# Help converting Lead Acid to Lithium please.



## AWDGuy (Mar 30, 2015)

I just picked up a converted '92 MR2 with 16 mostly dead D34 Optimas. Rather than spending a few thousand on more lead acid, was thinking I should invest in a Lithium system.

I am new to this, so be gentle please... I am not new to battery chemistry or charging, but that is on the much smaller RC scale...

Any help or recommendations would be appreciated.

This is the current car configuration...

Vehicle: 1992 Toyota MR2
Motor: Advanced DC XP-1227A Series Wound DC #011
Drivetrain: Taperlock adapter to MR-2 transaxle
Controller: Auburn Scientific PWC1200-192 Griz-Burger
Batteries: 16 Optima D34 750 DS, 12.00 Volt, Lead-Acid, AGM Yellow Top
System Voltage: 192 Volts
Charger: Manzanita Micro PFC20
Heater: Rusco electric hot water
DC/DC Converter: Todd PC-30
Instrumentation: a) Ammeter b) E-meter


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## Ziggythewiz (May 16, 2010)

Start by making a budget and goals. Look around at some cells and make a plan...then run it by for advice. We can't build it for ya.


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## AWDGuy (Mar 30, 2015)

Ziggythewiz said:


> Start by making a budget and goals. Look around at some cells and make a plan...then run it by for advice. We can't build it for ya.


I'd like to, but I don't know enough to make a plan.

To replace existing Optimas will be around $2500. If I can convert to Lithium for double that and double or more my range, that sounds like a no-brainer to me. If the answer is it will be 3-4 times the cost, maybe it doesn't make as much sense?

So, I guess that is my current plan/hope. Swap to Lithium for around $5000 or less.

I can assume I need new batteries and a charge controller, but am I still targeting 192v, or can my speed controller and motor work on more or less and if so, what is better?

As all my battery trays fit the D34s fairly tightly, is there a preferred cell/set of cells that take up the same amount of space? I would also assume I am going to have to add monitoring/balance charge wiring to the harness as I will have more lower voltage cells to manage.

I'm not even sure what else to ask beyond that...


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## Yabert (Feb 7, 2010)

With a 192v systems, you should start to look for a used Chevy Volt battery.
You will need to reconnect the battery from 360v 45Ah to 180v 90Ah, but 16 Kwh for around 2K$ is probably your best bet.

Just be sure to don't destroy your motor with all the power that will come from the new battery  
(probably over 200 Kw with your controller.... that is too much for your 8'' motor!)


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## AWDGuy (Mar 30, 2015)

Yabert said:


> With a 192v systems, you should start to look for a used Chevy Volt battery.
> You will need to reconnect the battery from 360v 45Ah to 180v 90Ah, but 16 Kwh for around 2K$ is probably your best bet.
> 
> Just be sure to don't destroy your motor with all the power that will come from the new battery
> (probably over 200 Kw with your controller.... that is too much for your 8'' motor!)


Thanks, but It doesn't look like you can break down the Volt battery into small enough modules to fit where my D34s are.  At least without major surgery from the video I found.

So the Lithium cells will generate more current than the Lead? I was under the impression the opposite might be true unless they are 10C cells. Am I missing something?


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## Sunking (Aug 10, 2009)

Well you have a bit of a problem. The Optima Yellow Top D34 batteries are made to deliver a whole lot of current for their size. That in itself is not a problem for Lithium batteries. The D34 is a 55 AH battery. When converted to Lithium you would only need 30 AH in lithium to replace it for an equal usable capacity. The D34 has an Ri of .0028 Ohms which is super low resistance which enables them to deliver very high currents. With 16 in series yields a total of .045 Ohms at 192 volts. They can deliver 15C load Current until fully discharged or 850 amps for roughly 10 minutes without any thermal damage. 

