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Old 10-10-2015, 14:52   #16
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Re: Alternator sizing and water pump side loads?

Before recommending any belt solution, we need to know what your daily power consumption and battery type and capacity is. Else it could be you don't need a larger alternator at all. If you have std deep cycle batteries, you need at least 500 A-hrs of battery capacity, the larger alternator won't do anything for you, your batteries won't accept current any more than your present 105 A alternator will output. Even if you have 800 A-hrs of capacity, the 165 A alternator won't do much for you when the batteries are 65% SOC.

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Old 10-10-2015, 15:44   #17
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Re: Alternator sizing and water pump side loads?

I have done a fair number of AT-165's on Yanmars with zero issues. All of them have been done with a 10 rib belt and Electromaax or Balmar/AltMount pulleys.. Yanmars engineering department has told me on sailboat engines they don't want to see more than about 200A and Universal/Westerbeke says a max of 190A so you are well within the safe range..

My own Westerbeke has approx 3800 hours on the water pump and runs a custom Mark Grasser DC Solutions 160A alt with a 10 rib belt. It is feeding a LiFePO4 bank so it is always running in bulk. Despite this abuse we have zero belt dust and use less tension than it took to drive the stock alt 1/3 the size with a 1/2" v-belt. Dual v-belts are not even in the same ball park as a single 10 rib Belt...

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Old 10-10-2015, 23:53   #18
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Re: Alternator sizing and water pump side loads?

Hello guys.
Have anyone installed the Balmar AT-200 on Yanmar yet?
Slightly lager than the AT-165 but should still fit i think.

I am currently running 2 X Balmar 60-150-SR-IG.
The battery is Winston 1000AH Lifepo4.
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Old 11-10-2015, 21:50   #19
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Re: Alternator sizing and water pump side loads?

When I installed an 80 amp alternator and smart regulator in place of a 50 amp regulated alternator on my 20 HP diesel the single belt slipped and the new alternator got too hot to touch.
I fixed that by having a new double pulley made for the alternator. Importantly I made it 10 mm larger in diameter than the original. That both decreases the load (like a bike with a larger rear cog) and increases the wrap (circumference) of the belt in contact with the pulley. It made no noticible difference to the alternator output and completely fixed the problem. Of course the crankshaft pulley had to be modified; grafting another one beside the original.

The machining was all done by an engineer and cost around $300 for his work. I removed the crankshaft pulley and reinstalled it so he didn't need to visit the yacht. If you haven't got a puller for the crankshaft pulley it is probably cheaper to buy one than have an engineer visit your boat. You simply tension the puller and wack the center of it with a hammer and the pulley pops off.

The original alternator pulley was 2 pressed steel segments held together by the shaft and nut. The new double one was made from solid steel and fitted the belt better.

(Sometimes competition vehicles have a larger alternator and water pump pulley to reduce power loss)

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