Parasitic drain need testing advice please

[NackJich]

Hello again.
My car battery is draining completely overnight. I charged it up and ran it through a fairly decent battery tester which resulted in a GOOD BATTERY advice at the end. It tested charging, cranking response, load at 2500rpm etc. A known old battery was a fail, so I'm reasonably sure the battery itself is okay (but might not have too long to live due to the draining to 0 volts x 2)
So, I youtubed as you do, and followed advise to connect a multimeter between negative terminal and earth wire. The drain is 80mA. Now my main question is: if I start with the boot lid open and the car electrics all off. Wait for a while for it to go into sleep mode. Then pull fuses and watch for a change in current. I am aware that if I open a door during the test I can destroy my meter. If I open the bonnet, and the relevant doors and boot lid prior to the test. (Maybe remove the boot lamp before?) can I just continue to pull the fuses as there will be no further events to cause a current surge through the meter? Sorry it's such a long winded question...? Any advice will b e greatly appreciated..

 

[DPG]

I'd be wary of saying the battery is good if it has indeed been drained to absolute zero on more than one occasion. Lead acid batteries hate this.

Remember some cars take a long time to go fully to 'sleep' as well, and often do it in multiple stages on modern cars.

What is the maximum DC current that your meter can read? The interior lights switching on shouldn't be a problem assuming you have a 10A (or similar) range. Remember to use the correct socket on you multimeter though.

 

[NackJich]

Thanks .. I'm not that hopeful the battery will have survived, but I need to trace the faulty component before I buy another. The meter goes up to 10 amps. I'll connect it in series with the doors/bonnet already open and wait an hour and then start pulling!

 

[DPG]

80mA shouldn't drain a good car battery overnight.

Is that what it reads with all doors and boot shut, and after leaving the car for at least half an hour?

 

[NackJich]

80mA shouldn't drain a good car battery overnight.

Is that what it reads with all doors and boot shut, and after leaving the car for at least half an hour?

 

[NackJich]

Hi again
I'll have to do a little experiment and get back..
Sods law this happens just as we are going away. We'll have to go away in her shed and I'll resume the testing from next Wednesday. Cheers!

 

[DPG]

Hi again
I'll have to do a little experiment and get back..
Sods law this happens just as we are going away. We'll have to go away in her shed and I'll resume the testing from next Wednesday. Cheers!

Keep up posted!