At 192 volts means you will need a 60S system or 60 LFP cells in series. So here is the problem. If you use say 40 AH LFP cells can only deliver 80 to 120 amps continuous or 400 amps for 10 seconds (acceleration time). You would give up a lot of acceleration limited to 400 Amps burst. Well that is if your controller is more than 400 amps. 

I tried to find your controller to see what amperage it is but no luck. *So what amperage is it rated at? *That is going to determine your minimum battery AH capacity. Typically LFP has a continuous rating of 2 to 3C and Burst at 10C. So if the controller is 600 amps will need at least 60 AH cells. 

You are going to have to reverse engineer it to find the minimum requirements based on the controller current rating.

As to weight, volume, range, and cost questions. A 192 volt 55 AH lithium battery will be 1/3 the weight, 1/2 the volume, and more than double your range. LFP battery cost are roughly 45-cents per watt hour so 192 volts x 55 AH = 10560 watt hours or $4800. However will last more than twice as long as the Optima.


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## AWDGuy (Mar 30, 2015)

Sunking said:


> I tried to find your controller to see what amperage it is but no luck. *So what amperage is it rated at? *That is going to determine your minimum battery AH capacity. Typically LFP has a continuous rating of 2 to 3C and Burst at 10C. So if the controller is 600 amps will need at least 60 AH cells.
> 
> You are going to have to reverse engineer it to find the minimum requirements based on the controller current rating.


Great info, thanks... Controller is apparently rated at 1200A, so if I read your info right, I am going to need 120AH cells just to handle the 10 second burst???!!!  

*Griz-Burger (Double Grizzly) PWC1200-192 (water cooled)*


Operating voltage: 96-240V
Nominal battery voltage: 120-192V
Motor & Battery current 1200 Amps
http://evalbum.com/auburn


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## Sunking (Aug 10, 2009)

AWDGuy said:


> Great info, thanks... Controller is apparently rated at 1200A, so if I read your info right, I am going to need 180AH cells!!!
> *Griz-Burger (Double Grizzly) PWC1200-192 (water cooled)*
> 
> 
> ...


Check your controller and motor specs and see how 1200 motor amps converts to DC battery amps. 

I have a HPEV AC-9 motor with 650 amp controller and it can draw up to 690 amps from the battery. I think you have a DC motor and that changes things. 

The battery AH rating will depend on the manufacture Burst Current Ratings. Most are around 10C. So if you need to draw 1200 amps then 120 AH. Don't give up just yet. DC motor currents are not 1:1 accelerating. I gotta a feeling the battery current only peaks around 600 to 800 because that is all the Optima can do.


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## major (Apr 4, 2008)

Sunking said:


> Check your controller and motor specs and see how 1200 motor amps converts to DC battery amps.


He tells you right there:


AWDGuy said:


> Motor & Battery current 1200 Amps


With the DC motor controllers, motor current is always higher than (or equal to) battery current. The 1200A is the current limit and applies to both battery and motor current. He would only see 1200A from the battery at peak power which would be WOT at base RPM. With his motor, the average battery current would certainly be less than 200A, likely less than 150.



Sunking said:


> I gotta a feeling the battery current only peaks around 600 to 800 because that is all the Optima can do.


What gives you that feeling? You claim those yellow tops have .0028Ω Ri. That is a short circuit current of 4500Amps. They could deliver the full 1200A and stay above 8V/battery.



Sunking said:


> They can deliver 15C load Current until fully discharged or 850 amps for roughly 10 minutes without any thermal damage.


Another place you lose me. A battery delivers load current of 15C. That is 4 minutes by definition, right? Where does roughly 10 minutes come from?

Also, you seem to lump all Lithium into your LFP model. Even in that chemistry, there are brands capable of much higher discharge. And there are other Lithium batteries available which don't have the limitations of your LFP. For his budget, EnerDel could fit the bill.


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## Sunking (Aug 10, 2009)

major said:


> What gives you that feeling? You claim those yellow tops have .0028Ω Ri. That is a short circuit current of 4500Amps. They could deliver the full 1200A and stay above 8V/battery.


