[Best Practice] Alternator/regulator set-up

[Valiente]

I have an opportunity to purchase a used Lester 135 amp alternator and a Xantrex regulator from a couple who have concluded a Caribbean cruise. This would upgrade my stock 55 amp alternator on my Westerbeke W-52, which has a two-belt-capable power take-off. As I am considering radically expanding my battery banks, plus adding loads of solar and wind charging capacity, it would be silly to keep the 55 amp as anything but a spare.

The mount is for a Yanmar, which may not fit my block, so I'll have to measure clearances, but it made me consider other ideas, and I'd like opinions, please:

1) Does it make economic sense to get two 75 amp Balmar-type alternators and to arrange them with two belts on either side of the block? Does "balancing" the physical pull on the PTO lessen wear?

2) Would I get better total output from two 75 amp alts or from one 135 amp?

3) Am I right in assuming that the Balmar-type alts are internally regulated, meaning I would not require an external Xantrex regulator?

4) Am I right in assuming that it might make better sense to have two identical alternators for redundancy of spares and for the fact that if one goes, I can still make amps, rather than for an "all my eggs in one basket" approach?

5) Would there be any consequences if one alt died or required service, to substitute the old 55 amp alternator in the charge circuit with the 75 amp?

Thanks!

[hellosailor]

Valiente-
"1) Does it make economic sense to get two 75 amp Balmar-type alternators and to arrange them with two belts on either side of the block?Does "balancing" the physical pull on the PTO lessen wear?"
Yes, because of the pull/wear on the bearing. But that's making rash assumptions without knowing how much pull the bearing is intended to deal with. Generally, irregardless of what it is designed to take, a bearing will be happier with "balanced" side loads.

"2) Would I get better total output from two 75 amp alts or from one 135 amp?" Depends on your regulator(s). In theory you get 150A max from the first and 135A max from the second, but in practice, the first has some slight (very slight) extra load from two pulleys, belts, etc.

There's one issue that Balmar will tell you about right up front: Once you exceed about 100A in a single alternator, you can't drive it with a single V-belt. You need dual belts, and if you run dual belts without a belt tension guage, you will continually be busting the one belt that is really carrying the load--and then you need to replace BOTH again in order to get them balanced again.

You'd be better off doing what the auto industry has done, switch to a RIBBED BELT so there is only one belt. Of course, that may mean a custom pulley on the PTO and a custom pulley on the alternator (unless you can find a stock one that fits) at a price around $125-150 for each pulley from a machine shop.

Incidentally--buying custom pulleys can make very good dollars and sense in any case, because you want to match your alternator output to the engine speeds you will be cruising at, charging at, and maximum at. This can be more valuable than your regulator itself.

"3) Am I right in assuming that the Balmar-type alts are internally regulated, meaning I would not require an external Xantrex regulator?" Balmar offers all kinds of things, even alternators with dual outputs, each separately regulated, to charge separate/redundant banks. Give 'em a call or email them, if they aren't out to the boat shows they are VERY willing to talk and advise.

"4) Am I right in assuming that it might make better sense to have two identical alternators for redundancy of spares and for the fact that if one goes, I can still make amps, rather than for an "all my eggs in one basket" approach?"
Well, I like eggs in baskets, plural. But the folks who fly the big jet planes say the fewer engines you have, the better the chance that one of them won't fail in flight. They have a point there. Whether you go with one or two alternators, keep something on hand as a spare, even if it is "just enough to run things but the food in the cooler is going to spoil".

"5) Would there be any consequences if one alt died or required service, to substitute the old 55 amp alternator in the charge circuit with the 75 amp?"
Consequences...only if you got the wiring wrong. IF both alternators use the same type of harness (i.e. both are "3 wire" type) and both use the same regulation (positive or negative frame, etc.)...they can be plug-and-play interchangeable. You just need to make sure that the hookups for both will be the same, or that you do what it necessary so that one night, when you are seasick, overtired, and bouncing around in a storm, you can "just" unplug the dead one and plug in the good one. Preferably by just changing one harness plug, and putting one (normally not used) belt back on the engine.

Or by unbolting the dead one, replacing it with the spare, whatever works for your setup.

But dual belts...uh-uh, don't like 'em, that's too many kids in the same sandbox, adult supervision WILL be required.

