Using standby with DC-DC system

adamis · 09-30-2003, 07:45 PM

I have read that a few of you guy's are using standby on their systems instead of hibernate for almost instant on off. I was wondering how long you guy's that do this are able to leave the system in standby before it kills the battery. According to mini-box.com one of the faq's said you should be able to leave a computer in standby for days without killing the battery. I wouldn't mind using this now that I have all of the bugs worked out of my system, but I'm learly of killing my battery any more.

mian34 · 09-30-2003, 08:06 PM

you could run it off a dual battery isolator setup if you're worried. run the carputa (and any audio accessories if you want) off a dedicated battery so you will always have one good for starting.. when the car is running both batteries will recharge.

skassama · 09-30-2003, 08:19 PM

use a tank circuit (battery) and that will elliminate all problems.....

adamis · 09-30-2003, 11:42 PM

I'm running a tank circuit with a small 12v 7ah battery already. I only use a diode so if the small battery goes dead it is going to suck on my car battery. I don't mind it, I just don't want the thing going dead all the time. I would like to move to using standby, I just want to know how long someone has been able to standby their system without killing the car battery.

skassama · 10-01-2003, 07:45 AM

the tank battery needs to be disconnected when the car is not being used, ie hook it to accessory point or a point which is switched on and off with the engine

adamis · 10-01-2003, 11:10 AM

Guess I could hook the tank battery up to the accessory line... From what I read in standby mode the system consumes something like 5 watts. Does anyone know this number for sure?

novalis · 10-01-2003, 11:13 PM

Quote: Originally Posted by adamis

Guess I could hook the tank battery up to the accessory line... From what I read in standby mode the system consumes something like 5 watts. Does anyone know this number for sure?

That is *entirely* dependent on the exact specifications of your system. Judging by your previous posts I'm *guessing* that you at least are running off an EPIA mini-itx board. This being the case, I can tell you that you will be looking at something along the lines of 150ma @ 12v. So count on about 15 hours (assuming you are using a *standard* sealed lead acid battery), or 30 hours if you don't care how often you need to replace the battery

Elmezie · 10-03-2003, 03:03 PM

I have been using standby for a few months now. The longest Ive had it in standby was about 2 days, but with my opus it just cut all power once my battery power started getting low. But you should be fine as long as you at least crank the car every few days, if you dont why do you even have a car computer.

EBJUSTIN · 11-30-2003, 11:07 PM

Quote: Originally Posted by Elmezie

I have been using standby for a few months now. The longest Ive had it in standby was about 2 days, but with my opus it just cut all power once my battery power started getting low. But you should be fine as long as you at least crank the car every few days, if you dont why do you even have a car computer.

I just got standby working on my carputer tonight, it's nice booting up in 5 seconds instead of 50 seconds. I am using a separate 5VDC regulator (TI PT6212) to power the +5VSB (purple wire) on the mother board.

Mobo draw: ~160mA
USB devices: ~140mA (serial to USB converter for CIMR IR receiver, XM PCR, powermate)

I noticed that the current draw was the same regardless if I shut down or went into standby.

I'm sporting a new Diehard Gold battery so I'm not too concerned about draining the battery but I'm definetly going to investigate how to reduce the current draw from the USB devices.

SuperSonic · 12-01-2003, 06:32 AM

I also noticed that current draw in shutdown or standby remain the same unless you really cut power somewhere between your pc power supply and the battery. This is really simple to explain:

ATX specs that a power supply should always have the 5Vsb (stand by) ready for the mobo. This is done for stuff like suspend-to-ram (S3), Wake-On-Lan, or Wake-On-Whatever-you-can-set-in-your-BIOS.

Since the system has to monitor for example the network card's input to detect a WOL package ('magic packet'), or the keyboard to power up on space bar, or the mouse or modem or so, even after a shutdown all ATX systems that support waking-up need that 5Vsb and will use it.

Funny thing is that Supend-to-RAM needs virtually no power extra as compared to a complete shutdown. So the current draw on the RAM chips and virtual circuits presents the same load on the 5Vsb, as a shut-downed ready-to-wake-up system would do.

Meaning if you don't hard-cut power to an ATX system every shutdown, you might as well use Suspend-To-Ram (power state S3) since you will be using the 5Vsb anyways!

My system for the moment draws about 150mA when in Stand-By or Shut down mode. It's a EPIA 10000, rest doesn't really matter unless you use power-on USB devices lika a mouse or keyb or so. I have a battery that has 70Ah rating. I guess I could leave my system 'suspended' about 5 days with no problems.

Morale : If you don't hard-cut power to the system every shutdown/hibernate (same effect - just different boot up times) you might as well use Suspend-To-Ram since you're wasting the energy anyways (2 sec. boot up anyone

).

Personally I think a car system has enough power to support a DC-DC PC solution with Suspend-To-Ram. After all your car radio draws current to save it's settings the same way ! You get a truckload of nice features like instant-on; instant-off; use while engine off; combined with smart shutdowns without manual intervention ever.

That way when someone comes in your car and sees the system they'll ask : Hey, where did u get this awsome stereo

Just my 5€cents

EBJUSTIN · 12-01-2003, 10:29 AM

Regarding your statement: "It's a EPIA 10000, rest doesn't really matter unless you use power-on USB devices lika a mouse or keyb or so." I'm also using an Epia10000, are you implying that the Epia will not power USB devices during standby if 'wake from USB device' is disabled in the BIOS? I don't recall if I have that enabled or not…I just know my USB devices are drawing ~140mA when the carputer is in standby or turned off.

SuperSonic · 12-01-2003, 12:48 PM

Well I'd certainly test that out in your setup. When I unplug my USB devices or not, I have the same load on the 5Vsb. But mine are unable to power up the computer, so maybe the system cuts power to those devices anyway. And they do not need so much power as yours apparently.

It is surely important to cut power to those devices when you would go with stand-by, if possible.

sigma957 · 12-01-2003, 01:11 PM

I tested the current draw on my system (Epia V 800 with PW-60 power supply). In suspend-to-ram mode it uses about 140 mA, and completely shut down it uses about 110 mA. I therefore agree with what others have said - unless you are cutting the power source to the computer when you shut down, you might as well just suspend it.

EBJUSTIN · 12-01-2003, 08:07 PM

Well I disabled 'resume from USB' in the bios but my USB devices are still powered. The main culprit is the XM-PCR........It's drawing ~120mA! Is there any way to unpower USB devices during standby?

I've been reading a couple articles on car battery parasitic load (key off) ....the consensus seems to be 20mA to 120mA

MeanGT · 12-01-2003, 08:22 PM

EBJUSTIN, I had the exact same setup you are using, with the +5v regulator into the purple wire setup. It worked, the only thing I didn't like was that for some reason my power draw would vary quite a bit, at some times it would be only 180ma, but sometimes it would draw up to 900+ma!! Perhaps it was my USB devices.

I finally gave up on it, and am instead using my regulator to power my GPS unit

. I will follow your results closely to see if you resolve the USB power issues.