# Headway battery packs?



## frodus (Apr 12, 2008)

I am trying to get the pack for my motorcycle finally finished. Here's the basic idea:









I know others use the building-blocks with no issues, but I opted for my own using milled UHMW Polyethylene plastic and custom bussbars because I can get them to fit in a tighter space. Testing so far is good, they do decent discharge rates, not as high as A123, Lipo etc, but it's good for me and better than other prismatics.

What kind of pack are you building? vehicle? discharge requirement?

I sell them, if you need batteries.


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## njloof (Nov 21, 2011)

frodus said:


> What kind of pack are you building? vehicle? discharge requirement?
> 
> I sell them, if you need batteries.


Nice looking pack!

My target is a 300-350V pack to feed a 250V motor. Space limits everything else. So if I go CALB/Thundersky I can fit no more than 60 Ah (1p81s), thus 180A continuous/300A peak discharge (at pack voltage; at lower RPMs it's less of a worry.)

The Headways would let me fit 75 Ah (5p81s)... on paper, at least... and give me 225A continuous/750A peak. That should be more than adequate for a little Miata (225kW peak?)...

Feel free to PM me your price in around that quantity 

[edit: fixed serial/parallel mixup]


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## Yabert (Feb 7, 2010)

Do you missed to read something: http://www.diyelectriccar.com/forums/showthread.php/smart-fortwo-ev-high-power-version-51472p8.html

I also chose the Headway cells for the space advantage. Really small advantage after the complete pack is build.

From what I know, the 15 Ah cells will sag deeply at 10C, so than you can probably expect a maximum of around 130-140 Kw (battery power... less at motor shaft).


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## njloof (Nov 21, 2011)

Yabert said:


> Do you missed to read something: http://www.diyelectriccar.com/forums/showthread.php/smart-fortwo-ev-high-power-version-51472p8.html
> 
> I also chose the Headway cells for the space advantage. Really small advantage after the complete pack is build.
> 
> From what I know, the 15 Ah cells will sag deeply at 10C, so than you can probably expect a maximum of around 130-140 Kw (battery power... less at motor shaft).


I did miss your thread when searching -- my apologies! That's just perfect.

And thanks for the experience as well; even at 130kw I'm still well above the stock ICE (96hp). Your sag would be worse with CALBs, no?


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## frodus (Apr 12, 2008)

Yeah, you need to account for sag. At 15C, the batteries are really going to sag.

As far as sag, it's dependant on the C rating of the cell, and the AH of the cell. A Calb 100Ah battery running 100A (1C), will sag less than a headway 10Ah cell running 100A (10C). The higher C, the lower the sag. Only real way to tell, is to test it. 

I can do some cell testing if you want, but it would be best if I test a NEW 10Ah or 15Ah (or 8Ah) cell, Mine are older.


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## njloof (Nov 21, 2011)

frodus said:


> Yeah, you need to account for sag. At 15C, the batteries are really going to sag.
> 
> As far as sag, it's dependant on the C rating of the cell, and the AH of the cell. A Calb 100Ah battery running 100A (1C), will sag less than a headway 10Ah cell running 100A (10C). The higher C, the lower the sag. Only real way to tell, is to test it.


Again, just so we're comparing apples to apples:

Space would require me to use 60Ah CALBs to hit 300V. The 15Ah Headways would let me build 5p, so for the same space I have 75Ah at 300V.

In addition, the Headways are spec'd at 10C peak versus 5C peak for the CALBs. So I'm expecting to be able to draw 125% more current at peak, and 25% more (3C continuous for both) continuous.

Not to say it isn't worth testing, and if you have the setup I'd love to see what you get, old batteries or not. What do you think?


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## Jimdear2 (Oct 12, 2008)

njloof,

We have used the headway 8Ah P (power) cells to build a 4P/50S battery for high current short duration. We used the factory cell holders and built a fairly compact unit. It weighs about 150 pounds and is about 18 inches wide x 6 inches high and about 32 inches long.

A caution on buying headways, check on the warranty the seller offers. Some sellers offer 1 year others offer only a DOA. If you go with headways use EXTREME caution when attaching the cells together. The negative end can easily break free and turn in the case. This will in many cases damage or destroy the cell. Check with the seller to see what headway is saying you should tighten the cells to. There have been at least two specifications. Ill attach a couple of photos of our pack as it was last year with only three of the four layers installed.

