Adding 2nd battery

[poggy]

Hi,

I am in the process of adding a second battery, we currently only have one which does everything and quite often we run it flat. I have bought a 120ah battery for the domestic circuit so it should give us some extra reserves.

I have also bought a new 3 way battery switch to split them. My questions are:

1. Has anybody tried the super flexible battery cable which is available and what diameter should I use. It is a 28' boat with no serious loads on the battery, only lights, bilge pump, diesel heating etc.

2. If you don't fit a split charger will it seriously affect the battery charge states, the engine battery will be 75ah and domstic 120ah. If I do need a split charge does anybody know a good source at a good price. The alternator is a standard Yanmar 1GM10 35amp one.

3. Does anybody know where to get a nice looking switch panel which doesn't look like it came from the science museum. Preferably with a low cost battery indicator.

4. Should I use tinned cable for some of the domestic re-wire to prevent corrosion, again does anybody know a good source.

Sorry it's long post, but I would appreciate any input on the above.

Thanks for your help.

Poggy

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[TonyBrooks]

1. - No, bit I have used some very thick multi-strand cable from the fridge circuit. It works fine for starting - its about the same diameter as "normal" starting cable.

If the new battery is only to be used for running teh doemstic batteries and charging the same you will find 120/0.30 cable will be more than enough. This will allow you to fit a 60 amp alternator at a later date.

2.- Assuming your switch is a 1, 2, both, off switch, then no - as long as you ensure you turn it to "both" when the engine is running, and away from this when the enginen is off. (this assumes it wired up for charge switching, raher than supply switchjing). Both batteries will "take" the cherge they want. Otherwise a split charge relay will be the cheapest option.

3. Depends on you defintion of nice - make your own? Low cost battery indicators tend to be specilly designed to scare their owners, are decroative rather than functional.

4. Ideally yes, I understand Radio Spares sell it. I also rather suspect that if you use ordinary cable & adhesive heat shrink terminals, you will get long and reliable service. It could well be a bit of a dog to remake a terminal because of the difficulty of cleaning the surface corrosion from each strand.

Tony Brooks

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[andyball]

The flexible cable is very handy in tight corners....sizewise depends if you want to be able to use your new battery & switch to start the engine if the engine battery fails....if so, then the cable to the switch needs to be as large as your existing battery cable. If not, use 8 or 10 sq mm (over the top perhaps, but you won't need much of it ).

Agree with Tony about the charging and esp the battery indicator part.

Index marine & other "marine" electrics places sell tinned wire.....I use glue filled heatshrink over the ends of normal wire + a blob of solder to seal if it's a large ring terminal 'cos the tinned stuff is ££ in larger sizes.



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