18 replies to this topic

[I_broke_it_again]

my daughter has a 1993 1275 cooper spi with a four fuse box. The battery is constantly going flat. It appears that about 140mA is constantly being drawn through fuse 3 4 in the main box. I have disconnected all the connectors to the steering column, removed the radio, removed brake test switch and reduces to about 110ma. The reduction is probably down to the clock and the radio memory feed being disconnected when I take apart all connectors at the steering column. My thoughts are that there is a fault in purple wire feeding from the number 4 terminal to the connector block under the steering column. Before I chop out the cable and re run another from the fuse block to connector block under the steering column, I wonder if anyone knows if I have missed anything obvious. No other accessories are fitted. I have tested the alternator and the output is good and fitted a brand new battery. 140mA parasitic load seems far too high and it is the same at the battery as well as through fuse 3 4 so it is not leaking through any other circuit?


Cheers

[xrocketengineer]

The other thing connected to the purple wires is the anti-theft alarm. You could try disconnecting that.

[I_broke_it_again]

Looking at the haynes book of lies wiring diagram, it does not show the immobiliser on the list, but then it does not show the clock. Is the immobiliser part of the ecu?

[Cooperman]

You could fit a battery isolator switch in the main battery cable run from battery to solenoid. Then there would be no battery drain at all.

[I_broke_it_again]

I toyed with that idea. As a short term fix until I find the"leak" I was going to put a relay in the circuit powered by the ignition switch. Therefore drain s only when engine is on and alternator going. Draw back is I lose the clock and radio settings. The immobiliser might be worth a check for the leak. She does not use it as no fob, but thinking of installing a rottveiler with rabies for any would be thieves!

Its the anti theft a single unit, or part of the ecu.

Hayne manual does not really describe its location very well.

[xrocketengineer]

The ECU and the Alarm/Immobiliser are separate. The Alarm/Immobiliser is behind the dashboard. However it only disables the starter if you have an early system which I think you do since it is pre 1994.  If it is removed the starter will not work, even though the car could be bump started.

 

[KernowCooper]

How long does it take for the battery to go flat? and what sort of trips does you daughter use the car for, its easy this time of the year to take more out than you put back on short trips.

[Cooperman]

I had a Rover 214 Si and if I left it for more than a week without doing a longish run or re0-charging the battery it would not start. It had a constant drain and in the end I used the battery master switch to isolate everything and the problem was solved. But then, it was a rally car so the radio had been removed.

[maccers]

I had this exact issue, it was a new loom, new battery, infact most of the bits were new, like radio, amp, retro fit ECU, it was a bare shell build up...!

 

I measured the draw accross the battery using a meter and found about the same amount of power drop. Car would hold charge for about a week maximum. I used to keep it on a trickle charge when not in use (its a weekend/dry use car only!)

 

Recently I decided to wire the stereo in correctly, and by that I mean connect to a live switched, and the constant feed for the memory. Previously I had them both connected to permenant live, and I used to power the radio on and off each time manually.

 

For some reason, maybe a faulty radio or something, the battery now holds charge perfectly! I have not re-measured the drop accross the battery, but suspect its gone right down. Its the only change I made to anyting electrical.

[gazza01]

Not big on electrics but I would fit a secondary earth strap just as a precaution. Only cost a few quid.

[I_broke_it_again]

How long does it take for the battery to go flat? and what sort of trips does you daughter use the car for, its easy this time of the year to take more out than you put back on short trips.

It goes flat in about 3 days. She does about 16 miles a day, albeit 6 miles on dual carriageways. I've switched on everything and the alternator is still managing to push 2amps into the battery at about 14v. I turned off everthing and the alternator was still pushing 2amps. I have a fully automatic battery charger and I checked the charge it was pushing in with no load at all, engine stopped and it was also about 2 amps. So from that I think that the alternator and regulator is fine.

My first thought was the radio, I have pulled it out and disconnected and it still draws 140ma.

