JP

[JP tankwa off grid]

Hi everyone new to forum. 
We live out in Tankwa and I have discovered this week that I voltage problem on my 48v lead crystal battery bank. 
System is about 4jrs old and all of a sudden just can’t give me much capacity. I fear the worst and suspect some of my batterys are now damaged as I get different voltages across all eight batteries two banks of 48v. Can I put a battery balancer HA-02 across bank to help with problem or is all lost and I have to get new batteries. 
Appreciate your input. 

 

[Coulomb]

6 hours ago, JP tankwa off grid said:

I fear the worst and suspect some of my batterys are now damaged as I get different voltages across all eight batteries two banks of 48v.

They may well be damaged beyond repair. But there is some hope. Try to bring them all up to about the same voltage (when rested) with a car battery charger. Make sure the car charger is isolated, or disconnect the battery module before charging it. You can possibly still limp along on one string, while the other string is disconnected, charging its weak modules.

6 hours ago, JP tankwa off grid said:

Can I put a battery balancer HA-02 across bank to help with problem

That's a good idea, but it's probably too late now.

If any modules are settling around 10 V or 8 V, then one or two cells have likely collapsed to zero volts. They rarely can be resurrected from that condition, but it can happen, especially if they don't spend too long in that condition. Your battery charger may refuse to charge them, however, in which case you could try a current limited power supply set to around 14.5 V and maximum current limit.

[JP tankwa off grid]

3 hours ago, Coulomb said:

They may well be damaged beyond repair. But there is some hope. Try to bring them all up to about the same voltage (when rested) with a car battery charger. Make sure the car charger is isolated, or disconnect the battery module before charging it. You can possibly still limp along on one string, while the other string is disconnected, charging its weak modules.

That's a good idea, but it's probably too late now.

If any modules are settling around 10 V or 8 V, then one or two cells have likely collapsed to zero volts. They rarely can be resurrected from that condition, but it can happen, especially if they don't spend too long in that condition. Your battery charger may refuse to charge them, however, in which case you could try a current limited power supply set to around 14.5 V and maximum current limit.

Thanks for quick response. I have already done as you suggested and took one string of paralleled batteries and connected charger for 24hrs. I left them for 24hrs again to let them settle and measured them they are all sitting at 13.01v to 13.07v which I take is a good sign. I have ordered HA-02 but it will only arrive in 8days so will have to take care until then. Hopefully not to bad but let’s hope for the best. 
I still think good old big lead acid batteries 6v might be the way to go other than lithium iron batteries as the temperature can get in to high 40’s in summer here. So if I had to replace will go with them. 
Thank you. 

[Coulomb]

3 hours ago, JP tankwa off grid said:

they are all sitting at 13.01v to 13.07v which I take is a good sign.

Yes, that's a great sign.

Did you charge the 12 V modules separately with (a) 12 V charger(s), or all together in series on a 48 V charger? The former would have been better.

[JP tankwa off grid]

3 hours ago, Coulomb said:

Yes, that's a great sign.

Did you charge the 12 V modules separately with (a) 12 V charger(s), or all together in series on a 48 V charger? The former would have been better.

Hi there. I connected 4 -12v cells in parallel and then charged them, but what I have noticed is the car charger can’t get charge voltage over 14.2v. 
So tomorrow I’m going to connect all eight cells in parallel and then connect one 450w panel on 12v PWM charger that can deliver 10amps. That should get voltage up I hope.Does my plan sound like it could work or do you have another suggestion. 
I would like to leave them charging during the day and off at night for about ten days. 
Would be great to hear what you think. 

[Coulomb]

I don't think that 10A will be enough for 8 modules in parallel. Perhaps pairs or singles on whichever charger (car charger or panel) can supply the most current. The 450W panel won't supply anything like nominal power at 14V. [ Edit: I know it's a lot more work. ]

It's also hard to parallel many modules effectively. One or more will end up taking more charge current than the average. Use diagonal connections where possible.

Edited May 4, 2021 by Coulomb

[JP tankwa off grid]

13 hours ago, Coulomb said:

I don't think that 10A will be enough for 8 modules in parallel. Perhaps pairs or singles on whichever charger (car charger or panel) can supply the most current. The 450W panel won't supply anything like nominal power at 14V. [ Edit: I know it's a lot more work. ]

It's also hard to parallel many modules effectively. One or more will end up taking more charge current than the average. Use diagonal connections where possible.

Great! I will do that. 
Appreciate your input.