diy solar

diy solar

Lifepo4 dead HELP

Ok i will try that. Altho is
Texas-Mark said:
Ok, then it looks like your cable is good (did not think it wasn't). So all I can think of short of replacing the BMS, is my suggestion above. Discharge it until the BMS cuts it off. Then try again.
Click to expand...
Ok i will try that. Altho it will shut down pretty quick being as the bms is already showing the voltage very low bcuz of only 3 cells.
 
If i have to change the bms. Wat bms would o use being as i dnt think this would be available to buy and id need the battery to go bk into series parallel with the other 3
 
I connected a load and now the bms shut down and at the terminals the voltage is at 5.96
 
Mickie said:
How whould i do that?
Click to expand...
Connect the negative terminal of the load directly to the negative terminal of the cell that currently goes to the BMS. You should still be able to monitor cell voltages with the app.
 
At the main negative and positive of the battery im getting 13.37 and it the terminals 5.97
 
Texas-Mark said:
Connect the negative terminal of the load directly to the negative terminal of the cell that currently goes to the BMS. You should still be able to monitor cell voltages with the app.
Click to expand...
Ok this sound like a good idea. Ill do that but keep monitoring to make sure they dont drain too far.
 
Mickie said:
At the main negative and positive of the battery im getting 13.37 and it the terminals 5.97
Click to expand...
If there is nothing except a BMS between the battery and terminals, it has to be a BMS issue.
Have you tried testing the balance wire voltages at the connector going into the BMS?

pin 1 is negative (connected to negative battery end cell)
pin 1 to pin 2 = ~3.2V
pin 1 to pin 3 = ~6.4V
pin 1 to pin 4 = ~9.6V
pin 1 to pin 5 = ~12.8V

what do your pin voltages measure?
 
Mickie said:
Ok this sound like a good idea. Ill do that but keep monitoring to make sure they dont drain too far.
Click to expand...

I will be curious to see if all of the cell voltages drop more or less evenly since the BMS seems to be contradicting it's self (showing 4 cell voltages, but saying it's a 3 string).
 
MisterSandals said:
If there is nothing except a BMS between the battery and terminals, it has to be a BMS issue.
Have you tried testing the balance wire voltages at the connector going into the BMS?

pin 1 is negative (connected to negative battery end cell)
pin 1 to pin 2 = ~3.2V
pin 1 to pin 3 = ~6.4V
pin 1 to pin 4 = ~9.6V
pin 1 to pin 5 = ~12.8V

what do your pin voltages measure?
Click to expand...
3.02
6.42
9.7
13.1
The cells arent balanced so i guess thats the voltage for each cell dont look like they should but thats essencially what it looks like.
 
Texas-Mark said:
I will be curious to see if all of the cell voltages drop more or less evenly since the BMS seems to be contradicting it's self (showing 4 cell voltages, but saying it's a 3 string).
Click to expand...
When the battery was working ok once the pack voltage was under 13.7 they balance. To . 001v under load, charging and at reat. Its just when it reaches above 13.7 they start drifting alot.
 
I connected the inverter to the main negative and positive of the battery now and running some load so once the inverter cuts out ill try waking up the bms to see if all 4 cells come back online. Fingers crossed.
 
Mickie said:
From here left to right.
Click to expand...
Hmmm. Sounds like the BMS bit the dust or you are missing a setting somewhere.
I had one die in a 'cheap' lifepo4' I got off Amazon, seller replaced the entire battery.
If you want to replace the BMS check current connected, overkill solar and even amazon
 
If it is the bms that is damaged. Could i still connet the battery to the other battery in series and make a 24v pack. Would the bms from the other batter be able to shut down over voltage and undervoltage for both battries?
 
Mickie said:
Its just when it reaches above 13.7 they start drifting alot.
Click to expand...
So it works just fine except when charging over 13.7V? This sounds like a rogue cell issue.
It may be a situation where you need to live with this and manage your charging to work best with this reality.

If you can get to 13.7V with all cells at ~3.425V you will be getting over 95% capacity from your battery. If you can set to charge to this point (or where ever they can be charged without runaway cell(s)) and set the absorb voltage for as long as possible, there is not reason you cannot get full capacity from your battery.
 
MisterSandals said:
So it works just fine except when charging over 13.7V? This sounds like a rogue cell issue.
It may be a situation where you need to live with this and manage your charging to work best with this reality.

If you can get to 13.7V with all cells at ~3.425V you will be getting over 95% capacity from your battery. If you can set to charge to this point (or where ever they can be charged without runaway cell(s)) and set the absorb voltage for as long as possible, there is not reason you cannot get full capacity from your battery.
Click to expand...
Yea i had it set to 3.5. 1 cell was always way off the others. So ur correct about the rouge cell. I could live with that.
 
MisterSandals said:
So it works just fine except when charging over 13.7V? This sounds like a rogue cell issue.
Click to expand...

Did you see the other issue where the BMS is reporting it as 3 string instead of 4 string? There seems to be something else wrong with the BMS other than the one cell. But that is why I asked him to drain the battery to see what that does to how the BMS reports.
 
Texas-Mark said:
Did you see the other issue where the BMS is reporting it as 3 string instead of 4 string? There seems to be something else wrong with the BMS other than the one cell. But that is why I asked him to drain the battery to see what that does to how the BMS reports.
Click to expand...
I should butt out as i have not been following as closely as you have. Sorry, good luck to all.
 
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