good performance and it was cheap 
I have about $3000 worth of batteries


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## Lionstrike (Oct 29, 2011)

Well, I was hoping for a work commuter. It's a 13 mile trip to work, and I can charge there. I need to be able to maintain a 55mph top speed, and I don't care about comfort at all. This is about getting rid of gas affordably, and I would endure the heat of summer and the cold of winter to do so.


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## racunniff (Jan 14, 2009)

Lionstrike said:


> Hello all,
> 
> I am considering building an electric car...
> 
> ...


In addition to cold weather making batteries sag, cold can also destroy batteries during charging. With lead, if you don't increase your charging voltage with temperature according to manufacturer's specs, then you will quickly destroy your pack with sulfation. With lithium, if you charge below freezing, you will also destroy your pack, but with lithium plating (lithiation?) So, regardless of battery chemistry, you need to have some way of compensating for cold weather when you charge. I have battery warmers on both my DIY vehicles (in Colorado).

Do note that AGM batteries only vent significant quantities of hydrogen if they are overcharged. However, your design does need to account for this somehow. And note that you should absolutely include a BMS with AGM batteries - they will quickly go out of balance when you put them in series, and then you will quickly destroy your pack as you overcharge and/or over-discharge your batteries one-by-one.

One piece of advice I have, after having done the lead->lithium upgrade: don't convert yet if lead is your only option. Save your pennies until you can afford lithium. The increase in range, lifetime, reliability, etc. that I've seen with lithium far outweighs the apparent cheapness factor of lead. As anecdotal evidence: the ElectroJeep has already seen more miles put on it with lithium, in just a few months, than it ever saw with a few years of AGM. The lead was just too finicky. I was given this advice myself back in the day, but ignored it, and basically just wasted the money I put into the lead pack.


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## dougingraham (Jul 26, 2011)

Lionstrike said:


> Lithium would then be the only option, but there's no other way to say this than:
> 
> "OMG!!!! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
> 
> ...


If you can afford $139 a month lease then you can afford to do a lithium conversion. Leases are just throwing money away. Presumably there would be some money down and then $139/ month. Open an investment account of some kind. An index fund would be a good recommendation and place the up front money in it. Invest the $139 per month. There will be a point probably about a year from now when you will have enough money saved to start buying the pieces. of the conversion. Use that time to locate the donor car that sparks your fancy and figure out what components you want to put in it. Look for used version of those and purchase when deals are located. Unless you put way more batteries in your car than you need for your driving needs, you are going to be ahead with lithium in about 3-4 years time compared to Lead Acid.

Alternatively there are Leaf's for sale on EBay in the $13000-$14000 range with less than 50k miles. It sounds like one of these will do your mission nicely. You should be able to get financing for one of these pretty easily if that is your preference. I would work it the other way and save up for a couple of years instead of making payments to the bank. The car will cost you a lot less if you can wait a couple of years and save up.


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## Lionstrike (Oct 29, 2011)

Thank you all for your advice. 

Saving up for a solid EV conversion is certainly on the table, but again, I still have the issue of compensating for the cold.

Last winter was absolutely BRUTAL in Pennsylvania and we had temperatures of -10 degrees for about 3 months. It was absolutely INSANE.

I would be very, very upset if I spent $5000 on some kind of battery pack and it didn't survive the winter. While I have a couple of dollars, I have none to just throw away.

If I do decide to go this route, there's just not a whole lot of room for error here.


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## racunniff (Jan 14, 2009)

Lionstrike said:


> Thank you all for your advice.
> 
> Saving up for a solid EV conversion is certainly on the table, but again, I still have the issue of compensating for the cold.


Again - battery warmers are what you need. Chevy Volts do this too (they can use their liquid "coolant" also to warm the pack). I use Farnham battery pads along with a thermostat. This is plugged into a separate 120V AC line than the charger. Right now, it's all manual (I don't plug the charger in until I see the temperature has hit my threshold - which I've set for 10 deg. C for LiFePO4). Maybe someday I'll automate a relay so I don't have to do it manually...

You'll want separate thermostats / control domains for physically separated packs. Budget and design for this and it should not be a problem.


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## Lionstrike (Oct 29, 2011)

So, just to clarify... this is only when charging right? Can batteries survive sitting in -10 degree weather?


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## Yabert (Feb 7, 2010)

Mine has survived at -30°C (-22F) with 125w of heating.
Heated and insulated and all will work well!


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## racunniff (Jan 14, 2009)

Lionstrike said:


> So, just to clarify... this is only when charging right? Can batteries survive sitting in -10 degree weather?


CALB quotes the discharge / storage temperature for the newer gray CA series as -20 deg. C (which is -4 deg. F). So -10 is a little outside the manufacturer's spec. But with insulated battery boxes, a daily warm-up to above freezing when you charge should keep the cells above that temperature.


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## ga2500ev (Apr 20, 2008)

Lionstrike said:


> Hello all,
> 
> I am considering building an electric car. I've built numerous electric bicycles, have two electric motorcycles (including one Vectrix), and well... I just love electric vehicle technology. I want off foreign oil dependence and to beat the rising costs at the pump. In short... I want off this ride.


Admirable goal. My rationale is similar in that electric costs are more controlled and solar is a future charging option.


> So when it's reasonably warm in Pennsylvania, I can ride my electric bicycles and motorcycles. They're great. I love them to death.
> 
> But in the winter... I am screwed. I'll freeze to death on my bikes, and if there's any... ANY ice out there, it's just out of the question entirely. But I want to be a four season EV enthusiast.


There is a reason why cars are the primary mode of transportation for most folks.


