LIFEPO4 Battery discussion thread

wingnut771 said:
and what about the 6 2V cells inside the 12V gel?

Anyway, if cavedog had patience then he wouldnt have to do a thing.
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I was going to ask, surely Lifepo4 is so common, and not everyone is technically inclined to do this stuff. But there are PV installs everywhere.

So just time is needed and the balancer takes care of it? Otherwise, we would be hearing about more of this by now.
 
cavedog said:
Yes I just want to be sure the balancer kicks in. Since i have no access or even an understanding of how the balancer works I'm sure at 3.5v the balancer will kick in if its passive.
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Just add it back to the bank and set inverter to 56V and move onto bat 3. Start with 54V overnight and see if you can bump it to 54.5V in the morning then 55V overnight then 55.5V in the morning then 56V overnight.
 
denmendez65 said:
I was going to ask, surely Lifepo4 is so common, and not everyone is technically inclined to do this stuff. But there are PV installs everywhere.

So just time is needed and the balancer takes care of it? Otherwise, we would be hearing about more of this by now.
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Most people arent even aware. Its only us OCD types that know the difference between kW and kWh.
 
denmendez65 said:
I was going to ask, surely Lifepo4 is so common, and not everyone is technically inclined to do this stuff. But there are PV installs everywhere.

So just time is needed and the balancer takes care of it? Otherwise, we would be hearing about more of this by now.
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Btw out of interest did some checking on how balancing is done in the cells for LA.

Main differentiator between the cells of LA and Lithium is that with Lithium you get a sharp rise in voltage when the cells are fully charged and the inverter/bms kills the charge.

With LA, you can hold the batteries at absorption/float for a long time without damaging them as if one of the cells got to the respective full charge voltage first before the others, it just gases but little to no damage is done to it. They vent through the valves. The others have plenty of time to catch up while being kept at that voltage.

Flooded LA has the advantage of Equalisation also. That forces whatever internal cells that are unbalanced to be balanced also.
 
wingnut771 said:
Most people arent even aware. Its only us OCD types that know the difference between kW and kWh.
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Cavedogs experience has definitely put me off Pre-built Lifepo4 batteries lol. The outdoor enclosure will definitely have a DIY bank if done with Lifepo4.
 
denmendez65 said:
Btw out of interest did some checking on how balancing is done in the cells for LA.

Main differentiator between the cells of LA and Lithium is that with Lithium you get a sharp rise in voltage when the cells are fully charged and the inverter/bms kills the charge.

With LA, you can hold the batteries at absorption/float for a long time without damaging them as if one of the cells got to the respective full charge voltage first before the others, it just gases but little to no damage is done to it. They vent through the valves. The others have plenty of time to catch up while being kept at that voltage.

Flooded LA has the advantage of Equalisation also. That forces whatever internal cells that are unbalanced to be balanced also.
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Thats what equalisation setting on inverters does, it overcharges the battery so the low voltage cells rise again while the high cells boil without going higher. You could have a fully charged 12V battery at 14V but it could be 1.5+2.5+2.5+2.5+2.5+2.5 instead of 2.33+2.33+2.33+2.33+2.33+2.33.

1780336999061.png
 
wingnut771 said:
Thats what equalisation setting on inverters does, it overcharges the battery so the low voltage cells rise again while the high cells boil without going higher. You could have a fully charged 12V battery at 14V but it could be 1.5+2.5+2.5+2.5+2.5+2.5 instead of 2.33+2.33+2.33+2.33+2.33+2.33.

View attachment 1912188
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Yeah, the main thing is on LA the voltage on each cell will stop rising. If you are keeping the whole bank at 14V for example, it is impossible to have the one cell at 1.5 for example if the whole bank is at 14. So it forces the lagging cells to reach the same voltage as the higher ones.

Lithium you can't do that. The voltage will just keep rising on the higher cell until you get into a thermal runaway situation.
 
denmendez65 said:
Yeah, the main thing is on LA the voltage on each cell will stop rising. If you are keeping the whole bank at 14V for example, it is impossible to have the one cell at 1.5 for example if the whole bank is at 14. So it forces the lagging cells to reach the same voltage as the higher ones.

