#1

'Smart' charger problem.

in Anything that's not Eriba-related. Thu Jan 19, 2023 1:31 pm
by Aaron Calder | 3.732 Posts

The 12v sockets in my Audi, unlike the one in my wife's Honda, remain live even when the ignition is switched off. Three weeks ago, when I put the Audi in the garage I forgot to unplug the dash camera so, hardly surprisingly, when I went to start it yesterday the battery was completely discharged showing only 2.5v across the terminals. Not a problem, I thought, my Cetec superwhizzo 'smart' charger will soon sort it out. How wrong I was.

To my surprise, after being connected for more than four hours the Cetec still hadn't started to charge and was stuck at the preliminary analytical stage. What I didn't know was that unless the battery you are trying to charge has a minimum residual voltage (typically 9.5 - 9.75v), a smart charger will not recognise it as a battery and accordingly as a safety precaution will not begin its charging cycle. Old-fashioned chargers don't have this problem but if you don't have one of those to hand, there is a way to get round it.

The trick is to connect a well-charged battery to the discharged one with a set of jump leads (+ to +, - to -) for a few minutes after which when uncoupled the discharged battery will have sufficient surface charge to be recognised by the charger which will then start its cycle as normal. You can leave the discharged battery in situ while you do this.

As my battery had been so badly discharged, I was concerned that the plates might be sulphated so I put it in 'recondition' mode overnight and to my relief by this morning everything was back to normal (12.98v) and the car started immediately.

I've heard it said that if you fully discharge a car battery you will need to replace it with a new one (£100 in my case). Others suggest they can be rejuvenated by pouring out the acid, flushing with Bicarbonate of soda, filtering the acid and returning it to the cells prior to recharging but a) this doesn't always work and b) messing about with acid somehow just doesn't appeal.

As most battery chargers sold today are of the 'smart' type this problem is bound to become more and more common and people may well be persuaded to throw away perfectly good batteries that could be restored using the above method. Worth a try?


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#2

RE: 'Smart' charger problem.

in Anything that's not Eriba-related. Thu Jan 19, 2023 6:35 pm
by Pepé Le Pew | 2.720 Posts

Quote: Aaron Calder wrote in post #1
The 12v sockets in my Audi, unlike the one in my wife's Honda, remain live even when the ignition is switched off.
This doesn't answer the question you want answered, but it might help...

It's been a feature of Audis for a while - if feature is the right word - that by moving the accessory fuse half a socket up or down in the fusebox, as it were, you can change the fuse from being permanent live to ignition-switched live.

If you look at the fusebox, and your car has this facility, you'll see what I mean.

You could do it in both the 2004 allroad and the 2016 A3 we had previously.

Despite the many commonalities across VAG cars over the years, not all of them will let you do this.

Our Skoda Karoq has the socket in the fusebox that looked as if you could change the accessory fuse from permanent live to ignition-switched, but rather irritatingly the appropriate metal bit that one of the fuse blades plugs into wasn't there.

This meant having to find another ignition-switched fuse to piggyback the dashcam to, in this case the rear wiper. No big deal really, just a bit of an annoyance.

I've no need of a permanently-powered camera, partly because I didn't want a flat battery in the event of a failure of the under-voltage auto-switch off gubbins that many cameras come with, and partly because I didn't want to have to remember to turn the camera off or unplug it when the car wasn't in use.

And I'd far rather have the dashcam hardwired with the cable tucked out of sight.

I doubt if I'd live long enough to see it, but I hanker for the day when everything is wireless. Everything.

Can't abide wires. Horrible things that need no excuse at all to tie themselves into the most appalling knots or just break and stop working without affording you the luxury of understanding why.
.



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#3

RE: 'Smart' charger problem.

in Anything that's not Eriba-related. Thu Jan 19, 2023 7:42 pm
by Poptop320 | 2.595 Posts

Most smart chargers will not bring back to life a totally flat battery, I have an old school battery charger which will give the flat battery the kiss of life and then I can use the trickle charger.


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#4

RE: 'Smart' charger problem.

in Anything that's not Eriba-related. Fri Jan 20, 2023 8:45 am
by Ray Lawrence | 664 Posts

I brought a dead leisure battery back to life using a dumb charger first and then the Ctek.
Great, got it up to the normal voltage.
Went off grid with solar panel and the battery was dead flat after 1 day, it had much reduced capacity.

Aaron, if that was my car I would take the hit and replace the battery. It will let you down in the most inappropriate place and you will wish you had spent that money.

My wife's car battery was starting to play up and I got it working again with a Ctek charger. A few days later it packed up whilst waiting at a railway crossing, blocking the route across. Motorist behind just sounded their horns and swerved round, nobody stopped to help. Eventually a pedestrian mum with a buggy and a couple of kids helped her push the car to the side of the road. Eventually I was able to get there with my car and jump leads. Lesson learned.


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#5

RE: 'Smart' charger problem.

in Anything that's not Eriba-related. Fri Jan 20, 2023 11:06 am
by Aaron Calder | 3.732 Posts

Thanks, Pete. I'll look into that.


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#6

RE: 'Smart' charger problem.

in Anything that's not Eriba-related. Fri Jan 20, 2023 11:11 am
by Aaron Calder | 3.732 Posts

I'll keep an eye on the voltage, Ray, and if necessary will replace the battery as I already have a newish spare that a friend gave me. The problem is, the discharged battery is a newish Varta silver 85ah and as a tight-fisted Yorkshireman I'm reluctant to ditch something that might be serviceable. Fingers crossed.


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