Brian R
New Member
- May 28, 2019
- 5
- Boat Info
- 2005 Sea Ray 300 Sundancer
- Engines
- 5.0L Mercruiser w/Bravo II Outdrives
I was replacing the alternator on my port engine, forgot to disconnect the batteries and shorted out the 90 amp fuse at the starter. It took a while to figure out the problem, as I didn't realize it happened, but I had no electrical power to the the engine. Looking at the wiring diagrams, it seemed like that was the only culprit, and we were able to confirm that by checking continuity between the battery and fuse (continuity), and the battery and the hot wire for the alternator (no continuity). The alternator is on the other side of the fuse. I wasn't able to reach the fuse, other than to touch a lead to battery side, so almost gave up and called a mechanic. According to the wiring diagram there are two things coming off that fuse: The orange 8 AWG wire to alternator, and a red wire that goes to a circuit breaker that I believe goes to the control systems and ignition. To solve the problem, we installed a 90 amp fuse at the bus for the port bank, and ran an 8 AWG wire and tied into the orange wire at the alternator. Electrically, I believe this is basically the same. The only difference I can see is that the power to the system before the engine is running is going through the orange wire from the alternator. Is there an issue with this approach? Why is this fuse 90 amps, when the alternator is limited to much less?