Battery testing?

[AlanO]

I run the genset in my View at least once a month even though it is plugged in to shore power which keeps the batteries topped off. This month the generator just clicked but would not start. I suspected that after 6 years the 2 coach batteries were weak. First I did voltage drop tests to confirm good connection for both ground and power.
Then I disconnected both batteries and load tested them individually. Both failed the load test and one had a defective cell.
Installed 2 new deep cycle batteries, all is working well again, hopefully for another 6 years.

[bigb]

Originally Posted by AlanO

I run the genset in my View at least once a month even though it is plugged in to shore power which keeps the batteries topped off. This month the generator just clicked but would not start. I suspected that after 6 years the 2 coach batteries were weak. First I did voltage drop tests to confirm good connection for both ground and power.
Then I disconnected both batteries and load tested them individually. Both failed the load test and one had a defective cell.
Installed 2 new deep cycle batteries, all is working well again, hopefully for another 6 years.

I am in the process of load testing a couple of Motorcraft FLA starting batteries today, did you use a carbon pile like the Harbor Freight 500 amp load tester?

[BarryLS]

Just about any auto parts store has a load tester. I made one once from an old resistance heater. Since I have a need for that about once every 5 years or so I just take them to the parts store now.

[bigb]

Originally Posted by BarryLS

Just about any auto parts store has a load tester. I made one once from an old resistance heater. Since I have a need for that about once every 5 years or so I just take them to the parts store now.

They only use 100 amps. A while back I picked up the Harbor Freight 500 amp with a coupon for under $40. After opening it up and tightening everything up per the reviews it has worked like a champ and I can load test my 850 CCA starting batteries at 425 amps.
What I am curious about is how the OP load tested his deep cycles, I don't think you can properly load test a deep cycle with a high load test. When I do mine I set up a bank of 12 volt lamps and measure the time vs watts against the amp hour rating.

[BarryLS]

Most starters on medium cars draw 4-500 amps. They make a pretty decent tester I think some of the bigger engines and diesels pull near 1000 amps. I've never had a problem testing with a lower amp draw though. YMMV. I think my homemade resistance unit pulled about 75 amps. Too long ago for my memory...

[AlanO]

I have 2 digital battery testers left over from my working life in my repair shop. One is a Midtronic’s and the other is a Solar. I use both but prefer the Midtronics unit. The loads can be adjusted for battery capacity and type.
It’s a very quick and easy way to verify the battery condition without guessing. Voltage drop testing is a sure way to check that connections are properly made for both grounds and power.

[bigb]

Originally Posted by AlanO

I have 2 digital battery testers left over from my working life in my repair shop. One is a Midtronic’s and the other is a Solar. I use both but prefer the Midtronics unit. The loads can be adjusted for battery capacity and type.
It’s a very quick and easy way to verify the battery condition without guessing. Voltage drop testing is a sure way to check that connections are properly made for both grounds and power.

Oh yeah a Midtronics that's the one the wealthy boat owners use
I'll just go back to my crude HF setup and home made lamp load bank now.....