Electric start on an Auxiliary engine?

[Epirb23]

Hi there everyone,
With a 40hp main o/b on the back of an 18' dayboat used in South coast estuaries,I have acquired a 6hp Yamaha as an aux that's electric start but never been used on that boat.Can you give me any advice on battery/electrics setup for the Aux please? Only have one 12v battery at the moment.
Thanking you in advance /forums/images/graemlins/smile.gif

 

[Talbot]

as the 6hp has an electric start, suspect that the engine has a rectified 12v charging circuit (probably of 4-6 amps) If it was me, I would get a very small car battery and wire the 6hp up to the small battery and not cross connect to the existing system. This would keep it all very simple. Alternatively to could have a switched connection to either cross connect the batteries allowing engine start on the other battery (but imho this would be better done by jump leads) and there are many other alternatives, all getting progressively more complex.

 

[DavidJ]

Agree with Talbot. Keep it independant and simple. Maybe a motorcycle/scooter battery would suit. They do some with a gel in and not liquid which would be safer.

 

[Epirb23]

Hi Talbot and I appreciate the info very much.
I want to keep the aux on a separate system to the main for simple aux safety reasons so I'm relieved to read you wouldn't cross connect in this scenario.Two minor questions as a follow up tho,if I may...
1) Do you know how I can check if it has a rectified 12v charging circuit? I guess ask the boatyard /forums/images/graemlins/tongue.gif
2) A very small car battery means what in Ah?
Thanks again,
Delphi

 

[Talbot]

I agree with DavidJ that a motorcycle battery for a 250c or above should be enough to start the engine, however they are likely to be a lot more expensive than the smallest car battery on the shelves (mini, reliant etc)