Mecer 2400VA Inverter (Community Support)

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AlphaJohn said:
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%
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Fancy charger should have an Absorption phase.
 
AlphaJohn said:
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.
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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.
 
AlphaJohn said:
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.
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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.
 
Georgios said:
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?
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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
 
AlphaJohn said:
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.
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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.
 
thehuman said:
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
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I will go get a 12v 5w light bulb tomorrow and do this as well. Will quicken the process. Thanks.
 
Georgios said:
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.
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This is what a LFP voltage curve looks like:
xLiFePO4-discharging.gif.pagespeed.ic.EQVEXWFoto.png


and charging:
1637863657603.png
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Georgios said:
I will go get a 12v 5w light bulb tomorrow and do this as well. Will quicken the process. Thanks.
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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.
 
wingnut771 said:
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.
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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.
 
Georgios said:
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.
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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
 
wingnut771 said:
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
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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.
 
Georgios said:
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.
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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?
 
wingnut771 said:
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?
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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.
 
Georgios said:
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.
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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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