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Date Posted: - Monday - 01/ 4/10 - 12:22am
Author: Randal, Murre, M31
Subject: More Questions
In reply to: Randall, Murre, M31 's message, "alternator regulators" on - Monday - 12/14/09 - 1:45am

Thanks for the great feedback, gents.

I always forget to go to Calder. Not sure why. Maybe the book's too damn big. But thank you for the hint. I read the "mind numbing" thesis you reference, which is really all of chapter one, and am now working through two and three. Essential. Should have read it first, but if I had, I might never have started.

Still have questions about the alternator and regulator, though, and these are questions I've not found answers to in Calder ... yet. Since this is a longish post, feel free to answer simply with "Calder" if I just need to keep reading.

ALTERNATOR: I think it's an oldish Delco, but I think this only because of the form factor--there's no branding on it, but it looks the same as those on the web, here: (http://www.motorcityreman.com/7127marine.html). It has two points: Batt and Ground and that strange black nodule that says "don't remove". It has SAE J1171 tapped onto the casing, which google tells me refers to "Marine Ignition Protected". Don't know what that means yet.

***Big Question Here: how can I tell its rated amp output? I need at least 100 and can go as high as 120. Can my digital voltmeter help sleuth this?

ALTERNATOR WIRING: The 10AWG hot wire from the alternator runs up over the engine and then splits into three directions: 1) red to the ignition switch at the aft of the boat; 2) red to the distribution panel (disconnected); 3) white to a shunt on the port side of the engine. This shunt has a 2AWG hot wire to the starter's hot point, which is wired to the starter battery. THIS WHITE WIRE IS THE ALTERNATOR'S CURRENT CHARGE PATH BACK TO THE START BATTERY.

***Is this arrangement even close to standard? Shouldn't the "split" be via a terminal block? Right now the wires are simply nutted together and taped. (Wow!)

***I want the alternator to charge the House bank, not the starter bank. Can I simply move the shunt and white wire to the house banks? (Can't see why not.) Is there anything sacred about having the Alternator hot wire pass into a battery via the Starter?

REGULATOR: It's an old, a small square box with no branding. It has three wires: red, black, and blue. Black goes into the meter in the cockpit, red goes to BATT on the alternator, and blue goes nowhere at all.

***If blue goes nowhere, can the alternator function? What's blue suppose to do?

I have the new batteries and new switches installed. One cranking battery for the starter; three deep cycle, 150 amp hour 12 volts for house (paralleled). Currently the alternator feeds into the start battery, not ideal, soon fixed. But I charged the lot this weekend anyway and via an Automatic Charging Relay. Pretty slick.

At moderate high to high revs, the alternator output was 14.2 to 14.4 volts, which I think is good. At the batteries however, the voltage jump was not the full volt ("or more") that Casey suggests is healthy, but it wasn't as low as his diagram either. The new house batteries were quite low on charge when I bought them: 12.15 volts. When I started the engine, they only jumped to 13.0. This voltage climbed steadily as the batteries charged. After two hours it was 13.31. After resting overnight, the charge was 12.4. Another two hours charge and resting overnight brought them to 12.55.

***Is the above suggestive of an alternator being asked to do too much (charge 4 batteries where it was use to charging only 2)? Is the regulator set too low? (I don't think it's adjustable.)

------

This is a drawing of the switch set up I just installed using Blue Sea hardware (http://bluesea.com/). I wanted to be able to separate the Start and House banks physically, yet combine them as needed. To do this, I installed a Blue Sea Dual Switch with an extra "Combine All" mode cross connected to a Single Blue Sea switch. The cross connect (red dotted line in the drawing) is what does the trick. Wired this way I can combine all batteries or, by leaving the start switch off but turning the dual switch to "combine", I can use the house batteries to start the engine but bypass the, presumably dead, start battery.

I also have all battery banks combined via an Automatic Charging Relay.

Dual Switch with Combine Function: http://bluesea.com/category/1/products/5511e
Single Switch: http://bluesea.com/category/1/products/9003e
Automatic Charging Relay: http://bluesea.com/category/2/productline/overview/387

Click to enlarge.

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Replies:

[> [> Electrical -- Steve M-32 SEAN O'Sea, - Monday - 01/ 4/10 - 11:25am

Oh boy, where to begin? I guess I'll start with the simple. "Marine Ignition protected" means that it is protected against sparking. The idea behind this is primarily with gas engines although it's not bad in regards to propane either. When you have an explosive, heavier than air gas on board (gasoline vapors, propane) it can build up in the bilge. That is why on gas powered boats you have to use a blower to vent the bilge before starting. It's also a good idea to do it on boats with propane installed. It's not required on diesel powered boats because the vapors aren't explosive. Diesel is rated as a combustible, not a flammable. I guess this a long answer to a short question but there you go.

As far as alternator size, there really isn't one that is too small but there is definitely one that is too big. A small alternator will charge your banks just as well as a big one, it will just take longer. When you get to the section of Calder regarding bulk charge vs top off charge etc I think that will become clearer.

I'm curious as to how you plan to maintain a charge in your starting battery?

A better investment for your money instead of a new alternator might be one of the multistage regulators on the market becuase the regulator was not designed to charge a house bank but a starting battery which has a different use/charge pattern than your house bank. Again, see Calder :-)

I'll stop here for now. Keep reading and ask away, I and the others here will try to not give you too much conflicting advice. One last thought. It is important to keep in mind what Calder is writing about. He is writing about an "off the grid" cruising boat with refrigeration, entertainment systems, pressure water etc. If your boat does not have all those goodies and you're not going out for more than a week at a time without pulling into a marina your system does not need to be anywhere near as robust as what Calder says is necessary. Calder himself tells you this in the book but it is easy to overlook that part.

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[> [> [> How do I charge the start battery? -- Randall, - Tuesday - 01/ 5/10 - 4:01pm

Check out the drawing on the previous post. Between the two switches I've installed an automatic charging relay that bypasses the switches and connects the batteries of both banks when **either** senses charge voltage coming from the other of 13 volts or more for 2 minutes. When this voltage drops belwo 12.75, the connection between the banks is severed.

Slick. And definitely works on Murre.

The reason I'm connecting to house is they are likely drained more than the start battery more often, and since the regulator senses only the bank it's connected to and defines charge delivered by that, I want it to sense the bank that needs the most help.

One error of mine that Calder has been kind enough to point out: I should have bought a deep cycle battery for start. The relay/regulator technology can't regulate charge to differing battery needs. The type of charge the heavy walled house needs is not the same as that needed by the thin walled start, so I will likely be overcharging the current start battery because house needs a heavier charge over a longer period.

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