Lithium you can't do that. The voltage will just keep rising on the higher cell until you get into a thermal runaway situation.
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I just used that as an example as my LA stats off the top of my head are not as accurate as my lfp stats.

I heard you cant equalise gel batteries. If you overcharge them then the bubbles destroy the gel. Only do it to flooded type.
 
wingnut771 said:
I just used that as an example as my LA stats off the top of my head are not as accurate as my lfp stats.

I heard you cant equalise gel batteries. If you overcharge them then the bubbles destroy the gel. Only do it to flooded type.
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Yeah, no you can't do that on GEL. You are the LFP guru at this point 🤣 .

Dries out the GEL inside the batteries. I do have the VRLA type which are held at higher charge voltages unlike AGM and Flooded. Goes as high as 29.4V which on 48V would be 58.8V which is damn high, I think.
 
denmendez65 said:
Yeah, no you can't do that on GEL. You are the LFP guru at this point 🤣 .

Dries out the GEL inside the batteries. I do have the VRLA type which are held at higher charge voltages unlike AGM and Flooded. Goes as high as 29.4V which on 48V would be 58.8V which is damn high, I think.
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AI says to float gels for 72 hours at float voltage to equalise them.
 
wingnut771 said:
AI says to float gels for 72 hours at float voltage to equalise them.
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I cant equalize even if I want to. My inverter can only push out 29.2V. Batteries can go 29.4V.

I also think AI is talking nonsense. All the research I did never mentioned and actually warned about equalising GELs. I charge at 28.8V and float at 27.6V. Should be good enough in my opinion and any cell imbalances should have shown themselves by now leaving the batteries at rest.
 
denmendez65 said:
I cant equalize even if I want to. My inverter can only push out 29.2V. Batteries can go 29.4V.

I also think AI is talking nonsense. All the research I did never mentioned and actually warned about equalising GELs. I charge at 28.8V and float at 27.6V. Should be good enough in my opinion and any cell imbalances should have shown themselves by now leaving the batteries at rest.
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29.2V is bulk voltage not float voltage. AI said float voltage so you float yours at 27.6V for 72 hours to equalise them. Why must I always repeat myself :P
1780340623151.png
 
wingnut771 said:
29.2V is bulk voltage not float voltage. AI said float voltage so you float yours at 27.6V for 72 hours to equalise them. Why must I always repeat myself :P
View attachment 1912199
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That’s not equalisation. That’s just normal charging lol.

Equalize is typically running over the specs of the battery for a certain time
 
denmendez65 said:
That’s not equalisation. That’s just normal charging lol.

Equalize is typically running over the specs of the battery for a certain time
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Sigh, it is just with a different method. How do you equalise gel batteries? You charge them at float voltage for 72 hours. That way the high cells dont bubble and the low cells have time to slowly catch up.

Normal charging is floating for a few hours while the sun is up then use them when the sun goes down then repeat the next day. You will never fit 72 hours into that normal charging schedule.

Leave Connected for 48–72 Hours: Keep the battery on this low-voltage float charge continuously for 2 to 3 days.
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wingnut771 said:
Sigh, it is just with a different method. How do you equalise gel batteries? You charge them at float voltage for 72 hours. That way the high cells dont bubble and the low cells have time to slowly catch up.

Normal charging is floating for a few hours while the sun is up then use them when the sun goes down then repeat the next day. You will never fit 72 hours into that normal charging schedule.
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I still have never seen anyone talking about doing equalising on GELs. That’s a flooded thing and it’s actually for removing the crystals off the plates. Not balancing if I recall correctly.
 
denmendez65 said:
I still have never seen anyone talking about doing equalising on GELs. That’s a flooded thing and it’s actually for removing the crystals off the plates. Not balancing if I recall correctly.
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its an any battery thing. cells in series need balancing. 12V battery has 6 cells in series. A series string adopts the characteristics of the weakest cell, just like solar panels etc. Then you land up with no roof tiles.
 
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