24v battery wiring and cable size

[4321loco]

I made a bank to test a 24v inverter yesterday, battery bank consist of 4 100ah batteries. I used random cables I had like 1/0 welding cable for inverter leads and used dual 8 awg cables for the battery jumpers. My voltages are really low on the batteries that have the inverter leads hooked up. I was running a constant 600 watt load so thought the cables would be fine for testing at this load. The readings are right before I turned off inverter and I had not noticed since I was going by the 22v reading instead of individual batteries. If the issue is caused by the dual 8awg wire would 2awg be sufficient for the battery jumpers or will I need 1/0 all the way.

24v Battery setup.jpg

[Mike90250]

600W at 120VAC is 5 amps
but at 24VDC, and adding in inverter losses, it's more like 30A from the batteries, very short length of 8g wire could work, but any distance, I'd use heavier wire.

[chrisski]

When I look at the battery voltages, I see 4 dead batteries that need t be charged prior to testing the inverter. I see 10.5 volts on my diesel when the 8 glow plugs are on to heat the cylinders prior to starting an engine. Without decent batteries, may not get a good inverter test.

Recommend putting each battery individually on a charger, With the 10.5 and 10.6 batteries, I would not be surprised if it said “dead” or whatever the charger uses as bad.

[4321loco]

600W at 120VAC is 5 amps
but at 24VDC, and adding in inverter losses, it's more like 30A from the batteries, very short length of 8g wire could work, but any distance, I'd use heavier wire.

Thanks. The 8awg wire I used was about 8" between series batteries and the wire used to parallel around 14". I will probably order some wire today and try again after charging batteries again.

[4321loco]

When I look at the battery voltages, I see 4 dead batteries that need t be charged prior to testing the inverter. I see 10.5 volts on my diesel when the 8 glow plugs are on to heat the cylinders prior to starting an engine. Without decent batteries, may not get a good inverter test.

Recommend putting each battery individually on a charger, With the 10.5 and 10.6 batteries, I would not be surprised if it said “dead” or whatever the charger uses as bad.

I had used a 12v charger days prior testing on all 4 batteries and then wired all the equipment. I ran a 600w load to see what capacity I could get from these batteries in an emergency. The test went lower than I wanted because I would monitor every hour. I will be running lithium in the future but that's a different topic. Anyways I left the solar array off and will be charging them again individually and hopefully wire gets here soon.

Thanks

[jasonl549]

What is the gauge of the wire that you used to connect the two series strings together in parallel? Also, are the lengths of the cables even or are there slight variations? Is the wire copper clad aluminum or pure copper? How old are these batteries? Were they all purchased at the same time? Are they all the same brand and model?