Can I ground both a 12V and a 24V alternator to the same ground

Might be a completely stupid question but I've got a 24 volt pair of motors on something I need to run while the trucks running on a 12 volt setup

so if I add a 24 volt alternator can I ground it to the same frame?

and can I run the motors directly off the alternator? no batteries, no regulator.

Ground is ground. It should make no difference. Both *need* to go to ground!

Ah but "can" they go to the same ground. I'd be inclined to say yes but, its a DC system so a 12V negative lead will have a different potential than a 24V negative lead. which might just cause a current flow that "could" be detrimental depending on several factors. One of which is if there are batteries in the loop somewhere and if those bats are on both loops or not. I'd be inclined to think that if only the lower voltage system on the same ground has a higher resistance by virtue of the batteries natural inclination to act as a diode bridge that any residual higher current moving in the wrong direction "up" the ground would meet that resistance and not damage anything except maybe slightly shorten the life span of the batteries. Basically I'm thinking that if an alternator only produces what is "drawn" from it then it will only produce the minimal amount of juice.

Hopefully.

so if I eliminate the bats on the higher voltage side and run straight off the alternator I'd not be bleeding that much 24V residual current into the ground system. I'm also hoping the alternator's output is actually self regulated.

Sorry I am of no use...but why are you running a 24v alternator?

Boston said:

Might be a completely stupid question but I've got a 24 volt pair of motors on something I need to run while the trucks running on a 12 volt setup

so if I add a 24 volt alternator can I ground it to the same frame?

and can I run the motors directly off the alternator? no batteries, no regulator.

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Although I am no electrical genious, I am going to say NO to both questions.

An alternator MUST have a battery to "absorb" and "cushion" the current, plus give the regulator something to sense the voltage of.

No battery = no source of voltage for the regulator to read.


Some form of voltage regulator is a must; else the alternator would go crazy high with the volts.


As for GROUNDing both 12-volt and 24-volt together, I may be wrong, but my limited knowledge says it won't work.


If you must use these 24-volt accessories, why not completely isolate them from the 12-volt system ??

Leece-Neville makes alternators that are isolated GROUND.

I have worked on several bus / Motorhome combo's with 24 volt start systems and 12 volt house batterys. the ground was the same. the bus chassis had a 24 volt battery (2 12volts in series) for starting the 525hp engine and two alternators. I know it had some 12 volt circits for all the coach lights and ignition. The unit had clearly marked fuse panels to seperate the DC systems. " Thats all I can say about that"

This is a great question, one that opens lots of debate, hmm...I'll be watching this one!

Ground can be the same with no issues. Will have to have batteries in order for first the alternator to excite and second to supply a cushion for the alternator. I deal with bus and rv electrical systems every day. Want to see something interesting hook a 12v fan up to a 24v circuit. Manager did this to me yesterday and it took me till today to figure it out. Never seen a fan turn so fast in my life.

No problem hooking both grounds together, don't matter what the separate voltages are, there is no closed circuit back to the 12VDC system But as said the 24VDC alternator should be hooked to two 12V batteries in series, depending on the current output of the alternator, it should be sized to what motors he is running, some alternators are self excited and internal regulated. if a self excited alternator won't put out, some times you have to polarize them. If useing batteries, they should be sized for the amp hours for his motors.

They covered it well, ground dont care if its 12 or 24 or both

do they make 24volt starters for our trucks?

Shouldn't matter about the ground. It's just a circut loop. Incomplete circuit loop means no charging, no power...no anything. Just ground the pair out to the same bolt and be done with her!

yes, you can ground 12v and 24v to the same ground. the military vehicles we build at work have dual voltage setups. they use four 12v batteries and a battery wiring setup that is a bit different but it does work.



i know it looks strange, but it works.

the above setup requires four batteries of equal size and roughly equal condition, which could get expensive. personally, i would leave the 12v circuit as it is, and just get a pair of small 12v deep cycle batteries (think $30 powerwheels batteries) that are wired in series for the 24v circuit. they should be capable of providing the inrush current that the motors will demand upon startup. you just wouldnt be able to run the 24v circuit for very long without the engine running.

david_lee said:

yes, you can ground 12v and 24v to the same ground. the military vehicles we build at work have dual voltage setups. they use four 12v batteries and a battery wiring setup that is a bit different but it does work.

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i know it looks strange, but it works.

the above setup requires four batteries of equal size and roughly equal condition, which could get expensive. personally, i would leave the 12v circuit as it is, and just get a pair of small 12v deep cycle batteries (think $30 powerwheels batteries) that are wired in series for the 24v circuit. they should be capable of providing the inrush current that the motors will demand upon startup. you just wouldnt be able to run the 24v circuit for very long without the engine running.

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Looks like a Crack victim engineered that, it's gotta be bizzare to work on. Not sure who came up with that setup all I know is that from that image the grounds flow through the singular 12v setup only...hmmm....bizzaro

Wow David we went over another question about drawing multiple voltages from multiple batteries and no one, not even some pretty hep electrical engineers threw that diagram out there.

with that system it looks like a common 12v alternator can be used, is that correct?

and to answer someones question there are two 24v motor running the big oil tank and filter I run the truck on. Although I've run 12v through the 24v motors in the summer the thicker fuel due to cold this winter will mean I have to provide 24 volts. A 12v motor of the same HP is to big to fit in the location.

two more batteries are cheaper than setting up an entirely new circuit off its own alternator. Assuming I can charge all four in the diagram above with the same 12v that I already have. So what say you Dave. How many alternators in those military vehicles