On two occassions my wife's '03 Sonata has had the battery light come on and for a split second the car had no power. On both occassion it had been raining and the streets were wet.

I could see the alternator belt could have slipped when wet but do not understand the momentary power loss.

Any help appreciated.

 

Start with the basics. I would check and adjust the tension on the alternator drive belt. Consider changing the belt if it has that glazed appearance or is cracked. I would also check and likely replace both battery cables. Either could be loose, but they also corrode with time. Depending on the age of the battery, I consider having the condition of it checked as well. If you are the handy type, these items are easy to do. If not, they are relatively cheap to have done by a mechanic.

 

^^ that right there tips me off. there is a wiring problem somewhere in the charging/alternator system. you should start by just cleaning battery terminals, same with alternator terminals, checking all associated connectors for corrosion, and checking wiring for any damage. also yes i can't hurt to check the belt and i would also get the battery tested. many auto parts stores will test a battery, alternator or a starter for free if you bring it in.

 

Has newer battery - connections good. I'll follow up with alternator connections. But why the momentary power loss?

Thanks

 

momentary power loss (total loss of power in the car i assume) would generally mean that you have a bad connection somewhere. the fact that you said that this happens in the rain gives further credibility to that theory. there is probably an exposed and/or corroded connection somewhere. when you get moisture in it you're right on the serviceable edge of that wire/connection. resistance becomes a bit variable and can jump too high.

start at the battery tracing the wires and checking connectors right up to the main fuse box under the hood and to the alternator connections. getting an alternator test wouldn't be a bad idea either, they're not exactly hard to pull in hyundais.