judging car battery condition from charge rate fall-off

David_Aston

Bit of a daft one for any car 'leccies. Don't use car much. Decided to charge the battery roughly every six weeks using a standard rate charger. Does the fact that the charge rate starts at say, 7 whatsits on the charger, and within half an hour has dropped to 3 or 4, actually give any indication as to the condition of the battery? The electrolyte "eye", is on green which seems to be ok. I do only leave the charger on for three or four hours to be honest, as I would rather not disconnect the battery to charge it, and lose all the computer and radio settings.
Cheers anyone!

TiTheRev

It probably means it's done charging when it drops every 6weeks or so it quite often, so wouldn't need much charge to get it to capacity.

David_Aston

Thanks for your opinion TitheRev. I did hope it was a positive sign. Because we joined the Norwich Union "insure as you drive", just before they stopped doing it, and consequently had the tracking box fitted, I'm assuming, said box will be taking something out of the battery all the time. As the battery is five years old, and the car rarely being started, the odd charging session did seem like a good idea.

Conor_3

David_Aston wrote: »

Bit of a daft one for any car 'leccies. Don't use car much. Decided to charge the battery roughly every six weeks using a standard rate charger. Does the fact that the charge rate starts at say, 7 whatsits on the charger, and within half an hour has dropped to 3 or 4, actually give any indication as to the condition of the battery? The electrolyte "eye", is on green which seems to be ok. I do only leave the charger on for three or four hours to be honest, as I would rather not disconnect the battery to charge it, and lose all the computer and radio settings.
Cheers anyone!

The only way to test it is with a dropper which puts a massive load on the battery.

David_Aston

Thanks for that Conor. Er, what is a dropper?

TiTheRev

It bridges the terminals and gives you a reading to say whether it's holding it's charge and what output it may give. Not a highstreet item, you'd need to see a garage for a drop-test.

David_Aston

Thanks for the additional info TiTheRev. I suppose I could ask my local Audi garage to drop test the battery, and then they could replace it if they decide it is necessary. Or, just keep poodling on with it until the car fails to start, a course of action which I do tend to utilise with pretty much everything else mechanical in our home. (Not of course including hi-fi, which obviously has to be replaced when the urge takes me!) Ooh. Don't tell my Missus I said that!

goldspanners

David_Aston wrote: »

Thanks for that Conor. Er, what is a dropper?

this is a dropper.

http://images.google.co.uk/imgres?imgurl=http://www.abbeypowertools.co.uk/webupload/APOWER/DRAPER/APOWERSMALL53090_blt100.jpg&imgrefurl=http://www.abbeypowertools.co.uk/subprod/battery-testers-and-accessories-0001394.aspx&usg=__XMF7gax1AJoCT9jWZFOLBpx4ijg=&h=300&w=161&sz=12&hl=en&start=8&sig2=mjK8GJ0p4DQeZ1d1AI1bOQ&um=1&tbnid=zqpddUU-pSRyxM:&tbnh=116&tbnw=62&ei=0dw2SZDYMIOw8ASrj4n1Bw&prev=/images%3Fq%3Ddraper%2Bload%2Btester%26um%3D1%26hl%3Den%26safe%3Doff%26sa%3DN

proper names can be high rate discharge tester or battery load tester.