2nd Battery wiring diagram

[Richard Rees]

Going to install 2nd battery,what is the best way to install? want to be able to charge off of alt. and use as back up. open to suggestions.

[gcarter]

Hi;
Use a two battery switch to select the battery in use.
To charge both batteries simultaneously, use an isolater,
take a look at;
http://www.e-marine-inc.com/products/alternators/iso1alt2bat.html
Hope this helps.

[gcarter]

You may already have a two battery switch. If so, the positive cable for the the battery is connected to the "BATTERY 1" position on the battery switch. Connect the positive cable from the 2nd battery to the "BATTERY 2" position on the switch. Your battery ground wires all run together.
:)

[Richard Rees]

George, Thank you very much! that's what I needed. Thanks again Scot great place and people.

[Richard Rees]

George, I only have a keyed on/off switch in engine compartment.

[MOP]

George your post is spot on, the only point I argue is bringing the negatives together, should the attaching point at the block fail you have no redundancy. Where as if the grounds are run separate from each battery to separate block attaching points you have the redundancy one looks for with a dual battery installation.

Phil

[Forrest]

I found that a battery "combiner" (http://www.yandina.com/c50Info.htm) tends to be more reliable than a battery isolator.

Detailed info on wiring a battery combiner. (http://www.yandina.com/acrobats/C50Data.pdf)

A ton of neat stuff and info on their web site too:

http://www.yandina.com

[gcarter]

George, I only have a keyed on/off switch in engine compartment.
Yeah Richard, you could look at a Perko or similar two battery switch.
Mop, your idea of two grounds is good. It could save some embarrasment.
Forrest, that's an interesting idea.
BTW, isolators use a diode (a very large one, or two), and they do reduce the voltage by about one volt, i.e. about 13.4 instead of about 14.4. This has never been a problem for me.
Also, in the past I've used a Ford starter solenoid to combine two batteries for starting from low batteries. The solenoid is triggered by an "intermittant on" toggle switch on the dash.

[DonCig]

My Donzi came with two batteries and a Perko battery selector. I want to remove one of the batteries. How do I need to handle the battery terminal ends of the battery cables on the one that I am disconecting?
Can I shrink wrap or electrical tape the ends (that connect to the battery terminals) of the unused cables and leave the other ends attached to the + Perko and - block.
This way if I want to reinstall a second battery at a later date the cables are right where I need them.

Thanks,

DonCig

[MOP]

The positive is the only one you need to cover to prevent possible contact with groud if inadvertently switched on, tape is messy. Buy some shrink wrap large enough and put two layers on.

Phil

[David Hartmann]

this combiner thing looks interesting
I have been thinking that I need an isolator

would the combiner tend to over charge on of the batteries or do you risk haveing a bad battery kill the other?

would it make sense to use a combiner, switch, and isolator.

Honestly I am an engineer that has restored 5 Donzi's and I do not know the best way to handle a 2 bat one engine situation.

any help appreciated