One or two batteries?

[reeljob]

I'm building a 20' Simmons and plan to power it with a 70 hp 2 stroke. The only electronics I'm going to put on it are a VHF and a GPS/chartplotter combo. Neither of these draw much power. Would I be better served to go with two batteries, on either side of the motorwell, or use a single battery located along the centerline somewhere? Since I don;t have a load of electronics to run all the time, would one battery be sufficient? Seems like two would noit be necessary. If I go with two, I'm thinking about using a Blue Sea dual circuit plus switch, where if the starting battery is low the house battery can help it along momentarily (i think). I'm not much of an electrician, so any insight helps.

Thanks

[paladin]

You can run everything from one battery...just remember NOT to start the engine with the electronics turned on...

[Thorne]

Wot, no steaming lights, cabin lights, anchor lights, etc?

Will you ever spend the night on the boat and need the cigarette lighter jack for cellphone charging or whatever?

Still for mimimal use one good deepcycle battery should do the trick.

[brad9798]

Hell, one basic SEARS diehard will run that boat just fine ... all the way around.

Like my old cneter console skiff ... one was more than enough, unless I got stupid! :)

[donald branscom]

For a very low cost you can get a fishfinder that
lets you know the depth and other info. But if you do get one
put the little paddle wheel on a little foldown bracket on the transom
so you can clean it. they get clogged up in one day. Also no hole in the boat.

I would have one battery for the engine and one battery for the
electronics. Very safe and reliable system. OR wiems and planth
makes a device that you plug into a cigerette lighter that is adjustable and gives off a warning buzz when the battery is on the verge of not being able to start the engine. I have one and it has saved me many times.
If you need a wiring diagram I can make one for you.
A SIMPLE SIMPLE diagram.

[reeljob]

Thanks for the replies. Seems like I could go with one and be fine, but also could go with two and be fine. I'll have to think about this. Might be easier to have two batteries to put on either side of the centerline. I do like the idea of having an entirely seperate starting battery. The Optimax on our other boat is very picky about battery power. If its not right at 12, it won;t turn over.

[Bill Lowe]

12 volts is a pretty low battery

[paladin]

11.2-11.8 izz ded....

[RodB]

Get an Optima crank battery, they hold voltage for a long time and can handle lots of vibration etc. I don't think you can get a better battery if left unused for a few months at a time. Weight about 35 lbs. The Red top comes with a 3 year warranty, the blue top only one...and the only difference is the connectors, which you can add with the clamp on type with gold wing nuts.

The two battery system is nice because you can battery switch to either battery to run the boat so you always have good back up redundancy.

RB

[Bob Cleek]

Six times out of ten, a call for help because an engine won't start is because the one battery is dead. The other four? Out of gas. Go with two batteries and buy plain old RV/boat batteries from Costco or wherever. Save the money on the fancy gold plated ones.

[mcdenny]

If you use two batteries be sure you remember to switch from A to B often to keep both charged. If one is unused it will die from self discharge.

[dcobbett]

The key question is whether you can manually start the engine if the battery is dead. There are other alternatives (portable chargers), but if that engine can be rope started, one battery should be O.K. and more than enough for the light loads you defined. If it can't be rope started, go with a second battery.

[Gary E]

You can run everything from one battery...just remember NOT to start the engine with the electronics turned on...

WHY NOT ?
it's done all the time with no harm,