Help: is my lifepo4 battery dead?

[SamTexas]

the pictures are so helpful. Thank you very much. Now I know what to look for. This is going to be my weekend project I think.

You are welcome. Good luck on your project. You'll have fun either way.

[dnmun]

it will only take 5 minutes to get it open, and measure the voltages on the cells. write down the voltages initially, then put it on the charger and record the voltages as it charges. you want to identify any cell that charges up faster than the others so pay attention and measure them all often and record the voltages as it charges. then you can graph the results and see which one charges up fastest.

[SamTexas]

it will only take 5 minutes to get it open, and measure the voltages on the cells.

Are you kidding? I took me 2 hours to do it. But I was extra careful and did not have any pictures to look at ahead of time.

[SamTexas]

SamTexas: when your BMS didn't charge, was you able to detect any life from the battery at all? did you see any led light up when you check for the battery level? In my case I don't see anything at all. It was just like the battery is completely dead.

There are 4 LEDs. Only the red LED lit up before the fix. After the fix, the three green LEDs lights up when full, and the red LED is not lit. Looks like (not 100% sure) that the red LED is lit only when the BMS thinks it's in trouble.

The pack voltage can always be measured from the 3 pin charging port (only 2 pins are used). Before the fix, the voltage at the charging port was 37V (max voltage is 42V for my 12s pack.)

[dnmun]

oh sam, i thought we finally got him to open it and you are spooking him, 2 hours and it will be solved.

really do not worry, you can take it apart and look inside without any problems.

it is easy really, get cordless screwdriver, set in reverse, 8 screws, zipzipzipzip , pull the end out and one end has to fold over to clear the inside of the tube, then slide the entire pack out the other end

flip it face down on the sense wires, take scissors and just run it up the blue shrink on the side facing up while the pack is laying on the carpet, from bottom to top, the sense wires are on the other side so no risk to the wires,

now unfold the sleeve, take off the plastic shields on the end where the terminal are exposed and put the voltmeter probes on each terminal of each cell, record and now you have got the info we need to figure out if it is dead.

[SamTexas]

oh sam, i thought we finally got him to open it ...

Sorry. My bad. Plus I was using a regular hand screwdriver

[dogman]

Good on ya for providing those pictures. You should get on the wiki and put them up there too. "how to diagnose a 36v 10 ah metal cased battery"

[SamTexas]

Good on ya for providing those pictures. You should get on the wiki and put them up there too. "how to diagnose a 36v 10 ah metal cased battery"

I can't. Mine is a 38.4V, 8.7Ah.

[dogman]

Well, just saying that was a great set of pics, and many could make use of them if they could be found again easily.

Many of us ES regulars haven't bought batteries of that type since we tend to be hot rodders. But we'll see more guys with one that is not working, just like we have with other types.

So whatever that pack is called, a wiki entry would be a good thing. Or just a thread with a title appropriate to making it easier to find in a search.

[SamTexas]

Well, just saying that was a great set of pics, and many could make use of them if they could be found again easily.

Many of us ES regulars haven't bought batteries of that type since we tend to be hot rodders. But we'll see more guys with one that is not working, just like we have with other types.

So whatever that pack is called, a wiki entry would be a good thing. Or just a thread with a title appropriate to making it easier to find in a search.

I know. Just pulling your legs.

[luvxu]

ok, it is official. My battery is truly dead. I was able to remove it from the aluminum casing and found that it had exploded. The smell of it was so bad that my wife quickly banished me to the garage. The BMS is totally burned. I just don't know what could have happened???

BTW, the brand name of this battery is TEHAO.

[SamTexas]

Wow! Are you sure it's LiFePo4 battery? Could it be LiCo or LiMn?

Never mind. I just looked at the link you provided in the first post. That's strange though. I thought LiFePo4 is a safe chemistry.

[dnmun]

ok, you answered your own question. you did ok. the BMS and the case may be useful for parts. it will be landfill gas next.

[dogman]

Wow. We can say now that it's dead allright. Puffed cells like that are toast. Too bad. Saving the bms might not be worth it,if a bms malfuntion lead to the battery death. It may have been allowing you to overdischarge it for example. I wouldn't know how to test the bms myself.

It was safe, it never burst into flames despite obvious damage. When I killed a 36v 20 ah lifepo4 with overdischarge, it also did not light my garage on fire, or even melt the tape on the battery. All it did was swell up like mad. In my case, I left a battery connected to a controller that was turned on, and went off to have west nile virus for two weeks. When the fever broke, I went to ride the bike and found the battery murdered. Presumably my bms low voltage cutoff did not work to save the battery.