Duff Alternator or Battery

Can anyone help with any information that will help me decide if my Alternator is not charging, or my battery is duff. I have a 94 Renault Espace diesel that is causing problems on the cold dark mornings, i.e..e often not enough charge to turn over enough to start. Last winter I had an alternator fault and had the alternator repaired at a local alternator & starter repair shop. I still had problems so decided I bought a new battery. spring/summer/autumn, driving without much electrical load so had no problems. This winter come dark nights, short drives and cold mornings and the starting problem is back. I tested the battery and alternator as per the Haynes manual (yes I have doubts as to whether I can believe this book). Battery volts cold were ok, about 12.7v. With engine running the battery volts were about 14.v with no load, so far all as per "the book". With full electrical load on, the battery volts dropped to about 12.3v. Haynes says the alternator should hold the output to between about 13.5 and

14.4v. I went back to the alternator repair place, and he said the alternator was doing what it should, and I needed a new battery. Who is right? The Haynes manual or the repair man? I obviously don't want to pay for a new battery if it is the Alternator, and vice versa.

Any help or helpful links appreciated

Thanks

John

Reply to
John White
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From what you say, the alternator is faulty or the loading is too much.

MrCheerful

Reply to
MrCheerful

Haynes. Plainly, if the volts are dropping below that with no load, the battery is being discharged.

Reply to
Dave Plowman

When the alternator was tested under load, what engine RPM was this test carried out at? If it was at idle, then you will get a drop in voltage under full load. Try testing again, bringing the revs up to around 2000rpm and holding it there during the test.

Also check for a battery drain. Remove the earth lead, connect a multimeter set to its highest amp range (at least 10A) and measure the current flow. DO NOT switch on the ignition or run the engine. You are looking for a maximum drain in the order of 30mA (0.03A). Any more than this will start to cause you problems. Usual cause for battery drains are faulty radios, interior lights staying on, faulty electric windows or dodgy regulator/diode pack in alternator.

HTH

Anthony Remove eight from email to reply.

Reply to
Anthony Britt

about 13.5 and

alternator was

Alternator, and

In theory a fully charged battery delivers 13.2 v, so the charging voltage must be higher. Anything below that figure means it's not being charged. Mike.

Reply to
Mike G

VERY VERY common fault on these- the earth strap from engine to body fails / has a high resistance. Your alternator and battery are most likely fine.

Remove and clean up the surfaces where the earth strap connects back to bright metal.

Personnally whenever I have a petrol Espace in with similar fault I always add an extra earth from one of the starter bolts back to the battery neg, as on these a high resistance back to earth from the block will very often blow the ECU when trying to start. You may wish to do the same.

Whilst your at it, I would also check the main feed to the starter from the battery, and also the noriously crap fusible links next to the battery which feed the rest of the electrical system. It wouldnt be the first time these are about to die...

Tim..

Reply to
Tim (Remove NOSPAM.

Thanks for all the helpful advice. Something to go at here. I will do further tests and add the additional earth strap and check the others as suggested this weekend.

Thanks again John

Reply to
John White

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