USB Devices = Always On??

**KingsDude** · 02-22-2005, 03:35 PM

Hi, I have two USB devices that always stay on, even though the key is out and nothing is running in the back, even the computer is off. The two devices are my Bluetooth USB adapter, and the Geffin Radio Shark which lights up blue. I know both are still on because they both have some sort of light that stays on. I was wondering, is this going to drain my battery in the future? I don't mind them on, I'm just worried about it draining my battery. My computer goes straight to shutdown, so its not like the computer still has power. Ti's off, but still has power.. Help!

**bobs987** · 02-22-2005, 03:45 PM

it shouldent be a problem as long as it not using power for more than those two leds, i dont think you should have anything to worry about, but if you are concerned you can take a mulitimeter and find how much amperage you are drawing, but i dont think you need to worry

**mpattonm** · 02-22-2005, 03:48 PM

Hmmm... I bet you are are running Epia M based carputer, right?

**jcdillin** · 02-22-2005, 03:49 PM

the bluetooth adapter I would not worry about, if that radioshark is powered from the USB bus you might want to check on how much power it draws, because if you dont use your car for a week it might drain your battery

**bobs987** · 02-22-2005, 03:53 PM

does anyone know how much voltage the wakeup feature has? cant be more than 5 volts.

**KingsDude** · 02-22-2005, 04:25 PM

Well, I'm running an HP e-PC so I don't know what it is. The radioshark is powered by the USB bus.. Ahh, now I'm getting worried. How can it draw power when the car isn't even on!!

**rando** · 02-22-2005, 04:34 PM

This has been discussed in MANY threads. If you're using any ATX compliant power supply (Opus 150W ) it will continue to provide +5V standby power to your motherboard. Your motherboard uses this power to implement handshaking with the ATX supply as well as power certain devices (NIC, USB, Modems, ...). What you're seeing is just a symptom of the behavior. The only way to know how much power your system is using while off is to measure it.

Depending on your motherboard, you might be able to configure it to reduce its power consumption, disable USB devices, etc while off. If you have an Opus 90W or M1-ATX, they can be configured to power down the +5VSB rail completely. There is a post on the forum with a work-around solution for the Opus 150W.