Battery Charging at Idle

Discussions about Cape Dory, Intrepid and Robinhood sailboats and how we use them. Got questions? Have answers? Provide them here.

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Russell
Posts: 2473
Joined: Feb 5th, '05, 11:14
Location: s/v Lady PaulineCape Dory 36 #117

Re: idle talk about charging

Post by Russell »

Troy Scott wrote:Matt,

I have an 85 amp Balmar and I plan on having 500 ampere hours of storage capacity. I think the 200 amp alternator for charging at 70 amps at idle is an excellent idea. With the regulator and a fuse it seems pretty foolproof. But I understand that nothing is really foolproof for a sufficiently talented fool. I might find a way to really screw up! I wonder what's the largest Balmar that will fit on my Perkins 4-108.....
I dont know about the 200 amp, but my 4108 is doing fine with the 150amp balmar. Full time cruising a big altinator really is nice to have. Those of us who still have the origonal perkins in our CDs are fortunate in the sense that they are real workhorses and really more power then nessisary for the boat, so the lost HP with huge altinators isnt an issue. Some folks with newer smaller yanmars really tax their engines with big altinators.
Russell
s/v (yet to be named) Tayana 42CC
s/v Lady Pauline Cape Dory 36 #117 (for sale)
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Matt Cawthorne
Posts: 355
Joined: Mar 2nd, '05, 17:33
Location: CD 36, 1982
Hull # 79

no need to limit

Post by Matt Cawthorne »

Troy,
If you have 500 AH of capacity there would be no need to build limits into a 200 amp alternator. That fits the 40% rule. The fuse you need, of course, because EVERYTHING connected to the batteries needs to be fused.

As far as fitting a different alterantor, a machinist can fit anything for a price.

Matt
Troy Scott
Posts: 1470
Joined: Jan 21st, '06, 01:23
Location: Cape Dory 36 IMAGINE Laurel, Mississippi

big engine, big alternator

Post by Troy Scott »

Russell,

It's good to hear about real world experience, and that the 150 amp alternator works well with the 4-108. The engine is definitely "big". We rented a hefty fork lift to get it out of the boat.

Matt,

Like a friend of mine is fond of saying "With an infusion of funds anything is possible".
Regards,
Troy Scott
L.DeMers
Posts: 21
Joined: Dec 5th, '05, 18:00
Location: CD30c "DeLaMer"
Sailing Lake SUperior

Re: No one has talked about the engine

Post by L.DeMers »

I doubt that occasional topping off at idle would be a problem, especially if the engine is run at cruising speed and temp regularly.[/quote]

Bill, the Balmar alternator I have takes about 4 hp to run at top output of 100A. I have 13 hp to start with, so this will make the load about 32% of the rated output. I could charge all day at low speeds, and there would be no problems. Now if that same engine was 50 hp, then the load would be in the 10% range, and indeed idling to charge would be foolish.
As you say, it all depends on HP and load.
Larry DeMers
S/V DeLaMer
Cape Dory 30c
Lake Superior
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