[Bill Mc]

Large Balmar Alternators typically are external regulator only. The regulator should be designed for the type of batteries that you have ie. AGM, Flooded Lead Acid, as well as a soft start capability to gradually load the alternator and not smoke the belts. I would retain the 55A alternator if both mounts are compatable, if your adding Solar and Wind power I would think this would be redundant enough to make most destinations here on planet earth Upgrade if possible and try not to worry so much about what if's

PS If you wire the regulator to your oil sending unit for sensing its on signal, your engine will start without an immediate load on it.

Fair Winds,

Bill

[Bill Mc]

Hellosailor, has made some good points. I would like to add that when you purchase multiple drive belts that you should request that they be a matched set. The minor size variations during production of v belts has little consequence with the exception of multi sheeve applications.

Fair Winds,

Bill

[hellosailor]

"a soft start capability "
Good point, Bill. I've seen a single V-belt (allegedly properly installed and all) literally take a big jump and the resulting "hump" in the belt walk right off the pulley, when a 70-80A alternator was switched from "1" to "1&2" and the load from a second battery was slammed on. That soft-start benefit has to be significant as the loads get heavier and you want to be gentler on the belts, if nothing else.

[PBzeer]

I bought a Balmar Hi-Output 70 amp alternator, but they recommend using an external regulator as well. With my setup, I have a 3 position switch for internal, off, external. The external regulator (Xantrax branded Balmar) has a 45 second rampup before engaging, and with the switch to the off position, the alternator pulley freewheels, giving back those revs to the engine if needed. I've been quite happy with the setup and it has worked well for me.

[Bill Mc]

I'm running a Balmar 110 amp alternator with an ARS-5 regulator with 1 alt and 2 batt thermo's. when you short out the thermo it reduces the output current this will give the Iron Genny a little more Ooooomph. At full load, I give up about 2 hp on my Yanmar 3gm30. I also purchased a cogged drive belt that is blue in color and the mfg stated that it will make for longer/cooler belt life. I haven't gotten back to the boat to install it though..

Fair Winds,

Bill

[Valiente]

Thanks for all the suggestions and replies, guys. You've cleared up some questions in my mind. I am that dangerous stage...no longer a beginner but not half as clever as I need to be if I'm going to go offshore, and I find asking fellow sailors what works and why is better than going to even the better sort of reference books out there (they are coming with me!).

[Rockter]

Running two alternators at once? If the regulators on each alternator were the constant voltage type, it should not be a problem as both will be regulated to very close to the same voltage, and each regulator will call in its alternator until, the regulator voltages are reached, in turn.

The problems may start if both alternators have independent "intelligent" regulation (the "three-step" regulator is one type). If both regulators are trying to be intelligent at the same time, they may confuse one another, methinks.

I like the idea of the twin alternators, but how could you keep them independently intelligent, if they are both charging the same battery bank?

Each alternator to one bank sound good.

I had good success with the Ample Power alternator and three step regulator, now into its 15 th year, and still running fine. A call to them... they are US-based.... would be worthwhile. They should be able to recommend a twin alternator system, and advise.

I have no hidden interest in Ample Power.

[Valiente]

Thanks for the suggestion. With the Canadian dollar approaching par, it makes sense to include more American smaller brands in my decision-making (the Tank Tender system is 25% cheaper to me today than last year, so I am glad I've held off on some purchasing decisions.

I guess the separator alternators to separate banks idea is a good one, but how about if I had some type of a combiner switch to charge everything off one bank?

My situation is complicated by the fact that I intend to charge only the start bank with the alternator (usually), and when that reaches full charge, I would shunt the alternator output into the house banks via the Xantrex inverter/charger, which will be generally charged by wind and sun.

I think it's time to make a big electrical org chart that explains my ideas and maybe submit them here for comments. It's not ridiculously complex, but it contains a lot of options for rerouting power from different sources to different banks at different times, all in the name of keeping the engine off unless I am going to motor or motor-sail some distance, at which point I am happy to make loads of power in addition to capturing the sun and wind output. (Actually, I would like to reroute sun and wind to the isolated windlass battery when underway, because 150 amps for a few hours a week is enough to charge my start and my house banks alone.)

Man, I need to make a circuit diagram.