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alternator kill switch


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flaviobonzer
New User

Aug 12, 2013, 3:21 AM

Post #1 of 4 (1666 views)
alternator kill switch Sign In

Hi everyone,
I am wanting to install a kill switch or something to enable me to control when the alternator charges the battery. This is actually for a diesel engine in a yacht and I need to cut the load that the alternator puts on the engine every now and again.
I have tried putting a switch in the field/ exciter wire. with this I can start the engine with the alternator off and then flick the switch and the alternator starts charging but then when I turn the switch off doesn't turn off the alternator as now the regulator is supplying voltage to the field circuit. Is there any way I can install a switch somewhere to achieve what I want? Was thinking maybe adding another batt in series to the sense wire so regulator thinks batt is full charged and cuts alternator output. Would this work?
Any suggestions greatly appreciated
cheers
Tim


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Aug 12, 2013, 4:45 AM

Post #2 of 4 (1656 views)
Re: alternator kill switch Sign In

Would help if we knew what kind of alternator you have.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


flaviobonzer
New User

Aug 12, 2013, 5:21 AM

Post #3 of 4 (1647 views)
Re: alternator kill switch Sign In

Alternator is a Mitsubishi. not sure of amperage or model etc. Alternator only has field/sense/tach connections on back of alternator. Apart from main batt + of course.

cheers


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 12, 2013, 5:57 AM

Post #4 of 4 (1640 views)
Re: alternator kill switch Sign In

You won't save a thing - forget that idea completely. Did a ton of pretty large yacht misc stuff over many years.

OK - just because the engine may not need electricity for anything to run there are a zillion things still using some power all over a typical yacht unless it's an empty shell.

Alternator is almost just a nothing pulley for power loss if not powering something anyway. Even the best deep cycle battery(s) w starting amps enough for a diesel engine doesn't like going low just tolerates it lots better and when you do enable it it would just make up drag to recharge them later.

Do you really want to risk it not starting because you let it get too low?

Last yacht I did a lot on had power for water for 3 sinks, ice maker, six bilge pumps, TV, radios, gauge lighting and 100 more things I can't think of right now and guess you could do without blowers for heat and A/C if equipped underway.

Even sail boats of size need power for pumps. Yes - most charge battery(s) slowly with just a little wind generator usually at the top of the mast.

The other problem is when you ask an alternator to charge hard with low battery(s) is you are really stressing it out and can kill it. Much bigger bucks than automotive as it must be designed not to make sparks.

In short - you save nothing and risk a lot. Last one I deal with a lot had SIX deep cycle batteries and could choose 3 at a time, all or either set such that a failure still left you with at least starting power if one set failed in any way.

Enough crap is always going wrong in a real yacht all the time and you want to mess it up even worse?

T







 
 
 






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