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Jedi Knight
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I'm working on a push lawn mower with electric start. The battery is showing 11.72 volts and will not spin the engine over. I plug the charger to it, let it charge several hours, same problem. I check the voltage out of the charger, 11.75v. Stupid question, shouldn't the charger be charging greater than 12v on a 12v system or am I missing something? When I hook up my regular battery charger to it, it charges at 12.5v on a 2 amp setting. This seems normal to me. Am I on the right path or what?:crazy:
 
Seems both chargers are a bit limp.

And: Have you pulled the sparkplug to be sure it'll spin with no compression?
 
Well, I left it on the regular charger for a couple of hours, reattached the battery and it spun over fine. I'll recheck the lawn mower charger, but I believe thats my problem. Thanks guys.
 
Just curious - what's the battery type in that lawn mower? One of the "standard" 12 volt lawn tractor type batteries? Or something specific for the mower, and it has a special charger?

Also, seems the mower's starter should spin - or at least try - even with 11.72 volts. Unless the battery itself is failing.

hint hint
 
My question would be, why do you have to constantly recharge the battery with an external charger? It should recharge with the engine running, if it doesn't, then the battery or the charging circuit is bad.
 
My guess is the battery is on its last legs.
 
Not a riding mower, guys. This is a push mower with a small electric starter on it. It uses a small battery similar to those used in UPS's and emergency lights. It doesn't have any charger winding built in it. It did "try" to start, but not enough oomph to spin it around. The battery seems fine now that it charged on a decent battery charger. I've been starting it up daily just to make sure. My question was about the charger voltage. I thought it SHOULD be greater than 12v. It wasn't. I do believe that's my problem.
 
A fully charged 12V battery should be ~12.6V. A 12V battery charger should put out 13.5V to 14.4V. At 11.7V, the battery is about fully discharged.
 
Just for fun - look on the mower's battery charger. I think every charger I've ever seen shows the output voltage, as well as AC or DC. Or at least, it shows what the output voltage *should* be.
 
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