Impossible CA is 750 amps which is given at 7.2 volts, short circuit current is not listed. 



major said:


> Another place you lose me. A battery delivers load current of 15C. That is 4 minutes by definition, right? Where does roughly 10 minutes come from?


Brain fart



major said:


> Also, you seem to lump all Lithium into your LFP model. Even in that chemistry, there are brands capable of much higher discharge. And there are other Lithium batteries available which don't have the limitations of your LFP. For his budget, EnerDel could fit the bill.


You are right there. I did use CALB as the model at 45 cents per wh. But with a 1200 amp controller will dictate the smallest battery he can use


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## major (Apr 4, 2008)

Sunking said:


> Impossible CA is 750 amps which is given at 7.2 volts, short circuit current is not listed.


So then the internal resistance you stated is wrong? Or Ohm's Law does not apply in this case? 



> PHCA: 1,400A at 80°F (27°C); for 5 seconds
> CCA: 740A at 0°F (-18°C)
> CA/MCA: 815A at 32° (0°C)
> HCA: 1,150 at 80°F (27°C)
> ...


ref: http://bigtimebattery.com/store/d35yellowbatterytop.html 

Basically the same thing.


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## Vanquizor (Nov 17, 2009)

AWDGuy said:


> Thanks, but It doesn't look like you can break down the Volt battery into small enough modules to fit where my D34s are.  At least without major surgery from the video I found.
> 
> So the Lithium cells will generate more current than the Lead? I was under the impression the opposite might be true unless they are 10C cells. Am I missing something?



You should really take a second look at the volt battery- from a quick google I put the D34 Optimas with a footprint of 1100 square inches, volume of 8694 cubic inches and a weight of 696lbs

From my own measurement and testing the chevy volt battery reconfigured as 2 parallel strings has a footprint of 700 square inches, volume of 7691 cubic inches and a weight of 290 lbs as 48v modules without mounting hardware.
Chevy rates them at 7.8C, but they will definately do north of 15C for a trip down the drag strip(1350A for the proposed parallel string) so I'd say more than enough for the controller.

The added capacity will give easily 2x the range of new Optimas, more likely 3x if you actually use the throttle at all so its a huge gain there.

If you feel like breaking out the tape measure the smallest easy to break out evenly module size for the volt is 9.5 inches wide, 9.2 inches long, and 11 inches high- you would have 8 of those.


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## AWDGuy (Mar 30, 2015)

Vanquizor said:


> You should really take a second look at the volt battery... If you feel like breaking out the tape measure the smallest easy to break out evenly module size for the volt is 9.5 inches wide, 9.2 inches long, and 11 inches high- you would have 8 of those.


OK, I am...  

I got the impression from the video I watched that The smallest modules the volt battery could be broken down into were:
7x48Volt packs
2x24volt packs
And I had not seen dimensions on those. 

Are you saying the 48V packs are 9.5"x9.2"x11"h, and thus the 24V are 9.5"x4.6"x11"h or are they 4.75"x9.2"x11"h?

Have you been able to source cooling end plates, or are you running without? Where are you sourcing the batteries? New or dismantlers?

There was also something about the Volt cells being NMC chemistry??? We haven't even talked about replacing my BMS / charging system yet. Any thoughts on that?


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## AWDGuy (Mar 30, 2015)

Major and Sunking, thank you so much for the discussion. You lost me along the way, but trying to catch up. I was looking at CALB type stuff and am not familiar with the Enerdel, but at first look, they look to be substantially more expensive assuming I would need 2 of the $10K 22WH 96v packs? Still $0.47/WH, but way out of budget.

$5000 is not a hard limit, I am about best bang for my buck. I don't think I want to spend $2/Wh for the latest and greatest, but range and longevity (TCO) are more important than 1 time cost.

Whatever I do, I assume I will need a new BMS which has a cost of $???, and maybe charger, though I am hoping the (Manzanita Micro PFC20) can be reused??? Maybe the new BMS include the charger...???

