Second alternator mounting

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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.
Thanks!
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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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Re: Second alternator mounting

Postby jmcj » Thu Feb 07, 2019 5:17 pm

Just viewed your post. Have done solar and if you want pics, I can send.
Jim McJannet
Unicorn V
1981-633
36CL
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Re: Second alternator mounting

Postby jmcj » Thu Feb 07, 2019 5:19 pm

Sorry, change “solar” to “similar” in my reply above
Jim McJannet

Unicorn V

1981-633

36CL
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Re: Second alternator mounting

Postby Bob Lowe » Fri Feb 08, 2019 6:50 am

Congratulations! A high output alternator is a good choice.

You will need to drive it with a good pair of at least 1/2" industrial grade belts matched.

I recommend you drive that alternator separately to spare your water pump from the loading required to drive the alternator. Whereas the water pump is recirculating and requires little belt tension, that alternator will require HD belting adjusted tightly due to its approximately 5 hp loading at load. Don't forget the belt dressing.

A smart regulator will be a wise choice and with distribution controls can result in an efficient and reliable electrical system with the high output alternator at the heart of it. :)
Good luck,
Bob Lowe
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Re: Second alternator mounting

Postby Nobby » Wed Feb 13, 2019 10:10 am

I have done a high output alternator several times now for clients and have had good results with just using the single high output alternator makes for a much simpler install.

I then use either a Pro Mariner Smart Isolater - Prosolcharge. Or the Balmar Series Regulator works really well - Digital Duo Charge.

I have designed my own custom alternator adjustment arm which I can supply which takes care of belt tension issues and should work for any alternator installed in the standard location though have yet to try it on a true large case as in a J180.

Cheers
Nobby
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Re: Second alternator mounting

Postby maxmikeb » Sat Feb 16, 2019 10:50 am

I have thank-yous and apologies for your responses: When I originally posted this I put posted in two locations on the forum. Once under this heading (Specifications) and once under Photos. I didn't know how to retract the duplicate. So...Jim, I do have your excellent pictures from the other thread. Thanks again. And Bob, thanks for your input. Some of the inspiration for installing the additional alternator was reading your past posts regarding charging.

Nobby, that's a sweet setup you've got there.
I decided to go with a serpentine belt (8g) to drive the new alt. So I'm going to have to have a pulley (sheave?) made to bolt to the front of the existing v-belt crank pulley that drives the original alt. I'll start looking for a local machine shop once I remove the two-belt pulley that's bolted on there now. I'm trying to work out a way to hold the crank stationary while I loosen the crank bolt.
I see you're on Long Island- we dock our boat, Giddy II, on the Connetquot River on the south shore.

Mike
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Re: Second alternator mounting

Postby Nobby » Sat Feb 16, 2019 11:49 am

Mike,
Connetquot just down the road from me here in Patchogue.
If your local I could lend you a pulley (got several engines lying around my shop) rather than pull yours off as well as suggest a machine shop that I use for my business. To get yours off either a high powered impact driver, I have a 1/2" Milwaukee unit that usually does it, or the old school way off pull the starter motor and put a prybar inbetween the teeth and let it fetch up on the starter hole to stop flywheel from turning. You'd have to do this anyway to retorque retaining bolt correctly back on again anyways.

Regarding the serpentine drive Altmount makes a kit for the Lehman (10 Groove), have yet to see one however the crank pulley is designed to slip over and cover the existing v grooves but I see no reason why it could not be flipped and used the other way as you describe even with perhaps a little machining adjustment or spacer. The cost of the kit will most likely be less than machining from scratch. I can supply one if you want at most likely a better price than what you see online.

Cheers
Nobby
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Re: Second alternator mounting

Postby maxmikeb » Sun Feb 17, 2019 12:38 pm

Nobby,
Well, the pulley has to come off anyway so I'll continue with that. Motor is in the boat so I'll be going with the old school method to remove the bolt. I have the starter out already. A prybar, a 3/4 breaker bar and a length of fence pipe should do the trick!
I would be interested in your recommendation for a local machine shop.
I'll send a PM.
Thanks.
Mike
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