Battery charging from portable booster, possible?

[dougt]

Hi,

my car doesn't get used as often as I'd like. Sometimes in the winter it will only just start because the battery is getting towards flat from lack of use. The problem I have it that my parking space is in an underground carpark and there's no power.

The car is full of electronics (it's a CLK55 AMG) so I don't want to fit an isolator switch as I think it would cause all sorts of mayhem.

So I was wondering if I got one of those portable booster packs and connected it to the car battery once a week would it charge it up enough to solve the problem?

Thanks for any advice

Doug

[HiRich]

If you mean one of the starter packs (which I think you do), then the answer is almost certainly no. The battery is actually very small, so a long drain will draw it down very quickly.
No power, no sunlight, and you're running out of options, other than the "use it more often".

The only route I can think of is a huge car/truck battery on a trolley. At it's most basic, a couple of jump leads off this slave, under the bonnet and attached to the car's battery. This could double or treble the storage capacity of the system, and you could haul it back to the house for a recharge every few weeks.
Variations on that theme might be:
- Dress up the trolley so you can lock it down.
- Put the slave battery in the passenger footwell, rig up a flylead to the cigar lighter (check it works with the ignition off). It's probably not a good idea to start the car with the slave in situ, just in case the current draw peaks a bit too high.
I'd go with this last option. You've got security of the car, you've got something you can take away and charge.

Another thought may be a bad earth or dodgy connection in the car, drawing too much power when the car's switched off (badly installed ICE is a common culprit). If drain is around 2 weeks or less, this is likely, more than 4 weeks and it's unlikely.
Procedure for checking is:
- Access to fuses
- Multimeter, set on voltage
- Mate holding multimeter to battery terminals
- Pull each fuse in turn. If the multimter jumps more than a fraction of a volt, look for something dodgy on that circuit.

[leorest]

If the battery has been discharged completely it is almost certainly (and I'm being polite here!) beyond it's best.
Once you're sure there are no electrical gremlins then buy a new battery and get the highest capacity one that will physically fit. I promise you, you will be amazed at how long you can leave it between runs.

When you do run it after a layup period, make sure you do so for long enough to ensure the battery has fully charged. Half an hour should do if you don't need lights wipers etc.

If you can get access to a mains outlet briefly when you come to start up, a good insurance policy is a 50m extension lead and a starter/charger. These boost charge for 10 minutes prior to assisting the flaccid battery for starting. This trick has got me to work on time on numerous occasions!

You could get really sophisticated with a dual battery setup with split charging where the primary battery is only used for starting and the secondary one for powering the fancy ancillaries... but IMHO one big heavy duty behemoth of a battery will work just fine.

It's obviously better for the battery and car to be run more regularly.
HTH

[GreenV8S]

You could always stick a second battery in the boot, leave it isolated while the car is parked up, connect it up via jump leads when you want to start the car. You can then trickle charge it from the car while it's running, or take it out and charge it from the mains.

[dougt]

Thanks everyone for the helpful suggestions, much appreciated

[K13 WJD]

my bosses 66 amg got left for almost 2 months.......started on the third turn !!!