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View Full Version : alpine 9855 and 9853 drawing power



VMF
02-22-2007, 10:33 AM
hey guys, i got a weird problem with my alpine 9855 head unit.
i noticed that if the car is not being used for around a week, the battery drains completely. my friend got the same problem with 9853 head unit and he said he got this problem only after he installed the head unit. so now my battery is dead again so i decided to do some measurements and here are the results.
i checked the resistance of the car with the head unit unplugged from the car's electrical system. it was 22.1 kohms then while checking the resistance i plugged the headunit back into the system, the resistance spiked to around 48 and then started to drop steadily all the way to 5kohm, after that i just unplugged it again and the resistance came back to the 22.1 kohms. it looks like the head unit draws a lot of power from the system even when the ignition is off. i wonder if its normal for these types of head units to kill the battery and if any1 else experienced it and if there any ways to fix this.

Thanx in advance

KaeZoo
02-22-2007, 05:38 PM
Resistance??? How exactly are you measuring that?

The way to test for a parasitic battery drain is to use a multimeter set to measure current, placed in series between the negative battery terminal and the battery cable.

A properly installed head unit should not drain the battery. I haven't seen any battery drain problems with those models in particular.

VMF
02-22-2007, 05:56 PM
it shows 400mA current.

Johnny's92RS
02-22-2007, 06:18 PM
I was having the same problem after installing my 9851, battery dies when car is parked for several days. There was a significant current draw when the car is off so I started pulling fuses until the draw went away. There was something wrong w/ the 9851, it was drawing too much current when the car is off. The HU was drawing current for the clock & memory but it should not drain the battery in a couple of days. I changed the HU & the parasitic drain went away.

KaeZoo
02-22-2007, 09:28 PM
it shows 400mA current.

That's definitely much higher than it should be. The next step is to pull the head unit fuse, or disconnect the head unit, and see if the current drops significantly. If disconnecting the head unit doesn't affect it much, then start pulling other fuses until you find the source of the drain.

Note that the fuse in your vehicle fuse box labeled "radio" may not be the fuse for the head unit's memory wire. You need to find the fuse that supplies constant power to the head unit.

VMF
02-23-2007, 11:02 AM
disconnected the head unit, did not c much of a difference yet, but i gotta fully charge my battery first. i have optima redtop battery and im really surprised that something like a headunit can drain it in a week.
i will update once i charge the battery and check the current with HU disconnected