Charging Systems

Sorry guys, but I seem to be a little slower than others understanding alternators, battery isolating, battery switching and stuff. It seems to me that with two 80 amp alternators on two engines that there should be a way to use the charging capacity of both on one bank without drawing down the other. This was suggested in another thread. Sounds like it will work, but I don't know enough about it. It is an automatic battery relay.

BLUE SEA SYSTEMS Solenoid at West Marine

What say the experts?

I'm no expert, but that's very close to the same setup I have on my boat with twin engines/alternators and separate start and house banks. I installed the Yandina combiner that only handles 100A. It's not nearly as stout as the Blue Seas ACR. If I was to do it again or improve the system, I'd install that Blue Seas ACR.

I also installed a LinkPro battery monitor to keep a close eye on the charging and discharging of the battery banks. I think that's a very critical component of a well designed electrical system. My unit shows all the needed details on the house bank (charging/discharging current, batt voltage, hrs remaining, % of charge remaining) and digital battery voltage on the start bank.

With the monitor, I'm able to see that when both engines are running, the charging current not needed on the start bank is being accepted in the house bank. I know this is happening when the charging current to the house bank exceeds the 75A output of the house connected alternator.

Thanks, Al. I have the Victron SOC meter for only one bank. I think it should still work with the ACR as it measures charge current. This is looking more and more like the solution to my conundrum. Having 160 amps of total charging capacity, and using only half for the house bank just seems like a waste. All I want to do is charge the house bank more quickly while underway.

Moonstruck said:

Sorry guys, but I seem to be a little slower than others understanding alternators, battery isolating, battery switching and stuff. It seems to me that with two 80 amp alternators on two engines that there should be a way to use the charging capacity of both on one bank without drawing down the other. This was suggested in another thread. Sounds like it will work, but I don't know enough about it. It is an automatic battery relay.

BLUE SEA SYSTEMS Solenoid at West Marine

What say the experts?

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I would think yo take full advantage you need something like this

centerfielder II (CFII-12/24)

in conjunction with a smart solenoid like you posted. The centerfielder keeps both alternators peaked but charges one bank until nearly full then the next.

I'm not sure you would use this setup...bt a call to Balmar would point you in the right direction if something like that is made or if the combo setup would actually fit the bill.

Most twin setus I have seen have a small alternator on each engine and a big alternator on one of the engines for the house bank.

Another one might be a big alternator on one engine for the house bank and a smaller one on one engine wired through a solenoid like you posted to charge one start battery then the other.

WOW! Thanks for posting that psneeld. That looks like a necessity in this application. Just shows how much I don't know about it, and don't understand much of what I do know. We do a lot of complicated electrical stuff on multi-unit and commercial projects, but the 3 types of systems on a boat seem more complicated to me. We do many back up systems with 408 and 120 volt stuff, but it is not as complicated a a purely self contained system that will run 3 ways.

Moonstruck said:

Thanks, Al. I have the Victron SOC meter for only one bank. I think it should still work with the ACR as it measures charge current. This is looking more and more like the solution to my conundrum. Having 160 amps of total charging capacity, and using only half for the house bank just seems like a waste. All I want to do is charge the house bank more quickly while underway.

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Don, the ACR would help, but in combination with the Balmar device Mr. Psneed linked to the solution would be better. The Centerfielder basically sidelines one of the alternator regulators keeping them from fighting each other when connected to a common destination, effectively giving you a 160 amp alternator while the ACR makes sure the battery bank doesn't drain the battery bank or vice versa when no charging source is present, or the house bank has been drawn down.

Moonstruck said:

All I want to do is charge the house bank more quickly while underway.

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That's all we wanted to do, too. But the way we do it (or did it-- we don't need to anymore) was in the true sense of the expression KISS.

The stock Motorola alternators on our FL120s normally charge only the battery associated with each engine. So the port alternator charges the port battery, starboard the starboard. This is with the battery selector switch in either 1 or 2, which determines which of the 8Ds (now golf cart banks) will fill the role of house battery.

When I mentioned to the proprietor of the marine electrical shop we use that it seemed a shame that only one alternator was charging the house 8D while the other one had the easy task of recharging the start 8D after which it was just along for the ride he checked the boat's wiring and determined that if we put the battery selector in the "All" position this would combine the alternator outputs so both of them would charge both batteries.

In fact, he said, this explained the mystery of why one of our alternators has a smaller drive pulley than the other one. The faster-spinning alternator would be the dominant one and thus prevent any conflict between the combined alternator outputs. (I don't understand this; I'm just repeating what he said.)

So from then on we would put the battery selector switch in "All" prior to starting the engines. The combined output of both alternators would recharge both batteries much faster and if we used heavy-load items like the anchor windlass or microwave on the inverter the batteries would not be drawn down as far and would be recharged much faster. When we shut off the engines the first thing we'd do is move the battery selector to "1" to designate it as the house battery.

We no longer need to do this (although we still could) but for years this simple process of using the battery selector switch as a charging "combiner" worked beautifully.

