How do you test an OTC Accuracy Plus digital battery load tester?

[Jbullfrog]

I have an older OTC Accuracy Plus 3155 battery tester that I have used and not questioned for 20 years. Today, I charged and tested the batteries in our combine and it showed them both as bad so I went to get a new set. When the parts guy at John Deere tested them with theirs, the showed as "Marginal". I tested the 2 new batteries and 1 showed at 100% and Good and the other showed at 43% and bad. Is my 20 year old meter finding problems that the dealer's newer meter isn't, or do I need a newer meter too?

 

[Zewnten]

I've had several of the digital meters give me false readings, so I keep a cheap HF carbon pile to double check it.

 

[Neggy]

that type of tester is such short money now, plus they do more than lead acid batteries, that the old ones are disposable

$50 bucks buys a good one

 

[signcrafter]

I would say it lost calibration. I had an older midtronics tester I've used for years. It gave some readings of dead batteries and when the batteries were taken in the parts store said they were good. Then it gave a reading of good when I had an intermittent no start condition so I spent time chasing other issues. Finally came down to a bad battery. Had a dead cell. Napa had some nice testers on sale so I took my old one down there and asked the manager if we could test some new and dead core batteries with his tester and then my tester and compare the readings. Mine was all over the place. So I had him order me a new one. Now I can test batteries with confidence. I paid around 500 bucks for the new tester but to me it's worth it to he able to do quick accurate tests. It also does all the newer types of batteries my old one didnt. I did contact midtronics to see about updates and they had a flat fee service but it was around 300 bucks if I remember right. Might as well just get a new one with more features.

I also bought an old school 500 amp toaster style tester too. Nice to be able to do multiple tests to be 100 percent confident condemning or passing a battery so you aren't chasing your tail. Yes you can take battery down to parts store to be tested but to keep the money spent is worth it to be able to do at home. And there are other tests that will give a reasonable doubt of a bad or good battery but if you do a fair amount of diagnostics and repair a tester is worth it. Batteries dont last anymore and go bad for all sort of reasons and all sorts of ways.

 

[kelpaso1]

Zew exactly. Those "electronic testers" are unreliable and they dont put any kind of meaningful load on a batt.
They merely show static state of a batt with no real meaningful load on it.

 

[kelpaso1]

I also bought an old school 500 amp toaster style tester too. Nice to be able to do multiple tests to be 100 percent confident condemning or passing a battery so you aren't chasing your tail. Yes you can take battery down to parts store to be tested but to keep the money spent is worth it to be able to do at home. And there are other tests that will give a reasonable doubt of a bad or good battery but if you do a fair amount of diagnostics and repair a tester is worth it. Batteries dont last anymore and go bad for all sort of reasons and all sorts of ways.

 

[kelpaso1]

And for those interested in how to properly load test a batt with a carbon piles tester. Hook it up to a batt and toggle the switch. For a 12V batt, if it stays at 10-10.5V for 10 seconds you are good to go. If it drops before that time, then the batt is getting weak and time to replace.