How do I test my batteries to see if they are filling properly?

nobody928

How do I test my batteries to make sure they are still good ? Im tryin to make sure my east penn agm batteries are still charging and discharging appropriately. I have gathered that I need to test them with a load on them but im not sure what that means or how to do that.

Cariboocoot

Re: How do I test my batteries to see if they are filling properly?

Without buying an actual load tester you'd just be guessing. But you can make an educated guess.

Leave them disconnected for at least 12 hours after charging and check the resting Voltage. It should be very close on all batteries, be at a proper level for the batteries (like 12.75 for 12 Volt batteries), and should not fall off noticeably over several hours with no load on.

Connect a load that's about 10% of the battery's capacity and see how much the Voltage sags immediately. Leave it on and watch how long it takes to bring the battery down to 50% SOC Voltage under load (i.e. nominal Voltage). Take it off and see how much it rebounds.

What you're looking for mostly is resistance to Voltage drop over time with and without load, and consistency between the batteries. Unfortunately interpreting this data without a proper load tester is a bit of an art.

westbranch

Re: How do I test my batteries to see if they are filling properly?

you can also check each cell during the load test and see if one or more cells drop lower/faster than the others. This is more useful for 2v cells in large banks.