The activities of the alternators could be observed on the ammeters. After startup, particularly after a day or so in an anchorage, both ammeters would show a high rate of charge where before only the meter on the alternator charging the house battery would show this high rate.

Then as our run progressed both ammeter indications would slowly come down together as the batteries were charged. Finally, when the batteries were fully charged, the slower-turning alternator would drop to its lowest charge stage while the faster turning alternator continued to carry the house load of electronics, refrigerator, lights, etc.

Very simple but very effective procedure.

The Centerfielder requires dual Balmar MC-614 regulators to function. If you don't already have the MC-614s, at $350 per regulator plus the $200 for the Centerfielder, you're looking at a $900 bill just for parts.

Based upon what I've read and seen, a switchable ACR or combiner with a monitor will accomplish the same functions.

Incidentally, my alternators were rewired to preclude the charge having to run through the starter cables and 1-all-2-off switch to provide power from the alternator to the batts. Each alt is wired directly to its own battery bank. Separate batt switches provide the capability to manually combine battery banks if needed.

FlyWright said:

The Centerfielder requires dual Balmar MC-614 regulators to function. If you don't already have the MC-614s, at $350 per regulator plus the $200 for the Centerfielder, you're looking at a $900 bill just for parts.

Based upon what I've read and seen, a switchable ACR or combiner with a monitor will accomplish the same functions.

Incidentally, my alternators were rewired to preclude the charge having to run through the starter cables and 1-all-2-off switch to provide power from the alternator to the batts. Each alt is wired directly to its own battery bank. Separate batt switches provide the capability to manually combine battery banks if needed.

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The ACR makes it possible to have a single charging source maintain two battery banks, but it doesn't actually address two banks and two charging sources. I believe the problem with just letting both alternators feed into a single destination is that one of the alternators will drop off, effectively cutting the charging capacity Don has in half. I'm also not sure you need two smart regulators. Just the Centerfielder to combine the alternators, the ACR to manage two battery banks and one smart regulator. I have the MC624 and like it a lot. Ample Power has a similar product to the Centerfielder and the MC612, and their products are also very good.

Two Engine/Alternator System

p.s. now that I look at the Centerfielder wiring diagram, I can see I was wrong about it. Balmar does want you to use two smart regulators for it to work, so it looks like the Ample Power product is the better choice as it is designed to address twin alternators using a single regulator. Looks like their Dual Alternator Controller costs about $160.00, and it is designed to work with a single smart regulator.

Thanks for posting the link to the Balmar site.

http://www.balmar.net/duo-charge.html

In looking at their Digital Duo Charge - DDC 12/24 they say I can eliminate isolator or battery switches. I have one alternator, 2 house batteries and a starting battery. Looks like I could set the system up using this and remove the 1-2-all switch if I parallel the house batteries?

This seems pretty cool.

To go simple the house bank would loose the 1-2 switch as a bigger bank is better than 2 smaller banks on rotation.

With the start and house seperiate only an $18 RV solenoid is needed , with an auto style key switch (that has ACC position). If you can charge at over 75A constantly 2,,, $18. solenoids are required.

The rotary switch could be left on board , should for some reason the Start batt die , and you wish to start from the house bank.

With a large house bank starting a diesel is very effective.

Moonstruck said:

Sorry guys, but I seem to be a little slower than others understanding alternators, battery isolating, battery switching and stuff. It seems to me that with two 80 amp alternators on two engines that there should be a way to use the charging capacity of both on one bank without drawing down the other. This was suggested in another thread. Sounds like it will work, but I don't know enough about it. It is an automatic battery relay.

BLUE SEA SYSTEMS Solenoid at West Marine

What say the experts?

Click to expand...

There's always many ways to skin the same cat but I'm not sure why people keep a large engine start bank independant of a large house bank. I understand the need for redundant systems but there are other ways to accomplish that which don't require carrying several batteries that are only ever used to start the main engines. This may not be the situation here and if so I apologize for my misunderstanding.

We carry 8 x 6 volt T105s set up as 2 x 12v banks that are normally combined through a rotary combiner switch. If I have a problem in one bank I can isolate it but for normal operations the switch is left on "both". The noisemaker has its own 4D start battery. In an emergency I could start the engine(s) with that battery but my more likely action would be to use the noisemaker to recharge one or both of my main battery banks.

I researched the Centrefielder and couldn't justify its cost for what it offered. Rather than the Centrefielder plus dual Balmar 614 regulators, I use a single 614 regulator to drive the field on both alternators. To guard against an energized field on a stopped alternator I use NO oil pressure switches on each engine. The field current for each side runs through a NO switch so the field can't be energized unless I have oil pressure. I also have a Xantrex Echo Charger which keeps the noisemaker battery topped off anytime that there is charge present on the main batteries.

The system won't let me upload my DC diagram but if anybody cares that much send me a PM with a real e-address and I'll email it to you.

I'm not sure why people keep a large engine start bank independant of a large house bank.

Great question , probably inert1a , that's how the boat came.

For most boaters with under 250Hp diesels that do not require a cold soak start at 0-F , a single Series 31 will do the job. Do winter starts , get a pair.Be sure the alt "sees" the house batts for best charging.