Hard mind set getting used to lithium iron phosphate batteries

[DennisBrady]

I'm in my 48th year running our homestead off grid. Up until last February I exclusively ran Trogan L 16 flood lead acid batteries. Now I have 6 EG4-LL Lithium Iron Phosphate battery 25.6V (24V) 5.12kWh powering a 4024 Magnum inverter. I'm having a hard time breaking my old habit of always trying to keep my batteries as close to 100% as possible. For decades if I woke up in the morning and my batteries dipped into the high 80% I freaked. I'm trying to get a handle on the range I should be keeping my new batteries in. Some say run them down to 20% then charge back up to 90%. Other say take them closer to 0% then charge. Our 4.5 KW solar array keeps these at 100% all summer and most of spring and fall but I run a backup generator in the winter. My problem is trying to get used to these new charge paramiters without having my anxiety level explode. Any one else have this same problem?

 

[Steve_S]

I will make this as simple as can be.
You can go from 3.000 volts per cell (24.0V) to 3.400 Vpc (27.2V) with No Concerns.
LFP like other chemistries has 2 Voltage Ranges.
1) the Allowable Voltage Range, where no harm/damage or wear occurs BUT is not for "daily use". This range is from 2.500 to 3.650 Volts per cell.
2) The Working Voltage Range which is what actually delivers the rated AmpHours. This is from 3.000-3.400 Volts per cell.

Most folks run a "moderate" profile, charge (Bulk & Absorb) to 3.450 (27.6V) and float at 27.5V (3.437)
This allows the cells to settle post charge (normal & expected with LFP)

 

[HighDesertOffgrid]

I have 20kwh. I charge them to 90% daily. Guess I'll see when the 4-10k cycle life actually ends. Do you monitor your system and only charge when they get down to a certain level?

 

[PreppenWolf]

I'm running a 48V system and in winter I run 51V to 56V because this gives me a "just in case" buffer. This is 3.18V to 3.50V. In summer I widen 48V to 56V (3.00V to 3.50V).

 

[time2roll]

Does the system need manual intervention daily? Try to limit the checks to once a day or every other day if possible.

 

[Mattb4]

You can micro manage them if you want. However unlike FLA they can just pretty much set them with a working range (as already mentioned by previous posters) and get used to ignoring them. No SG to check. No water to add. No worry about acid corrosion. No need to worry about equalization charging. Low self discharge rate.

They make using solar power a different world over the old lead acid battery days.

 

[alcook62]

I'm in my 48th year running our homestead off grid. Up until last February I exclusively ran Trogan L 16 flood lead acid batteries. Now I have 6 EG4-LL Lithium Iron Phosphate battery 25.6V (24V) 5.12kWh powering a 4024 Magnum inverter. I'm having a hard time breaking my old habit of always trying to keep my batteries as close to 100% as possible. For decades if I woke up in the morning and my batteries dipped into the high 80% I freaked. I'm trying to get a handle on the range I should be keeping my new batteries in. Some say run them down to 20% then charge back up to 90%. Other say take them closer to 0% then charge. Our 4.5 KW solar array keeps these at 100% all summer and most of spring and fall but I run a backup generator in the winter. My problem is trying to get used to these new charge paramiters without having my anxiety level explode. Any one else have this same problem?

I fully understand what you're talking about. I too started with the L16 Trojan batteries when I went off-grid. We (wife and I) were constantly watching/tending to these things. After switching to the LiFePO4 chemistry it was literally life-changing! I do still monitor the two batteries closely, however, not because I need to. Now it has become a hobby/source of entertainment.
The learning curve between the two chemistries does take a bit. It took the wife about a year to stop asking me every morning if we had enough juice to run her blow drier or straightener while doing her hair. I no longer look at the state of charge to run the microwave.
Before the switch, I had a calendar up to remind me when to check SG or run the equalization. Now the calendar is up for the interesting photos each month!

 

[alcook62]

They make using solar power a different world over the old lead acid battery days.

Could not have said it better!

 

[Steve_S]

I started my offgrid adventure with Rolls Surette Lead Acid... Ohhhh the freedom with LFP is so nice...