What is the correct resting lifepo4 voltage?

[jaycocreek]

I bought a Enjoybot 100ah lifepo4 battery when they were $349..The resting voltage after 24hrs was 13.30 without a load..Back and forth with the seller was interesting,so I decided to do a capacity test on it from a full 14.47V and I quit at 11.89V under a load and 12.0 resting for a few minutes foran even 100 amp hours...

I am assuming that a 13.30 resting 24hr voltage without a load is okay as it appears to have the advertised 100 amp hours plus a couple...All opinions welcome...

Resting after a couple minutes at 100 amp hours.



Under load when I hit 100 amp hours..



I had to raise the amp hours to 102 in the settings to get the % closer..

[jaycocreek]

I only switched to the lower amp when I had to leave it unattended and I didn't feel comfy leaving the heat lamp on while I wasn't there, towards the end...This was the amps used for the majority of the test..

[otrfun]

jaycocreek wrote:
I bought a Enjoybot 100ah lifepo4 battery when they were $349..The resting voltage after 24hrs was 13.30 without a load..Back and forth with the seller was interesting,so I decided to do a capacity test on it from a full 14.47V and I quit at 11.89V under a load and 12.0 resting for a few minutes foran even 100 amp hours...

I am assuming that a 13.30 resting 24hr voltage without a load is okay as it appears to have the advertised 100 amp hours plus a couple...All opinions welcome...

jaycocreek wrote:
Some of this stuff is hard to understand and can consume one to try and understand it but I think different cells and make up give different results and in the end what I want is the amp hours I payed for and a fully functional battery..Battleborn uses cylindrical cells just like the new lifepo4 solar generators like Bluetti while others use prismatic which seems to be the most used in lifepo4 rv batteries...

While this battery resting is on the low side,it produces the full 100ah plus some,so I'm pleased with the purchase....One article says 3.30 resting is 90% another says it's still 100% and normal...Laffin....So if 3.30 resting gives me over 100ah,it must be full..right...:B

Available, usable ah is the most important consideration IMO. It appears your battery produced its rated 100ah, so all appears well. Sure, it would be nice if the voltages aligned perfectly with whatever lifepo4 SOC chart you choose to follow, but it's certainly not necessary from an operational perspective.

Based on your pic, get the impression you did you your ah capacity test with a 3.16a load? If so, that's a very low load current. It would be interesting to see how your battery performs under much higher loads, say .50c - .75c (50-75a with your 100ah lifepo4). These type of loads tend to quickly bring out any BMS and/or mis-matched cell issues which may not be apparent with much smaller loads.

Enjoy your new lifepo4!

[jaycocreek]

I use the chart posted above and this one for comparison..



Thanks

[BFL13]

jaycocreek wrote:
Some of this stuff is hard to understand and can consume one to try and understand it but I think different cells and make up give different results and in the end what I want is the amp hours I payed for and a fully functional battery..Battleborn uses cylindrical cells just like the new lifepo4 solar generators like Bluetti while others use prismatic which seems to be the most used in lifepo4 rv batteries...

While this battery resting is on the low side,it produces the full 100ah plus some,so I'm pleased with the purchase....One article says 3.30 resting is 90% another says it's still 100% and normal...Laffin....So if 3.30 resting gives me over 100ah,it must be full..right...:B

You can use the table shown as a guide for your particular battery, since you don't need to know exact numbers, but just want an idea of when to haul out the generator---today?, or can it wait till tomorrow?

The key to the high SOCs and voltage is what FWC pointed out a while back--the voltage drops as soon as you load the full LFP, down the knee it went up near the end of the recharge. So you see that 13.4 at 99% down 0.2 from 13.6 at 100% Then it flattens out so it is only down 0.1 from 99 to 90%.

The usual advice it to use your AH counter for LFP SOC since the voltages are so flat over the SOC range. IMO you can still use the "sort of almost resting" morning voltage as a cross-check on the AH counter. IE-before any solar can jack up the voltage and while the furnace is not on between cycles, no fans and lights. As soon as you have your reading you can turn stuff back on.

[wa8yxm]

otrfun wrote:
We've done a number of deep discharge SOC tests with our 200ah lifepo4.

Good to know. I've been wondering about the voltage SOC curve for my small LiFePO4 that I use with a radio for portable use.
The radio will object if the voltage goes too low
TOO LOW for the radio is 0% on your chart ((or lower))

Sounds like I'm good to talk till the power storage jar is (Battery) is dry..

Got a new portable antenna I need to test likely tomorrow or friday (Weather dependent testing today is a tad...er... damp)

[jaycocreek]

Some of this stuff is hard to understand and can consume one to try and understand it but I think different cells and make up give different results and in the end what I want is the amp hours I payed for and a fully functional battery..Battleborn uses cylindrical cells just like the new lifepo4 solar generators like Bluetti while others use prismatic which seems to be the most used in lifepo4 rv batteries...

While this battery resting is on the low side,it produces the full 100ah plus some,so I'm pleased with the purchase....One article says 3.30 resting is 90% another says it's still 100% and normal...Laffin....So if 3.30 resting gives me over 100ah,it must be full..right...:B

[otrfun]

We've done a number of deep discharge SOC tests with our 200ah lifepo4. Found the following chart reasonably accurate as long as there is no dynamic charge voltage or load voltage sag present. BTW, this chart contains the same voltage/SOC data as the BB chart in BFL13's link.

Note, there's two voltage readings (13.6v and 14.4v) that reference 100% SOC in this chart. We found this to be true when the converter is on (in 13.6v absorption and/or 14.4v bulk mode), *and* little (<.1a) to no charge current is flowing.

This chart and personal testing has confirmed our decision to keep our 3-stage (13.2v/13.6v/14.4v) lead cell converter to charge our lifepo4 (vs. using a lithium/lifepo4 1-2 stage 14.6v converter). Zero chance of overcharging, plus for all practical purposes we're still able to charge our lifepo4 to 100%.

I might add we did try charging our lifepo4 with our our dc to dc charger at 14.6v (vs. 14.4v) several times. Discovered it provided no noticeable difference in available ah (or SOC), vs. charging at 14.4v.

[wa8yxm]

The manual is for the battery I use for portable radio use.
The battery specs are not as detailed as I'd like but it says output up to 14.6
So that would appear to be "Full charge" voltage

https://cdn.shopify.com/s/files/1/0219/0154/files/BLF-1212AS_User_Manual_rev_04_24_2019.pdf?271

[time2roll]

I read 13.3 to 13.4 is typical to rest down from 14.4-14.6 charging.

[BFL13]

13.6 resting is 100% SOC but it drops right off so 90% is 13.3 and then it is fairly flat going lower in SOC --there is a table with the BB's 100AH batt info on their site ISTR

https://1t1pye1e13di20waq11old70-wpengine.netdna-ssl.com/wp-content/uploads/2019/01/BB10012-Spec-She...

[2oldman]

13.3 is fine

[Second_Chance]

14.2 - 14.6 VDC.

Rob