# Batteries for 1983 AMC Eagle with AC90 Motor



## eagle (Feb 24, 2010)

I'm finally at the last stage of "buying stuff" for my EV.

I have a 1983 AMC Eagle SX/4 with 35-inch tires, solid axles, and an 8-inch suspension lift. The transmission has been removed but the transfer case remains. The motor will connect directly to the transfer case and the rear differential currently has either 4.10 or 4.56 gears.

I was fortunate enough to locate an factory-built EV donor. It's a 1999 Solectria Electric Stepvan that was originally sold to DHL. The Solectria AC90 and UMOC445 is being removed from the stepvan and will be placed in the Eagle (along with the onboard charger and DC-DC converter). Here is a spec sheet for the very similar Azure AC90 and DMOC445. It's a 312V system with 414A max current.

http://www.azuredynamics.com/products/force-drive/documents/AC90_DMOC645ProductSheet.pdf

My guess is that this vehicle, without batteries is going to weigh about 3000 pounds. Obviously, the aerodynamics will be atrocious. 

I need to buy some batteries pretty soon so that this project can get finished off. At this point, I just want to get this thing running. What is my best, but most economical option? What is the least hassle-free battery option? 

I'm inclined to go with some form of lead acid, but I'm concerned that there may not be space to put them. I'm concerned with LiFePO4 because of cost and complexity. 

Thoughts?


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## rillip3 (Jun 19, 2009)

Most economical will be flooded lead-acid (FLA). I wouldn't be intimidated by the perceived difficulty in Lithium if you can afford it.

What's the GVWR for the vehicle? The amount of weight left that you can carry may make a large difference in your selection.


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## eagle (Feb 24, 2010)

At this point, I might need to go with the most economical route. The GVWR is up in the air. 

From the manufacturer, it was about 4800 pounds, but there has been considerable modification that has taken place over the years. The axles are now heavier duty solid axles (Dana 44) and I have coils on all four points for the suspension.


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## rillip3 (Jun 19, 2009)

If you want FLA, figuring out the weight and cost is dependent on the range.

In generic, it would look like this:

Ah = (wh/mi) x mi / v x 1.2 x 1.5

where v is your voltage, the miles is the range you would like, the wh/mi is the efficiency, 1.2 is for Depth of Discharge, 1.5 is for Puekert.

So, just to kick around some numbers, let's say you're going to get 400 wh/mi (pretty bad) and want to go 30 miles with a 312v system. That's 400 x 30 /312 x 1.2 x 1.5 = ~70 Ah batteries. And of course because you have a 312 system, you're looking at 26 (12v) batteries. My batteries, just for a point of comparison for you, are 75 Ah AGM batteries and weigh 58.6 lbs. each. That's 1523.6 lbs of batteries. I'm not sure if FLA would weigh more or less. They're about 10.25 inches long, 6.13 inches wide and 9.13 inches tall. So if you put them in rows of 6 and 7, you'd be looking at 42.91 inches across, and 41 inches deep. That's a big freaking pack! That's assuming a single height setup. You may have to get creative!

These particular batteries are ~$155 each, or right around $4,000 for 26. They are not ideal for my conversion, but I got 12 for free, so I'm using them anyway.  Floodies would most likey be cheaper, but this kind of gives you a feel for the ballpark with real world battery numbers. I don't know if the FLA would be any smaller or not.


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## eagle (Feb 24, 2010)

This is good stuff--thanks for your numbers. I was hoping to ask about C-rating. How many C can an FLA or AGM pull. The max current on my controller is 414A. If I were to get a battery rated at ~70AH, then that means it would need to withstand about 6C for when the controller is peaking--is that right?


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## racunniff (Jan 14, 2009)

eagle said:


> I'm finally at the last stage of "buying stuff" for my EV.
> 
> I have a 1983 AMC Eagle SX/4 with 35-inch tires, solid axles, and an 8-inch suspension lift. The transmission has been removed but the transfer case remains. The motor will connect directly to the transfer case and the rear differential currently has either 4.10 or 4.56 gears.
> 
> ...


Well, I have a somewhat similar build of a Jeep Cherokee at http://electrojeep.com - I went with sealed lead acid. But I went without battery regulators - and am regretting it. With 26 batteries in a string, it is very easy to get some out of balance. I'm busy adding Manzanita digital regulators to it and hope it will settle things out.

