hughstary

Hi ,

I have recently acquired a 1998 1.8LX Mondeo. I've has 2 batteries in it, both 2nd hand so I can't vouch for their condition. However, if I charge one out of the car and then put it in, the car will start OK for a couple of days and then the battery will be flat again.

I tested the charging voltage yesterday, and with no extras on (no lights, fan, etc), the reading at idle was 14.5V. If I turn on everying, it drops to about 11.5. At about 2500 revs it climbs to 12.5, but I guess that still isn't good for charging !

I've checked the +ve alternator connection and that's clean. I guess the -ve is through the mounting ? Am I looking a a duff alternator now, or are there still some other possibilities ?

Cheers

hugh

dojj

iTrader: (3)

some of them have a regulator built into the ecu

take it to a sparky to test out as there is also a fault on the wiring in the wing that the focus' tend to have a lot of the time

Nash_mr2

shit earth

The Youth.

iTrader: (1)

from what you have said the charging circuit appears to be fine, check for battery drains by isolating circuits one at a time whilst checking battery voltage.

steve

foxy12304

with the vehicle rpm held around 2500 with several electrical circuits on ie headlights heater etc for the alternator to be acceptable you should see around 13.5v any lower i would doubt its doing a good job and would need replaceing. however this test will prove nothing if on both occasions you may or may not of used a duff battery. you need to drop test the battery first, then assuming battery good, with fully charged battery retest chrge rate.

if acceptable and your battery still goes flat in a couple of days you DEFO have a current draw ( a electrical circuit failure, short to ground or positive)

get a multimeter next and disconnect the earth starp, set the meter to to highest amp's range possible and connect positive to ground strap and earth connector to battery earth... and higher than about 0.3 of an amp you have a issue...

sorry but from that point i would need to be there to isolate the bad circuit, but at least you would know...

hughstary

Thanks for your replies guys. I checked the earths near the battery holder tonight and all seemed OK. Battery is on charge to test again tomorrow. Foxy12304, not sure what you meant by drop testing the battery ? Is that a heavy load test ?

Cheers

Hugh

foxy12304

[quote=hughstary;3565806]Thanks for your replies guys. I checked the earths near the battery holder tonight and all seemed OK. Battery is on charge to test again tomorrow. Foxy12304, not sure what you meant by drop testing the battery ? Is that a heavy load test ?

Cheers

yes, something like this would be fine..
http://cgi.ebay.co.uk/Sealey-12v-6v-...d=p3286.c0.m14

hughstary

Well, I used a meter between the earth connection and battery -ve post, and only read 0.01A. The battery probably wasn't fully charged but it had enough guts to start the engine. Also saw a pulse of up to 5A when making the connection which I guess was due to the central locking kicking in.

If some components are switched out by relays, though, is it possible for a short to only be in operation when the car is running or ignition is on ?

Cheers