Externally Regulated Alternator for Atomic 4 - Page 3 - SailNet Community
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post #21 of 24 Old 06-15-2010
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I can speak highly of Ample Power. It is still on there and still charging after 18 years. It has probably worked out cheaper in the long run.

I had a reserve 100 A alternator (not Ample Power) that lasted one afternoon. I kid you not. One afternoon. It cost me $75 back in 1982. I never even pulled much load off it, perhaps 50 A, and not for long.

I have no latent interest in Ample Power.

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post #22 of 24 Old 06-15-2010
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Originally Posted by Omatako View Post

They have internal regulators that will have the old problem of tapering the charge off long before the batteries reach float and I was contemplating having them modified for an external reg and then using a Next Step or similar.
Most internal regs these days are set at higher than the old 13.8 that gave them the "tapering charge" moniker. Some internal regulators turn off and on when this set point is reached based on battery need. Some do not turn on and off and will continue to put out a very small amperage, based on acceptance, usually under 1% of bank capacity, at the voltage set point.

Many I have measured are set at 14.2-14.4. I have done side by side comparisons of the identical alt running a stock but adjustable reg (the Leece-Neville reg pictured earlier) vs. a multi-stage reg set at the same voltage and they both performed within minutes of each other. I have had three Balmar regulators fail so had lots of opportunity to compare back and forth between the dumb regulator and the "smart" one.

Single stage regs simply try and reach a voltage set point but until that point will output what the batts will accept. From 50% SOC to 80% +/- SOC, the rage most cruisers are using, the dumb regulator will perform nearly identically as a smart one. At about 80% the older style regs with a set point of 13.8 will not fully charge the batt unless you ran it for a LONG time but one set at 14.2 will..

Those Bosch alts may be set at 14.2-14.4.. Of course if you run AGM or Gel batts a multi-stage reg is a very worth while investment..

-Maine Sail / CS-36T

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post #23 of 24 Old 06-15-2010
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I'd suggest it isn't just the voltage that's to be looked at. For instance, the Delcotron's will *only* put out 14.3-14.4 volts, no matter what the battery voltage is. There are other alternators that work the same way, using pulse width modulated DC and only putting out 14.4 volts and varying the "number of zaps per second" that they give the battery. So while the alternator is running, a simple voltmeter may only see 14.4 regardless of battery voltage.

IIRC a conventional car alternator cuts down to about 10% of full output within 15 minutes, so running it for an extra hour might mean you have run it for 3x-4x as long as you could have run it, with a real regulator applying full output for a much shorter period. I'd go for external regulation, or at least find out for sure how your Bosches were making decisions, and perhaps just install a manual override so you could get full charging from them. (i.e. fool the sensing wire, and in the alternator outputs are combined, make sure there's just one sensing wire controlling them both.)
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post #24 of 24 Old 06-16-2010
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Thanks for that - so I will continue to develop the genset mods with the alts the way they are then when it's running is the time to do some tests and then decide on the mode of regulation.

I have no gel or AGM, only flooded cells (Trojan 105's).

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