Second alternator mounting

Issues related to boat specifications or performance

Second alternator mounting

Postby maxmikeb » Mon Oct 01, 2018 8:50 am

I’ve just pulled the trigger on a large case 200 amp alternator from Compass Marine for my ‘74 32 with a single Lehman. I got what I think was a great buy on a what I will use as second alternator to charge my future six T-105 AGM house bank. I plan to keep the original 55 amp alt. to charge an isolated start battery and set up the second alt. as a separate charging system with a three stage external regulator and monitor.
Now comes the fun part- I’ll need to fabricate a mount. I’m thinking I’ll leave the original in it’s place and mount the second alt. low on the starboard side of the engine. The engine already has a 3 v-belt pulley on the crank from a compressor that the original owner had installed at the factory (the compressor is gone). So I’ll use that. I’ll have the alt. built with a two belt pulley.
Does anyone have a picture of a similar setup? I’m a pretty good fabricater so the installation doesn’t scare me. Just looking for ideas for the mount.
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Re: Second alternator mounting

Postby AllanKay » Tue Oct 02, 2018 7:46 pm

I do not have your setup and have twin Lehman with one 90 amp alternator on each. I find the setup works fine with my Xantrex 3kw inverter and newer AGM 500 amp-hour house bank. So, as it charges up, the batteries reach enough quick charge where thereafter the system takes a lower amp output for charging to full capacity. It almost becomes a trickle charge nearing full capacity. Once I realized that this is why the batteries are never at absolute peak unless a day or two passes at the dock on A/C power, I lost all interest in changing to a large frame alternator (140 amps) or twin alternators. Unless one intends to boil the batteries, if there isn't a controller in the loop, then all the amps in the world can only go in so fast..... another note... there is a practicing professional engineer on my dock with a 36 Woodie. He hung up a high efficiency solar unit on the mast. Measures about 18" x 12". He gets 4-5 amps all day. This really has my interest.
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