help with hardwire here

hongchu · 04-08-2008, 01:51 AM

hi all, i've been reading and reading and no answers still. I have all my parts and ready for the istallation process of my carputer. My question is, i know hardwiring an lcd to the cig is bad but im planning on hardwiring it to acc. Is that the same... I am under the impression that those two are not equal in volts and if so it safe for me to do so? The link below shows what lcd I have. Thanks in advance.

http://cgi.ebay.com/ws/eBayISAPI.dll...ksid=p3907.m29

DarquePervert · 04-08-2008, 06:10 AM

There shouldn't be an issue with powering your screen from the cigarette lighter. The power draw for an LCD screen is very small compared to the power draw of the PC itself.

And you mean AMPS, not VOLTS. Big difference there.

hongchu · 04-08-2008, 10:16 PM

correct me if im wrong, so your saying i can hardwire it to the cig lighter instead of using acc... I understand that the lcd draws very little amp to work, but will the spiks and drops caused by the cig lighter during ignition cause any issues assuming I have the lcd hardwire to it...?

DarquePervert · 04-09-2008, 06:31 AM

A Lilliput brand screen comes wth a regulator. Wire that and it will be fine.
Xenarc brand screens have internal regulators, so it will be fine.
I can't speak for any other brands of LCDs, however.

Answer me a question. What do you mean by "hard wire to ACC"? Are you talking about the actual ignition circuit in the steering column?

Also, are you planning on retaining the cigarette lighter or replacing it with the LCD screen? If you're going to retain the cig lighter, I would recommend not using that circuit to power the LCD, since the heating element in the lgihter draws a lot of power by comparison and you could possibly overload the circuit, blowing a fuse. Not a HUGE deal, but a pain, nonetheless.

hongchu · 04-09-2008, 09:41 PM

Thanks for all your help...

yes I have a lilliput (EBY701) and it comes with a cig adapter with a regulator. My plan is too set it up to power up once the ignition is on (I am aware that you can enter a code for lillputs to auto turn on with power) rather than powering it from remote or the power button . Basically I would like it to turn on at the same time my stereo turns on and I believe the ACC (ignition wire) can provide this.

From testing, I know the car cig lighter provide a constant power so I don't want that.

To answer your question, no I'm not keeping the cig lighter. I don't smoke and I don't like the cig adapters for any of my incar hardware because it's just plan ugly and out of place. I like to keep everything clean.

FusionFanatic · 04-09-2008, 10:10 PM

you shouldn't power any device directly off the ACC circuit. it is ok to use it as a 'signal' line to switch a relay, but the actual power to the device should come from another source. although the monitor doesn't draw much power, it may still be too much for the thin ACC wires to handle. the cig lighter circuit can provide more than enough power for the monitor, but you should hook up a relay to have it turn on/off with the car's key switch.

relays are cheap to buy and easy to hook up, if you need more info check it out the "relay FAQ"

good luck

hongchu · 04-09-2008, 10:18 PM

I have a shutdown/startup controller... can I use that as a relay and if so how do I wire it (I am also connecting my laptop to the shutdown/startup controller.

below is the controller I have
http://store.mp3car.com/Micro_Shutdo..._p/pwr-007.htm

also are u saying that if i was to hardwire my lcd to the cig, that i would need a relay?

ecog · 04-10-2008, 08:34 AM

Lilliputs have input voltage range of 11-14V. So wiring it straight to your battery (to a Constant or ACC line) shouldn't be an issue as a lot of batteries hover around 13.8V. However, there are batteries that pump out more than 14V and more importantly all vehicle batteries will have voltage spikes once in a while. These voltage spikes will damage your unit sooner or later.

I would recommend you power your Lilliput monitor from a regulated 12V source. There are a few ways of doing this, but what most people do is either they buy a point of load regulator or they pull a regulated 12V rail off of their regulator or power supply.

The 12V rail on your PC PSU is the yellow(+) and black(-) pair of wires on any molex connector inside your case. More than likely you have some extra molex connectors (unless you are using a laptop, macmini, aopen minipc or anything similar). Snip off that extra molex connector (FYI the red and the other black wire on the molex are 5V) and extend the yellow and black wires to your monitor. If you wire your monitor this way, the unit will turn on as soon as you PC turns on and turn off whenever your PC shuts down.

hongchu · 04-11-2008, 02:21 AM

Okkkk ... after hours/days of researching, I notice lots of BMW owners hardwire their navs and radar to the ACC wire of their car with no issues. I understand these devices draw very little amp just like the lilliput lcd. So why is it not a good idea to do this? I can understand why not to do it for a computer lol but a device as an lcd that draws less than 1 amp... can it be that bad?

hongchu · 04-15-2008, 09:48 PM

just an fyi... i tapped into my acc wire to power the lilliput with a 2amp fuse and it's been fine since ( knock on wood)