parasitic battery drain

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parasitic battery drain

Postby shanklylfc » Sat Nov 20, 2010 12:54 pm

Hi guys need some help again

a fully charged battery is only lasting about 5 days before the car wont start. Alternator was reading 14.87v, so replaced with a second hand one and new one is reading 14.17v so that seems acceptable.
still the battery is running down, took the gauge, radio 1 + 2, and Am1 fuses out to stop the aerial motor running while testing, put a multimeter on the 10A setting across the disconnected negative cable to negative on the battery, and its reading 8.00A and above. So I removed fuses one by one and the only one that changes the current is the ECU-B in the passenger side fuse box and it drops to about 0.08 amps which is 80 milliamps, and still a bit too high. the only fuse I couldn't remove to test was the ALT 100A in the engine.
anyone got a clue as to what going on.
am I testing wrong,
how to remove ALT fuse,
any fuses I'm missing, got the ones in engine, trunk and passenger side door
shanklylfc
 
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Re: parasitic battery drain

Postby life of bryan » Sat Nov 20, 2010 1:39 pm

Have you renewed the battery? Alarm and radio do use some power so if your battery isnt up to scratch it will drain down.
life of bryan
 


Re: parasitic battery drain

Postby shanklylfc » Sat Nov 20, 2010 1:56 pm

It was a brand new battery about 5 months ago, but with the drain problem its been almost flat a few times, and draining all the time. but if I'm testing correctly, then I have up to 8amp draw on the battery when parked up. maybe I didn't leave it long enough to go to sleep before testing.
shanklylfc
 
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Re: parasitic battery drain

Postby life of bryan » Sat Nov 20, 2010 2:15 pm

life of bryan
 


Re: parasitic battery drain

Postby shanklylfc » Sat Nov 20, 2010 2:32 pm

Thanks life of bryan.
I had a look through that post earlier, Ive disconnected the -battery terminal now and going to leave it for an hour to make sure its gone to sleep and test again, I don't have a good multimeter to be honest, so might have to borrow a better one and test again tomorrow.
The battery might be knackered by now, because of the old alternator or I bought a duff one to start with. but I'm sure something is still draining it.
shanklylfc
 
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Re: parasitic battery drain

Postby cclarke99 » Sat Nov 20, 2010 2:48 pm

8A is a very high current, equivalent to nearly 100W dissipation in whatever is draining it, and will run the MR2 battery flat in about 2 hours. The ECU-B fuse supplies the instrument cluster, and if that was draining that much current it would be very hot. So I think the meter may be reading wrongly.

Did you measure 14.17v at the Alternator or the battery terminals. The Toyota manual specifies 13.2 to 14.0V, so this alternator is a bit high, but probably OK. the previous one at 14.87V was too high and has probably damaged the battery
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Re: parasitic battery drain

Postby shanklylfc » Sat Nov 20, 2010 2:59 pm

Thanks cclarke99
The 14.17v was across the battery terminals, I did read on here somewhere that it should be 14v but other places say up to 14.5v so I was thinking it would be ok. I think you are right about the other one damaging the battery. I'm going to test again soon to see if the 8A was because the car wasn't in sleep mode.
forgot to say, I also get the same drop in the amps removing the ECU-B1 in the engine fuse box, what is that one for? is it the same as the other one
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Re: parasitic battery drain

Postby shanklylfc » Sat Nov 20, 2010 3:41 pm

OK I have, gauge, radio 1 + 2, and Am1 fuses out, my multimeter set on 10A it reads 0.30 and fluctuates a bit before settling down around 0.08. but it still jumps around between 0.08 and 0.15, If I remove the ECU-B1 it reads 0.01.
On that 10A setting, would that be , 80mA and fluctuating up to 150mA or 800mA and 1.5A
Which of the fuses I removed will stop the aerial rising up when I test it, and which one is the alarm?
shanklylfc
 
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Re: parasitic battery drain

Postby cclarke99 » Sat Nov 20, 2010 8:08 pm

Unfortunately my data refers to a US spec car, and doesn't show the alarm. The fuse ECU-B1 feed fuses ECU-B, DOME (cigarette lighter, instruments, clock & interior light) and the radio It's impossible to tell exactly how it works, but if you want to stop the aerial going up/down then remove the RADIO 1 fuse from the fusebox inside the car. If that doesn't work then remove RADIO 2
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Re: parasitic battery drain

Postby Thudd » Fri Jan 21, 2011 2:07 pm

5 days is crap. My car was parked up for three weeks in the recent bad weather, started first turn.
Hope i've not cursed it now :oops:
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