My daughter has a 72 plate Kodiaq which this morning had a random flat battery for no obvious reason.

When it was last serviced 2 months ago by our excellent independent VW/Audi specialist (who have looked after various cars in our family over the last 10 years) they indicated the battery was starting to fail.

We jump started it and she's been using it without problems all day (the engine management light which had been triggered went off as well).

She booked it into to Halfords this afternoon for a battery replacement and they strangely found the battery to be in good health but found a high Diode Ripple reading of 1.21V. They did not consider the battery needed replacing but suggested a further diagnostic check.

I'd not heard of diode ripple before but looking it up online suggests it's a warning of impending alternator failure. This seems very strange in a car with 23k miles only and otherwise running perfectly.

Does anyone have any experience of this issue or advice please.

Many thanks.

Hi, welcome.

No but your independent or good (when you can find them) auto-electrician, can test the alternator and/or confirm diagnostics, it might possibly be a wire or connector to/from alternator, Halfords misreading or mis-diagnostics and the fault(s) elsewhere.

Cars are now very complex, German marques such as VW have been (over) complex for decades, alternators and charging system and monitoring of such by the computer(s) is complex.

You might find more and better information in the Kodiaq section particularly if this is a common fault to your model and/or year. - https://www.briskoda.net/forums/forum/365-%C5%A1koda-karoq/

Edited 5 May5 May by nta16
typo

I had similar on my 23 Superb ...1 garage said alternator another with a reader said defo battery - it was the battery although ive had 2 older superbs and the alternators have all failed, albeit after 140k.

Not sure about the Kodiaq but mine is a 'intelligent Alternator' which alternates the power outage that can confuse a lot of ppl not used to Skodas.

Many thanks for the comments. We went ahead and simply got the battery changed at a different branch of Halfords. The guy there didn't quibble at all.

All now seems good, stop-start working properly, no warning lights. Fingers crossed!

Cheers.