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DIY - A123 Systems Lithium-Ion Battery repair?

52K views 61 replies 32 participants last post by  ericdelage 
#1 ·
This DIY is a bit different, because I have already opened my battery, I have discovered what is broken, but I'm not quite sure just yet how to fix it! I'm hoping one of you can help! We are going to need someone with a background in electronics to point me in the right direction, so lets get started investigating just what really is inside your mysterious lightweight McLaren car battery?

BUT FIRST - The "WHY?"

I dropped my car off at the body shop 2 weeks ago to have an annoying scratch touched up, and somehow they let the battery drain all the way down. Now what I don't know is what exactly happened after that? Maybe they tried to jump start it? Maybe they crossed the positive/negative just for a millisecond? Maybe they read the owners manual and they did everything exactly by the book and used my battery charger, etc. Well, We will never know for sure... but what we do know is now my 3,000.00 battery is kaput!

I still have not accepted reality and I still want to fix the battery myself, even if to just to say I did it and prove it can be done! I know in the end I may have to pony up and buy a new one, but I am not the kind of guy to not investigate all options before handing over my money.



Your 12C will run a standard lead acid battery! (The owners manual even says you can do so in an emergency).

Things I learned running on a lead acid battery:

1) 100.00 at the auto parts store and your back on the road again!
2) lead acid battery's are HEAVY!
3) You will lose some functionality
4) The battery meter will always read "zero" and the car will play it safe and will not allow you to roll your windows all the way up that last 1/4 of an inch. I'm sure this is so you can still open the doors if the battery really was "zero", but it is annoying none the less.
5) Just when you think your windows are destined to be slightly cracked forever, after about 15 minutes they suddenly rolled themselves all the way up! Don't get too excited, the whole process starts over when you restart the car.
6) The car does not trust me anymore. If I put it in reverse with out my seat belt on, the parking brake will reengage itself. This makes you stop. Unexpectedly. After you are already moving.
7) My park sensor/side mirrors switch flashes red at low speeds, and give a long beep when I reverse. Not sure why?
8) I feel disadvantaged knowing I have 35+ extra pounds up front now. I can't wait to get back to normal with my super expensive Lithium Ion battery.



Now lets talk about the technology. "A123 Systems" manufactures these great little Lithium-Ion power cells that are very versatile and modular allowing an infinite number of configuration possibilities. Way back in 2009/2010 they partnered with McLaren and configured 12 individual Lithium-Ion power cells into a tidy little package to become the primary battery power source for our beloved 12C's.

There are 3 main components inside the battery:

1) Power Storage - Once A123 Systems stacks the 12 Lith-ion cells side by side, they then solder the +/- tabs into groups of 3 creating 4 cells approximately 3.40 volts each. Those 4 cells are then wired in a series configuration allowing the voltage of each cell to add to the next bringing the total voltage to around 13.60 volts. Perfect for starting a car! (I am aware amperage and current draw are also part of the equation. The batteries sticker says this configuration is good for around 400 amps)


FYI - Turns out My 'Power Storage' part of the battery is super healthy! None of the cells are swollen or puffy, and they all have the correct voltage. This is the heart of the battery, and I'm happy that it is ok.


2) Power Management PCB - Ok, I'm sure some other people here can describe this better and in a much more technical sense than i can (and I'm hoping you guys are gonna help me out with the solution to fix this battery as well). Basically there are two circuit boards inside the battery. One is a very low current device, and it looks to be the brains of the operation. In order for the 12 individual cells to work together you need a smart charging solution that can monitor and charge each of the 12 packs individually, yet allow them all to work together to provide a combined amperage and voltage to run the starter and other electronics on-board the MP4-12C.

3) Heavy Duty Power distribution - The second circuit board looks very heavy duty and I believe it is the heart of where all this voltage and amperage is either combined or separated when it comes to charging each cell individually.


If you look at the pictures below you will see the process of cutting the battery open, how it is assembled, and finally you will see my heavy duty circuit board went up in smoke on the negative rail side.


