Battery Test Good... But

[PopJack]

I believe I have been seeing some symptoms of a bad battery on my bike. At one auto parts store they tested it, however, and it tested good.

Still, I have trouble believing it is good. (Looses voltage very quickly, can't stand even light loading without going flat. Bike had to be pushed started one (after which, admittedly, I did find a bad connection).

Does anyone know how good these testers are?

 

[TomD]

I have an electronic tester and have read good and bad on the same battery within minutes. Fully charging the battery and load testing it is best for determining the batteries health.

Tom

 

[Silver Bullet]

All depends on how they tested it ,just a voltage test or did they test it under load ,also I don,t know if a auto parts place can actually do a good test on a small motorcycle battery ? Sure sounds like it has a bad cell and won,t hold a charge !A fully charged battery should read about 13.4 volts or there about,s .My vote is bad battery !

MIKE

 

[Dinkie Diesel]

Doing a load test is the best way to determine a battery's perfomance. If you put a charger on it for a while and then checked the voltage you may see something over 12.6. Each cell should be 2.1 volts at full charge. If it is more than that (12.6v) I think they call it "parasitic". Drawing even a light load like turning the key on for one second will remove that parasitic voltage. Then if it is under 12 volts after that you may have a problem.

Also it is a very common problem to show 12+ volts until a load is put on the battery and then it goes to almost nothing. The Yuasa for our bike is rated at 230 cold cranking amps. If the auto place you had check it put a draw on it of 200 amps and it held 10 volts it's probably good. If it went to 8 volts or less I'd scrap it and buy a new one.

 

[CABINPETE]

Here is the battery load test procedure. There are two ways to determine the load, one is to multiply the amp hour rating by 3 the second is divide the cold cranking amps by two. Apply the load for 15 seconds if the voltage reading is 9.6 or above the battery passed. Re-charge and check the charging system, amp draw, etc. if the battery voltage drops below 9.6 it failed.
A fully charged battery with no surface charge will read 12.72 volts.

 

[Dinkie Diesel]

Here is the battery load test procedure. There are two ways to determine the load, one is to multiply the amp hour rating by 3 the second is divide the cold cranking amps by two. Apply the load for 15 seconds if the voltage reading is 9.6 or above the battery passed. Re-charge and check the charging system, amp draw, etc. if the battery voltage drops below 9.6 it failed.
A fully charged battery with no surface charge will read 12.72 volts.

Yeah, what he said.