What to do with chinese 48V 100Ah 19" battery

[PyroRider]

Hi, I have a chinese 100Ah 48V 19" Battery pack which has a cheap crappy seplos bms clone, horrible software and sadly one cell which is drifting away from the others. I am going to upgrade in may, so any ideas what to do with the chinese battery pack? Take it apart, throw a jk-bms with balancer in, test the real capacity (which is not even close to the 105AH they promise) and try to sell it somewhere in the diy community? or take it apart into a large 12 volt battery or 4 small 12V batterys? Or use the single cells for something?

 

[12VoltInstalls]

Take it apart, throw a jk-bms with balancer in, test the real capacity

Since you seem to have the skills and tools it might serve someone well if you figured out the cell that’s wonky and - depending on the results of that - throw a bms in and sell it to someone for $550. Too bad it has an issue; I wonder if you couldn’t replace the weakened cell with a cheap cell and use it?

 

[PyroRider]

Since you seem to have the skills and tools it might serve someone well if you figured out the cell that’s wonky and - depending on the results of that - throw a bms in and sell it to someone for $550. Too bad it has an issue; I wonder if you couldn’t replace the weakened cell with a cheap cell and use it?

My new cells will arrive in may, then I have the time and possibilities to take the current one apart, one problem I have regarding cell replacement is that the cells are welded to the busbars, I might be able to cut the faulty cell out but I'm not a 100% sure.

 

[Supervstech]

How many cells in the case?

 

[PyroRider]

How many cells in the case?

16

 

[Supervstech]

Good, at least it is a real 51.2V battery

 

[PyroRider]

Good, at least it is a real 51.2V battery

Yea but the chinese manufacturer really did a shitty job with that battery, I cant charge it over 55V because the one cell drifts away so much, all 4 temp sensors are glued on the same cm2 in one corner of the battery and arent even used by the bms, the promised charge/discharge currents are only 3/4 in reality, ... that pack of shit made me trouble for half a year until I gave up.
I could try to remove the faulty cell, make a bridge, put in a new bms with balancer and then sell it off as 15S pack

 

[time2roll]

Verify the bad cell and replace if needed. New BMS if needed and let it sit charged as an emergency reserve battery.

Possibly use it in parallel service to verify condition and sell.

 

[PyroRider]

Verify the bad cell and replace if needed. New BMS if needed and let it sit charged as an emergency reserve battery.

Possibly use it in parallel service to verify condition and sell.

New bms is definitly needed, wont trust the current one further than I can throw it. But I dont need a reserve battery, I have a 3.8kWp pv array and my new battery will be 15.5kWh (16S 304Ah cells) so there really is no need for another 5kWh, I'd rather sell it for a low price (like ~500€) to someone who actually needs it
Just now read your second sentence XD

 

[MisterSandals]

I cant charge it over 55V because the one cell drifts away so much

55V - 3.65V flier = 51.35V
51.35 / 15 cells = 3.42Vpc <-- thats pretty much full without loss.

Back it down to keep the flyer to 3.60V or something safe and you have VERY close to a full capacity battery.

 

[PyroRider]

55V - 3.65V flier = 51.35V
51.35 / 15 cells = 3.42Vpc <-- thats pretty much full without loss.

Back it down to keep the flyer to 3.60V or something safe and you have VERY close to a full capacity battery.

Thats what I'm doing currently, when the flier is at 3.6V all the others are at 3.3/3.4V (if I remember correctly, havent looked into the bms for a while)