You might also want to check out Jack Bauer's thread starting on page 39 or so.

http://www.diyelectriccar.com/forum...d-motor-works-35098p39.html?highlight=headway

Another place to look at for a compact high draw battery is the A123 20 ah pouch cells that are available. Look up RWAudio in the threads for his take on them.

Jim


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## frodus (Apr 12, 2008)

Yes, you'll draw more current, but your peak power will be lower than you think, due to voltage sag. They're good batteries,

I've already tested at 5C, which is what I'm designing around. I don't really NEED to test cells for ya, there's 5/10/15C discharge curves all over.

http://evlithium.com/html/HW_Battery/50.html

here's one of mine, at 5C. Sagged to about 2.87V at a discharge of 50A continuous, temp reached about 125F:


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## njloof (Nov 21, 2011)

Jimdear2 said:


> We have used the headway 8Ah P (power) cells to build a 4P/50S battery for high current short duration. We used the factory cell holders and built a fairly compact unit. It weighs about 150 pounds and is about 18 inches wide x 6 inches high and about 32 inches long.
> [...]
> You might also want to check out Jack Bauer's thread starting on page 39 or so.
> 
> http://www.diyelectriccar.com/forum...d-motor-works-35098p39.html?highlight=headway


Those are both very helpful -- thanks!

Everyone also seems to have gorgeous-looking copper or (zinc plated copper?) bus bars; I'm assuming those are custom machined according to the pack geometry?


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## njloof (Nov 21, 2011)

frodus said:


> Yes, you'll draw more current, but your peak power will be lower than you think, due to voltage sag. They're good batteries,
> 
> I've already tested at 5C, which is what I'm designing around. I don't really NEED to test cells for ya, there's 5/10/15C discharge curves all over.
> 
> ...


Ah, okay -- that's great. I see what you mean about the sag, with a nominal 320V pack at 10C I may be just over 250V. Still -- better than what I can get from CALBs at that discharge rate.


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## drgrieve (Apr 14, 2011)

I've collected some real world sag results from folks completed projects.

Unfortunately not many people post their results so I've only collected a few.

But Calb 100ah cells are good up to 8/9C burst, the 60ah should be better than that. I've heard (only spec sheets and manufacturer testing result) Sinopoly is slightly better.

Results for headway 8ah indicate 20C. I don't have results for 10a or 16ah, but from individual cell testing I've seen the 16ah is no where as good as the 10ah.

Thread is here: http://www.diyelectriccar.com/forums/showthread.php/cell-comparisons-please-contribute-62326.html


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## duedl0r (Nov 7, 2009)

With your setting of 81s5p you have a lot more sag:

At 10C you have: 210V 500A = 105kW
or 15C: 186V 750A = 140kW

though, I doubt your headway cell will live long with 15C.

81*5 cells will cost you around 8000.-

Edit: I'm talking about the 38120S cells..


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## njloof (Nov 21, 2011)

duedl0r said:


> With your setting of 81s5p you have a lot more sag:
> 
> At 10C you have: 210V 500A = 105kW
> or 15C: 186V 750A = 140kW
> ...


I was actually aiming for the H-40152S cells -- so, 15Ah instead of 10Ah -- but your point is well taken. Given the tests that have been done, I'm not sure the sag on these would be any better than an equivalent quantity of Sinopoly batteries -- and the Headways are a lot more work.


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## pgt400 (Jul 12, 2008)

njloof said:


> I was actually aiming for the H-40152S cells -- so, 15Ah instead of 10Ah -- but your point is well taken. Given the tests that have been done, I'm not sure the sag on these would be any better than an equivalent quantity of Sinopoly batteries -- and the Headways are a lot more work.


I've compared Headway 10ah cells to Calbs...there isn't much difference at all (my headways are the original blues from 10'). I would spec Headways at more like 3C continous, same as Calb (both sag to ~ 3v at 3C)....are new headways better? I don't know. When you compare how easy it is to make a pack with Calbs...its a know brainer IMO.


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## frodus (Apr 12, 2008)

Yeah, while they're good cells and it's nice to configure them into 10Ah increments for my motorcycle, it's a complete PITA to build a large pack. I wouldn't want to build one with 400 cells, that's for sure.


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## Yabert (Feb 7, 2010)

Right, not really much more power, cost more and....


