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Author Topic:   Electrical Polarity Reversal

onemoreday posted 01-30-2010 04:52 PM ET (US)
I installed a 2009 Yamaha 50-HP on my boat, and I needed to tilt it up to take it to the dealer for final hookup. I had a buddy hold the main wires while I held the motor and worked the switch. I thought I was done but the cowling was blocked and I wanted to back it off a little. My buddy reversed the wires for [two seconds], and now [the engine] won't move. I'd like to know what repairs to expect so the dealer doesn't [used a rather crude metaphor regarding criminal sexual conduct. Please don't use this type of crude metaphor. Criminal sexual conduct is really not a good topic to use as a metaphor for charges for repairs].
Eddie Mucciolo posted 01-30-2010 04:54 PM ET (US)
First check the fuse.
onemoreday posted 01-30-2010 05:08 PM ET (US)
The motor was from a boat the dealer sent to another dealer and I haven't got an owner's manual yet. where's the fuse?
Chuck Tribolet posted 01-30-2010 07:14 PM ET (US)
Main wires on the battery?
With high likelyhood you have fried the alternator diodes.
If you got REALLY lucky, the fuse went before the diodes.
Maybe both went.
The fuse is under the cowling SOMEWHERE. Some yammie owner
can probably tell you just where.

Chuck
jimh posted 01-30-2010 07:52 PM ET (US)
Most people only make a mistake like this once. After they pay for the repairs they become very careful about not reversing the polarity on the main power connection.
number9 posted 01-30-2010 08:22 PM ET (US)
You can download the Owner's Manual from the Yamaha site. It should show location of the fuses.
contender posted 01-30-2010 09:46 PM ET (US)
boats.net will give you a blow up diagram of your engine. Good luck
jimh posted 01-30-2010 10:40 PM ET (US)
There typically is no fuse on the connection between the alternator output and the battery. When you reverse the polarity, all the diodes in the alternator become forward biased and a large current can flow. However, some voltage regulator designs can limit the current flow.
Finding a fuse in an outboard engine should be fairly simple. Remove the cowling. Look for a fuse. Follow the battery positive wiring. It should lead to a fuse.
AZdave posted 01-30-2010 11:40 PM ET (US)
The fuse should be toward the rear of the starboard side of the outboard. Yamaha may have included a spare in a holder near the fuse. When I did this to my 30 hp Yamaha, the diodes were not ruined. Good luck.
pglein posted 01-31-2010 11:35 AM ET (US)
Did your friend think that by reversing the battery cables the tilt would reverse?
If so, I suggest you never let this friend come anywhere near your boat again.
onemoreday posted 01-31-2010 02:05 PM ET (US)
Everybody makes mistakes, but if own up to your mistakes and honor your word, that's a friend for life! Thanks for the help everybody.
pglein posted 01-31-2010 09:49 PM ET (US)
I didn't mean to suggest that your friend was anything but a good friend. Just that, perhaps he's not one you want to rely on for help with mechanical projects.
I have several friends that are wonderful, honest, and loyal, but who don't know the first thing about repairing engines, cars or boats. I vale their friendship very much regardless.
floatinghat posted 02-08-2010 01:42 AM ET (US)
I did this on mine two years ago. I have a 70 hp Suzuki, it blew a 30amp fuse. Check the fuses inside the cowling.

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Author	Topic: Electrical Polarity Reversal
onemoreday	posted 01-30-2010 04:52 PM ET (US) I installed a 2009 Yamaha 50-HP on my boat, and I needed to tilt it up to take it to the dealer for final hookup. I had a buddy hold the main wires while I held the motor and worked the switch. I thought I was done but the cowling was blocked and I wanted to back it off a little. My buddy reversed the wires for [two seconds], and now [the engine] won't move. I'd like to know what repairs to expect so the dealer doesn't [used a rather crude metaphor regarding criminal sexual conduct. Please don't use this type of crude metaphor. Criminal sexual conduct is really not a good topic to use as a metaphor for charges for repairs].
Eddie Mucciolo	posted 01-30-2010 04:54 PM ET (US) First check the fuse.
onemoreday	posted 01-30-2010 05:08 PM ET (US) The motor was from a boat the dealer sent to another dealer and I haven't got an owner's manual yet. where's the fuse?
Chuck Tribolet	posted 01-30-2010 07:14 PM ET (US) Main wires on the battery? With high likelyhood you have fried the alternator diodes. If you got REALLY lucky, the fuse went before the diodes. Maybe both went. The fuse is under the cowling SOMEWHERE. Some yammie owner can probably tell you just where. Chuck
jimh	posted 01-30-2010 07:52 PM ET (US) Most people only make a mistake like this once. After they pay for the repairs they become very careful about not reversing the polarity on the main power connection.
number9	posted 01-30-2010 08:22 PM ET (US) You can download the Owner's Manual from the Yamaha site. It should show location of the fuses.
contender	posted 01-30-2010 09:46 PM ET (US) boats.net will give you a blow up diagram of your engine. Good luck
jimh	posted 01-30-2010 10:40 PM ET (US) There typically is no fuse on the connection between the alternator output and the battery. When you reverse the polarity, all the diodes in the alternator become forward biased and a large current can flow. However, some voltage regulator designs can limit the current flow. Finding a fuse in an outboard engine should be fairly simple. Remove the cowling. Look for a fuse. Follow the battery positive wiring. It should lead to a fuse.
AZdave	posted 01-30-2010 11:40 PM ET (US) The fuse should be toward the rear of the starboard side of the outboard. Yamaha may have included a spare in a holder near the fuse. When I did this to my 30 hp Yamaha, the diodes were not ruined. Good luck.
pglein	posted 01-31-2010 11:35 AM ET (US) Did your friend think that by reversing the battery cables the tilt would reverse? If so, I suggest you never let this friend come anywhere near your boat again.
onemoreday	posted 01-31-2010 02:05 PM ET (US) Everybody makes mistakes, but if own up to your mistakes and honor your word, that's a friend for life! Thanks for the help everybody.
pglein	posted 01-31-2010 09:49 PM ET (US) I didn't mean to suggest that your friend was anything but a good friend. Just that, perhaps he's not one you want to rely on for help with mechanical projects. I have several friends that are wonderful, honest, and loyal, but who don't know the first thing about repairing engines, cars or boats. I vale their friendship very much regardless.
floatinghat	posted 02-08-2010 01:42 AM ET (US) I did this on mine two years ago. I have a 70 hp Suzuki, it blew a 30amp fuse. Check the fuses inside the cowling.