What did I just buy for $400? TWO 48v Server Rack Batteries

[boarder2k7]

I was looking at Facebook Marketplace earlier today and came across someone selling a PAIR of server rack batteries in unknown condition for $400. Figured at that price I couldn't lose, so I hopped in the car and snagged them. Cases are pretty beat up looking with bent rack ears and some dents, and the display on one is smashed. No big deal at that price.

Got them home and put 48v on the one with the good display to wake it up. Scrolled through the menu and found the BMS in "protect" mode, one of the cells was reading double voltage, and the next door cell 0v. Popped the cover off and found a broken balance wire and a couple loose screws on the balance leads, quick soldering job and some tightening and the BMS came out of protect mode.

Now the interesting question is that the pack is showing 49V, but a 0% SOC. I grabbed the only load tester I had and was able to pull 3.5 amps from the pack (maxing out the tiny load tester) and it seems to behave normally.

It's reading the following, so a little weird.
SOC: 0%
SOH: 100%
RM: 0.00 Ah
CC: 100.00 Ah



More pictures can be found here:

https://imgur.com/a/QCNbtaJ

I haven't started looking in to the one with the smashed display yet, I'd appreciate any help identifying these so I could source replacement parts and figure out the weird BMS readings where it thinks it is at a 0% SOC while being at a voltage that would make me expect 70% SOC.

Thanks for any help

 

[AntronX]

LOL @Smeeg you snooze you lose.

 

[boarder2k7]

Hahaha that's too funny!

 

[JWLV]

Sell the other one to Smeeg for $200?

 

[AlpineJoe]

Any issues with 15 cell vs 16 cell 48V packs? Guessing not given the wide range in voltage from drained to full.

 

[DVD]

Bonanza!
You scored big time! Deep cycle it and see if SOC resets

 

[Partimewages]

Any issues with 15 cell vs 16 cell 48V packs? Guessing not given the wide range in voltage from drained to full.

You shouldn't parallel the two in the same system. Pick one or the other.

 

[boarder2k7]

Can anyone recommend a good coulomb meter to use for testing and monitoring going forward? Something I could integrate into Home Assistant would be ideal.

 

[42OhmsPA]

Can anyone recommend a good coulomb meter to use for testing and monitoring going forward? Something I could integrate into Home Assistant would be ideal.

Victron smart shunt would probably be your best bet. Current Connected should have them.

I've been happy with my Won Von (juntek clone) but I don't know if it will communicate with HA.

 

[740GLE]

Can anyone recommend a good coulomb meter to use for testing and monitoring going forward? Something I could integrate into Home Assistant would be ideal.

Always Victron!

 

[Smeeg]

Damm you beat me to it by a couple hours the guy seemed like a dick on messenger. Hope it works out for you

 

[Smeeg]

https://www.aliexpress.com/i/3256805452399918.html?gatewayAdapt=4itemAdapt

 

[Smeeg]

https://www.msn-battery.com/lithium-battery/telecom-lihthium-battery/

 

[boarder2k7]

Damm you beat me to it by a couple hours the guy seemed like a dick on messenger. Hope it works out for you

He said he had a bunch of people lined up for after work, first come first serve. I took advantage of my flex time at work amd took a long lunch instead

He seemed fine enough to me and was nice enough in person I suppose. Sorry he was rude to you.

Thanks for the links, I tried contacting a couple of the companies with identical pictures and none seemed interested in selling me just a BMS so I guess I'm looking elsewhere.

The BMS in these units seems to turn itself all the way off after no charge/discharge for an extended period of time, I looked this morning and the status lights were no longer flashing after having used it for those basic tests 2 days ago. Will be interesting to see how it turns out, might need two BMSs.

At the very least as far as I could tell all cells were charged to a reasonable range so hopefully there is useful life left in these even if they both require a new BMS.

 

[boarder2k7]

I pulled the one with the smashed screen apart tonight. It was dropped pretty darn hard on the front face, I'm surprised the case didn't show damage from that happening. The internal support bracket was crushed up against the back of the BMS and one of the negative cables was cut by the event, BMS is totally smashed.

https://imgur.com/a/YzM3nVz

The good news is all the cells clock in at a 3.27v across the board on the second pack so those cells are probably alright as well.

Is it normal for a BMS to fully shut down after left disconnected from a power source/sink for an extended period of time?

 

[boarder2k7]

Bonanza!
You scored big time! Deep cycle it and see if SOC resets

SOC has started coming up as I've gotten it charged over 50V. I can only charge at 5 amps and don't really trust this charger unattended so it'll take me a bit. I have it up to about 30% SOC now though