Battery not charging

[bnmotorsgt]

I have an older Craftsman rider. The "battery discharging" light illuminates when mowing and the engine is under a load and also when I turn on the headlights. If mowing shorter grass or engine is not under a load, the light is not illuminated. Hard to conduct tests since I can't do them while mowing. Need to put the engine under load to do electrical testing. Any ideas?

 

[Retiredcarguy]

Do the easiest first. A question. Does the battery hold a charge? Does it have to be charged externally?

Now, I would suggest that you remove both and fully clean the battery terminals. Make them bright and clean. Negative terminal - first and last! Inspect for corrosion at the terminals, crimps and solder. Look for corrosion of the copper wire, under the insulation too. Remember to attach the negative terminal last!

It could be just the simplest of causes.