For All the Battery Experts

First race of the season and I grab my Coleman starters off the basement floor. Problem, it doesn’t spin up. The battery read 12.5V and the solenoid works. The gears aren’t jammed. Has to be the electric motor, right? Wrong. Tore the motor apart and it was fine. Back to the battery and it still reads 12.5V, but it has 0 amps.
How can a battery have better than 12 volts and zero amps?

Batteries should always be measured under load, not static. I bet that drops to near zero when you put a load on it.

Anyhow, it sounds bad. Not knowing what type of battery it is I’m not sure what to recommend.

You need a new battery you have dead cells

Thanks for the replies. While purchasing a new battery, my old was tested. Zero cranking amps. I posted this so someone else won’t make the same mistake and to understand why. My understanding of batteries is that the internal cells are connected in series to obtain the desired voltage. Four 3v cells connected in series would result in 12v. A bad cell would either short the entire battery out or drop the output of the battery by the amount that cell would have produced. My theory gets weak in regards to the result of the electrolyte evaporating.

Here’s a good diagram on current/voltage/resistance that I think of us racers can understand: