Battery Drain Current

[Tom Fenton 1,542]

So since I did my turbo conversion my 205 will flatten its battery if I don't use it for more than about 10 days or so. Before that I could leave it for weeks and it would fire up no problem.

Now I know that one cause of my problem is that the ECU power supply is a permanent live, e.g. all the time, so the ECU stays powered up. I ended up doing this, as with it connected elsewhere it would drop out on cranking and thus the car would not fire up.

 

So tonight I got my Fluke out and did some current measurements

 

With the ECU connected, alarm not armed, current draw 0.26A

 

With the ECU disconnected, alarm not armed, current draw 0.15A

 

With the ECU disconnected, alarm armed, current draw 0.16A

 

So really the question, has anyone else ever measured this, and what did they come up with? What is an acceptable amount of current draw with the car sat static, and is the extra 0.1A the ECU is drawing enough to flatten the battery compared to it not being connected?

[grandos 16]

Those figures are quite high in general (although I've never measured the current draw on my 205) I know on the modern machinery I work on the try and keep the figure below around 40mA with the vehicle sat off and locked.

 

How long does the battery last if you leave it with the ECU disconnected? (You may have another draw causing the problem)

 

I would definately say that the extra 0.1A would easily make a big difference to the longevity of your battery.

[Tom Fenton 1,542]

It lasts a bit longer with the ECU off, but I must admit I haven't really carried out a very scientific test yet! I'll sort the supply to that first and then have another look I guess.

[grandos 16]

Could you put a switch in the line for the ECU (ie hidden switch in the dash also act as an immobiliser of sorts) so that you can switch it off.

 

I would rule out the alarm as it only draws 10mA's which is minimal.

 

What sort of condition is the battery in and is it big enough for the job (Amp / hour rating)

[tidypug 5 2 Cars]

do you have electric windows? I had a similar problem which turned out to be a dodgy electric window relay on the fuse board

[Tom Fenton 1,542]

I'm going to re wire the ECU feed so it comes from an ignition switched live, so that will sort that out.

 

I've actually a pair of batteries on rotation at the moment, one is a decent one, the other a new one, both big enough etc.

[grandos 16]

Do the measurement again and pull fuses out of the fuse box one at a time to see if you can locate the circuit the fault is on.

 

That is if there is a fault but 150mA is quite a high current draw and would flatten most batteries in a couple of weeks.

[Tom Fenton 1,542]

That was my next plan TBH, I'll see how I get on.

 

Would be interested to hear any other 205 owners static current draw too.

[GLPoomobile 958]

Check to see if the battery loses any voltage whilst disconnected completely. Mine was doing this when sat in the kitchen. It would drop from 12.75v after a charge to below 12v if left for about a week.

 

I guess it's simple enough, but since we are on the subject, how do you measure current drain with a multimeter?

[grandos 16]

Just wondering how you've got on with this Tom?

 

GLP - You need to use the other connectors on the multimeter marked A with a 10A rating (Very Important),set the meter to Amps,

 

Then make sure all electrical consumers are switch off in the vehicle (don't want to blow the internal fuse of the multimeter)

 

Connect the multimeter 'in series' usually easiest with the earth connection, disconnect the battery / body earth connection and connect the multimeter to both the battery cable and the body / battery (whichever place you diconnected it from.)

 

It should then show a reading preferably in mA.

 

It may then be possible to set the alarm / lock the car but I'm not sure how much current that draws. (don't go above 10Amps as it'll blow the internal fuse in the meter.)

[Tom Fenton 1,542]

TBH I've not been back to it yet. Car is tucked up in the garage with the battery disconnected, hopefully I'll get back on it later in the week.