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I do not have XP on Mecer + LiFePO4's so do not know if constant float ever fills em to full?

Cause If they never go full I would rather bottom balance than top balance. Only reason I top balance is cause I use Lead acid and dont ever go below 50%
Fancy charger should have an Absorption phase.
 
Did you get the batteries as part of the same batch? cause it might be that they bottom balance, so top will give diff V readings.

LiFePO4's suffer from insta death if you run current through an empty battery.
I think they were just at different states of charge. They should have been fully charged with a fancy 12V charger before connecting in series. Not sure what you are saying about insta death.
 
LiFePO4 cells die when they 0% and you still pull current through them. Example when batteries are in series, and one has charge but second one is empty.
That's what the BMS is for. The whole bank will suffer, this is the weakness of series connection. It cuts off when a cell almost gets to 0% or over 100%. On the subject about top balancing the S-100, I think this only happens at 14.4V, a normal charger won't reach this voltage which is fine. top or bottom balancing is only needed if you want to use 100% capacity which we can't anyway with the mecer.
 
I decided to measure the voltages of my 2 Hubble batteries. Battery 1 is 13.97v and battery 2 is 13.27. my Mecer 24v seams to think this okay. What do you guys reckon? Do I need to balance them? If so how would you recommend I do that? I have a fancy charger that can charge PB, should I connect it to battery 1 and charge battery 2?
What you could also do is connect a small 5w 12v bulb to higher voltage battery, let it run for a hour , disconnect bulb and check voltage again, repeat till voltages similar
 
Did you get the batteries as part of the same batch? cause it might be that they bottom balance, so top will give diff V readings.

LiFePO4's suffer from insta death if you run current through an empty battery.
Not entirely sure what you mean. I am busy charging the lower voltage battery. I have been charging it for 6 hours now at 5 amps. It's sitting at 13.54v.
 
What you could also do is connect a small 5w 12v bulb to higher voltage battery, let it run for a hour , disconnect bulb and check voltage again, repeat till voltages similar
I will go get a 12v 5w light bulb tomorrow and do this as well. Will quicken the process. Thanks.
 
Not entirely sure what you mean. I am busy charging the lower voltage battery. I have been charging it for 6 hours now at 5 amps. It's sitting at 13.54v.
This is what a LFP voltage curve looks like:
xLiFePO4-discharging.gif.pagespeed.ic.EQVEXWFoto.png


and charging:
1637863657603.png
 
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I will go get a 12v 5w light bulb tomorrow and do this as well. Will quicken the process. Thanks.
What's the rush? It's very hard to gauge how full an LFP battery is by looking at the voltage. Better to use the charger and do a full charge on both. You will probably find the other battery not taking as long.
 
What's the rush? It's very hard to gauge how full an LFP battery is by looking at the voltage. Better to use the charger and do a full charge on both. You will probably find the other battery not taking as long.
There is no rush at all. I didn't realise it would take so much charge. What should I set the cutoff voltage to for these Hubble batteries? The charger us set it to 24.4. Not sure if that is correct.
 
There is no rush at all. I didn't realise it would take so much charge. What should I set the cutoff voltage to for these Hubble batteries? The charger us set it to 24.4. Not sure if that is correct.
What inverter is this? You can't set anything on the mecer.

Depends on how low you want to go, I guess anywhere between 24V and 25V.
1637866159792.png
 
What inverter is this? You can't set anything on the mecer.

Depends on how low you want to go, I guess anywhere between 24V and 25V.
View attachment 1201378

I have the Mecer inverter which cannot be adjusted.

I am using a charger I have for my LiPos for my radio control gear. I can manually set the cutoff voltage. I'll set it to 14v as per your guide.
 
I have the Mecer inverter which cannot be adjusted.

I am using a charger I have for my LiPos for my radio control gear. I can manually set the cutoff voltage. I'll set it to 14v as per your guide.
Oh, you mean upper limit cut off. How high can you go? Can you set it to 14.4V? Maybe the BMS will top balance the cells then?
 
Oh, you mean upper limit cut off. How high can you go? Can you set it to 14.4V? Maybe the BMS will top balance the cells then?
The cut-off voltage fully adjustable. It is currently set to 14.4. currently the battery is showing 13.57v under a 5 amp load. Unloaded it is 13.48v.
 
The cut-off voltage fully adjustable. It is currently set to 14.4. currently the battery is showing 13.57v under a 5 amp load. Unloaded it is 13.48v.
I would leave it on that setting. It's probably going to take a while. 5amp charger will take 20 hours to charge 100Ah.
1637872711802.png
 
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