Solar charging batteries

[redneck joe]

10.27 charge as of this morning

 

[redneck joe]

10.36 5 hours later.

 

[tpenfield]

Those voltage readings look a bit suspect. It will be interesting to see what you get with the batteries at their 'resting' voltage (charger disconnected) after a day or 2 of charging.

Those are 50 Ah batteries, IIRC, so they should charge in a day or so. I know my AGM batteries, which were almost flat dead, took a few days to charge up. But my LiFePO4 batteries were not as difficult, since the low-voltage protection kicked in.

I am wondering if the BMS is those batteries do not have all of the typical features?

Once you get charged, you should have a resting voltage of about 13.3 volts.

 

[tpenfield]

BTW - if you want to check out the DIY solar forum ( https://diysolarforum.com ) there are a few not-so-kind posts about the CHINS batteries.

 

[redneck joe]

10.88 this morning

 

[redneck joe]

This seems to be a good article.

Don't murder your batteries, tips for winter storage of LFP batteries

Learn how best to store your LFP batteries during a layup. Make sure your batteries aren't damaged during extended storage.

panbo.com

 

[Grub54891]

At the shop we have a yard trailer, one tech put a small solar charger on it and it did not work well. Another tech put a regulator on the charger of some kind and now it works perfectly. I’ll try to get a model of the regulator this coming week. Note: I did not read all the responses on this thread.

 

[redneck joe]

11.09v this morning. Getting close......

 

[airshot]

Why so slow ? My LifePo4 battery charges over nite and that is 140 ah...do you have enough charger ?

 

[redneck joe]

It is a 20 amp. If you have not read the whole thread these were left unattended for a couple years and when I started this a few days ago this one read less than 1v. Im assuming, since I don't know sh.t about them that it is waking g up from the dead and that may take longer.

Iirc 11.6 is the magic number to know if there is a chance at resurrection,

 

[tpenfield]

If/When the voltage gets up into the 12.5+ range, I would disconnect from the charger to see if the voltage holds.

When charging a battery is often difficult to determine how much of the voltage is the battery vs. how much is the charger.

Anyway, the rate of charging is suspect. It is almost at the rate that you might expect from a trickle charger.

 

[redneck joe]

Don't cost much to chase this rabbit so....

 

[airshot]

It will be a miracle if they come back, usually once dead, they are dead forever.

 

[redneck joe]

11.66 this morning

 

[tpenfield]

Following this battery charging saga . . . here is the progress summary.

I do better with pictures

 

[tpenfield]

I think on the other battery, where the charger would go on & off, it is probably dead.

The 0.49v and then the 14.48v readings are the charger cycling for '0 volt activation', but the battery is not activating.

Still a puzzle as to why/how the other battery is taking so long to come up. Might be more of a charger issue than a battery issue.

 

[redneck joe]

Im a chart guy as well...

 

[Grub54891]

Can you “trick” the charge into thinking there is life in it? I know with modern chargers you have to have a load of sorts to get the chargers to sense it. Solar may not work like that.

 

[tpenfield]

If the voltage numbers are correct, and you assume that the battery has no more than 20% charge after 4 days based on the voltage, then it looks like the charger is running at about 100 milliamps (basically float charging).

 

[redneck joe]

The field, day on was actually .49 v