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Discussion Starter · #1 ·
Hi,
After rebuilding my alternator it still was not charging my batteries. At full throttle it only put out 12.26 volts. I hired a tech to come on board because I thought I had a wiring problem. He used an amp meter to determine that my alternator was only was putting our .5 amps! The reason being that I have a low RPM diesel that cannot not spin the alternator fast enough.

My motor is a 30 year old 7 HP Petter Diesel paired with a 28 amp Lucas ACR15 alternator with internal regulator. Only 600 hours on it so its hardly broken in. My batteries are also getting to the end of their life. There are 3, 85 amp hour gel cells that have relied on my solar charger for charging, now the solar power can't keep them up. One was discharged down to 10 volts when I checked it yesterday.

The tech suggested that I get a high output at low RPM alternator of around 50 to 70 amps and some new batteries. Balmar alternators are very expensive. Can anyone suggest a good less expensive one?

My energy budget is modest. Just instruments, and occaisionally laptop, cabin lights and stereo, but I want to do more distant coastal and offshore cruising and racing and therefore need a reliable power supply.

Any thoughts or suggestions would be helpful.

Thanks - Larry
 

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Discussion Starter · #4 ·
Alternator and battery choices

Hi John,

Thanks so much for your response. I have owned this boat for 5 years and I don't think the alternator has charged the batteries during that time or the previous 25 years either. The solar panels have been solely responsible for charging the batteries. Originally, there were just 2 grp 27s on board but I was inspired by Nigel Calder to make some changes, but at that time I did not realize that the alternator was not charging.
4 years ago I replaced all the battery wiring; adding a new ACR battery combiner and selector switch and fuses. I also replaced the batteries. I went from 2 batteries to 3 batteries: 1 for a starter and 2 for the house bank. They were 3 year old 85 amp hour gel cells that came from a bank UPS system. My solar charger kept them topped up year round with no problem. (My boat lives in Richmond on the San Francisco Bay where there is lots of sunshine.)

Since the solar panels were able to keep the batteries fully charged, wouldn't if I got 3 new batteries for the bank?

Thanks - Larry
 

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Discussion Starter · #5 ·
Pulley sizes

One problem is that my alternator works fine on the bench but not on the boat because of the slow Engine RPM. (When at low low idle I can actually count the belt RPMs as the belt revolves! ) The pulled on the alternator is 2.5" and the engine pulley is 3.5" If I went to a 2" pulley on the alternator and a 5" pulley on the engine would that help? There are 2 belts on the engine. One belt drives the alternator and the other drives the 2 water pumps. If I increase the size of the engine pulley, would it damage the water pumps by making them spin too fast?

Any suggestions on where to find a 2" pulley for the new alternator?

My alternator has 2 feet. Can I use a single footed one like this one from JC Whitney? MARINE ALTERNATOR : JC Whitney: Auto Parts & Accessories

Thanks for your help.

Larry
 

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Discussion Starter · #8 ·
I think I will try this approach:
1. Buy a new 45-50 amp alternator
2. Place a 5" pulley on the engine and a 2" pulley on the new alternator.
3. replace batteries with 2 100 amp hour batteries .
4. eventually add a another solar panel.

ANY suggestions on who has the best pricing for alternators? I could not find a Delco alternator with an external regulator for around $100.00.
I did find this one. MARINE ALTERNATOR : JC Whitney: Auto Parts & Accessories
 

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Discussion Starter · #11 ·
Thanks for all your responses, know that I have a plan of action I am having trouble finding the parts. Does anyone know where to get a bigger pulley to put on my camshaft? I need a double grooved, 5" diameter pulley to fit onto a 1" shaft. I will also need a 1.5" pulley to go onto my new alternator, as soon as I find one that is. I haven't found a dual footed, small frame, 45 amp alternator yet either!!

Thanks
 
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