Charging battery on the car?

[Sijones]

Does anyone know if it's "safe" to charge the battery whilst still in situ and connected on an S4 cabrio? Only I used to regularly do this on my 3.0 A4 with no issues. I know you have to be careful of the gas build up so always switch of charger when disconnecting etc. I had more issues disconnecting the battery and charging as you can lose the key programming etc and I know car electronics don't like have all the power "removed". Will the charger damage the rectifier or alternator or would I have to buy a specific/special charger?

Thanks

Simon

[linkman72]

I am not technical in this respect mate but in my slightly inteligent opinion if you can plug a solar panel charger into a lighter socket or direct to the battery via croc clips to trickle charge your battery in situ then a low voltage charge should be fine ?

Any other input 'cos given my battery drain issue this would interest me as well

[adsgreen]

How do you think the car's alternator does it?

Yes, it's absolutely fine to charge the car with the battery in-situ.
Obviously remember the golden rules...
1) FFS don't get the positive and negative charger leads mixed up. Any decent charger should have a warning light/buzzer in the event that they are connected incorrectly.
2) connect battery charger with the power to the charger off.. then switch on.
3) some chargers have multiple voltage settings. Whilst most automotive electronics should be good for 24v it's not worth the hassle. make sure it's set to 12v.

As for solar chargers... you *will* need a relatively large unit to even stand a chance of keeping up with parasitic drain.
I have a couple things and for the rs4 use a 30w crystaline panel (about the same size as the parcel shelf... slightly smaller) linked to a simple charge controller. The charge controller prevent draining at night and over charging. It also takes the raw voltage from the solar panel (17-20v) and regulates it to *just* above the current battery level. As I understand it this is the optimimum way to recharge a battery long term.

Even then this panel only just adds charge to the battery and a week in summer will add a tiny amount.

[linkman72]

Feck

Id be better off with a wind turbine where I live ( last time we saw the sun out they called the airforce out in a fit of panic )

[Sijones]

Thanks, I was hoping you'd say something like that. Next question then- do you know of a decent trickle chargers that won't cause hundreds of pounds of damage?! I don't recognise any of the brands on EBay - they all look like Dixons own make to me!!

[linkman72]

AHAA !! Straight from the owners manual

"When charging with a low current ( eg small battery charger ) the battery cables do not normally have to be disconnected"

It does go on to say you must disconnect the leads if you are fast charging though ( page 267 in the manual )

I have and still use an old Autocare 4amp charger, and the trick is with ebay if its nameless its crap ( you would put your name on a product you are proud of ) but I would probably just go to your nearest machine mart and revell in the warranty you will get.

[linkman72]

Just spotted this ( may be a better alternative to connecting up a full charger )

Ive seen a couple of similar set ups on classic cars stored over winter ( I just disconnect the battery cos there aint no electrics on me 74 manta )

http://www.frost.co.uk/automotive-elect ... aster.html

[Sijones]

Thanks mate- that looks perfect! Although you know you're never really meant to read that manual don't you?!!

[linkman72]

Its was 4am and there was feck all on TV

[Sijones]

Lol - fair enough! Beats Jeremy Kyle I guess!!