Yabert said:


> *Question for you*: How many time do you need to complete the assembly of a 12.3 kwh battery pack with headway cells (more than 1300 parts)?
> *Answer*: A lot and a lot!!!!..
> 
> Tonight, I think about large prismatics cells!!! Trust me!! _(Hummm! 48 rectangular plastic block with only two terminal)._
> A good advice: If you have the extra space to put large prismatic in your car and if the extra weight isn't a real problem, go ahead with large prismatic cells! It's so much less trouble.


 
So, the only good reason to use this headway cells in large quantity is to save some space or build strange shape.


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## frodus (Apr 12, 2008)

At the time I bought 38120S cells, CALB weren't really around, so I passed on Thunderky batteries and Hipower. Plus the size constraints on my V4 honda frame, the prismatics didn't fit that well.

I'm still glad I bought them, they're super easy to replace just one (and I have spares), but I'd reconsider other options if I were doing it now. It's a bit of work.

Boils down to what you want to design around.


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## pgt400 (Jul 12, 2008)

frodus said:


> At the time I bought 38120S cells, CALB weren't really around, so I passed on Thunderky batteries and Hipower. Plus the size constraints on my V4 honda frame, the prismatics didn't fit that well.
> 
> I'm still glad I bought them, they're super easy to replace just one (and I have spares), but I'd reconsider other options if I were doing it now. It's a bit of work.
> 
> Boils down to what you want to design around.


Right, and A123 20ah cells make headways look easy to work with! However, they will happily output 5C plus AND hold 3 volts while doing so.


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## frodus (Apr 12, 2008)

Yeah, that is the nice thing about A123, I just wish they were easier to assemble. While the power levels are higher with A123, I was a bit surprised that the Headway batteries ran just 45 seconds less overall until depleted, albeit with higher sag.

Here's another graph comparing the 2 at 5C:











A123 20Ah cell and Headway 38120S cell both at 5C
A123 20Ah at 100A
Headway 38120S at 50A
CBA-II using CC400 amplifier
X is time, Y is voltage

A123 went for 11.78 minutes
Headway went for 11.00 minutes

Sag initial at 1 minute:
A123 20Ah: 3.132V
Headway 38120S: 2.825V

Sag at 5.5 minutes"
A123 20Ah: 3.103V
Headway 38120S: 2.9V

Power at 5.5 minutes and 5C:
A123 20Ah: 310.3W or 15.515W per Amp-Hour
Headway 38120S: 145W or 14.5W per Amp-hour

So a 81S pack, 80Ah equivalent lets say:
A123 20A (81S4P) power at 5C would be: 100.537kW
Headway 38120S (81S8P) power at 5C would be: 93.96kW
Difference of ~6.58kW


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## pgt400 (Jul 12, 2008)

Very surprising.... Over 10ah from a headway at 5C, I've never seen that. Mine came in about 9.5 ah at 1C. That headway graph is best I've ever seen...even from Headway! Have not found any discharge graphs pulished by A123....but 12 AH is very low. Docbass did a 5C test and got 18.2AH on ESI. Looks like a dud A123 and a Lucky Headway.


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## njloof (Nov 21, 2011)

pgt400 said:


> Very surprising.... Over 10ah from a headway at 5C, I've never seen that. Mine came in about 9.5 ah at 1C. That headway graph is best I've ever seen...even from Headway! Have not found any discharge graphs pulished by A123....but 12 AH is very low. Docbass did a 5C test and got 18.2AH on ESI. Looks like a dud A123 and a Lucky Headway.


That's not what that graph says. It says the A123 lasted 12 minutes at 100A (that's 20 Ah) and the Headway lasted closer to 10 minutes at 50 A (8-9 Ah).


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## pgt400 (Jul 12, 2008)

opps...my bad. Not used to seeing time on the x axis. Much better!


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## DavidDymaxion (Dec 1, 2008)

The 8Ahr Headway "P" cells are significantly more powerful than the other Headway cells.