FWIW, I estimate roughly 400 watt-hours per mile for it. The batteries are 80 Ah. I rarely pull more than 100A.


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## eagle (Feb 24, 2010)

Very creative with the battery boxes. But I guess you had no choice but to be.

Yes, both of our vehicles are very close in weight and drag--both of my axles and transfer case are from Jeep Cherokees. 

What brand of SLA did you end up going with? Are SLAs considerably more expensive than floodies?


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## eagle (Feb 24, 2010)

@racunniff: You are running an AC55, correct? Is it with a transmission, or direct drive? 

What kind of range and speed are you getting?


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## racunniff (Jan 14, 2009)

eagle said:


> Very creative with the battery boxes. But I guess you had no choice but to be.
> 
> Yes, both of our vehicles are very close in weight and drag--both of my axles and transfer case are from Jeep Cherokees.
> 
> What brand of SLA did you end up going with? Are SLAs considerably more expensive than floodies?


I went with Concorde AGM-1280T wheelchair batteries. They seemed to have a good Peukert constant and reasonable capacity. However, you should look around at what is available these days - I get the sense that the 1280T is a little finicky in series (although I'm doing fine with them in my 216V AC 914).

SLA tends to be more expensive than flooded - especially because you really need something to regulate / balance them - you can't just overcharge them like you can floodies. However, for me, the convenience factor of not having to water them, plus the fact that floodies *will* make a mess sooner or later, makes sealed very attractive.

Eventually the cost of lithium will come down to where I can afford to replace the SLA with something more fun. Keeping my fingers crossed...


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## racunniff (Jan 14, 2009)

eagle said:


> @racunniff: You are running an AC55, correct? Is it with a transmission, or direct drive?
> 
> What kind of range and speed are you getting?


Yes, AC55 with DMOC445, hooked up to the original transmission. Range is about 40 miles to a reasonable DOD (70%). Speed and acceleration are very good - better than the original, at least for in-town driving (I have not taken it out of town / on the highway).

You can see some performance notes here: http://electrojeep.blogspot.com/2009/01/more-motor-notes.html - you could theoretically go direct drive with the AC55. I currently drive around in 3rd quite a lot in-town.

One other thing - with 312V, you need to be *very* careful with pack isolation and finger safety - I like Cam-lok connectors and liqui-tite conduit.


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## rillip3 (Jun 19, 2009)

eagle said:


> This is good stuff--thanks for your numbers. I was hoping to ask about C-rating. How many C can an FLA or AGM pull. The max current on my controller is 414A. If I were to get a battery rated at ~70AH, then that means it would need to withstand about 6C for when the controller is peaking--is that right?


I cannot foresee you using full amperage. You would need to be pulling 129,168 watts of power to do that. That's 173 HP. The largest motor I could find was only 100 HP at 460v. 

Now the C rating is a legitimate concern. The best number I've been able to come up with as a maximum is 5c. I've read before, but can't recall where, that it's best for life if you keep it to 3c. At 3c you're still at 65k, or 87 HP, which should be more than enough to meet your needs. I doubt that this will be an issue, but you should probably install an amp meter and watch it closely until you've had a chance to get confident this is the case.


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## eagle (Feb 24, 2010)

Great news: I'll now be able to pursue LiFePO4 batteries instead of lead acid. 

These are the options that I am thinking about. I'll be making a decision in the next week, so any input that you have will be greatly appreciated. 

As a recap, I have a highly un-aerodynamic conversion that will end up weighing about 3000--before the battery pack is added. At this point, I just want to get this beast rolling, so I am no longer concerned with range. I just want to test the car within the drive system's optimal voltage band. 

The motor/controller is an Azure/Solectria AC-90 and UMOC 645. The controller is able to handle 414A, but I doubt that it will ever need to pull more than 120A in real world conditions. Nominal voltage of the motor/controller is rated at 312V.

Based on the information above--and the fact that I'm no longer super-concerned with my 65 mph cruising speed and 50-mile range, which of the following would you recommend. Please keep in mind that I will eventually add an addition twin to whichever pack that I decide on to extend range and performance. I just want to get something put together at a reasonable cost as soon as possible so I can actually drive this thing before the winter starts kicking in Chicago. 

I already have a similar conversation going on this thread, so please reply here:

http://www.diyelectriccar.com/forums/showthread.php?p=202428#post202428


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