Just fried my alternator - anyting else possibly damaged?-gctid383031

[Guest]

Well this really sucks.

What's even worse is finding out afterwards how stupid of a mistake it was (and it was all my fault).

I was putting the batteries back in the boat after winter storage. The way my cables are physically routed, it "suggests" placing the batteries in the bay in a certain direction/position. I should have known better - but I wasn't paying enough attention, and ended up putting the leads on the battery in the opposite direction - so I had all the Positive cables on the Negative terminal of the Deep Cycle battery.

I then hooked up the Positive cables to the Positive terminal of the Cranking battery (This one for sure was correct). At this point, everything seemed ok. Thinking I had all the Positive cables correctly hooked up to the positive leads of both batteries, I then proceeded to hook up the 2 Negative cables to what I thought was the Negative lead of the Deep Cycle battery - which of course due to my not paying enough attention, this was actually the Positive terminal. So after a few sparks trying to attach the bolt - I realize the terminal is getting hot, and start to remove the bolt - but by then it was too late. Yeah I know the sparks should have been my first clue something was wrongop-

I heard, smelled, turned around, and saw smoke coming out of the alternator.:sorrow:

OK - so it took me a while to think through what I did, and then when I went back and took a look, it dawned on me the Deep Cycle was indeed "backwards".

I've got a new alternator on order - but what else might have been damaged in the time the cables were still attached backwards?

[Guest]

bump
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[Guest]

basically all electronic stuff which is permanently attached to the battery can be fried. If you had the master switch off you already saved a lot of them.

[Guest]

Allow me to ask some clarification questions:

1) Was the ignition key in the on or start position at anytime when you had the batts connected backwards?

2) Have you inspected any of your fuses on the fuse block? You may have a main ~50A fuse and other service fuses or you may not have a 50A main and just have individual service fuses.

Let me know, and we will proceed from there. BTW, it's likely that the alt just has the diode pack burnt out, and it may be replaceable all on its own. Ask the auto elec shop if they can test the diodes, and repl them alone, or if the whole asm needs to go. Usually, on a reverse current situation, its just the diodes that are fried, and not the wiring but that depends on how the alt is connected, and how hot things got in there.

[Guest]

docmirror wrote:
Allow me to ask some clarification questions:

1) Was the ignition key in the on or start position at anytime when you had the batts connected backwards?

No. The key was never in the ignition at all.

docmirror wrote:


2) Have you inspected any of your fuses on the fuse block? You may have a main ~50A fuse and other service fuses or you may not have a 50A main and just have individual service fuses.

I didn't realize at first the battery was backwards - So when I realized what I had done, I disconnected the Alt, taped off the leads, connected the batteries the right way (no sparks at the terminals this time). I then tested several systems - radio, blower, bilge pumps, lights, trim tabs, lowered the outdrive, etc. Everything was in working order.

I then proceeded to test the engine - everything there worked just fine too.

For now it seems I am lucky enough and the only part damaged was the altenator.

docmirror wrote:


Let me know, and we will proceed from there. BTW, it's likely that the alt just has the diode pack burnt out, and it may be replaceable all on its own. Ask the auto elec shop if they can test the diodes, and repl them alone, or if the whole asm needs to go. Usually, on a reverse current situation, its just the diodes that are fried, and not the wiring but that depends on how the alt is connected, and how hot things got in there

That's a good call about just being the diode pack - and it very well may be just the diode - but I saw flame. When we take the kids out boating this summer, we usually end up in an area where there aren't any other boats. Considering how important it is to have a working altenator charging the cranking battery - the cost of buying a new altenator is a little insurance that will go a long way.

[Guest]

I did the same thing on my Beachcraft a few years ago. I fried the alternator and felt pretty stupid:tinhat over it for a long tiime, but nothing else was harmed.

[Chief_Alen]

Beating yourself up isn't going to solve anything. But i will bet the farm you will never do that again. You will know soon enough after you install the alt. and start up the boat what else fried .

Your radio should have a inline fuse, that one should have a memory and most leave that one hooked straight to the battery.

Vhf same thing. You could look at the fuses, reset the breaker " the big red button " on top of the starter.

We all have done stuff that we kicked ourselves in the behind for.

[Guest]

Robert K wrote:
No. The key was never in the ignition at all.

I didn't realize at first the battery was backwards - So when I realized what I had done, I disconnected the Alt, taped off the leads, connected the batteries the right way (no sparks at the terminals this time). I then tested several systems - radio, blower, bilge pumps, lights, trim tabs, lowered the outdrive, etc. Everything was in working order.

I then proceeded to test the engine - everything there worked just fine too.

For now it seems I am lucky enough and the only part damaged was the altenator.

That's a good call about just being the diode pack - and it very well may be just the diode - but I saw flame. When we take the kids out boating this summer, we usually end up in an area where there aren't any other boats. Considering how important it is to have a working altenator charging the cranking battery - the cost of buying a new altenator is a little insurance that will go a long way.

This is what I was expecting. The rest of the wiring on the boat is protected by fuses. Back current will blow a fuse very quickly(not the direction, fuses don't know direction, but the accessory will short quickly), so no dead fuses means they didn't get back current.

As for the alt, if you got flames, and of course you rely on the alt heavily in a boat getting it replaced is a good call. Only other thing I can think of is to check the heavy gauge wire from the alt to the starter lug for heat damage. You may have to run a new primary wire from the alt + to the starter if it melted.