Quick fix is a solar panel battery charger on the rear parcel shelf. A 2.5w is pushing about 150ma in this weather so it is at least holding its own during the day.

I think the intermediate fix will be to install a relay between pin 4 and the output cable powered from one of the fuses that go live when the ignition is turned on.

I assume looking under the dash that the alarm is just above he radio? So to disconnect it I will have to take the dash off?

The wire broke between the alarm/imobiliser and solenoid some time ago and it has been bypassed from the ignition switch to the solenoid.

I assume if this is all it has an effect on, I can remove it from the circuit.

Haynes does not appear to have a wiring diagram for the alarm. Is there one available any where?

I assume the power to it comes out the loom and there is no convenient pace to disconnect?

Cheers for the help

[Dan]

The wire broke between the alarm/imobiliser and solenoid some time ago and it has been bypassed from the ignition switch to the solenoid.

 

  So the immobiliser is bypassed?  Are you sure it's not actively working all the time then?  It could be the drain.

[KernowCooper]

Something wrong if the 140ma drain is flatting the battery completely in 3 days?

 

If the battery is a 60a/hr fully charged then it would supply 1amp for 60hrs, 500ma for 120hrs and so on to flat. these are flat readings where as 10v your not going to turn over on the starter

 

Are you sure the alternator is putting out enough current? and how are you measuring the amps into the battery on charge?

 

When you say the batteries flat do you mean No Voltage showing on the meter? or wont turn over?

 

have you fully charged the battery and then used a tester to drop test it? I have seen batteries show full charge and then a small drop test and they collapse completely

 

If you indeed have only 2 amps going back into the battery and your alternator is the later A127 then the standard amperage is 55amp, then you have a lot of current draw?

I would run through the alternators checks here to identify if it working at its full capacity http://www.theminifo...ng-basic-tests/

Edited by KernowCooper, 10 February 2014 - 11:28 PM.

[I_broke_it_again]

Sorry, when I mean flat I mean not enough to crank the engine but enough to energise the solenoid. The battery is showing about 11.8v.

To check the alternator is charging the battery, I start the engine and place my meter on the neg terminal and neg wire and then separate the connection leaving the flow to go through my meter. That way it stops me frying my meter at start up and maintains continuity when I break the circuit by lifting off the neg terminal. That is when I am getting the 2 amps. My meter shows direction of flow so I know it is going in.

From memory, the alternator regulates the output by monitoring the voltage and changing the magnetic flux in the alternator and either increasing or reducing the output to stop frying the battery. My thoughts were that the alternator is ok, because it holds 2amps into the battery when under high electrical load and also when everything is turned off. My "smart" battery charger matched these results as it detected the same state of the battery and delivered 2amps, which then slowly reduced to a trickle charge when the battery was fully charged.

I hope my deduction is right, but it was a long time ago I did my electronics and I was still using a slide rule in those days. (those under 50 and want a laugh, google it and see what us old timers used at school instead of a calculator)

Voltage out of the alternator is about 14v and the earths are good and I have checked resistance between battery and body and is 0 ohms

Fan belt is good and not slipping and good earths between engine and body.

She is having 2 new tyres fitted on Saturday and the tracking done, so I think I will get them to do a drop test to check.

If it is the battery, good news

Cheers for the help

[I_broke_it_again]

In terms of the immobiliser, the fix appears to be a splice into the starter circuit under the steering column, leaving the cable intact to the immobiliser this then goes direct to the solenoid. The original cable to the solinoid which was broken is disconnected. My thoughts are that the immobiliser will not "know" there is any change in the system. I have measured the voltage at the boot and bonnet sensor and it is 0v. Without the wiring diagram, I suspect that he alarm/ immobiliser is not activated as I would think there would need to be a voltage to detect the break in the circuit when the boot or bonnet is opened.

If it is not th battery, then is it the immobiliser faulty and just using juice?

Cheers