24 volt

[jeffro]

just put a yanmar 2gm20 in my yacht which for 30 years has lived on 24 volts so instead of converting everything to 12 volts i have fitted the old 24 volt alternator and run it through the old charging system my problem is .the starter is 12 volts so i'm taking 12 volts from one of my batterys just to start will this be a problem long term?

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[paulrossall]

I would not see any problem with what you are doing. My 9 year old, 1084 hours use 2GM20 starts instantly so hardly uses any current to get going. You could swap over your batteries half way through the season so each battery gets a turn at starting, I would not worry too much. Paul

<hr width=100% size=1>" there is nothing-absolutely nothing-half so much worth doing as simply messing about in boats".

 

[halcyon]

Yes, you will kill the batteries, you will have different internal resistance in each bank and thus a charge inbalance.
You could put a 12 volt battery for starting, and charge it from the 24 volt via a volt dropper, or use two 12 volt batteriers, charge in series, use in parallel.

Brian

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[William_H]

Are you sure that the 12 volt starter was not what was intended for the engine on 24 volt system? Even if not the 12 volt starter should be ok on 24 volt provided you don't flog it too long if the engine won't start and providing a replacement is not to expensive. A series moter (as in a starter ) starts to generate a voltage internally when it starts to turn which opposes the battery voltage. So form rest the current is high but drops dramatically as the starter spins. As the 12 volt starter on 24v will spin a lot faster the current will not be 4 times as much as Mr ohms law would suggest.(only at the instant of hitting the button) However take more advice on this approach but don't try to use half of your battery bank as the inbalance will cause troubles. The other alternative would be to fit an auto alternator and change to 12 volt. regards will

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[jeffro]

thanks for your help the old engine was a watermotor and that was a 12 volt starter with 24 volts running through it never had any trouble with that so i might try the same with this one Jeffro


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