Some day I'll likely look at replacing the motor with something regenerative, but that has to be for round 2... Though perhaps it plays into this decision too? Does what we choose for a battery solution now impact my ability to change propulsion systems in the future?

Thanks again for the help. please continue...


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## Sunking (Aug 10, 2009)

major said:


> So then the internal resistance you stated is wrong? Or Ohm's Law does not apply in this case?


Major I know the specs do not line up, but for Pete's sake all I am doing is quoting the MANUFACTURE SPEC NUMBERS. Look for yourself, scroll down to D34 specs, and argue with Optima. .


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## Vanquizor (Nov 17, 2009)

AWDGuy said:


> OK, I am...
> 
> I got the impression from the video I watched that The smallest modules the volt battery could be broken down into were:
> 7x48Volt packs
> ...


I think the 2 halfers would be ~9.5x4.6x11, but I'm at work so I don't have the parts in front of me right now. End plates weren't a concern for me as my plan is to mount them as 2 9.5x36.8x11 blocks. I sourced mine from a wrecker.

No BMS as of right now- as I am not pushing limits at all not sure if I will add one or just do periodic monitoring.
-Noel-


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## major (Apr 4, 2008)

Sunking said:


> Major I know the specs do not line up, but for Pete's sake all I am doing is quoting the MANUFACTURE SPEC NUMBERS. Look for yourself, scroll down to D34 specs, and argue with Optima. .


Sorry to confuse you. I've tested a thousand Optimas and know darn well they can put out over 1kA; way more.


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## major (Apr 4, 2008)

AWDGuy said:


> Still $0.47/WH, but way out of budget.





Sunking said:


> I did use CALB as the model at 45 cents per wh.


I see 2 cents difference 

BTW: How often do you punch it to 1200A?


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## AWDGuy (Mar 30, 2015)

major said:


> I see 2 cents difference
> 
> BTW: How often do you punch it to 1200A?


Sorry for the confusion, it is not the $0.02/WH difference. All I found searching for Enerdel were 22KWH 96V packs which I assumed I would need 2 of for 192V and they are over $10,000 a piece! Open to cheaper alternatives if they exist. Budget target is still $5000 but could spend 1/2 again as much or maybe double for the "Right" solution, but not $20K!

I have never punched it to 1200A as the car barely moves on the existing Optimas and I just acquired it.


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## Sunking (Aug 10, 2009)

AWD despite the back and forth between Major and I the minimum requirement is the Battery Burst or Peak Current for 10 seconds should be Equal to or Greater than the Controllers Peak Current, Plus the the battery Continuous Current be Equal to Or Greater than the motors Continuous current at the voltage you will be using. 

So for example let's say your controller is 1200 amps, and you continuous motor current is 240 amps @ 192 volts. In a CHI-COM large format cell line up you are looking at something like a 120 AH minimum cell with a Continuous rating of 2C and 10 second Peak aka Burst of 10C. 

The reason I use CALB as the model because they are one of the lowest priced cells you can get. Certainly not the best money can buy, but the best Value. But they do not make a 120 AH cell. 

On the other end of the spectrum you can go as low as using A123 26650 cells. They have a Continuous C-Rate of C28 and 10 second Burst of C48. At minimum would require 600 cells configured 60S10P. That would give you 192 volts @ 25 AH. They only cost $16 per cell x 600 cells = $9600.

CALB wh cost are roughly 45-cents per watt hour. A123 26650 cells cost roughly $2 per wh. I think you get the picture now.


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## major (Apr 4, 2008)

AWDGuy said:


> Sorry for the confusion, it is not the $0.02/WH difference. All I found searching for Enerdel were 22KWH 96V packs which I assumed I would need 2 of for 192V and they are over $10,000 a piece! Open to cheaper alternatives if they exist. Budget target is still $5000 but could spend 1/2 again as much or maybe double for the "Right" solution, but not $20K!
> 
> I have never punched it to 1200A as the car barely moves on the existing Optimas and I just acquired it.


