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Battery charge, alternator and or earth drains

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Hi all

Well the rear crank shaft seal clutch and the timing belt change went ok in the end but where was a small hiccup when I reconnected the battery negative lead to start the engine the battery was down on power and needed a few hours charge to start the engine thought nothing of it but the battery is too weak to start it again today.

The 90 has a large Bosch battery which is around a year old or younger the battery fluid is ok for level.

So now it's cold and dark out side the battery is on charge and I will see if it will start latter this evening. But there could be an underlying problem.

The alternator was removed for the engine out/timing belt work and refitted the moulded plug was to be honest just pushed back on could this have more than one position and therefore in the wrong one I will need a mirror to look can do this latter.

It could be that the alternator is tired and not charging as the engine is a 200Tdi and therefore runs its self ones started and the battery therefore being drained down by the lights while driving without recharging the battery.

Also there could be a fault or drain that is pulling the battery down as it is stood on the drive over a few days and therefore too weak to start the engine.

Just to confirme to test the alternator is charging using a multimeter when stood the battery will read 12v and when the engine is running and the alternator charging it should read around 14.5v does the alternator charge at tick over or does it need to be at say 1500rpm and above.

If it is an electrical fault dragging the battery down where are the usual places to start looking.

If it's the alternator can I upgrade to a larger powered one easily or is it not worth it as above I do have a lage battery and intend fitting a second one in the future the only none standard electrical load is 6 extra spot lights. If an alternator upgrade is possible does anyone have a part number so I can get one from a local motor factors and is it a straight swop.

Some feed back on the engine out for the crankshaft seal from my point of view is engine out is the easiest way and I could then work on it in relative comfort of my garage and fit the seal and do the timing on the engine stand.

One little thing when putting the engine back in it would not engage with the gear box for over an hour and a half of struggling this was a simple error when cleaning the bell housing there was a 10mm stud missing so I bought one and fitted it oh dear latter found it should be missing as there is no hole for it to fit in the gear box.

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When fully charged your battery should read around 13.2V (2.2V per cell).

With engine running the voltage should be approx 14.5V at a little over idle. It should still charge at idle, but probably won't be the full 14.5V (nominal).

If you have a good multimeter, pop the earth lead off and put the meter (on current range) in line and measure whether there is any current drain. I would expect some, depending on what electric items are fitted, but it should probably not be above 100mA or so.

Of course, you may just have a failing battery, even at a year old. Did you keep it trickle charged (conditioned) while not in use?


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