> I thought about a car. I don't even mind not having heat or AC. But there are more problems than that.


Heat and AC are actually both doable with a bit of work. So there's not necessarily a need to completely dismiss them...


> I understand batteries have BAD voltage sag in the winter. Happens to my Vectrix too. Cold hurts the range HARD. My impression so far was to not even try it, especially with lead acid.


For the most part lead acid should be off the table anyway. I'll address your primary concern below in a bit...


> I also understand that lead acid batteries vent hydrogen gas when charging (even the sealed, AGM ones). That's a problem too. I work third shift and would have to charge while sleeping, so they'd be unattended. I have a condo and no garage so I'd have to open the trunk or something while charging. In the rain I have a serious problem. More than that, there are kids on my block. I don't want them ANYWHERE NEAR that battery pack and have no way of protecting them from it. Lithium would then be the only option, but there's no other way to say this than:
> 
> "OMG!!!! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"


First off hydrogen venting only occurs in an overcharge situation. Properly charged batteries shouldn't vent at all.

Second instead of opening the trunk, you could rig up a fan based venting system.

Finally lithium has come down significantly in price. It's at a point now where the cost of capitalization comes into play. Just like EVs vs. ICE, lithium has a higher up front cost with a lower overall total cost. Lead acid typically will last less than 500 charge cycles, or just short of two years. Lithium can charge cycles of 4-5 times that. So if the price/kwh is in that range (and it is) it becomes a comparable total cost.

I'm hanging my hope on two possible configurations:

1. Using Nissan Leaf battery modules. These modules comes in a 2S2P 60 Ah 7.6V configuration but can fairly easily be converted into a 4S1P 15.2V 30Ah config in the same can. In the latter config they can be driven up to 120A continuous current and 270A pulse current (double these in the original config). This place  has modules in starting in singles for $109 a module.

Now let's compare that to what is likely the cheapest lead acid you will find, the Walmart MAXX 29 12V deep cycle battery. It's running about $99. The nominal numbers are 12V and 125 Ahr. However, that 125 Ahr number is a rouse because it's measured at a 1A rate. Your radio will pull more than that. A more realistic measure is the Reserve Capacity which is the usable time at a 25A draw. Note that an EV will be pulling 3-4 times this. The RC rating is 210 minutes which translates to 87.5 Ahr of capacity (210 minutes/60 minutes/hr * 25A). Again you'll be pulling a lot more (hence the sag). So the usable AH capacity will be at most half of that 87.5 which is somewhere in the ballpark of 45 Ahr. So 12V*45 Ahr = 540 Whr of total capacity.

The Leaf module is 15.6V (nominal) * 30 Ah = 468 Ah. It's not going to drop due to high current draw. Also it'll last a lot more cycles than the MAXX 29.

6V golf cart batteries are much more expensive than that.

2. Use standard LiFePo4 cells but buffer them with lead acid. This is an hybrid pack that ZiggytheWiz has documented in this thread. Each of the pack types supports the weakness of the other. In the case of the lead, it buffers the massive amp draw that kills the capacity. In the case of the lithium you can use smaller/cheaper cells (40-60 Ahr) even though the EV will exceed the maximum current draw of those cells. It facilitates putting together a lithium pack piecemeal instead of having to purchase it all at once. However, it comes at a complexity and weight cost to do so.



> That cost would take this project out of my range. The other option would be to lease a Smartcar ED for $139 a month which is a reasonable price to pay.


This is actually one of the items I don't really understand. Essentially leasing is a financing option with the ability to bail out after the lease period, where you have to give the vehicle back.

Why exactly can you not finance the batteries for your project and pay the $140/month back for the financing of the batteries? After the lease period you'd own the batteries while getting the use of them during the lease period.


> Another option still would be to invest in cold weather riding gear so that I can get more days in on my bikes, but all in all.... a car would be AWESOME.
> 
> Any advice for me? I like the idea of a car but it's got some real problems for me logistically. Thanks all.


Let's do some off the cuff calculations. Say you need 300 Whr/mile to travel. Two of the Leaf 45V packs would give you [email protected] = 5.4 KWh of capacity for a total cost of $1300+shipping for the pack. The 5400 Whr/300 Whr/mile gives you an effective range of 18 miles which is within your 13 mile range with a bit of spare available.

Does that fit into your budget?

ga2500ev


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## Lionstrike (Oct 29, 2011)

Wow. Masterful analysis.

I want to thank you all for your fantastic advice. Two days ago, I wrote off the idea of building an electric car for the concerns listed above. Now that we've had this conversation, my current understanding is that these concerns are indeed concerns, but they are not *insurmountable *concerns. There's a way to beat the problems I've discussed. That's huge to me, thank you.

See, I love the idea of an electric car and as I've mentioned I own other electric vehicles. But I need to make sure that this doesn't end up as an educational project for me and ends up being a solid, reliable commuter. You've all given some really great advice.

I had NO IDEA that a lithium pack could be obtained so reasonably, or that commercial battery warmers were even available to beat the cold weather, expressly engineered for that purpose. That's amazing.

Folks, I am putting this electric car idea back on the table.

Now a 60ah leaf pack can get me 18 miles? I just want to be sure that I understand that correctly. How about a pack at 96v 60ah? How do we get to range calculations? It's based on the motor yeah? I haven't exactly decided on a motor but I was thinking of an Advanced DC 4001. That one seems to be popular and I have one in a conversion that I bought from ebay that specs out well.

Thanks again for the great advice.


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## Lionstrike (Oct 29, 2011)

I am also considering that "OPEN REVOLT" controller. Man that thing looks cool.


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