Powering electronics from car battery...

[XA04]

I've currently got an amp and sub in my boot - however I will be building a car PC soon and will need to power that as well as another amp.

Now the details of that I have sorted, but what I want to know is - can I use the original cable from the battery and split it say three ways? Or would I need to run 3 full length cables into the boot!?

If I can use the existing cable, do I need something to distribute the power evenly or will it just take what it needs?

Thanks!

[Konan555]

It's going to depend on the gauge of cable you've already run to the boot.

Whatever you connect to the end of that cable, will be supplied with the same voltage. However, if you've under specced the cable and the sub/amp draws enough the voltage will drop to anything connected to it. It'll depend on the supply spec for the computer as to weather this will cause any issues.

Whatever you do, running multiple cables to the boot isn't worth the hassle. Just one that is capable of handling the load you place on the other end.

You've probably already done this, but PLEASE make sure that it's fused as close to the battery as possible.

[CAT-THE-FIFTH]

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[XA04]

It's going to depend on the gauge of cable you've already run to the boot.

Whatever you connect to the end of that cable, will be supplied with the same voltage. However, if you've under specced the cable and the sub/amp draws enough the voltage will drop to anything connected to it. It'll depend on the supply spec for the computer as to weather this will cause any issues.

Whatever you do, running multiple cables to the boot isn't worth the hassle. Just one that is capable of handling the load you place on the other end.

You've probably already done this, but PLEASE make sure that it's fused as close to the battery as possible.

Hmm. It's 10AWG apparantly? Is this good enough? If so, then is it ok to split it at the boot end into three wires? or is there something I should wire it into that produces more outputs?

Don't worry, it's fused

[Konan555]

I assume you're using the car body as ground?

Working on the assumption you've got about 4m of cable running font to rear you should be good up to 250W, to be conservative. Do you know the figures for your sub/amp?

As for splitting it, no, there is no device required. Just connect them up.

[XA04]

I assume you're using the car body as ground?

Working on the assumption you've got about 4m of cable running font to rear you should be good up to 250W, to be conservative. Do you know the figures for your sub/amp?

As for splitting it, no, there is no device required. Just connect them up.

That's correct. Using a ground in the boot.

What figures do you need to know? Sub is rated up to 1000W but only running a 400W 2 channel (bridged) amp.

CarPC will be a laptop (Intel Atom processor, so quite low power) and a monitor. Both of these are 12V input.

Will need to run a second amp to power the normal speakers as obviously there isn't one built into the laptop.. This is also 12V.. 400w.

Sound ok to just split it in the boot then? Keeping in mind the above..

Thanks

[Konan555]

Does it list the current requirement's for the audio gear? The wattage that the speakers are rated at most likely won't tally, else you'd be pulling 70 odd amps (getting on for what some car alternators can put out).

[XA04]

This was what I was looking at. 41RMS per speaker.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...:X:RTQ:GB:1123


I would imagine that would be similar to that you would get in a normal head unit?

[Konan555]

Going from the marking on the image, it requires 5A. That's 60W.

All sounds within reason for 10awg

[XA04]

Going from the marking on the image, it requires 5A. That's 60W.

All sounds within reason for 10awg

As you can tell, I'm not 100% hip with electrics Does that mean it will be under powered then? Or 60W per speaker?

[Konan555]

Power in terms of what you're drawing from the electrical system won't turn out to be the same number as the audio power rating.

In terms of the power supply, that amp requires 12V 5A. You're actually pushing nearer 14V when the car's running, but it'll be designed with that in mind.

This guide indicates that 15' of 10AWG cable should be able to supply 20A without undue drop in the supply voltage. In other words, you should be able to run 4 5A loads like that amp from the feed you have installed already.

http://www.engineeringtoolbox.com/am...uge-d_730.html

The only proviso is that the load may 'surge' on audio equipment, which is why people start to run a 2nd battery in the boot. I don't think you're into these realms yet but it's a bit beyond my experience.

[XA04]

Thanks for your help!