loss of battery charge

**John612** · 05-02-2022, 01:57 PM

Dropped off the 5W at the storage unit 4 days ago, 100% charge.
Came back this morning, charge at 20% and 12.4 volts on the battery,
Never had this problem before, doubled checked everything, battery was still disconnected.
Pulled it out into the sun, battery went to 14.4v.
Have 3 AGM batteries, 4 years old.

Thoughts?

Thx,
John

**Hoopy Frood** · 05-02-2022, 02:35 PM

Loose connection. Unless you have solar panels.

**Soundsailor** · 05-02-2022, 02:38 PM

14.4v seems pretty high for AGM batteries. Do you have a solar charger? Could it be set to lithium?

**John612** · 05-02-2022, 02:38 PM

sorry, yes we have 3 100w solar panels.
crazy thing is it's been parked during this 4 day period, so I would would wires are ok
thanks

**John612** · 05-02-2022, 03:01 PM

I haven’t changed any settings, so believe it’s still in AGM, but will grab the manual just to make sure.
Currently:
14.4 v
21 % of full charge
-212 amp hours

**Second Chance** · 05-02-2022, 05:04 PM

When you say, "battery was still disconnected," do you mean the battery cut-off switch or the cables removed from the battery? I ask because the battery cut-off switch doesn't disconnect everything and there are still parasitic loads unless the cables are disconnected at the battery.

Rob

**John612** · 05-02-2022, 08:58 PM

Thanks, Rob, yes, just the battery cutoff switch. That's what I do when it's in covered storage, sometimes up to 1.5 months.
Prior to this instance, it's never gotten below 65 over that period.
John

**Second Chance** · 05-02-2022, 09:01 PM

Originally Posted by John612

Thanks, Rob, yes, just the battery cutoff switch. That's what I do when it's in covered storage, sometimes up to 1.5 months.
Prior to this instance, it's never gotten below 65 over that period.
John

At four years old, you might have the batteries load tested. That said, with just the battery cut-off switch in the off position, a number of things are still powered that can draw the batteries down.

Rob

**Tom Traveler** · 05-02-2022, 11:10 PM

Originally Posted by John612

I haven’t changed any settings, so believe it’s still in AGM, but will grab the manual just to make sure.
Currently:
14.4 v
21 % of full charge
-212 amp hours

I'm missing something here. I am assuming you are measuring 14.4v at the battery terminals. To be at 14.4v, the solar panels must be in the sun or reasonably bright shade and the solar charge controller must be connected to the batteries and turned on.

How are you determining that the batteries are at 21% of full charge? With a battery monitor? Are you using the -212 amp hours as a % of total amp hours (270 ah) to determine the state of charge (SOC)? That can be misleading unless the battery monitor has been synchronized lately and all loads and sources are going through the monitor. The peukert effect can cause the monitor provided state of charge to be off a bit.

If you turn off the solar charge controller or disconnect the solar lead from the batteries, what is the battery voltage after 30 minutes or so of rest - disconnected from any source or load. At 12.4v, AGM batteries, at rest, are about 75% SOC. 21% SOC voltage would be about 11.7v. Voltage at rest is the only reliable measurement of SOC. So the % of charge isn't matching up with the stated voltage.

**sande005** · 05-03-2022, 05:25 AM

Also - use a meter and test each battery separately. I just woke mine up from a long winter's nap, and while I had a bit of power, all seemed near death (jacks wouldn't jack, etc.). Each battery tested fine though...which led me to pulling jumper wires/connections on the batteries and cleaning the terminals/wires. Boom! Full power everywhere again. You may find that, or you may find one or more of the batteries is different than the others.