Is it a bad idea to start the car with a battery charger hooked up to the battery terminals? Ive been reading through some archives and found this ambiguous statement:
https://rennlist.com/forums/3501436-post22.html

Maybe this is something well known but I used to do it all the time with Audis. I'm having electrical issues and wondering if I fried something by starting it with the charger hooked up?

 

charger or tender.

the former could cause an issue, the latter seems to be no big deal, done it several times.

 

Charger. I thought it was a smart charger. Jokes on me. I left it on the car while it was running for about a minute. I think this is the issue I'm running into with the electronics. Not sure where to look downstream for fried pieces.

 

one would be better off charging the battery for about 20 minuites to 30 minuites then reconnecting the battery cables, then try to start the engine normally. one could fry a dme or ignition relay further preventing the engine from starting. The engine should not be running with a battery charger attached. quick charging any battery weakens it longterm.

buy a multimeter, check fuses

 

Thanks Lopro. I have a multimeter and will check fuses. The car starts fine, but the cooling fans are staying on indefinitely. I assume at least those fuses are ok. Will scour the car today again and figure out this problem.

 

Came back this morning after leaving battery disconnected overnight and the problems I was experiencing are gone. Either way, I'll always remember not to start the car with a charger on it again. Thanks for the help guys.

 

it sounds like you have current drain somewhere and you may find yourself stuck down the line

its important to find the source of the electrical drain

continue in this thread ---> https://rennlist.com/forums/993-foru...ing-noise.html

 

Yeah, in this scenario I always remove the charger before I start unless it won't start w/out charger connected, but even then I disconnect the charger as soon as it starts.

That's just me, no idea if it's required.

 

I've cranked the car over with the charger in the "START MODE" with no issues. I've only done this when the battery is at a low point where it just not strong enough to crank the engine over and is disconnected immediately after the engine starts. Otherwise I'll do an overnight trickle charge.