Carnetix or relay'ed Auto Adapter?

monkeyracer · 07-07-2008, 03:18 PM

OK, I just got a great deal on a broken screen laptop. Everything works perfectly on it. It's only a little older than a year and has been well-kept (except for the screen) and I am going to use it for the CarPC.

I've been researching the different options for powering it and getting it to start and shut down with the car.

I've narrowed it down to the two following options:

Get a Carnetix P2140, and power the laptop on the primary rail (at 18.5V), and the Dynamix 816 on the secondary rail (at 12V). And get a W3bMa5t3r Auto Turn on Module Cost around $135, plus $35, plus shipping.

Or...
Laptop Car adapter or this from ebay, and wire that and the screen straight from the battery, both on relays so they aren't powering anything without ignition, also with the auto-turn on module. Cost around $15 - $25 plus $35 plus shipping.

For both options, I will have the computer sleep after 1 minute on batteries, so when I turn off the car, it will sleep. (Having an issue with this while RR is running, though.)

Option one provides clean regulated 12V power to the screen, and 18.5V to the laptop, and starts and shuts down with the car.

Option two is less expensive, but will power everything, and turn on with the car through the relays.

So the question is, first, am I missing something important in either option, and second is it worth the extra $100 or so to have the clean power to the screen (or is there an option I am completely missing?)

I know there are plenty of users here that have experience with it, and up until now, I didn't think of a laptop for the car since I had the old desktop. The laptop though will actually be less expensive for me than what I would have gotten with the desktop.

colin · 07-07-2008, 03:21 PM

Go with the second one! Laptops can be powered by car adapters and if it saves you some cash, do it! As long as the relays work, they're accomplishing the same function that you're paying extra cash for in a shutdown controller...

monkeyracer · 07-07-2008, 03:25 PM

I'm leaning more towards that because of the cost, but wanted some seasoned expert opinions on it.

monkeyracer · 07-07-2008, 04:30 PM

hmm... if I go with option two, I might also eventually add this:

OPUS POL, capable of 12V 1.25A output to give the screen regulated voltage. Now I have to go home and check if 1.25A is enough for the screen though.

hmm...

monkeyracer · 07-07-2008, 09:12 PM

Just checked:

Quote: Originally Posted by Dynamix Computers

Power Source 12VDC@950mA

So the POL supplies enough power at 1250mA.

I may have answered my own question with a little further searching. (Believe me, I did search, a few days worth. I've read A LOT of threads on the subject)

So I think I may end up doing this:

Battery 12V>Fuse>Relay (on switched 12V)>laptop car adapter>HP laptop>ground
12V Switched>Auto Turn On Module>Laptop Power Button
Battery 12V>Fuse>Opus POL (Dynamix Car adapter)>Dynamix screen>ground
Battery 12V>Fuse>Relay (on switched 12V)>Power Inverter>PS2 (rarely connected)/USB Hub/Whatever else I might need to plug in.

The three circuits will end up on the same fuse block, and then split off to the relay and the Opus and inverter. The screen will probably be wired with the car adapter it came with until I get the POL. The inverter will barely be used, other than to power the USB hub through it's USB port.

Cost:
Car Adapter - $13.99 + $10.95
Auto Turn on Module - $35 + 7.64
Total for now: $67.58, and another $34 plus shipping later for the Opus.

To the experts: does this sound like this is right or am I missing anything?

JonnieBlaze · 07-22-2008, 09:52 AM

I'm not an expert by any means, in fact I don't even have my laptop installed in the car yet. But I've been doing a ton of research just as you've been doing and I'm pretty sure you wouldnt need the Auto Turn on Module with the Carnetix in your first option. The Carnetix has the two wires that you hack into your power button that will boot the laptop up. I just got my Carnetix in the mail the other day for my laptop and that's how I plan on using it at least.

I can't remember which thread on this website convinced me to get the Carnetix instead of a car adapter for the laptop, but if I find that thread I'll link you to it.

Hope someone else with a bit more experience chimes in to help you out.

monkeyracer · 07-22-2008, 10:28 AM

I already got the laptop car charger, so I am going to go that route.

I'm trying to calculate the current so that I get the right fuses, here's what I came up with:

Car Adapter - Cheapo Ebay, no specs on current draw, but I think I can calculate based on output: 18V @ 3.5A = 63 watts, 63 watts / 12V = 5.25 amps. So, I think I need either a 7.5 or 10 amp fuse on that line.

Screen - according to dynamix - 12vdc @ 950mA so a tiny 2 amp fuse should be fine.

so, am I way off on this? or does this look like it will work?

colin · 07-22-2008, 11:09 AM

Quote: Originally Posted by monkeyracer

Car Adapter - Cheapo Ebay, no specs on current draw, but I think I can calculate based on output: 18V @ 3.5A = 63 watts, 63 watts / 12V = 5.25 amps. So, I think I need either a 7.5 or 10 amp fuse on that line.

