Any Auto Elec in the House
Discussion
So battery on the mini ran completley flat from Sat afternoon to Monday morning. New battery fitted on Friday. So flat, imob not even working.
So I read that amp drain from a battery should be about 35 milli amps which would run the clock, alarm and immobiliser.
So did a test by putting an amp meter, poss from neg term then neg term of meter to the neg battery clamp, did it so the clamp didn't actually stop the power supply.
So the meter was measuring the battery drain, and it showed up as 0.35 amps, which I guess is 350 mili amps, which if correct is way too much. So something is taking a lot of amps out of the battery, but everything seems to work ok, no earthing issues etc. So a bit stumped as to how to trace where the drain is, presumably a live must be drawing too much current and sending it to earth
So I read that amp drain from a battery should be about 35 milli amps which would run the clock, alarm and immobiliser.
So did a test by putting an amp meter, poss from neg term then neg term of meter to the neg battery clamp, did it so the clamp didn't actually stop the power supply.
So the meter was measuring the battery drain, and it showed up as 0.35 amps, which I guess is 350 mili amps, which if correct is way too much. So something is taking a lot of amps out of the battery, but everything seems to work ok, no earthing issues etc. So a bit stumped as to how to trace where the drain is, presumably a live must be drawing too much current and sending it to earth
I'm no expert, but what about pulling the fuses out one at a time to see which circuit it causing the drain. This would give you a short term solution until you locate the problem on that circuit.
Edited by JimexPL on Monday 1st February 20:20
Edited by JimexPL on Tuesday 2nd February 10:19
The seurity systems on late cars can be a problem.
I have a Rover 214 Si and if I lock it, thus arming the seurity system, my new battery goes flat in about 3 days. So I leave it unlocked whilst it's in my drive (it quite secluded here) and then it's not a problem.
I really don't know what the cure is nthough, sorry.
I have a Rover 214 Si and if I lock it, thus arming the seurity system, my new battery goes flat in about 3 days. So I leave it unlocked whilst it's in my drive (it quite secluded here) and then it's not a problem.
I really don't know what the cure is nthough, sorry.
I recently had a battery drain problem of the same magnitude.
The way I tested it was as you say with the ammeter.
I then took each individual fuse out and put the ammeter between the terminals to locate the offending circuit.
Once I did that, removed individual items to locate the source of the problem, in my case earth from stereo. Check all lighting and other relays (2 in dash behind steering wheel for dim/dip and indicators and 3 at bulkhead) are working properly also (remove in turn and check amps at battery as before and when amps reduce you have the faulty relay).
Check terminals at brake fluid reservoir are OK.
Check positive battery lead under car - casing can crack causing it to go to earth and check neg battery strap is good. Check engine to bulkhead earth strap on left of engine as you look at it next to steady bar. Check positive terminal at battery not touching bodywork.
Have you added or changed anything recently?
The way I tested it was as you say with the ammeter.
I then took each individual fuse out and put the ammeter between the terminals to locate the offending circuit.
Once I did that, removed individual items to locate the source of the problem, in my case earth from stereo. Check all lighting and other relays (2 in dash behind steering wheel for dim/dip and indicators and 3 at bulkhead) are working properly also (remove in turn and check amps at battery as before and when amps reduce you have the faulty relay).
Check terminals at brake fluid reservoir are OK.
Check positive battery lead under car - casing can crack causing it to go to earth and check neg battery strap is good. Check engine to bulkhead earth strap on left of engine as you look at it next to steady bar. Check positive terminal at battery not touching bodywork.
Have you added or changed anything recently?
Edited by PGM on Tuesday 2nd February 12:42
Anything NOT working?
Interior Light on?
Door switches for interior light shorting out behind bodywork cos wire snapped chaffed?
Shorting out through the distributor?
Heater motor
Wipers seized so draining battery
Addition guages shorting out?
Battery knackered?
Wires to rear lights chaffing? But not enough to blow fuses
Good idea about removing fuses could further isolate by pulling each wire off fuse box (without pulling wire off terminal!!) Then recheck readings.
Is the immobiliser shorting out, that could be odds on favourite
Interior Light on?
Door switches for interior light shorting out behind bodywork cos wire snapped chaffed?
Shorting out through the distributor?
Heater motor
Wipers seized so draining battery
Addition guages shorting out?
Battery knackered?
Wires to rear lights chaffing? But not enough to blow fuses
Good idea about removing fuses could further isolate by pulling each wire off fuse box (without pulling wire off terminal!!) Then recheck readings.
Is the immobiliser shorting out, that could be odds on favourite
After a lot of testing etc, found the problem. When the engine builder put the engine back in, he pluged in a single point MEMS Relay!!! The single point relay will run everything except it puts voltage to the injectors and stepping motor all the time, that was the current drain.
The multi point box (which looks the same, but has a different part number), only switches power over once the ignition key is turned, the ECU then sends an earth to the relay, which engergizes a cap, and then opens the relay to allow voltage flow. What a bummer to fault find!!!
I even swapped the relay box with one off my K series Caterham and found the same symptoms, so assumed it wasn't the relay. It was only by chance I found out there were two different boxes.
At least its fixed now
The multi point box (which looks the same, but has a different part number), only switches power over once the ignition key is turned, the ECU then sends an earth to the relay, which engergizes a cap, and then opens the relay to allow voltage flow. What a bummer to fault find!!!
I even swapped the relay box with one off my K series Caterham and found the same symptoms, so assumed it wasn't the relay. It was only by chance I found out there were two different boxes.
At least its fixed now
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