The 8 Ahr "P" cell is rated for 25C continuous and < 0.004 Ohms of internal resistance.http://www.manzanitamicro.com/produ...page=flypage.tpl&product_id=61&category_id=29

The 10 Ahr cell (same size as the 8 Ahr P cell, BTW) is rated for 10C continuous and < 0.006 Ohms of internal resistance. http://www.manzanitamicro.com/produ...page=flypage.tpl&product_id=83&category_id=29

The 15 Ahr cell is rated for 10C continuous, but has < 0.008 Ohm of internal resistance -- meaning it'll sag worse than its 8 Ahr and 10 Ahr siblings. That's twice the sag of the 8 Ahr batteries, and 4x the sag per Ahr of battery! http://www.manzanitamicro.com/produ...page=flypage.tpl&product_id=84&category_id=29

The real benefit of a Headway is the 8 Ahr P cell with the high power and low internal resistance -- for the others the benefit is not much over a big prismatic cell.


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## frodus (Apr 12, 2008)

njloof said:


> That's not what that graph says. It says the A123 lasted 12 minutes at 100A (that's 20 Ah) and the Headway lasted closer to 10 minutes at 50 A (8-9 Ah).


I said:


> A123 went for 11.78 minutes
> Headway went for 11.00 minutes


This is from hovering over the actual endpoints on the CBA software. These are exact data points.

~47second difference


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## frodus (Apr 12, 2008)

pgt400 said:


> Very surprising.... Over 10ah from a headway at 5C, I've never seen that. Mine came in about 9.5 ah at 1C. That headway graph is best I've ever seen...even from Headway! Have not found any discharge graphs pulished by A123....but 12 AH is very low. Docbass did a 5C test and got 18.2AH on ESI. Looks like a dud A123 and a Lucky Headway.


Yeah, it's minutes. I did minutes to show back to back how they compare, since they're different AH capacities.


Straight from the CBA software:
The actual AH of the A123 20AH for 5C was 19.5922Ah
The actual Ah of the Headway 38120S for 5C was 9.1869Ah

But I never did a 1C test on the A123, so it's hard to compare how much less it would be than at 1C.


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## njloof (Nov 21, 2011)

frodus said:


> This is from hovering over the actual endpoints on the CBA software. These are exact data points.
> 
> ~47second difference


Yeah, sorry, I was just doing a back-of-the-envelope estimate to validate the general scale of the results. Thanks for posting your Ah actuals.


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## frodus (Apr 12, 2008)

No worries! Just wanted to clarify so things don't get misquoted later


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## pgt400 (Jul 12, 2008)

frodus said:


> Yeah, it's minutes. I did minutes to show back to back how they compare, since they're different AH capacities.
> 
> 
> Straight from the CBA software:
> ...


Yeah, I didn't even know the CBA could do minutes....nice feature and best way to do it. When did you run this? Where did you source your 20ah cell?


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## pgt400 (Jul 12, 2008)

"A123 20Ah, 3.132V" after 1 minute at 5C....these cells are beasts! I'm thinking once my pack is done, sag under 250 amp accel is going to go up from 68v to 75v. Going to need to upgrade my "400 amp" Kelly controller next...seems no matter which pack I have in I can't exceed 240 amps.


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## pgt400 (Jul 12, 2008)

"I was a bit surprised that the Headway batteries ran just 45 seconds less overall until depleted, albeit with higher sag."

Trav what were you surprised about? That the Headways made 9ah at 5C?

When a cell is speced at XC continous, what is the cell voltage used at XC continous for the spec? or is it cell temperature that used? I'm guess 3v?


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## frodus (Apr 12, 2008)

I mean, I think it's good that headway batteries lasted as well, they seem to be pretty good for the money, although with the A123 packs flooding the market, it's hard not to choose A123 for a pack.

For cell testing, you rate the Ah capacity at a 1C rate. Voltage varies like in the graph, so it entirely depends on where you are on the state of charge. Most of the middle is fairly flat, but as you can see, the cell voltage for 5C between 2 different cells is quite different.


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## pgt400 (Jul 12, 2008)

Not talking about AH test, understand thats 1C....talking about the C rate for continous. If a Calb or any cell is rated at 3C continous for example what is the voltage for the continous rating?


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## frodus (Apr 12, 2008)

Haha, good question. How does each manufacturer determine max C-rate.... Not sure. I guess I'd consider it the max continuous rate you can deliver without going thermal.... but I'm sure there's other markers too, like what would give the longest life, or acceptable sag.

In the end, it's kind of a crapshoot, there's no standard.