Screen - according to dynamix - 12vdc @ 950mA so a tiny 2 amp fuse should be fine.

so, am I way off on this? or does this look like it will work?

They're correct, but you forgot one thing: nothing is 100% efficient. That cheapo eBay adapter probably wastes a whole bunch of power to convert that 12v to 18v and regulate it. Keep that in mind. With that said, Id lean towards the 10 amp fuse. For the most part, the fuses are for keeping your wires from melting, and your wires can handle more than 10 amps, so you should be fine like that.

Im not too fond of using many power supplies for different things though, it seems extremely wasteful to me. I would look toward an all-in-one solution. For example, rather than powering a whole bunch of things separately, I just bought an M2ATX that can provide more power than I need. Now I can power hubs, the screen, etc off of it without worrying.

monkeyracer · 07-22-2008, 04:44 PM

Quote: Originally Posted by colin

They're correct, but you forgot one thing: nothing is 100% efficient. That cheapo eBay adapter probably wastes a whole bunch of power to convert that 12v to 18v and regulate it. Keep that in mind. With that said, Id lean towards the 10 amp fuse. For the most part, the fuses are for keeping your wires from melting, and your wires can handle more than 10 amps, so you should be fine like that.

I figured it was inefficient, so that's why I added 50% (75% efficiency) but I'll probably just do a 10 amp fuse, with a 5 amp fuse on the screen line, and another 5 amp on the usb hub.

Quote: Originally Posted by colin

Im not too fond of using many power supplies for different things though, it seems extremely wasteful to me. I would look toward an all-in-one solution. For example, rather than powering a whole bunch of things separately, I just bought an M2ATX that can provide more power than I need. Now I can power hubs, the screen, etc off of it without worrying.

I was considering that kind of thing since there is more than just a 12V rail, and I don't think I really want to use the inverter in the car. I really only need to power one hub and the screen, and there's not a whole lot of wattage needed for that. So even an M1 would work.

So, I could use the Opus POL and a 5V/15 watt regulator for $25 + $35 and shipping, or the M1 or M2HV for $75, or the p1900 for $100...

I don't really care if there are multiple power supplies, there is really only one in the car - the battery (charged by the alternator, which is turned by the engine) and anything connected to it will get the same power.
Really, I have many different separately powered devices (deck, amp, headlights, laptop, screen, USB hub, etc) they will all be connected to the battery and be grounded at the same point, so there will be no ground loops, and they are all separately fused, so if one goes out, it doesn't affect everything. I understand your point, but to me it's not a big deal.

colin · 07-22-2008, 05:24 PM

Oh I didn't mean anything about power sources. I just don't think its efficient to use a whole bunch of regulators all over. I mostly didnt like the idea of having a power regulator AND an inverter, but if you're running a PS2, theres not much you can do about that...

monkeyracer · 07-22-2008, 05:44 PM

The PS2 will be in a later install, like a year later, so there's no good reason to have the inverter in before that.

FockMasterDan · 07-22-2008, 08:33 PM

What kind of laptop are you using? I'm working on a similar setup but got a real power adapter made for my line of laptops.

Right now I'm struggling with how I want to achieve regulated power sources for my devices. I've got a couple options but I just don't know enough yet to pick one and go with it.

monkeyracer · 07-22-2008, 10:06 PM

I've got an HP DV5234US, and I bought this adapter:

Ebay Adapter

It has been working just fine so far. I didn't feel like paying that much for a charger I am just going to end up cutting up. If I start to see issues with it, I will invest in the money, but the carnetix PSU's seem to be a good way to go as well.

You have a dell, and they take a special charger, so the cheapo's wouldn't work too well for you, my HP is a pretty standard charger.

NSFW · 07-23-2008, 12:43 AM

FWIW, I'm running my laptop off a 120v inverter and the power supply that came with the laptop. The inverter gets hot but it hasn't been a problem. I have a 12v power supply for the laptop en route, so I can get rid of the inverter (and also bring the 120v supply back inside, so I can sit down with the laptop if I want to hack on it).

The screen (Xenarc) is powered from my cigarette lighter (which had to be removed anyway). I have a 4-port USB hub that is getting power from the laptop alone. The USB hub is only used for the touchscreen, an OBD2 cable, and a bluetooth radio, so it doesn't need much power.

And I'm using the webmaster auto-on module.

It's all been in my car for about two weeks and it's working pretty well. I was originally planning to get a Carnetix but I don't think I will bother.

do7d · 07-24-2008, 01:20 AM

i am at the same point as most in this thread.. if i may give my $.02:

i was given a great laptop with a broken screen- with the original power adapter. just pick up a 400W inverter from Autozone (the one with a modular connection, that comes in a case) for $50. you will have to hardwire it with 8 gauge wire, but you'll have enough power for powered usb hub, usb hd, etc. d/l Shutcontrol 2.21 from HERE and buy a good usb DAC (Silverstone EB01-B Premium) for $90, so you won't have any audio noise from the charger.