Thread: Parasitic Current Drain

Originally Posted by jimbo110

The Defender cranked over a bit slow the other morning, probably due to it being -5, but I thought i would check that nothing was dragging the battery down anyway, so I fitted a digital amp meter and started testing. Since I had the meter on there already, i also tested the current drain of pretty much everything you could run on acc, without the engine running to charge the battery. The sort of situation when your sitting in the truck waiting for your wife to do her clothes shopping etc
My truck has a Uniden alarm, so that will always be causing a drain (bugger all though), Uniden CB, Uniden PRS, Pioneer stereo (50W x 4) with Response active sub.


All readings are in Amps:

All switched off ___________________________0.013 or 13mA
Alarm armed ______________________________0.020 or 20mA
Ign switched to ACC _______________________0.059
AM CB turned on __________________________0.200
AM CB transmitting (5W) ____________________0.917
PRS radio turned on ________________________0.400
PRS radio transmitting (5W) _________________1.575
One interior light ___________________________0.789
Stereo on quietly __________________________0.980
Stereo on quietly with sub __________________1.300
Stereo on loud with sub _____________________8.00
Heater fan on low __________________________2.500
Heater fan on high _________________________5.800
Park lights on _____________________________5.800
GPS plugged in to cig lighter _________________0.114
Imobiliser off ______________________________0.300

Some things I am wondering about whether they are normal or not are:

1, When I switch the ign to ACC a relay clicks inside the dash
2, The headlights only work when the ignition is on
3, The heater fan works in the ACC position, so it's very easy to leave on when the truck is parked with the keys still in it

Does the last 3 sound normal for a 300 TDI Defender?

Yep to the last 2 on my 300Tdi Defender

Re Defender headlights switching off but parkers stay on when the ignition is turned off: The wire for the headlights from the headlight switch goes to the dipswitch via one of the yellow relays by the fuse panel on the firewall - which is actuated from the ignition switch. (Then back to the fuse panel and through the four headlight fuses. )

I prefer lights to stay on when ignition is off, even with increased possibility of flat battery from unintentionally leaving them on. So connected wire from headlight switch directly to dipswitch. I think it also made the headlights slightly brighter from the current not going through a relay and more than a couple of feet of wire.

Yep agree with all above -same for my 300Tdi. Agree that the headlights going off and parkers staying on is not ideal. To easy to miss lights left on resulting in flat batt.