Battery charging question

[bobins]

Is it OK to charge a car battery in-situ with all the +/- cables still attached to the car or will only bad things happen and it should only be done either disconnected from the car or preferably on the workbench ? I'm thinking specifically of my C5 X7 here - with the ignition off...... obviously !

[dnsey]

I'd say it depends on your charger.
I wouldn't risk an old-fashioned basic unregulated one on a connected battery, still less a fast boost job, but a modern regulated one should be OK.
Personally, I use a modified 15V laptop charger, which has caused no harm so far

[Richard_C]

I was wondering the same thing. My X7 is occasionally left in the garage for 2 or 3 weeks and can be sluggish to start after that. I guess the alarm and a few other things take a little current. As the load space 12v socket (its a tourer) is 'always on' and not via the ignition I had though of connecting my 12v 800mA lawnmower battery charger via a time switch to give it a few amp-hours a day but I too worry about damaging things. I can't imagine it being any more damaging that the fluctuating voltage you get when you start the car but things are so much more complicated these days.

[xf1ref]

Usually a battery charger voltage is over 15v. If you want to charge the battery but without disconnecting the leads you should use a regulated charger with max 14.4 output voltage. Is better for car equipment (alarm, clock, ecu) which in stand-by use some energy to be supplied with the same voltage like engine is running ( between 14 - 14.4v).

[sparksie]

Hi
Yes, the charger will be the deciding factor.
If it's a so called "intelligetnt" charger, you can charge while still connected, as this is what they're designed for.
One point to watch out for, though, is the desulphate function a lot of chargers have. Make absolutely certain this does NOT run while that car is connected. It uses pulses of high voltage (perhaps as high as 80V!) to blast the sulphates off the plates in the battery. ECUs will not like that!
LiDL had one in their weekly specials recently, for 20 euro, or roughly UK£16.
There are lots of them about, with prices starting around £20 and rising to £600 or more, though the more expensive ones are aimed at the marine, or camper van market, where multiple battery banks of differing sizes are the norm.
For cars, as stated by another poster, you want the max boost voltage to be 14.4V. Any higher and you'll lose water from the cells at an unacceptable rate.
Most of the bigger intelligent chargers offer 14.8 and 15.1 for very specific duties, so make sure you choose 14.4 when setting up one of these.
At the other end of the sophistication scale, Draper used to offer a "battery saver", which was (is?) just a small transformer and rectifier that reaches 14.5V, open circuit, and can deliver about 2Amps if faced with a discharged battery. This is not intended as a charger. It's meant to run the electrical loads of the car, allowing the battery to remain charged over long periods.

[Bandit12]

Try one of these. Bit pricey but they are very good.

My mate ran a motorcycle training school and all the bikes were hooked up to one overnight. you can leave the leads permenantly attached to the battery and just plug in the plastic connector.

http://www.ebay.co.uk/itm/Optimate-4-Ba ... 1279693937" onclick="window.open(this.href);return false;

[Rhothgar]

Optimates are mint!

Well worth the money.

[KP]

If your thinking of a charger then dont bother with others, just go straight for a CTEK.

I can not rate them highly enough even bringing some batteries that looked and tested as dead back to life after a few reconditions.

I have an MXS 5 that sits in the back of my range rover charging it all the time until i get it running again, and even then i have rigged up a towsocket adapter so i can plug it into that at night and then drive off in the morning without ripping the lot to shreds It gives enough information back to show you what it and the battery are upto and they come in sizes all the way upto 30amps IIRC which are used by the diagnostic types when flashing ecu's so as to ensure the batteries dont drain.