12V ve 24V

GrahamM376

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24 volt systems often utilise thinner wire than for 12 volts but, as instruments only draw milliamperes you shouldn't have any problems connecting them to your 12 volt supply.
 

Playtime

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My starter motors run on 24v and all my instruments have died or are well out of date . Can I replace with 12v intruments with out any detrimental effects.My internal boat power supply is 12V.

Does the 24V circuit power anything other than the starters - keyswitch, relays, glow plugs etc. ?

If so, you will need to ensure that the new 12V instruments are kept entirely separate from the 24V stuff. If you are comfortable with electrickery it shouldn't be too difficult.
 

DownWest

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You presumably have 12 & 24 volt charging systems (one on each engine?) Can't see any problem.
I used to look after a boat with a similar system. + a 220v genny. Lots of different wires...

Also depends on the sensors. They need to be matched to the instruments.
 

savageseadog

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I think a fair few instruments are dual voltage or extended voltage range ie 6-36V.
If you are using 12V in a 24V environment it would be worth making sure there's good suppression and regulation and it would be worth having something somewhere on the 12V to "crowbar" the the supply if it goes over 12V. Crowbar is a correct technical term by the way overvoltage protection may yield the same or similar result. Can't suggest any particular product.
 

BlueLancer

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I do have 2 sperate charging systems. The 24v only starts both engines and one engine supports a 24v alternator always started first.The reason I am thinkling of going 12v is I am changing the sensors on the engines from cappilary to electric and the 12 v sensors and supporting instruments seem to be cheaper
 

BGW

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I do have 2 sperate charging systems. The 24v only starts both engines and one engine supports a 24v alternator always started first.The reason I am thinkling of going 12v is I am changing the sensors on the engines from cappilary to electric and the 12 v sensors and supporting instruments seem to be cheaper

You are only buying them once, not every season. - Is the price difference worth the extra time and complication required to manage and install a dual system?
 

SHUG

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If you are retaing the 24v for the starter you can get a 24 to 12V invertor from Maplin to run 12V instruments.
See http://tinyurl.com/4d5wtgh
As was mentioned earlier , many modern instruments run on 9v to 32 v but , for example , Raymarine ST50 instruments are 12V only.
 

Playtime

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As was mentioned earlier , many modern instruments run on 9v to 32 v but , for example , Raymarine ST50 instruments are 12V only.

BlueLancer - are you looking to replace sailing instruments or engine instruments?

Given the reference to starters I thought it was the latter, hence my earlier question.

If it is sailing instruments then it should be much easier to keep the 12V circuits separate from the 24V (engine only) circuits.
 

BlueLancer

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BlueLancer - are you looking to replace sailing instruments or engine instruments?

Given the reference to starters I thought it was the latter, hence my earlier question.

If it is sailing instruments then it should be much easier to keep the 12V circuits separate from the 24V (engine only) circuits.

Engine intruments are what I am replacing The originals have died and the oil pressure gauges are capillary, which I wish to change to electric.I thought it would be easier to go 12v, as I have to rewire the engines anyway.
 

Playtime

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Engine intruments are what I am replacing The originals have died and the oil pressure gauges are capillary, which I wish to change to electric.I thought it would be easier to go 12v, as I have to rewire the engines anyway.

OK - then back to my original question below

Does the 24V circuit power anything other than the starters - keyswitch, relays, glow plugs etc. ?

I would expect everything on the engines (except the 12V alternator) to be 24V - instruments (as you have recognised) but also glow plugs, relays (for glow plugs if nothing else), stop solenoid (if fitted), instrument lights, instrument alarm etc.

I think your next step should be to find a circuit diagram for the engine electrics and see how much needs to be changed. If my thoughts above are correct it will be a non-trivial job.

If you are in any doubt, post a copy of the wiring diagram here and we'll try to help further.
 
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