NASA Battery Monitor Installation

[kspirit53]

I am about to install a NASA BM1 battery monitor on my Beneteau Oceanis 311 but am uncertain which of the two batteries is the domestic one.

Battery 1 is located under the companion way steps immediately forward of the engine and Battery 2 is located aft of the engine under the aft berth. Battery 2 appears to have a few small diameter wires attached to the live terminal in addition to the heavy duty cables whereas Battery 1 only has the larger diameter, heavy duty cables connected.

I suspect Battery 1 is my engine battery so Battery 2, being the domestic one, is the one I need to monitor. I know this may seem a simple question to some but any expert guidance would be appreciated.

 

[philip_stevens]

Have you got a 1/2/both/off switch or two seperate isolators?

If only the former (1/2/b/o), then basically either is the engine and either is the general, or both can do either. If you have seperate isolators, find out which one gives you power to the general electrics.

Other than that, try to trace which positive cable goes to the engine starter motor/relay.

Remember, that the NASA battery monitor can only be installed on the negative side of the battery - that from an engineer at NASA, and in the installation instructions.

 

[kspirit53]

I have two separate switches so, from your notes, this would seem to make identification of the domestic battery easier.

Thanks for your help.

 

[Guest]

So if you have 2 separate switches for power .... put the lights on and switch of each battery power switch in turn ---- which one is domestic - lights go out !! surely ??

 

[kspirit53]

Thanks sbc - Having read many of your previous posts, you must be one of, if not the, the most knowledgable contributor to this forum!

 

[alan]

I used to have a 311 for six years, so ....

The domestic battery is under the aft berth. The engine battery is under the steps.
If the wiring hasn't been changed then the isolator on the port side is "number 1" and for the engine battery, and the starboard side (when viewed looking from the aft bunk lookinf f'ward) is the domestic isolator. Note: that the output (load) side of these isolators are paralleled, so that you can use battery1 or battery1+2 for engine starting. Also note that for charging from the alternator, you need to have both isolators closed (i.e. "on").

If you have any other questions regarding the 311, please P.M. me and I'll try to help. I fitted an second domestic battery, Adverc, splitting diode and generally "pigged" with the wiring on mine; so can remember pretty much how it was hooked up.

 

[Guest]

I can think of many who would not agree !!!

I'm learning like everyone else .... and am far short of the competence / knowledge you attribute me with ....

I always like looking at others boats and despite my "talkative" nature ... listen and observe well. Having surveyed many different boats and types ... I remember bits and bobs from literally all .....

At the end of the day ... I love Boats .....