The EC8S4P EnerDel module is $879 from Evolve. That is $.46/Wh. It can match the Calb as far as C-rate.

The point is that you're screwing yourself looking for a 1200 Ampere battery when you don't need one. If you need to drag race the thing with 1200A, get a racing battery. Put a dang ammeter on the dash and keep your foot out of it and manage the battery current. 

And there is a well respected member on ES selling new A123 20Ah pouches for $.55/Wh. Likely won't last long. Deals are out there. Heck, I was selling EnerDel for $.32/Wh. See the classified section.


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## AWDGuy (Mar 30, 2015)

major said:


> The EC8S4P EnerDel module is $879 from Evolve. That is $.46/Wh. It can match the Calb as far as C-rate.
> 
> The point is that you're screwing yourself looking for a 1200 Ampere battery when you don't need one.


I did not yet know I was looking for a 1200A battery.  Still just trying to learn and understand my options.

So I would need 6 of the EC8S4Ps to do 172V. How does one manage the individual cells on something like that? Are there taps on each cell or just each module?

I assume from a BMS perspective, I am better of with fewer larger cells. From my RC scale world (2-10 26650 and smaller cells), balance charging and monitoring is fairly key to pack life, so I assume it is even more true in the 60 cell large pack world???


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## major (Apr 4, 2008)

You treat parallel cell groups as single cells for BMS.


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## AWDGuy (Mar 30, 2015)

major said:


> You treat parallel cell groups as single cells for BMS.


Understand that, but still 12s in that 12s2p EC8S4P EnerDel pack. Just asking if there was some sort of tap for each? Assume there is, but don't see anything on the Evolve page.


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## major (Apr 4, 2008)

AWDGuy said:


> Understand that, but still 12s in that 12s2p EC8S4P EnerDel pack. Just asking if there was some sort of tap for each? Assume there is, but don't see anything on the Evolve page.


The EC8S4P is 8s4p. So 8 parallel groups per module. And yes, ring terminals can be fastened. Assembly is all nuts and bolts, no solder or welds.


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## AWDGuy (Mar 30, 2015)

major said:


> The EC8S4P is 8s4p. So 8 parallel groups per module. And yes, ring terminals can be fastened. Assembly is all nuts and bolts, no solder or welds.


OK. I was going by this page that said it was 12s2p... 
http://evolveelectrics.com/enerdel/enerdel-ec8s4p/


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## AWDGuy (Mar 30, 2015)

Vanquizor said:


> I think the 2 halfers would be ~9.5x4.6x11, but I'm at work so I don't have the parts in front of me right now. End plates weren't a concern for me as my plan is to mount them as 2 9.5x36.8x11 blocks. I sourced mine from a wrecker.
> 
> No BMS as of right now- as I am not pushing limits at all not sure if I will add one or just do periodic monitoring.
> -Noel-


Were you able to confirm which dimensions it was?

If I can get these packs for significantly less than new cells, I think I am leaning this way if they will fit.

Can they be they be easily bridged to 2p or even 3p or 4p within a given block or do we gent in to hairy crossed bus bars?

DO you have good shots of the top of the packs?

What are the ramifications of dropping from 192v TO 180v ~5% reduction in ??? Acceleration, RPM, ???

Thanks


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## Vanquizor (Nov 17, 2009)

Wasn't sure you were interested in going that way so I didn't check- I can get some pics and measureemnts tonight, let me know exactly what you want to see.


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## AWDGuy (Mar 30, 2015)

Vanquizor said:


> Wasn't sure you were interested in going that way so I didn't check- I can get some pics and measureemnts tonight, let me know exactly what you want to see.


Thank you. 
Footprint including cooling line fitting locations would be great.

If I have room, I was thinking about getting 2 packs and making a 160AH 180v pack out of them or 120AH 192V with spare modules for other tinkering/spares. 

