Hello Focus Fans, 

After two years of problem free blatting around, the battery warning light came on during a journey and at the end of it  then battery was drained low enough that it wouldn't start and had to be jump started. Drove home with no warning light :) Next day , warning light came back on at night. I tried all the wiggle testing I could for loose connections, no change in the battery warning light.

I checked the three-wire-block to the top of the alternator for wear and breaks as far back into the wiring loom as I could - no breaks. There was some oil on the the connector though which i cleaned.

Multimeter check at the battery showed 8.3 v - 11.30 v, so I go a new alternator and fitted it. Multimeter check showed 14.4 volts immediately and I thought I had fixed the problem.

After a long days drive yesterday including a 2 hour night drive with lights on -  all was good. But on a short drive  today the battery warning light came back on. Checked the voltage at the battery with multimeter and its jumping from 13.4 to 14.2 volts and all volts in between.

Has the Smart Charge system got a fault? Is the wiring to blame? Or something else?!?

I do have a lead acid battery - not a silver calcium - but this has been fine for two years or regular use.

Hair-pulled, swear-jar full, oil under the finger nails standard; tether-end reached.  Any help gratefully received! 

Thanks

2002 diesel estate ford focus C1 engine TDc

Over time SmartCharge will fry a lead acid battery, I'd get the battery tested as it may be on it's last legs.

Garage fitted a lead acid battery by mistake to my 1.8 TDCI MK2 as well as a new alternator.....the battery was dead within 12 months.

Going to bump this with my Alternator problem.

Ive a Focus MK1.5 2003 1.8 TDCI Ghia Estate, in August the battery light stated to come on so I put a multimeter on while idling, 10v Reading so I knew that the alt needed replacing, went to ECP got a Remy 90A unit with 33% off swapped it over with the original denso 90A unit, all fine until I put front heated windscreen and then the battery light comes up, full load, big NO, with the multimeter I'm getting a 11v reading. The volts always drop when the heated windscreens front/back are on, It has a new silver calcium battery aswell

Any ideas.

guessing a bit here, they might both be 90a alternators but the 90a will be max output. perhaps the newer one is not so good as the older one at lower rpm. 

I was thinking of going back to ECP and getting the Lucas 105A unit