24v to 12v reducers

[Shark]

I know this more than likely should be in the auto electrical section but i thought everyone with an MQ is here so thats where the question should go.

Basically im gonna buy a reducer and i was wondering what size i should get?? 10 amp or 20 amp or even 30 amp.

Im gonna be running a 4 channel amp, nothing too powerful, my alarm, my deck and possibly a couple of fluro's.

Let me know casue i have no idea

MArc

[MQPatrol]

Quick and safe way is to pull all your fuses and combine them for the total max current drain.

Very unlikely that you will be running everything connected flat out enough to pop fuses but this way it gives you a bit of a buffer zone and keeps the voltage reducer cool too by running at less capacity than it can do.

Tis always better to go one bigger than you need just incase the amp just isnt quite big enough to make your ears bleed and you need another . Common sorta rule of thumb - get the biggest you can afford and fit.

Cheers

[Snabelost]

Why not just tap 12v between the cells/batterys? No need for a regulator.

/Magnus

[totto]

Why not just tap 12v between the cells/batterys? No need for a regulator.

/Magnus

Because this will cause the batteries to charge unequally, thus eventually lead to destruction of one of them cuased by overloading.

[Snabelost]

Why not just tap 12v between the cells/batterys? No need for a regulator.

/Magnus

Because this will cause the batteries to charge unequally, thus eventually lead to destruction of one of them cuased by overloading.

I have learned that a winch or a real big consumer will be a problem. But i migth be wrong on this.

/Magnus

[totto]

Why not just tap 12v between the cells/batterys? No need for a regulator.

/Magnus

Because this will cause the batteries to charge unequally, thus eventually lead to destruction of one of them cuased by overloading.

I have learned that a winch or a real big consumer will be a problem. But i migth be wrong on this.

/Magnus

I had my stereo ONLY tapped in on the first battery, and that was enough. just takes a little longer with small consume than larger consume.
I had to charge the no.1 battery separately once a month, and finally the other one gave up. I even had to call a towtruck in the middle of the night to get a jump-start
The battery dealer was cool, though, gave me a replacement on the warranty.
Now the stereo is powered by one of the TWO converters that was there before i bought the rig. Last owner must have been blind or totally lame to wire the stereo like he had.....

[PJ]

Fully agree - do NOT run any long-term load (even a 'light' one) off the 12V feed - You will kill the 1st battery (the one connected to ground). Best to take the 24V rail down through a supply regulator.

[Scrapper]

A friend with an early MQ SWB had a few things tapped on the 1st battery and used to swap the batteries around every few months to 'keep wear even'. He said it was a pain, as the batteries are a little bit too heavy to be regularly swapping (risk of spilling corrosive substances on yourself, bodywork, wiring, etc in addition to strain injuries).

Due to the 'slow' nature of regulators, even for a small amplifier, I would recommend doubling the rating, for as a percentage swing, the reaction is less to allow the current flow at a given voltage - as suggested at least as big as the total of fuse values. If you are serious, put a local capacitor next to your amplifier. This provides extra current as a local reservoir to reduce clipping due to voltage drop under load.

I used to build competition car sound systems (if it doesn't at least have twin 12" subs it isn't a real stereo!), - not good when the sound system in your car is worth about double the vehicle it is mounted in... ($1800 head unit, $800 stacker, etc, etc, etc,) The last truck (Datsun 720 4x4 crew cab SD25) only had a SSB-CB (AM/FM dead, took out and threw away!), the SWB had the radio removed before I bought it and the LWB has some dodgey PoS that has a 24V regulator built in... So I haven't had a 'car radio' since before I got into 4x4's.

In light of what I'm reading from people's posts, either "Convert to 12V" or "Use voltage regulators".

[Patroldude]

Never trust 24V - ask my mate - douing 12V swap this weekend.... got sick of on board fires.....

Expensive and not worth it - just by 12v loom/bit - much easier and more reliable too.

Mk

[PJ]

Have you looked at some of the 24V-a2V pre-fab units from Jaycar - they have a 20A (continuous load) unit for $120. You can also run these units in parallel to increase load current rating.

[PJ]

That last post should have read 24v-12v @ 24A

Anyway, Altronics also have a similar unit - sounds a bit better engineered with overload protection, etc. it also has a lower profile than the Jaycar unit.
The down side is the $165 price tag

[mud13s]

The voltage reducer out of the truck patroldude mentioned is dead,

This morning the bloke who's truck it is got the sh1ts and beat it to death with a big hammer!!

Lucky we were in the process of doing the 12V swap hey...

Paul

[pjhsv]

Never trust 24V - ask my mate - douing 12V swap this weekend.... got sick of on board fires.....

Expensive and not worth it - just by 12v loom/bit - much easier and more reliable too.

Mk

Why do you say that 12Volt is more reliable?? And why on earth do you think that 24Volt is more prone to fires?? If the car is wired up correctly, with correct rated wire, correct rated fuses, and proper connectors/solder, (not all wires twisted together and electrical-taped up), there is no reason at all for it to cause fires.

As for the easier argument, you're right...it's sometimes a bitch having to run stuff through reducers, but you get used to it.

Paul

[mud13s]

The 24V truck MK refers to didn't have a lot of luck with fires, and the electrical work was all done by an auto sparky

Also things would randomly stop and start working for no particular reason (that anyone could find).

12V seems to be more reliable when the truck behaves like this hey...

And the reducer just had a mind of its own!

Paul