Deep cycle battery charger

[jefword]

Hi, Not sure if this should be in the section for boats or DIY or whatever so please feel free to move it.

I have a narrowboat which has three deep cycle leisure batteries and a conventional car type starter battery all linked together and charged by an alternator which also has a battery boost controller wired into the circuit.

As the narrowboat spends most of it's time stationary I bought a special deep cycle battery charger as the normal car ones cut off too early because they are not designed to fully charge a leisure battery.

I just wondered if anyone knows if this type of charger would damage the conventional starter battery by trying to force too much charge into it.
In the mean time I will disconnect the starter battery whilst using the charger & possibly put a separate isolator switch on it (is it best to put the isolator switch on positive or negative side or does it not matter?)

Thanks in advance for any help & information.

[Mojocvh]

Intrigued by deep cycle leisure batteries, what are they..??

[Simpo Two]

Leisure batteries are designed to give a small current for a long time, as opposed to 'car' batteries which give a high current for a short time, aren't very good at small loads like lighting.

[jefword]

Hi, A deep cycle, also known as a leisure battery is used on boats & in caravans (and maybe golf carts & invalid scooters among other things).

They are designed to give a smaller current for long periods to run lights, fridges & water pumps etc. whereas the main requirement of a car battery is to give a massive burst of power for a few seconds to start the engine.

This is a very simple and probably only semi accurate description of the two types. A better one is here

http://www.windsun.com/Batteries/Battery_FAQ.htm

[jefword]

Hi, You just beat me to posting the answer. You probably would not have done if my wife had not been in my ear hole all the time I was trying to compose a technical explanation but thanks anyway.
Cheers.

[Simpo Two]

This is a wife-free zone. You'd be amazed how much you can achieve...

[Mojocvh]

jefword said:

Hi, A deep cycle, also known as a leisure battery is used on boats & in caravans (and maybe golf carts & invalid scooters among other things).

They are designed to give a smaller current for long periods to run lights, fridges & water pumps etc. whereas the main requirement of a car battery is to give a massive burst of power for a few seconds to start the engine.

This is a very simple and probably only semi accurate description of the two types. A better one is here

http://www.windsun.com/Batteries/Battery_FAQ.htm

Good link that, thanks.

[maser_spyder]

I have 1 x deep cycle and 1 x engine battery, and a single battery charger that does the pair.

I've never looked to see if it charges them separately, but from memory, it doesn't.

Leaving any battery on charge 'indefinitely' won't do it any good.

I left mine all turned off in late September, went back last week, and both still have a decent charge, started the engine first time. Comparing that to the Maser battery, which is flat inside about 14 days.

Marine batteries seem a lot more capable of holding a charge for a longer time than auto batteries. You might get away with less regular charging?

[Simpo Two]

What about a solar-powered battery conditioner? (from Maplin for example)

I use a mains one for the TVR and it does a perfect job.

[jefword]

Hi, Thanks for the replies but I probably didn't explain the circumstances clearly.

I didn't want to leave the batteries on charge when I'm not on the boat, I just switch the charger on whilst I'm staying on it during the occasional weekend etc, to run the fridge (for the lager of course) and other electrical items such as lights.

I would probably be best to not do this and let the leisure batteries discharge somewhat and then put the charger on. There is a diode in circuit to stop the "domestic" items draining the main starter battery.

My question is would the deep cycle charger, although perfectly ok for the leisure batteries, damage the engine starter battery by trying to overcharge it, if this was still in circuit.

[Fishtigua]

If your diode, I'm assumeing it is like a VSR (Voltage Sensitive Relay), the charger will send charge to the lowest charged bank. If your House bank batteries are 'wet' rather the Gel and so is the enginestart battery, you should be okay.

Gel batts charge at a different rate to 'wet' batts and cannot be mixed.

[jefword]

Hi, Thanks for the info. I didn't realise that you could not mix wet & gel batteries. Fortunately mine are all wet.