Starter Motor Amps

[CPD]

Following a recent problem with the starter circuitry, I have been looking at replacing the 1,2,both,off switch and maybe also the engine battery isolator switch. As a matter of interest, doesa nyone have any idea what sort of current would be drawn by a 23hp md11c starter motor ??. the selector and isoltaor switches are rated at 100amp continuous, 175amp intermittent. If I had an ammeter to connect, what do you think would be seen roughly ??

 

[pvb]

The starter motor would typically be rated at about 1.5kW, so it'll draw around 120A - well within the intermittent duty rating of your switches.

 

[VicS]

[ QUOTE ]
The starter motor would typically be rated at about 1.5kW

[/ QUOTE ] According to the owners manual the MD11C starter motor is indeed rated at 1.5kw.

Centaur Pipedream would be well advised not to scrimp on quality if fitting a 1,2, off, both switch. They have a bad reputation and many would not even consider them, prefering separate isolating switches. Some are known to come unscrewed internally when turned anticlockwise!

 

[halcyon]

You need to cover stall current, not running current, these could be 200 amp depending on size or type.

Brian

 

[Gunfleet]

Bluesea are very high quality. Fox's stock them.

 

[William_H]

I would suggest that this would be an excellent time to replace 1,2,both switch with 2 individual on off switches.
I would suggest that perhaps you redefine the system to have one battery for engine one for services. That will then require another smaller current switch for the services to the service battery and another to provide charge for the services battery. (unless you go for a VSR.)
You can if you wish use one high current switch for the engine battery on/off and provide a jumper lead for emergency start off the services battery.
i think the switches are usually pretty poor and the philosophy is not the best for battery management. olewill

 

[CPD]

I already have seperate engine and domestic batteries with isolating switches on the +'ves of both. Thinking about it now, I am going to do what VicS recommends and remove the 1,2,both, off switch and simply connect the +'ves together after the isolating switches. The combination of settings on the 2 isolating switches then does exactly the same as the (unreliable) 1,2,both,off switch. Or have I got this wrong ?. When I installed the wiring, I did it to the "book" but on hindsight, the 1,2,botgh ... does seem to be a great source of overengineering and possible unreliability bearing in mind the current that must be drawn through it on startup.

Thanks once again gentlemen ! /forums/images/graemlins/smile.gif