The great battery thread

[UrbanHunter]

I finally ordered 1 LiFePo4 battery for use inside the house with an inverter/charger that I had on hand for a year or so. When I checked the inverter/charger I discovered lithium batteries were not on the charge selector list... not happy. I looked at an AIMs inverter/charger that was very similar in design and it had a "sealed lead acid/LiFePo4" selection. I looked and the charging voltage profile matches the "sealed lead acid" charging profile on the unit I have. Now I need to decide if I am willing to chance it or do I drop another $800 to get one with a lithium charge profile....

 

[Biggkidd]

I finally ordered 1 LiFePo4 battery for use inside the house with an inverter/charger that I had on hand for a year or so. When I checked the inverter/charger I discovered lithium batteries were not on the charge selector list... not happy. I looked at an AIMs inverter/charger that was very similar in design and it had a "sealed lead acid/LiFePo4" selection. I looked and the charging voltage profile matches the "sealed lead acid" charging profile on the unit I have. Now I need to decide if I am willing to chance it or do I drop another $800 to get one with a lithium charge profile....

What is the high voltage? What is the float voltage? From what I can tell using regular chargers isn't so bad as long as they either A) don't float charge or B) the float charge is low enough. Low enough being somewhere around 53.5 for a 16S LifePO4 48 volt battery from what I understand. I don't know the specs for other voltage systems

 

[UrbanHunter]

I am looking at a 12V LiFePo4 200Ah battery and the inverter/charger unit setting has a charge voltage of 14.4V and a float voltage of 13.6V. I will have to think it through for a while.

 

[Supervisor42]

I am looking at a 12V LiFePo4 200Ah battery and the inverter/charger unit setting has a charge voltage of 14.4V and a float voltage of 13.6V. I will have to think it through for a while.

I was hoping @Biggkidd would jump in because he is working with LiFePo4 batteries.
He's right, if the float voltage is not high enough, you only maintain them at 95% SOC which is not bad.
If the float voltage is too high, then it affects battery life. By his numbers (13.37v), 13.6v should be ok. Gell-cells float around 14.5v to be happy, and that would be bad for LiFePo4 . (I would think. I don't know diddley about LiFePo4.)
Edit:...But I can learn . They are showing 13.6v as the float-voltage for the 12v LiFePo4 ones:
https://footprinthero.com/lifepo4-battery-voltage-charts

 

[Biggkidd]

The big thing to remember is try and keep LifePO4 batteries between 20% and 80% SOC for the longest life. So float charging is not the best answer nor is it the worst. A selectable charger where you can set the voltage for YOUR desired end result is the best answer. In my case I want my batteries to last as long as possible so I try hard to stay between 20% and 80%. If I needed maximum amp hours before recharging then I would charge them differently and use the upper 15% and lower 10% staying between 10% and 95% SOC but then you shorten the battery life.

 

[viking]

So today I made my first check on the new batteries, especially since after changing the old ones out the charger was putting some serious amperage on the new ones, I thought perhaps that the electrolyte might have boiled off but as it turns out the electrolytes were perfect, after the experience of checking electrolytes of the old set of batteries I have come to the conclusion that I need to check them at least once a month, it might not be so important if we didn't get so many power outages as we have been getting lately. The extra bank I hooked up may also reduce the gassing off, at least I'm hoping it will because it's been averaging about five plus gallons of distilled water to refill all the 60 cells of original 20 batteries every two months.

 

[viking]

So yesterday I checked the electrolyte levels and added about two gallons of distilled water even though the cells were still in a safe zone, since we may have some hot dry weather ahead I feel better having all the cells topped off and we have had grid outages since my last post. The quality of this set of batteries seems to be much better than the first set, also by adding another bank of four batteries it may have made the system more effiencent, anyway being that it has been eleven months since I did a full cell topping, the batteries have done exceptionally well.