My 2005 Legacy had a completely dead battery after sitting for six days. Original battery almost six years old. This has never happened before so I suspected the new aftermarket radio. With the ignition off(no key) I disconnected the negative cable from the post on the battery and placed a multi-meter between the negative cable and the battery post. I showed over 11 volts and .13 amps. I was not sure whether that was normal since the computer and radio are probably pulling a little something to keep settings. So I did the same test on my 2003 Focus and I got zero volts and zero amps.
??? What should I see for a draw against my battery in terms of amps? Is my .13 amps normal?
I am getting the battery tested tomorrow. The guy who installed the radio says he expects to see a draw on a battery and that cars usually die when parked for a week or two. I disagreed with that opinion since I have had cars parked for longer than that without draining. But hey I am proved wrong on a regular basis so what do I know.?
- The multimeter is set to 10A when I am checking amps. I am not sure of what .13 translates to in milliamps.
I'd say it's a battery issue. A draw of .13 amps shouldn't drain the battery that fast.
.13 amps = 130 milli amps....
not sure how you got voltage with the multi-meter in line with the cable and the post... current = ya... voltage ????
It would show voltage, but it doesn't mean much. The 130 miliamps does, though. That's a bit high. 6 years on a battery is a bit old. Between the two, there goes your charge in 6 days. My Esprit does about that too, and kills a new battery in about the same time. But it's English.
With your meter in line and set on amps, start pulling fuses one at a time and replacing them. When the current drops down, you found the circuit causing it. Or you could try disconnecting the new radio and see if that's it.
Generally accepted draw is around 40 milliamps. You need to hook the ammeter up, then let it sit for a period- sometimes up to 40 minutes before all the modules go to sleep.
I'd be looking at the new radio, for sure. Once the radios out and everythings gone nighty night, start pulling the fuses if its still got a draw.
6 years is also very close to the end of your batterys life, too.
I think you should see 0.05 amps. Something in your ECU or PCM is drawing. current. Use your DMM do check the wires to these systems to see if there is current running through them.
Steven
Dr. Hess wrote:
It would show voltage, but it doesn't mean much.
that's sorta what I meant ... hint for OP ... voltage = parallel (across something)
amperage = in line
Dr. Hess wrote:
It would show voltage, but it doesn't mean much.
that's sorta what I meant ... hint for OP ... voltage = parallel (across something)
ie post to post....
amperage = in line
Don't forget as voltage to a component drops the amp draw increases. But as noted the best thing to do is to hook up your test rig and wait an hour, then go back and check. If it's over 50 milliamps, start snatching fuses.
Streetwiseguy wrote:
Generally accepted draw is around 40 milliamps. You need to hook the ammeter up, then let it sit for a period- sometimes up to 40 minutes before all the modules go to sleep.
So should I wait for 40 minutes before testing the amperage? Should I just leave the battery connected for 40 minutes then disconnect and test? Unfortunately my leads don't have alligator clips so I can't leave the meter connected.
Buy alligator clips or clip leads. Put the meter in line and wait 40 minutes.
Dr. Hess - excellent advice, the reading changed dramatically after 40 minutes. A wine cork and a rubber band stood in for alligator clips for the probes. After 40 minutes it now flashes between 10 milliamps and lower. I had the battery checked and it is fine. Now that I know the battery is OK and the draw does not appear to be too much I am completely stumped as to why my car completely died after sitting for a week. +1 for diagnostics, -1 for confidence this will not happen again.
Your battery is at EOL. If this is your DD, just suck it up and put a new one in, or you will put a new one in at a parking lot somewhere soon. And buy some clip leads. They're cheap.
The only reason I did not want to put in a new battery is that I wanted to diagnose the problem first. I am not worried about the money, it is relatively cheap. So even though the Kragen test indicates my battery is OK I should probably just get a new one, huh?
Set up your multi meter again on amps and pull fuses one by one. ECU might draw a tiny bit. See which circuit draws the bulk of it and let us know.
... but .13 isn't much.
My last measure after waiting was .01 - .00 so I won't really be able to tell much if I pull fuses with this meter. I just sucked it up and bought a new battery an hour ago. I am going to use the other car for a week and let this one sit with the new battery. Hopefully it starts next week.
If it only went dead once, maybe its an intermittent draw. More likely is the battery is draining internally. Disconnect the battery, let it sit for a week, see if the battery is dead.
Or just get a new one.