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## pgt400 (Jul 12, 2008)

frodus said:


> Haha, good question. How does each manufacturer determine max C-rate.... Not sure. I guess I'd consider it the max continuous rate you can deliver without going thermal.... but I'm sure there's other markers too, like what would give the longest life, or acceptable sag.
> 
> In the end, it's kind of a crapshoot, there's no standard.


No...continous C voltage is what I'm wondering? Max C I would guess to be 2.1 ? Or untill thermal runaway?


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## frodus (Apr 12, 2008)

I'm not understanding you then, explain more what exactly you're looking for.


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## pgt400 (Jul 12, 2008)

frodus said:


> I'm not understanding you then, explain more what exactly you're looking for.


What makes a manufacture state that their cells have a continous discharge rating of 3C, 5C, or "X"C? Is it down to a certain voltage? Or temperature? I usally for the current at 3V.


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## frodus (Apr 12, 2008)

Thats what I was trying to explain. There's no standard. It could be the C-rate that allows for XXXX cycles, or it could be the c-rate that allows a full discharge without going above XXX degrees C or maybe it's the c-rate that allows a cell to stay above XXXVolts for XX% of the discharge.

Since there's a curve to it, you can't really say 3V, it'll be just above that, and just below that on the beginning and end of discharge, obviously, so there's got to be a XX% attached to it....the "middle" part of discharge.

My thoughts are, since there's no standard, the manufacturers are left to their own devices to come up with their own standard.

The BEST way, is to discharge it yourself and see how the curve compares to others.


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## pgt400 (Jul 12, 2008)

Agreed..but than I'd have to buy every battery out there since not all manfactures post discharges beyond 1C. Understand the curve part of course, but there is a flat-ish zone in the middle. Even an average voltage at the rated continous discharge would be nice...or just a discharge plot at the rated cont dis.


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## frodus (Apr 12, 2008)

Oh wouldn't that be nice....

I have already started a small library of my own, just A123 M1, 20Ah, a Kokam and headway 38120s. I wouldn't mind maybe testing a few, but Problem is, once I get the cell, I need to keep it because I can't re-ship legally (hazmat issues) since I'm not a battery vendor.

I need to get my big ass discharger working


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## pgt400 (Jul 12, 2008)

"I need to get my big ass discharger working







" I assume you mean your bike?


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## frodus (Apr 12, 2008)

That too, but I was referring to this:










Should be good up to about 1000A


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## ricklearned (Mar 3, 2012)

I have had some bad luck with a recent order of 12 Headway cells that I ordered from Headway Headquarters in March. I didn't get around to testing them until the middle of April and 4 of the 12 had Ahr capacities of less than 5Ahrs. I tested them with my West Mountain Radio CBA III. I contacted Jim Delgado and arranged for an RMA and sent him a copy of the test results and the serial numbers of the cells in question. It has been a month now and after repeated phone calls and emails I have heard nothing. 

Does anybody know what is up with Headway Headquarters? I have had about 3 transactions with them in the past 6 months and they have all been good except for this latest one.


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## DavidDymaxion (Dec 1, 2008)

Sorry if this is asking the obvious. How do you know they were fully charged to start? Did you then charge them up to be sure they were full and retest?


ricklearned said:


> I have had some bad luck with a recent order of 12 Headway cells that I ordered from Headway Headquarters in March. I didn't get around to testing them until the middle of April and 4 of the 12 had Ahr capacities of less than 5Ahrs. I tested them with my West Mountain Radio CBA III. I contacted Jim Delgado and arranged for an RMA and sent him a copy of the test results and the serial numbers of the cells in question. It has been a month now and after repeated phone calls and emails I have heard nothing.
> 
> Does anybody know what is up with Headway Headquarters? I have had about 3 transactions with them in the past 6 months and they have all been good except for this latest one.


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## ricklearned (Mar 3, 2012)

DavidDymaxion said:


> Sorry if this is asking the obvious. How do you know they were fully charged to start? Did you then charge them up to be sure they were full and retest?


Yes, I charged them first and then tested them. I retested the ones that were rejected.


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## batterybill (Jun 6, 2012)

Good idea not to use prismatic folded cells, I think your estimation of using 3C discharge on this batteries is little too much to expect, my experience is not to go over 1C continuous discharge and 3C peak, you will end up with unbalanced cells and other issues, especially if you draw those currents around 70% DOD. Just suggestion, since I have done this before.


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