Lifepo4 voltage drop recently

[Echo Dawn]

By the way, I’m waiting for everything to settle down. I’m not putting any load on it for an hour.

 

[MisterSandals]

I’m not putting any load on it for an hour.

Measuring battery voltage requires it to be settled and at rest (no charge or discharge).

 

[PotusGobbleBottom]

14.38 is trying to come in now so I guess it’s still charging

Remember, it will not stay at 14.4. If you charged it to 14.4 and left it alone for 3 hours it would probably look more like 13.6. That is called the surface charge.

 

[Echo Dawn]

I don’t know why people think I think that. Lol I never thought that I understand how the voltage drops after a charge. I’ve actually been charging batteries for years just not lithium.

 

[Echo Dawn]

But I’m so damn appreciative of all you dudes so much you’re awesome thank you

 

[PotusGobbleBottom]

I’ve actually been charging batteries for years just not lithium.

We tend not to assume more than we should

 

[Echo Dawn]

Well, if you ever need to know, anything about domestic structural engineering, like high-end custom homes, you know who you can call.

 

[sunshine_eggo]

This is right now
The previous photo was first thing this morning. So now I won’t touch anything lol like I did first thing this morning lol.

14.36 with 0.68A of charging is full.

 

[PotusGobbleBottom]

Well, if you ever need to know, anything about domestic structural engineering, like high-end custom homes, you know who you can call.

I'll keep that in mind :

 

[Echo Dawn]

I figured as much after my conversation with Mister Sandles

 

[Echo Dawn]

A W E S O M E

 

[Echo Dawn]

Mister Sandals
Sorry for the mistake on the spelling however, I get it you’re a pilot correct? ALS I’m on it.

 

[Echo Dawn]

Or is that ILS?

 

[wattmatters]

Then I wasn’t pleased realizing what I’m about to see and hit the reset button now for the last five or so hours the only thing that was drawing off the battery was my 60 W furnace in my RV.

Why are you hitting a reset button? There should be no need to reset anything.

Looking at this image after an overnight discharge:

I'm not seeing a problem. Looks fine to me.

The battery while discharging is at 13.33 V, and the cells are all ~3.3 V. Internal battery temperature is cool but not at a level to cause concern. All seems perfectly OK to me. The battery would appear to have a lot of capacity remaining.

Looking at this image from the night before when it was charged up:

Indicates what should be an all-but fully charged battery, reaching 14.4 V with a tail current of < 3A into a 280 Ah battery. This is assuming the charger was set for a 60 A charge rate and it had tailed down to this 2.8 A of its own accord.

The BMS likely reset to 100% SOC because one of the cells probably reached a high voltage warning state.

Unless you are playing with a reset button. Only time you really need to do that is when you are sure the battery is fully charged and the BMS has not reset to 100%.

The cell balance is a bit out of whack though. Cell #4 is ~ 200 mV lower the other three cells. At close to 3.45 V though it should still have a decent charge but because there is still some voltage pressure it might be masking things. Being that far behind the other cells is not helpful and that battery needs some balancing help. It's not disastrous by any measure but 200 mV is getting up there for a cell voltage imbalance.

A battery is only as good as the weakest cell. This is not suggesting that cell is weak but it is an early warning sign suggesting a little attention to cell balancing would be helpful. I think it can right itself with good charging practice from here on.

In this battery's case I think it's been caused by not getting enough time at absorption charge state - remaining in a state of partial charge has meant the BMS's balancer has had little chance to do much work.

Frankly I think all your issues just come back to not having fully charged this battery for a long time.

If you stick to a routine of regularly fully charging it and allowing a reasonable absorption period (say 30-min give or take) to give the BMS cell balancer a chance to work (with a 200 mV imbalance it might take weeks or months to get there) then I'm sure you'll get good long term use of of this battery.

 

[Echo Dawn]

Yes, I realized my mistake, but it was too late

 

[Echo Dawn]

But it’s all better now, right?

 

[sunshine_eggo]

Hey

 

[sunshine_eggo]

Echo!

 

[sunshine_eggo]

Consider

 

[sunshine_eggo]

keeping