Battery or Alternator

Ok got in Disco 2,2 nights ago & battery was dead got jump start & got home put battery on charge all night ( not sure exactly how much it charged up )seemed fine yesterday & this morning but went dead again this afternoon,jump started to get me home but lost all flashers horn lights speedo etc, then even worse started stopping & starting would hardly pull away. Dont want to get battery or alternator until im sure which 1 is causing the problems.....cheers..

Get the system tested. Leaking diode in the alternator could be draining the battery.

Once started an efficient Alternator would throw out enough charge to keep everything running so it does seem to point to that! A fully charged battery would just run down in such circumstances, best to use a multimeter to confirm regards. Chris

This thing is not so simple as it appears, as wammers said, it's possible to be one or two shot diodes(out of 8) in the rectifier then the alternator will still deliver the required voltage which will show around 14 with DC multimeter but it's not well rectified and contains a sine wave component which can hurt the battery but more dangerous is that it can affect ECUs, in this case when ignition is off the battery will be drained through the fubar'd diodes too, the only certain way to rule this out is with oscilloscope and unfortunately the garages where they check the charging system are not using that only making sure that there is enough charging voltage, it's better that the alternator to be completely fubar'd cos at least it will be changed with a good one

Although this may not be applicable to an oil burner, but asimple test to check the workings of the alternator is by running your car engine, then disconnecting the positive connection of the battery, if the car stops, then you most likely have a problem with the alternator.
Another simple test is to check your interior lights, as an alternator charges your battery when the car is running if the interior and dashboard lights are Illuminated brightly but then slowly start to fade with the engine rpm then it indicates a problem with the alternator, this demonstrates that the alternator cannot keep the nessary charge when the car is running.

Start with the slmples first, a DIY test...

discool said:

.... a simple test to check the workings of the alternator is by running your car engine, then disconnecting the positive connection of the battery,.....

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i rarely disagree with you but in this particular case i must warn you to not do that ON A D2 again cos if let's say the alternator is good you risk to hurt one(or more) of the ECUs... the battery acts as a "damper" for the alternator's output, if you disconnect the battery while the engine is running there is the risk to get a voltage spike up to 18-20V from the alternator which is dangerous, also if the rectifier is not in the best shape the sine wave component will be much ''agressive''.

I can give you guys a bit more info & im sure you might in turn be able to help me a bit more.Ok up until my battery went flat I noticed that my interior lights went off ( when i opened doors no lights came on ) am i right in thinking this could be
A. Something draining my battery overnight / when ignition is off.
B. Knackad alternator
C.Duff battery
cheers

the answer to your question is YES

So do i need a new Alternator or a new battery ? Cheers...

Hi mate
To be honest i would take a trip to holfords and get them to have a look at the battery. But then again i know MONEY but new battery @ £110 new alternator (TD5 ?) with pump @ £150 Job done @ £260 ??????

sharpster500 said:

So do i need a new Alternator or a new battery ? Cheers...

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alternator or battery... depends on which of them is fubar'd...and you've got some info how to check that... i strongly recommend to not change the alternator if the battery is fubar'd or vice versa

sharpster500 said:

So do i need a new Alternator or a new battery ? Cheers...

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Sierrafery doesn' t have a crystal ball, so how do you expect him to know?
Do the simple tests, or maybe better if u find someone that will do them for you, then tell him what results u have found.

chris7 said:

Once started an efficient Alternator would throw out enough charge to keep everything running so it does seem to point to that! A fully charged battery would just run down in such circumstances, best to use a multimeter to confirm regards. Chris

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id go with alt too

Thanks a lot....just been out to have a look to see fuse for lights / horn / speedo etc & noticed this hanging...dont suppose this could have something to do with my problems....its actually hanging next to a pretty similar 2 point plug ( black )with the same metal retaining clip.....must be for something.....

if it has pink/black and yellow/white wires in it it's the fuel temp sensor plug, it must be connected to the sensor in the FPR, being unplugged can give difficult start and consumption issues

Hi many thanks for your reply could you please tell me what the FPR is. You say it could cause starting issues & fuel consumption issues, i am experiencing both these at the minute.........cheers

FPR - Fuel Pressure Regulator.

sierrafery said:

alternator or battery... depends on which of them is fubar'd...and you've got some info how to check that... i strongly recommend to not change the alternator if the battery is fubar'd or vice versa

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Hi took battery off & put it on trickle charge from 7pm last night until 10am this morning popped it back in & everything works spot on.Took it to a Auto shop to test battery & he says its absolutely spot on, the problem lies with the Alternator but beforw removal he suggests i check everything for bad earths / loose wires etc & ECU. Dont know where to start now............any pointers in the right direction would be greatly appreciated......cheers

why not stick a multi on it and see what it is pumping out?