Should I crack open my battery (spoiler: I did)

[Mr.M]

I bought a 12v 100ah Lifepo4 about 8 months ago. Brand/model: Vestwoods VC12100Plus. Used it without issue for a few months then let it sit unused at about 50% SOC for approx. 2 months. Wasn't connected to anything, just on a shelf in my house. Went to charge it up for a trip and noticed it wouldn't take a charge or connect to its Bluetooth app. Output at terminals is 5.5 volts. Since it does have Bluetooth I figured it must have drained it over the 2 months and it was in "sleep mode." Well, tried charging with a wake up capable charger and no luck. Also tried briefly connecting to another 12v battery without any luck. Output at the terminals still 5.5 volts. The (rather janky) android app for it is called "Pow Bank" and the battery seems to recognize the battery's Bluetooth ID when I search, but never successfully connects.

Vestwoods/ the amazon seller have honestly been good, and are sending me a replacement, but it's going to be awhile and I'd like to salvage this one for an upcoming trip if at all possible.

Anyone have any other suggestions before I try and crack this thing open and start poking around (using all the proper precautions ha). Any advice on what to check/look for once it's open is also appreciated. If I do open it I'll post pics, bms info, etc.

 

[cs1234]

I bought a 12v 100ah Lifepo4 about 8 months ago. Brand/model: Vestwoods VC12100Plus. Used it without issue for a few months then let it sit unused at about 50% SOC for approx. 2 months. Wasn't connected to anything, just on a shelf in my house. Went to charge it up for a trip and noticed it wouldn't take a charge or connect to its Bluetooth app. Output at terminals is 5.5 volts. Since it does have Bluetooth I figured it must have drained it over the 2 months and it was in "sleep mode." Well, tried charging with a wake up capable charger and no luck. Also tried briefly connecting to another 12v battery without any luck. Output at the terminals still 5.5 volts. The (rather janky) android app for it is called "Pow Bank" and the battery seems to recognize the battery's Bluetooth ID when I search, but never successfully connects.

Vestwoods/ the amazon seller have honestly been good, and are sending me a replacement, but it's going to be awhile and I'd like to salvage this one for an upcoming trip if at all possible.

Anyone have any other suggestions before I try and crack this thing open and start poking around (using all the proper precautions ha). Any advice on what to check/look for once it's open is also appreciated. If I do open it I'll post pics, bms info, etc.

Hit it with a solid 13 to 13.6 volts at 5-10 amps for 30 to 60 minutes and see if it takes any charge and wakes up. I know you said you used a charger capable of "waking it up", but it might want some serious current for a bit. Disclaimer, keep it somewhere flame retardant while charging cells you can't monitor.

What was the wake up capable charger sending during it's charge attempts?

 

[JWLV]

Some LiFePO4 batteries takes some time to wake up if it's been disconnected by the BMS due to over-discharge.
Do what @cs1234 said and connect it to a good power source. It may take even more than 60 minutes to finally wake up.

 

[Mr.M]

Hit it with a solid 13 to 13.6 volts at 5-10 amps for 30 to 60 minutes and see if it takes any charge and wakes up. I know you said you used a charger capable of "waking it up", but it might want some serious current for a bit. Disclaimer, keep it somewhere flame retardant while charging cells you can't monitor.

What was the wake up capable charger sending during it's charge attempts?

Thanks for the reply. The wall charger I'm using is actually one the seller sent me when I told them about the issue. It's a 20a charger and is sending 14.75 volts. I'm going to leave it hooked up for an hour and see what happens (hopefully not magic smoke).

 

[Mr.M]

Unfortunately, no change after an hour on the charger. I'm gonna carefully pop the case this evening and see what it looks like in there.

 

[Bud Martin]

How come you have Black probe of the meter in the 10A input terminal of the meter? That is not right.


Correct way.

 

[Mr.M]

How come you have Black probe of the meter in the 10A input terminal of the meter? That is not right.

View attachment 139590
Correct way.
View attachment 139591

Very simple explanation, I'm an idiot and forgot to switch it back ha. Thanks for the heads up. Sadly, I put the pins in the correct location and it still reads 5.5v.

 

[Mr.M]

Well, I opened it and took some pictures. Literally everything is glued together.

Here are some close ups of different parts of the bms in case anyone recognizes anything.



On the underside of the bms I did find one area of potential burn/damage. But it's hard to get a good look at without tearing things apart further.


Lastly, I connected my multimeter to the main pos and the neg terminal on the only accessible cell, bypassing the bms and got a reading of 12.81 volts. This is relatively good news right?

I am a total beginner, so I apologize for anything I'm saying that's wrong and greatly appreciate everyone's assistance.

My beginner guess is that something on the bms is fried and the bms is in a permanent protection mode, maybe I can just replace the bms? What do you guys with more experience/knowledge think?

Almost forgot, there is a small green light on the bms that blinks slowly, might not be helpful, but just want to include everything I found so that, if nothing else, people know what it looks like inside (haven't found a teardown on this specific battery yet).

 

[Rednecktek]

Yup! Looks like a failed BMS. Fortunately a BMS swap should be really easy, the harness looks pretty universal and you won't need to split the cells at all. If the company is sending a replacement then you can get a rocking battery pretty cheap! ?

 

[cs1234]

@Mr.M

Thanks for tearing it down and posting pictures. I have one of those batteries and now I'm sad.. that looks pretty shoddy. Fortunately I don't run it much over 10-20 amps most of the time. It was one of the least expensive lifepo4 batteries with bluetooth at the time, so I can't say I don't get what I deserve.

Once you tear it down further, some pictures of how the balance leads connect to the cells, and how the cells are connected together in general would be nice. All the stuff under the BMS basically.

 

[Mr.M]

@Mr.M

Thanks for tearing it down and posting pictures. I have one of those batteries and now I'm sad.. that looks pretty shoddy. Fortunately I don't run it much over 10-20 amps most of the time. It was one of the least expensive lifepo4 batteries with bluetooth at the time, so I can't say I don't get what I deserve.

Once you tear it down further, some pictures of how the balance leads connect to the cells, and how the cells are connected together in general would be nice. All the stuff under the BMS basically.

Glad to do it and I bought for the same reason. Will probably wait until I get a bms to tear into it further (can't wait to dig through all that spray foam ?), but will definitely post more pictures when I do! The one unexpected positive has been the customer service, they pretty much always replied within 24hrs and like said, are supposed to be sending out a replacement, at least gotta give them that.