Thread: AGM Battery Charging

My understanding is that you need to disconnect any load or charging and let the battery sit for a bit then check the voltage.
If its under load you're not going to get a valid reading. As an extreme example - your battery might be full charged but if you crank the engine the voltage could come down to 10v or so (which is lower than a completely discharged battery if you look at the SOC charts).

Steve

Originally Posted by pjlhat

Hi Tim thanks for the details between you and Deano I have a lot of info to digest. I want to get this right as future camping will be long periods and off the beaten track with a compressor fridge.
Is there any way that a laymen can test the amount of charge in an AGM battery, I currently use the voltage as my indicator when the fridge is drawing power.
Peter.

PS Thanks to Dave and all who are responsible for this forum enabling us Landy owners who like to do their own work and modifications an avenue of expert help. Many thanks

I have two ways to test mine.
1. I bought a plug from Jaycar which plugs into a cigarette lighter and reads the voltage. So it is reading whatever the current is flowing through the electrical system. If the engine is running it will read what the alternator is putting out. If the engine is stopped it is reading the battery. When I start the vehicle I can watch the reading go up as the alternator kicks in, usually to sit around 13 volts.
I can plug it into my camper and read the camper's battery. Only cost about $20. Very useful.
2. If I attach my multi-stage battery charger it first gives a reading of the state of the battery, before beginning to charge it.

Originally Posted by drivesafe

Hi Mick and Yes.

Agms are lead acid batteries, as are Gel batteries.

BTW you can mix any type of lead acid battery ( Wet, AGM or Gel ) with any other type and solar regulators and alternators, charging the same battery or batteries, will have no problems fully charging them.

Yes, I've used my 80 watt solar panels with the regulator on both wet cell deep cycle and AGM batteries and it all worked fine. In sunny weather the battery is usually fully recharged by mid-morning after running down a bit during the night. Then it just stays charged while there is sunlight.

Hi pjihat and as per our phone conversation, here is the Loaded Voltage Chart.

Originally Posted by steveG

My understanding is that you need to disconnect any load or charging and let the battery sit for a bit then check the voltage.
If its under load you're not going to get a valid reading. As an extreme example - your battery might be full charged but if you crank the engine the voltage could come down to 10v or so (which is lower than a completely discharged battery if you look at the SOC charts).

Steve

Hi steveG, there is a lot to this subject and the link below will give you a bit more insight to SoC and battery capacity.

Battery Voltage, State Of Charge.

Originally Posted by drivesafe

Hi pjihat and as per our phone conversation, here is the Loaded Voltage Chart.

Yes, I read somewhere that a cell is typically 2.1 so 6 x 2.1 is 12.6. Probably varies I guess.