Using leisure batteries only

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Laundryman

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My set up has 2 leisure batteries 100 amp each and a start battery. A typical 1,2,both,off switch and a modern mains intelligent 20amp charger. My volvo 2020b starts instantly always,hot or cold. Because of that i have never bothered to turn the 1,2 both switch to the Start battery and so it has had no use at all. My Domestic bank has coped with my malpractice for the last three years without complaining. I'm currently looking to update my electrics and favour the smart gauge/smartbank route but before i start spending, why cant i do away with my Start battery and replace it with 2 leisure batteries, turn the switch to both and effectively double my house capacity? Then i would no longer need the smartbank/vsr and the money saved will almost buy the batteries. I always carry an emergency power pack and a silent (only if you're deaf) generator should the worse happen. I know the forum doesn't like the 1,2,both switches but its only function will be to parallel the 2 banks or turn the whole lot off. Am I missing something? Thanks Alan
 
I know people who do exactly what you are suggesting and never have a problem. I am sure there will be plenty that will tell you why you can't.
I have just removed a split charge relay and installed a 1,2 both switch to switch my engine alternator output. The off part of the switch will be inhibited to stop the output being broken. This worked for me for the last 15 years on my last two boats.
 
I've always used Avocet's single leisure battery as a starter battery. The engine is only 12HP though, and has a decompressor. It doesn't seem to adversely affect the battery life. On average, they've lasted about 6-7 years each.
 
Normal practice in the US is to have "main" and "reserve" rather than "engine" and "house". So they have a big battery which usually runs everything, and a smaller one which is occasionally topped up but otherwise left disconnected. In the event of the main battery becoming flat, they switch to the reserve to start the engine.

Apart from the portapower not being hardwired in with a switch, your proposal exactly mirrors this.

Pete
 
prv said:
Normal practice in the US is to have "main" and "reserve" rather than "engine" and "house". So they have a big battery which usually runs everything, and a smaller one which is occasionally topped up but otherwise left disconnected. In the event of the main battery becoming flat, they switch to the reserve to start the engine.

Apart from the portapower not being hardwired in with a switch, your proposal exactly mirrors this.

Pete
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That US system is actually a very good idea for most people. The only downside is that you get generalist batteries to do two different jobs. Starting relies on a high drain for a short period, domestic on a low drain for many hours. However, unless you have proper deep cycle batteries in your domestic set up then it becomes a little academic.
 
I put all my batteries into the house bank and then added a tiny TPPL battery for the starter. The wet lead acid house batteries are now 10 years old and the TPPL five. Low stressed batteries live longer.
 
jac said:
That US system is actually a very good idea for most people. The only downside is that you get generalist batteries to do two different jobs. Starting relies on a high drain for a short period, domestic on a low drain for many hours. However, unless you have proper deep cycle batteries in your domestic set up then it becomes a little academic.
Click to expand...

I don't think a decent-sized deep cycle bank would have any problem starting a smallish yacht engine.

Pete
 
prv said:
Normal practice in the US is to have "main" and "reserve" rather than "engine" and "house". So they have a big battery which usually runs everything, and a smaller one which is occasionally topped up but otherwise left disconnected. In the event of the main battery becoming flat, they switch to the reserve to start the engine.

Apart from the portapower not being hardwired in with a switch, your proposal exactly mirrors this.

Pete
Click to expand...

The reason for splitting start from service power is volt drop and noise when running the starter motor, this was, and still does, cause drop out of navigation equipment or memory.

This can be a boat on boat situation, one boat can have a engine that starts instantly, next boat can be a pig, with a new boat it's fitting a system that will not be a problem, one that is not going to have new customer complaining. The system may be no problem with fully charged batteries, but coming to the end of a trip with low batteries, starting the engine can cause very low voltage and navigation equipment drop out. Thus having a separate engine battery allows instant turn key and start engine with no problems,

As with all things on boats it's what are you as skipper of the vessel happy with.

Brian
 
halcyon said:
The reason for splitting start from service power is volt drop and noise when running the starter motor, this was, and still does, cause drop out of navigation equipment or memory.

This can be a boat on boat situation, one boat can have a engine that starts instantly, next boat can be a pig, with a new boat it's fitting a system that will not be a problem, one that is not going to have new customer complaining. The system may be no problem with fully charged batteries, but coming to the end of a trip with low batteries, starting the engine can cause very low voltage and navigation equipment drop out. Thus having a separate engine battery allows instant turn key and start engine with no problems,

As with all things on boats it's what are you as skipper of the vessel happy with.

Brian
Click to expand...

+1

Much depends on boat use, whether day sailing or living aboard for extended periods. We have 2 house banks totalling 480AH plus a dedicated engine battery. Prefer 1,2,both switching as nothing to fail which can't be fixed on the spot.
 
prv said:
Normal practice in the US is to have "main" and "reserve" rather than "engine" and "house".
Click to expand...

halcyon said:
The reason for splitting start from service power is volt drop and noise when running the starter motor, this was, and still does, cause drop out of navigation equipment or memory.
Click to expand...

I'm just reporting what thousands of people do.

My boat has "house" and "engine".

Pete
 
My boat has house and engine batteries because the engine has to start when the amps get low due to the load from my nav equipment. On a long passage, I often have to charge the house battery twice especially if there's been night sailing. The house battery has occasionally got too low to run the plotter. I don't use the plotter during channel trips any more as the PC drains the battery too much.
 
Lots of solutions to this, and there's an element of personal preference.
FWIW - what works for me -

When I got the boat (just a little 25' coastal cruiser) there were two batteries, each of about 75 Ah - just normal "leisure" batteries - one for engine starting and one for everything else, with a 1 - 1+2 - 2 - OFF switch. The original installation wasn't good in a number of respects, the relevant one is that the ship's battery got a caning from various bits of electrical kit including a compressor fridge, especially since the engine didn't get a lot of running if there was a decent breeze.

What I eventually finished with (so far) was two batteries in parallel for ship's supply, so now about 150 Ah available. The space for battery installation was a bit limited so the engine start battery is a small car battery of about 40 Ah which fits into the remaining space. Although small, it can provide about 440 A for engine starting which for a small diesel (Yanmar 1GM) is enough.

When starting the engine, the switch is set to 1+2 and then not touched until after the engine has stopped, when it is switched to the ship's batteries. This ensures that all batteries are being charged when the engine is running, and that I always have at least one battery that can start the engine.

From time to time I start the engine with either the ship's batteries alone, or with the engine battery alone, just to show that the batteries are OK.

A very simple system but I can't see a good reason for complicating it.

If I had enough space I would probably add another battery to the ship's bank.
 
jac said:
I do wonder if the fear of that is overstated.

We accidentally switched both to off whilst motoring earlier this year (only for a second) and alternator still fine. Wouldn't do it again though!!!
Click to expand...

I suspect it may depend on how much load was on the alternator at the time. Lightly loaded and you'll probably get away with it. Heavily loaded probably not.

Some alternators have surge protection diodes anyway.

Worth keeping an eye on it for a while after such a mishap to be sure it still performs as previously because some some diodes way be blown while others not. If in any doubt get it checked
 
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