Please, any of you super-intelligent electronics experts! Can you tell by looking at this board if the parts needed are common? I can only comment that it looks very similar to a MOSFET device used in an audio amplifier. Hopefully it is common, and an electronics repair shop can do the work? Looking forward to all of your responses!
 

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#6 ·
A guy can hope! I have sent them two emails and still no response. They do not have published phone numbers...

Also, a quick call to my Mac Dealer and this battery is old news. The part number has been superseded and to use the 2500.00 new battery that replaces it, one must also purchase a 600.00 retro fit kit.

That information in itself means there are no spare replacement boards sitting around for purchase. FYI - the board that went up in smoke is dated 2010.
 

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#4 ·
Was the battery accessed directly at the body shop? Were panels removed to expose it?

If so, quite possible they used a high-amperage jump box to try and start it...maybe even one of the plug-in style.

LiFePo4 batteries do not like to be charged at too high a rate...thus the battery management circuitry. And if you shove too much down it's throat, bad things happen.
 
#5 ·
Yes, the battery was already exposed before I dropped it off at the body shop. I had just completed my DIY moldy headlight repair and I had just left all the screws out until the entire project was completely finished. I have considered pressing the body shop for the cost of the battery, but I use this body shop extensively and I might win this battle, but ultimately lose the war. Does that make sense?

Additionally, the evidence is completely circumstantial, I only have a strong suspicion why the battery is cooked. Their is still a chance that it was just gonna happen regardless due to a complete discharge cycle happening.
 
#7 ·
Those are power MOSFETs and are easily damaged. When they fail, they short in most cases. Basically, you (or someone you trusted with your car) let the smoke out.

They can be replaced, its not a big deal to do so. The key becomes if everything goes back to normal again. If it does, you are golden. If not, you will need to look at the logic board to see if something on the "driving" side is not functioning. This can be more difficult.

BTW, if I had to guess, the only reason to use soooooo many high power MOSFETs in a design is to do high side switching. Basically, the FETs are acting as a switch to disconnect the positive side of the load from the car. This requires that the driver board generates even higher voltages to "switch the MOSFETs on". It is an overkill way to prevent deep discharge of the battery (which kills the A123 cells) as the battery simply disconnects itself when any one cell's voltage drops too low. Expensive but overkill effective.

For what its worth, I use a six cell LiFo battery from Ballistic on my MX2. That little 2.75 lb battery will hot start an IO-540 with 10:1s multiple times which is no easy feat. https://www.ballistic-batteries.com/main.php
 
#8 ·
Those are power MOSFETs and are easily damaged. When they fail, they short in most cases. Basically, you (or someone you trusted with your car) let the smoke out.

LOL! Thanks Lolachampcar. My first career was as a Car Audio Installer and I'm pretty comfortable around all things 12 volts. As we used to say in the business when someone fried an electronic component, "Once you let the smoke out, you cannot put the smoke back in". :laugh:
 
#9 ·
#10 ·
From the hot spot board burn those are likely the failed MOSFET devices. Perhaps you could remove one of the board end MOSFETS and check the devices characteristics on a curve tracer to determine a replacement MOSFET device part number. From the number of pins they appear to be dual MOSFET packages.
Also if some one has access to a "bad" battery, maybe your friendly Dealer?, would give it to you and you could extract and reuse the MOSFET board.
Interesting project
 
#11 ·
Lithium ion batteries are not easy to repair. these batteries are having compact structure and there electronic design is difficult to understand easily.

So mainly these batteries are cheaper than the lead acid batteries, or we can say these are the use and throw batteries.

If we try to repair it or just open it, then it is of no use. And it is dangerous to open it for repairing.
 
#16 ·
Do the MOSFET's have a part number on top of them? If you cannot order the board, I'd give it a shot and replace all of them, not just the bad ones. But DON'T put the battery back in the car. After you've replaced the MOSFETs, use your battery tender outside to test the charging. I'd then run a load (outside) on the battery for an hour and then charge again. After you've successfully tested the battery, then put it all back together and install.
 
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#22 ·
UPDATE!!!

