Which Book on Boat Electrics?

nigelmercier said:
I stand corrected. What a silly system. So you don't have dedicated starter/domestic batteries?
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Not as far as the wiring is concerned, it's a convention you stick to in how you use them. Let's say you nominate 1 as the engine battery. You leave the switch on 2 when sailing and anchored, then when you decide to start the engine you move the switch to 1, start it, then switch to Both to charge both batteries. As soon as you stop the engine, you go back to 2 so that number one will remain fully charged ready for the next start. Alternatively you could use the same wiring for a "Main and reserve" system, or even a "one big battery bank and I'll use the starting handle if it comes to it" system.

I've sailed on plenty of boats with this kind of manual switching, including our own Kindred Spirit when we bought her. After the first year I did a complete electrical refit, and the damn switch was always going to go.

Pete
 
prv said:
Not as far as the wiring is concerned, it's a convention you stick to in how you use them. Let's say you nominate 1 as the engine battery. You leave the switch on 2 when sailing and anchored, then when you decide to start the engine you move the switch to 1, start it, then switch to Both to charge both batteries. As soon as you stop the engine, you go back to 2 so that number one will remain fully charged ready for the next start. Alternatively you could use the same wiring for a "Main and reserve" system, or even a "one big battery bank and I'll use the starting handle if it comes to it" system.

I've sailed on plenty of boats with this kind of manual switching, including our own Kindred Spirit when we bought her. After the first year I did a complete electrical refit, and the damn switch was always going to go.

Pete
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So it was a waste of time me buying a car type battery for what appeared to be the starter battery and a leisure battery for the house battery?
 
Tam Lin said:
So it was a waste of time me buying a car type battery for what appeared to be the starter battery and a leisure battery for the house battery?
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Not necessarily. With a 1,2, both, off switch you can select the starter battery for engine starting and then once topped up change to the leisure battery which remains selected to power all the other stuff when the engine is not running.

Just remember to never switch to the off position while then engine is running or you will very probably toast the alternator diodes. Never allow any one but yourself to operate the battery selector switch.
 
Tam Lin said:
So it was a waste of time me buying a car type battery for what appeared to be the starter battery and a leisure battery for the house battery?
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Not at all: You've done exactly the right thing.. The selector switch determines which battery is brought into play. As others have said, the normal use for these things would be that you'd switch it onto "1" (starter battery), start the engine (using the starter battery), then turn the switch to "Both" (so both batteries are charged by the alternator). When you switch the engine off you turn the switch to "2" so that drain from your VHF, autopilot, instruments etc. is from the leisure battery.

Of course that's a hassle and people like me would frequently forget to do that (especially when short handed) meaning I'd either put a shock load on the house batteries starting the engine, only charge up 1, or run down both after the engine is turned off. That's why I have my engine battery wired to the starter motor, house batteries to everything else, and charge using a VSR. Still have the off-1-2-both switch but it is essentially just an on/off switch for the house batteries at the moment (re-wire in planning).
 
laika said:
Of course that's a hassle and people like me would frequently forget to do that (especially when short handed) meaning I'd either put a shock load on the house batteries starting the engine, only charge up 1, or run down both after the engine is turned off.
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I generally remembered, but it just seemed silly to me to have to manage this kind of thing manually like it's the 1930s.

I wired the alternator output directly to the house battery, the starter motor to the engine battery, and had a SmartGauge / SmartBank system with a big relay that connected them together when charging.

Pete
 
Nigel Calders book is good.However he can have some weird ideas,like when he suggested yachts should have Can Bus technology.That would make working on the electrics impossible without an electronics degree.
 
If I may keep this thread going and ask another question. I went out to the boat this evening and put the new dynast art on and it worked fine. Started the engine OK and I ran it for about ten minutes. I felt the dynastart and it was quite hot, almost too hot to touch. It was Ok to touch after starting the engine and the alternator wasn't hot. In my research on dynastarts it says on one wiring diagram max. 150 amps. Is this referring to the battery bank, which is way over that. How hot should the dynastart be getting and if it is too hot what might be causing it. Thanks for all your replies so far!
 
How long we're you spinning the engine. Above hand hot is ok, above say 80c then too hot. I presume the dynastart was charging the battery after start, and dynamos are not very efficient, so a big battery could cook the thing.
 
superheat6k said:
How long we're you spinning the engine. Above hand hot is ok, above say 80c then too hot. I presume the dynastart was charging the battery after start, and dynamos are not very efficient, so a big battery could cook the thing.
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There were 3 batteries on the boat when I got it, all very old and knackered, I replaced them with a big leisure battery, 125 amps, a smaller one of 85 amps and a starter battery of 85 amps thinking that this would give me lots of power. Did I overdo it? Should I disconnect one of them and see how the dynamo performs?
 
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