hooking up cd/dvd player to second battery (accesories)

[THICKNICK]

gday lads,

want to run my cd player off my second battery, and my roof dvd player. So i can pull up and camp and leave the radio going without killing the main battery. but still use accesories (so they switch on and off with the key still), im sure there is a way do do it with relays etc.

anyone point me in the right direction.

cheers
nick

[chimpboy]

Do you mean you want to run the radio without killing your main battery, but still have it only work when the car is switched to accessories?

Or do you mean you want to be able to run the radio off the second battery when you're camping, with the rest of the car switched off and the keys out?

[THICKNICK]

keys still in car, i dont think it would be possible to do so with keys out.

i was going to hook them up to constant on the second battery and just switch them on and off when i need them, but dvd player drains to much power even when switched off, so needs to be hooked up to accesories.

hope this helps

[chimpboy]

I'd say it would be easier with the keys out. Just a sort of "override" switch to power the radio (only) from the second battery when you want to. It would just be a dedicated rocker switch (or whatever) next to your radio that you flick on when you settle down at a campsite.

It would be pretty easy. The hard bit is actually keeping the setup from backfeeding power from your second battery to everything else on the accessories circuit. This may or may not be an issue depending on what else runs off the ACC circuit, some cars run the a/c blowers and all from this circuit and this would drain your 2nd batt pretty fast.

I think you can actually get away with just a single two-way switch if you wire it right. How is the radio wired? There are two main styles, one is a red wire for main power and yellow for memory, the other is a red "trigger" wire to switch the unit on and off, and a yellow wire for main power and memory.

If it is either of those two setups I think I can tell you how to do it.

[THICKNICK]

yer the stereo has the 2 red and yellow wires, one to constant one to accesories.

also the drop screen dvd needs its own power source too.

i like the idea of having the key in, as then you just pull the key out to switch everything off, as you normally would. was just thinking of a way that everything works like it normally would except the cd player and dvd player always run off the second battery. so was thinking of running a relay to a accesories wire that triggers it ro run power from the second battery.

if there is a better way of doing it let me know.

[THICKNICK]

i think i just got my head around what you are saying about the overide switch, i think i like the idea of that.

just trying to figure out how wire up the switch. i dont know if a normal switch would do it. just picturing it in my head you would need three pins. one to the radio itself, one to your second battery and one to your accesories. and the switch would toggle between the accesories and the second battery. and im guessing the yellow wire from the stereo would hook up to the second battery. and the red to the switch.

am i on track here.

[chimpboy]

The only problem is that anything else on the accessories circuit will also be powered up this way.

But yes it is easy to use a relay so that the stereo/dvd/radio are always running off the second battery, but they need the key to be in. Your main battery would need to be involved but only to power the relay.

Then it is just up to you to remember to turn off the cabin blower, AC, or whatever else is running off ACC on your main battery, otherwise you can still run your battery flat.

I think the way to do it would be with a typical automotive, the kind that has 85/86/30/87 terminals.

- yellow radio wire to second battery +ve.
- red radio wire plus all DVD etc power wires to 87
- 2nd battery +ve to 30
- 85 to ground
- 86 to accessories

This means everything is running off your 2nd battery except the little coil in the relay, which is negligible.

But, if your 2nd battery goes completely flat you'll lose your radio memory.

[chimpboy]

i think i just got my head around what you are saying about the overide switch, i think i like the idea of that.

just trying to figure out how wire up the switch. i dont know if a normal switch would do it. just picturing it in my head you would need three pins. one to the radio itself, one to your second battery and one to your accesories. and the switch would toggle between the accesories and the second battery. and im guessing the yellow wire from the stereo would hook up to the second battery. and the red to the switch.

am i on track here.

Yes! That is exactly what I had in mind; you switch the radio's red wire (plus all your other gear) to the switch. Then you use the switch to choose between ACC from the key or just "2nd battery power mode".

And yellow wire to the 2nd battery.

It's called a double-throw switch, very common. Sometimes it's described as an "ON-ON" switch or "ON-OFF-ON" (with a middle position where neither wire is connected).

Random example from google:

http://www.allelectronics.com/make-a-st ... TCH/1.html

[rumpig89]

i wired mine up so that when camping i flick switch and i can have keys out of ignition and still listen to radio and uhf - drawing off second battery. When normal driving switch it back and it all turns on and off with accessories.

I just ran a power wire (from second battery) to SPDT (single pole double throw) switch... the common switch terminal goes to radio,uhf, etc... and the other side of switch to accessories power.

Simple fix. no relays (most good switches are good for 20A). keys are out of car so no accidents can happen. Worst case scenario is second battey completely flattened - fridge, radios, etc.

[THICKNICK]

thanks for the help fellas.

just been out and bought a double pin double throw switch, as have the cd player power and the dvd player power too. the redarc just turned up the other day and have built a spot in the rear draws to hold the second battery so am off to wire it all up today, will let you know how i go.
cheers
nick

[THICKNICK]

well i got it all in guys, and very happy with it. I think its a great way to set it up.

only thing is, the clock and fans come on with the stereo also?????