Battery, alternator or electric gremlins? Now sorted, fingers crossed.

Jamie25 · Post by **Jamie25** » Tue Mar 05, 2019 10:22 am

Driving home from a night shift this morning on the motorway and the battery light came on. Moved into lane one and 60mph and everything felt fine so thought I'd nurse it home.
Couple of miles on and a whole host of warning lights came on for about thirty seconds then all went off except the battery light. Again everything felt fine.
Off the motorway and found a downhill spot to stop (in case it needed a bump start). Engine off for about a minute, then started on the button but battery light still lit. Drove home all fine.
Parked on my drive and left it running whilst I dug out my multi-meter. Read 10.6v whilst running then started running really lumpy. Got to the drivers seat just in time to see another array of warning lights before it cut out. Wouldn't start, nothing but a click on the turn of the key.
Left it ten minutes and it started on the button again. Again 10.6v whilst running and when switched off (I think).
Probably just some puddle splash but looked like a little water on the under tray beneath the radiator. Check the level and it needed about 500ml to brim it, but I don't think I'd checked this in about ten months.
I've now hooked up a smart charger to the disconnected battery.
I would think from the 10.6v reading that this suggests a faulty alternator but I'm not sure why it started fine ten minutes after it cut out.
I'm about to get a bit of sleep and I'm hoping someone more knowledgeable might have some suggestions whilst I'm in the land of nod. Either that or I'm already asleep and it's all been a bad dream!

ph001 · Post by **ph001** » Tue Mar 05, 2019 10:58 am

New alternator required - or wire connection to it corroded / broken.

Jamie25 · Post by **Jamie25** » Tue Mar 05, 2019 2:48 pm

Just checked the battery and charger after a little broken sleep. Displaying as 100% charged. Unhooked the charger and after a minute the battery measured 13.31v. I shall retest in a couple of hours. I hoping to see the voltage settle above 12.6 for a healthy battery....... Does that sound about right?

Jamie25 · Post by **Jamie25** » Tue Mar 05, 2019 2:59 pm

ph001 wrote: ↑Tue Mar 05, 2019 10:58 am New alternator required - or wire connection to it corroded / broken.

Ph001, you sound fairly confident. I can't think what else it cloud be to be honest but I was a little confused by the fact it started up so happily after it had cut out then rested for ten minutes.

It's more than possible that the lack of sleep has slightly addled my brain! Think I'll check the wires and connections now (they all looked good on a cursory check this morning) then buy an alerternator whilst I'm waiting for the battery voltage to stabalise.

On a positive note I have no more night shifts for at least three months.

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ph001 · Post by **ph001** » Tue Mar 05, 2019 3:17 pm

Your voltage expectations for a good battery are about right. Ideally you would load test and measure volt drop with one of these:

https://www.ebay.co.uk/itm/6V-12V-100Am ... Swj5BcRvpC

...as that will tell you if the battery internal resistance is good, but if it started the car well then probably OK.

I think the fact that you measured 10.6V on the battery with the engine running says it all really. 99% sure that will be alternator related one way or the other as it should be >13.6V at idle. Not a big surprise that it still started the car OK again when you first stopped though - battery prob still had a good amount of charge in it at that point. Then as you drive the battery is discharged more and more until the lumpy running etc.

BTW, go for a reconditioned or re-manufactured alternator rather than new. Will save you a packet and just as good.

Jamie25 · Post by **Jamie25** » Tue Mar 05, 2019 3:55 pm

Thanks for the in depth reply.

About to order a Lucas alternator from ECP for £214 after I've deducted the refundable deposit. Can't find any in sock today unfortunately. I think these are the reconditioned units but not sure.

Jamie25 · Post by **Jamie25** » Wed Mar 06, 2019 3:28 pm

Battery still over 13v this morning. New alternator fitted and showing 14.4v when running. No warning lights. Off to Alysbury now for an overnight jaunt, might have to go the twisty route just because. Fingers crossed it's all good now.

Thanks for the advice ph001.

ph001 · Post by **ph001** » Wed Mar 06, 2019 5:26 pm

Glad to hear the Z is back in fine fettle. 14.4V when running sounds perfectly healthy.

If you still have the old alternator, it's worth stripping it down to get to the regulator pack - these are often the culprit and can be replaced for £30 or so. Might be worth fixing it and selling the alternator on to recoup some of your costs.

Jamie25 · Post by **Jamie25** » Wed Mar 06, 2019 8:13 pm

That makes prefect sense and I wish I'd done that instead of taking the 70 something pounds for the old one. That said it would've sat in my garage for a couple of years rather than getting rid. Enough stuff I've been meaning to ebay forever already.

Blast over to Alysbury went well and considering I hit rush hour around Oxford it could been a lot worse. Few stretches to have a blast around Bibury. Even got a wave back from an (at a glance) identical E85 in silver near Thame.

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