How to determine which is the faulty battery in a bank?

[daveasdf]

I have 4 batteries, 8 months old - if solar charges them to 100 in the day, they're at 80-85 early evening with nothing attached to them. They generally are running at 75% capacity with nothing significant running, and the amp hours now don't reduce appropriately, they're gone too fast.

The store says they need a picture of the voltmeter reading of the faulty battery for the warranty process.

What is the best way to find the faulty battery, and then take a picture of its voltmeter reading?

I tried testing each one individually with an inverter hooked up to a charging laptop, when the bank was at 100%, but I couldn't determine if any one battery's voltage was dropping faster than the others.

Thank you in advance

 

[daveasdf]

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[daveasdf]

 

[newbostonconst]

Usually unhook them and check voltages....the lowest one is usually the one to look at.

You can also put a load on each individual battery and check the voltage drop.

 

[daveasdf]

Ok ty, I appreciate that

 

[daveasdf]

... couple other questions - if I find the culprit, how would I rig up the 3 remaining good ones until I get the replacement? The wires I mean.

Also, is it normal practice to leave things like 12v motion sensor lights and security cameras running off of the batteries, that are constantly being regenerated by the solar panels? Is there any damaging factors to consider with this, that might have contributed to a battery dying? Also considering it's heading into the canadian winter?

 

[TacomaJoe]

Not sure of your wire size or lengths but there is a problem with connections relating to balance. Your charger, as wired, has good balance between the 4 batteries. The inverter and fuse panel have a shorter path from batteries A and D, and a bit longer path (more wire jumps) from batteries B and C. This result in balance issues down the road. The inverter and your loads will pull a little more from A and D than from B and C.

You may not have a bad battery but rather have a couple that aren't keeping up with the other two because of the wiring imbalance.