I do not think I am prepared to tear apart the "batteries".
Is it possible to reconfigure the bus bars on individual 24v and 48V blocks/modules to make them 12v and 24V, or am I going to have to parallel them at the 24/48v level to make higher AH packs? Would rather do it within the block/module than across multiples. Better from a BMS perspective I think as well to group them in smaller hunks.

I am wading through all the great information in the Volt battery thread, but appreciate the help here.
http://www.diyelectriccar.com/forums/showthread.php/2012-chevy-volt-battery-93101

Thank you.


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## Vanquizor (Nov 17, 2009)

Here are some pics I took last night of 2 modules together- combined length ~18.25 inches, 9.5 inches wide at the maximum width of the cooling jackets. The cooling nipples on the end are 1.25 in length.

This is not the only configuration of cooling fittings in the pack, but its the one I found easiest to use by putting this one on one end of my string and a flat plate on the opposite end I had both sides of my cooling loop in the same spot. The modules are just held together electrically by 2 bolted metal straps in the middle, and mechanically by a band strap around the top and a couple long bolts running along the cooling passages. There are o ring seals on all the cooling passages so if you get a long section of all-thread you can stack together as many or as few modules as you like into a package.

Making parallel or series strings of modules is just a matter of replacing the metal straps with appropriate jumpers regardless of how the modules are mechanically bonded together. I haven't looking into what it would take to reconfigure cells in a module but you are definitely past the nut and bolt stage at that point.


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## hmincr (Jan 20, 2012)

I have been trying to sell 4--45-48V OR figure that as 2--96V blocks of Chevy modules in the Classifieds on this forum. . They are not difficult to break down into 48V or even 24V modules. Plenty of threads on these batteries. That includes cooling tubes, hoses, end plates and all BMS pieces. There are hacking threads for using these BMS systems. That would give you the 192V @45Ahr pack. $1400.00+ shipping ?


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## AWDGuy (Mar 30, 2015)

hmincr said:


> I have been trying to sell 4--45-48V OR figure that as 2--96V blocks of Chevy modules in the Classifieds on this forum. . They are not difficult to break down into 48V or even 24V modules. Plenty of threads on these batteries. That includes cooling tubes, hoses, end plates and all BMS pieces. There are hacking threads for using these BMS systems. That would give you the 192V @45Ahr pack. $1400.00+ shipping ?


Thank you for the offer. I may be in touch. I'd probably be looking for a 90Ahr or maybe 135Ahr if I can find the space... 

I am trying to figure out what will fit. The space in an MR2 is limited, and the existing battery boxes are multiples of D34 size which the Volt and Leaf packs are not. Even the standard prismatics I've found aren't really drop ins for the D34s. So still working on it.

I have 3 in the trunk which is: 
31x7.125x7.5 tall. 

3 in the tunnel which I haven't been able to measure as it is only accessible from under the car, but assume is nearly identical to the trunk.: 

31x7.125x7.5 tall.

Singles behind both seats: 

2 x 10.5x7.5x10 tall. 

And last but largest is in the front but T shaped. 

28.75x10.75x10 tall (Top of the T) + 16x10.75x12tall. 

And lastly, a singe box where I think the original battery was just in front of the firewall:


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## AWDGuy (Mar 30, 2015)

Doing the math, I think I can fit 3x48v across the top of the T if I can get the height clearance and another 48V in the down portion of the T. So that gets me 45AH. I'd love to figure out how to get another 4 in somehow if only to rebalance the car. 

They are not going to fit behind the seats or in the tunnel I don't think, leaving only the trunk. Redesign that rear battery box may be a challenge as I don't think there is much space left.

Maybe time to dig into it this weekend.


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## hmincr (Jan 20, 2012)

The measurements will be checked on Sunday. My Son is visiting me and will return home where the batteries are this Saturday. 

He will get exact measurements and I will post them here.


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