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  Topic Review (Newest First)
12-04-2008 05:37 AM
Rockter Fishfinder :

Sounds like you know your alternator fairly well.

Go into the back of the alternator, and find the field wire. The field wire accepts the current from the regulator to energise the rotor of the alternator. It is this field current that the make-before-break battery master switch is supposed to disable before it swops over the batteries. It looks very much like it is NOT doing that, as you have noticed the loads being switched off as you turn the switch.

When you find the field wire, you are going to cut the wire close to the alternator, and join a length of conductor to that wire. lead the length of wire up to your instrument panel and fit a wee switch for it, then lead the wire back to the alternator regulator again. Effectively what you are doing is allowing a manual interrupt to the field wire via a big loop.

MANUALLY, you must throw that loop switch to disable the alternator field wire before you move the alternator switch. Then after moving the switch, you enable the field wire again.

This is my set-up, and has been for years.

You simply remember to throw the disable switch each time.

It works too, and you can see the effect on your ammeter, if you have one. Don't trust that battery switch of yours. The loads must not drop out when you turn it. Your alternator diodes will not take that for long. It is possible to put a "snubber" at the back of the alternator to give you some defence, but mine fell off.

My alternator is the US-supplied Ample Power 100A, small frame model. It is a damn good alternator, now 16 years on, and still running.

You don't need fancy monitors and read-outs and flashing lights. One big storm in open water and the whole show will be soaked anyway. Man, getting soaked in seawater sorts out the junk from the necessary, I can tell you. A simple manual switch and a wee ammeter will do fine.
12-04-2008 12:11 AM
normal use of 1 and 2?

In most older sailboats (we have a1984) is the normal convention that 1 is for engine starting and 2 is the house batteries?

Thanks, Saltypat
09-12-2008 03:13 PM
Originally Posted by hellosailor View Post
A 30-year old battery switch may not be making proper contact anymore, the contacts do wear and sometimes shift. I'd be tempted to replace it, or to install a battery combiner switch (West/Yadina or Hellroaring) which starts you on the starting battery, then combines both to charge/run once the alternator has come up to full voltage in a minute or two. When you shut the engine, it disconnects them again, so your starting battery is just isolated for starting use while you are on the house bank.
Be sure to use a high quality switch with more than enough of an amp hour rating. Best ones are Blue Sea and Cole Hersey. Most quality models can be opened to clean/inspect the contacts. A "Zap-Stop" on the alternator will protect against transient spikes, including switching off. There are battery switches which have an alternator field cutoff, so the alternator won;t be zapped.
The combiner option is one I have on my boat, but with an override, so I can switch it off manually. Sometimes you want to.
Personally, I recharge the engine start batteries to about 95%, then the house batteries to a similar level before switching to "Both". When in the "Both" position, the batteries will flow juice from one to another. Gnerally not too big a deal when the engine is running, but can be. If the "house batts" are flat, you switch it on "Both" there can be a current overload as both the alternator and engine batts try to recharge the house batts. Also, if the engine should die, or be shut off at that point. it's possible the engine batt will have been drawn down so the engine can't be restarted.
09-08-2008 02:26 PM
Originally Posted by surfnrg View Post
I have a Catamaran with two seperate 12V starting batteries - one for each engine - along with a house bank consisting of 6 6V Trojan deep cycle batteries. I also have 2 alternators - one on each engine.

Is it best to have both the starting batteries allocated to the "1" position then the house bank designated to the "2" position? Or, should I find a way to isolate the two starting batteries from each other? Is there a switch that offers 1, 2, 3, ALL and OFF positions? And if so, would that be the most desirable for my setup?
If you bring both batteries to a central switch, that would defeat the purpose of having one starting battery per engine since you still need the long battery cable runs. The answer is also dependant on whether or not you are always running both engines at the same time. Still what has been said before applies to your case:

1) I would have both alternators charging the house bank
2) I would have either a single starting battery bank or one dedicated per engine.
3) I would charge the starting battery(ies) from the house bank with a DuoCharge or equivalent.
09-08-2008 05:58 AM
surfnrg I have a Catamaran with two seperate 12V starting batteries - one for each engine - along with a house bank consisting of 6 6V Trojan deep cycle batteries. I also have 2 alternators - one on each engine.

