dead batteries and now no charging

[jhiestand]

I apparently left the ignition on last weekend and got to the ramp today with dead batties (both). I switched out one of the batteries and was able to get her started, but then was getting no charge from the alternator. Well, at least, the voltmeter wasn't showing any reading.

Now for the part I really don't want to mention. When putting in the replacement battery I accidentally hooked it up backwards. A quick spark and I instantly knew what I had done, but not sure if that could've blown a fuse to the alternator? I'm not sure where to look for such a thing (if it even exists). This is an 08 with the EX343. Anyone have any ideas on where I might start? I'd like to try easy stuff before yanking the alternator to get it checked.

[Nautiquehunter]

Did you check all the fuses in the relay box on top of the engine near the ecm?

[jhiestand]

good call. Yes, I did. I'm suspect now it may be the alternator, although I'm having some issues getting it bench-checked. Doesn't seem any of the places around here are able to check an alternator off a marininzed engine.

[homer12]

If the only thing you're going off of is the gauge how can you be sure the issue isn't the gauge? Maybe you fried the electronics at the gauge. I would hate to see you having done damage there but if you have it hooked up and running have you checked that the alternator is putting out voltage?

[MLA]

good call. Yes, I did. I'm suspect now it may be the alternator, although I'm having some issues getting it bench-checked. Doesn't seem any of the places around here are able to check an alternator off a marininzed engine.

LOL........Do what? its an alternator and works just the same as the one on a road vehicle. Seriously. If its bad on the bench, its bad where it is in the boat. Start there and test it. Test is just as accurate as a bench test. However, testing while in the boat, you get to check the boat wiring that can effect the alt. Pulling the alt and taking to a parts house, only tests the alt.

Did you check for a tripped engine breaker? The ones that are typically 50A and have a big red button? Or a fuse link thats bolted to the starter stud? I dont have actual schematics for your setup, but these are very common across many boat engines.

[azeus17]

^^I agree, if it's already off the boat, just take it in and don't tell them it's from a boat. If they ask, just say a chevy truck.

MLA- If one of those locations you mentioned were tripped/blown, wouldn't it not start or turn over at all?

[pSchwade]

I would check the continuity between all of the breakers. The problem might be in your battery isolater setup, if the second battery wasn't dead when the you put the first one in backwards there would be a lot of current running through it.

[jhiestand]

Bench check of the alternator came out okay. Put it in today and put the boat in the water to check it above idle and I don't think it's the voltage gauge, since it goes from a "pegged" reading to around 11v when the boat is started. It doesn't come off that reading, though. I checked at the batteries with a voltmeter with the boat running and they are reading 12.3v or so. No charging appears to be getting there.

The 50a breaker and checking continuity is a good call. Should there be one for each battery? In retrospect I should've checked voltage output directly off the alternator while running, but I had the panels back in so it was tough getting down there.