12V headunit into 24V system

YouTube · Post by **El_Freddo** » Tue Feb 14, 2012 9:16 am

G'day everyone.

Got an ok head unit to shove in my brother's truck, but the truck is 24V and the head unit is 12V. The truck has two 12V batteries in series to make the 24Vs. Is it too simplistic to reference power from one battery only for the power to the head unit?

The idea is to power the head unit from the one battery that's triggered by a 24V relay on the accessories of the ignition switch. Would this work or would I still get 24V by referencing the one battery.

I've not looked into this with the multimetre, the truck's away at the moment but it would be good to know if I need more wiring or if I need to find some sort of 24V to 12V step down transformer.

Cheers

Bennie

Post by **Alex** » Tue Feb 14, 2012 9:27 am

i think alot of decks and amps these days are compatible with both 12v and 24v.

RSR 555 · Post by **RSR 555** » Tue Feb 14, 2012 9:28 am

Nah Bennie.. no need for a transformer. Just like you say, run the 12v off one battery through a 24v relay that is wired to the accessories feed. Of course the 24v would supply to the coil side of the relay and the 12v through the switching side.

RSR 555 · Post by **RSR 555** » Tue Feb 14, 2012 9:29 am

Oh and by the way.. don't forget a fuse off the battery for the 12v system

YouTube · Post by **El_Freddo** » Tue Feb 14, 2012 9:37 am

Alex wrote:i think alot of decks and amps these days are compatible with both 12v and 24v.

Yeah that's what we thought, glad we checked it out as the sticker says "DC/c.c. 14.4V" so I guess it's not 24V compatible.

RSR 555 wrote:Nah Bennie.. no need for a transformer. Just like you say, run the 12v off one battery through a 24v relay that is wired to the accessories feed. Of course the 24v would supply to the coil side of the relay and the 12v through the switching side.

Yep, my thoughts exactly!

RSR 555 wrote:Oh and by the way.. don't forget a fuse off the battery for the 12v system

That's a mandatory requirement for any of my wiring

Sweet. Thanks for the info fellas, I'm glad it's going to be as easy as this in theory!

Cheers

Bennie

Post by **Alex** » Tue Feb 14, 2012 9:55 am

i just had a quick google and everyone says to use a 24-12v transformer. Apparently theyre cheap and easy.

alex

Matt · Post by **Matt** » Tue Feb 14, 2012 9:12 pm

Yeah transformers are cheap these days, either way will work

90brumby · Post by **90brumby** » Tue Feb 14, 2012 10:59 pm

yea there cheap and easy to use a transformer or run the power off one battery but make sure you use the positvie and negative off the battery that supplys the earth to the truck otherwise the head unit can earth and make it 24v which will blow up the head unit

tristan

vincentvega · Post by **vincentvega** » Tue Feb 14, 2012 11:06 pm

90brumby wrote:yea there cheap and easy to use a transformer or run the power off one battery but make sure you use the positvie and negative off the battery that supplys the earth to the truck otherwise the head unit can earth and make it 24v which will blow up the head unit

great advice.

Alex wrote:i think alot of decks and amps these days are compatible with both 12v and 24v.

terrible advice..

YouTube · Post by **El_Freddo** » Wed Feb 15, 2012 10:14 am

90brumby wrote:run the power off one battery but make sure you use the positvie and negative off the battery that supplys the earth to the truck otherwise the head unit can earth and make it 24v which will blow up the head unit

That's good to know! I hadn't thought about that and didn't know about it previously.

Cheers

Bennie

RSR 555 · Post by **RSR 555** » Wed Feb 15, 2012 2:32 pm

Not necessary to run the earth but you do need to make sure you connect the power feed (12V) off the 1st battery in the series.. which will be the battery that goes to earth.

Earth to - battery + to - battery + to fuses = 24V

This one where the red plus is

RSR 555 · Post by **RSR 555** » Wed Feb 15, 2012 2:43 pm

90brumby wrote:yea there cheap and easy to use a transformer or run the power off one battery but make sure you use the positvie and negative off the battery that supplys the earth to the truck otherwise the head unit can earth and make it 24v which will blow up the head unit

tristan

This is also good if you have plenty of twin cable available

or you work for Boral

:D:D

SubieMad · Post by **SubieMad** » Wed Feb 15, 2012 3:17 pm

And make sure you test it with a multimeter first, just to be sure!

90brumby · Post by **90brumby** » Wed Feb 15, 2012 9:28 pm

RSR 555 wrote:This is also good if you have plenty of twin cable available or you work for Boral :D:D

Haha yes but as u said just select the right positive and earth it in the cab all sorted

And Alex is kinda right all our head units are now multi volts but if the head unit doesn't say it is then it wond be lol

Tristan

YouTube · Post by **El_Freddo** » Mon Feb 20, 2012 9:59 pm

90brumby wrote:And Alex is kinda right all our head units are now multi volts but if the head unit doesn't say it is then it wond be

Yeah but it always pays to make sure!

I've got access to plenty of triple wire so there's no issue there. Now I just need time to get to the truck to do it - no rush though, it won't really be seriously used until may/june...

Cheers

Bennie