THE LITHIUM-ION BATTERY IS REPAIRABLE!!!!

I finally got around to reassembling my Lithium-Ion battery after having the MOSFET's replaced. IT works PERFECTLY!!!! The Lithium Ion cells even held a full charge for the last 6 months all the parts have been setting "apart". The battery has been back in my Mac for two weeks now and it's like I never had any issue. My battery meter reads 100% charged as well.

pics!
 

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#29 · (Edited)
4s3p g15a2ps06

That did it. Now I know what you have. You have a prismatic cell battery pack with 4 cells in series and in 3 parallel (12 cells total). The mosfets are in parallel to handle the startup current. Other than that it looks like a standard battery protection circuit (BPS). It looks like a prismatic version of a battery pack for E-Bikes. (99% of that was said in the OP, I'm a Dumbass sometimes)

Glad you got it fixed! Who did your soldering work on the board?
 
#31 ·
I actually found this thread when researching a possible battery issue in my daily driver (2015 Mercedes S63 Coupe).

It is an A123 Systems, 78Ah / 1030 Wh, 13.2v lithium battery. Mercedes charges about $1400 for these, part# A001-982-90-08. No idea if it would work in the McLaren but might be worth looking into rather than paying $3000+ to a McLaren dealer for a new one.
 
#32 ·
I am dealing with a dead battery in my 2013 12C Spider. I have been in contact with Braille Battery as I ordered a battery through Jeggs that we thought would work as a replacement, however, after talking to them it seems the battery only has 2 posts and the McLaren battery has a 3rd input to control electronics within the car. Braille advised me if I get the battery out of the car, they can refurbish the old battery. See their comments below. I did talk to a contact at a McLaren dealer and he advised for me to check if the tender is bad, then take the trunk out and try to battery pack jump it, if not, it is toast. Keep in mind this car only has 2500 miles and is always on the lithium ion tender when not in use. So at this point, I am sure the battery is toast and needs to be rebuilt or replaced.

("Now, there is one thing about the setup they have in those cars is that there is a plug on the OE battery that communicates with the car and not sure how the car works without that info. Have you heard or read about anyone using a battery other than the original battery and not having the dash board light up or anything like that? Our batteries are all direct replacements to any other “dumb” battery, but not sure how it works in the street car compared to every other car we have our batteries in.

Another option, which we have done several times, is to actually rebuild the OE battery that the customer sends in. We test to make sure the electronics are still good and then put our race pack into the existing case and it can still plug into the car the same as before. This is a $2500 upgrade and would give you more power & capacity than the B128L (because it is larger & heavier), so that may be an option you may want to consider unless you know that the car works fine without being plugged into the battery. I would assume someone on the forums has tried something like that?

If you want to go that route and ship us the stock battery, we can certainly look at going that route. It will take a little longer, but is certain to work. Just an option and somewhat surprised that some of the customers we have done this rebuild for haven’t passed along that option.)
 

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#35 ·
Braille advised me if I get the battery out of the car, they can refurbish the old battery. See their comments below. I did talk to a contact at a McLaren dealer and he advised for me to check if the tender is bad, then take the trunk out and try to battery pack jump it, if not, it is toast. Keep in mind this car only has 2500 miles and is always on the lithium ion tender when not in use. So at this point, I am sure the battery is toast and needs to be rebuilt or replaced.
This backs up my theory that keeping batteries on tenders wears the batteries way way more than leaving them off tender. Knock wood, dont want to jinx it, but my car is a 2012, over 26000 miles, regularly go 8 weeks without driving it during winter time, and still fine.

I've noticed a loose correlation of battery deaths in the forums from those keeping it on tender regularly.
 
#33 ·
yogi95 - The plug on that battery looks incredibly similar to the OEM McLaren battery!

Can you take a picture of the inside of the 3rd small electrical connector on the OEM McLaren Battery and also a picture of the same prong inside the connector on the aftermarket battery? basically a side by side comparison?

Please ask the aftermarket battery company to provide a wiring schematic of what the wires in there battery were designed to connect to? and what application was that battery designed for?

Thanks!
 
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