Is it best to have both the starting batteries allocated to the "1" position then the house bank designated to the "2" position? Or, should I find a way to isolate the two starting batteries from each other? Is there a switch that offers 1, 2, 3, ALL and OFF positions? And if so, would that be the most desirable for my setup?
09-07-2008 07:59 PM
Preferred Setup

Originally Posted by btrayfors View Post

Good advice. Charge them separately or, better, use a Xantrex EchoCharge or a Balmar DuoCharge device (NOT a battery combiner or an isolator, etc.).

Sorry, halekai36, while I very much value your expertise and thoughts on many things, I have to disagree on your philosophy re: starting batteries.

The preferred setup is:

1. ONE large house bank, charged by every onboard device (battery charger, alternator, solar, wind, generator, etc.);

2. ONE starting battery, sized for your engine and NOT a deep-cycle battery; and

3. an EchoCharge or DuoCharge device, as per above.

This gives you a near bullet-proof, very efficient setup, and provides all the safety and redundancy you need.

Switches, fuses, breakers, etc. are a related but separate topic.

I would even make a stronger statement: this is not the preferred setup, this is the only setup that works over the long run. The 1+2+1 switch is a solution that has flaws (some of them reported here) and over the long run one is going to forget putting the switch in the "House" mode after a charge session in the "Both" mode (I know there are a few of you out there who will never forget!). There are other considerations such as the inrush current when combining dischared and charged batteries, the fact that the charging current does not "balance itself", etc etc which makes the 1+2+1 a bad design choice.

Battery combiners have most of the flaws of the 1+2+1 switch except that they cannot be forgotten in the "Both" position. That's an improvement.

I use the Balmar DuoCharge and it works as advertised.

FYI, I also have a secret way of combining both banks but it is not accessible from any panel.
09-02-2008 10:59 PM
Originally Posted by sailingdog View Post

YOu're talking about the BlueSea dual circuit plus battery switch... I installed it on my boat and two others so far.... and they're great, especially with the combiner.
That's what I'm talking about. The page referenced is a kit containing the Blue Sea Dual Circuit Plus switch, plus the ACR.

Unless somebody can come up with a down-side to this system, it's the way I'm planning to go. (Already got the ok from the Admiral and family CFO to spend the $100+ on that, as opposed to $40 or so for a vanilla OFF/1/BOTH/2 switch.) I do have one question, but I'll start a separate thread so as no to drag the OP's thread off on a tangent.

09-02-2008 09:09 AM
donradclife My battery switches have been on ALL since I bought the boat 14 years ago, but for reasons which probably don't apply in this case. I have 3 gel cell banks, and combining them cuts down on the discharge percentages and extends their life. However, I have alternative charging sources (solar, wind and water), and can recover from a shorted cell.

In this case, installing a ZAPSTOP would be the cheapest and easiest way to keep from frying the diodes when the in-laws are 'helping'.
09-02-2008 06:21 AM
KeelHaulin So if I add a single starting battery with an isolator between my existing 2-banks (2x 280Ah house/starting); I could have a starting circuit that protects my engine alternator and leave the 2-banks on my safety main as-wired?

Can the starting bank be isolated from the ignition switch; so that section does not need to be wired directly to the starting bank?
09-01-2008 11:39 PM
Repos Diodes are killed by a back high voltage pulse (peak reverse voltage)produced by the alternator coils when you abruptly disconnect the alternator on the battery with a defective switch or. My simple solution: I connected the alternator directly on the house bank and I charge the Start battery with the dock charger or put the battery switch to Both occasionnaly when the house bank is near full.
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