Idle car to charge battery - 2012 xkr

[PH XKR]

Guys

taking the XK over to Belgium for a few weeks, during which time it may sit idle for a while. Unfortunately there is no option to trickle charge where it will be stored but I wondered if running it once in a while with no systems on, would that be enough to keep the battery charged?

[8bit]

Can you disconnect the battery if it's going to be stood for a while?

[PH XKR]

8bit said:

Can you disconnect the battery if it's going to be stood for a while?

Sadly not, its a convertible so your screwed with access issues (ie manual roof lift/reset) if you disconnect - perhaps a kill circuit switch could be an option

[8bit]

Ah ok, does that require some sort of reset procedure once you reconnect the battery, like the window one-touch reset?

I'd say if you could take it like a ten mile or so run once a week you ought to be safe enough providing the battery is in good condition.

[New Relic]

I was told that you'd never bring the 90 amp battery up to charge, even on a long, long run - and it would only reach a full charge on an battery tender.
So, a ten-mile jolly would be somewhat pointless?

What would be better is to have a battery in tiptop condition, before you leave/store the car.

Failing that, and if you're unable to trickle change (for whatever reason) then I'd be stuffing a second, charged battery inside the vehicle for an emergency.

[Dave.]

Solar charger no good?

[jimattfield]

PH XKR said:

Guys

taking the XK over to Belgium for a few weeks, during which time it may sit idle for a while. Unfortunately there is no option to trickle charge where it will be stored but I wondered if running it once in a while with no systems on, would that be enough to keep the battery charged?

Nope, the energy you'd take out to start the car to idle it would be unlikely to be recouped in the idling. My XK8 will sit for four or five weeks and still start, my XK will certainly sit for two/three weeks and still start (so you'll likely be OK assuming no unidentified parasitic drain e.g. Bluetooth adapters, trackers, etc.) but if you are really worried then top the battery on a decent charger (e.g. C-Tek) before you go and if you think you will have real problems if it doesn't start get a cheap battery and jump leads or an emergency portable battery - it only has to assist the main battery once after all so doesn't need to be anything exotic.

[8bit]

New Relic said:

I was told that you'd never bring the 90 amp battery up to charge, even on a long, long run - and it would only reach a full charge on an battery tender.
So, a ten-mile jolly would be somewhat pointless?

Doesn't need to be brought back to full charge, just enough to comfortably start the car. Might not even need that, a good quality battery in decent condition should stand for a few weeks OK providing there's nothing causing parasitic drain.

[New Relic]

8bit said:

Doesn't need to be brought back to full charge, just enough to comfortably start the car. Might not even need that, a good quality battery in decent condition should stand for a few weeks OK providing there's nothing causing parasitic drain.

Without any wish of appearing pedantic, jimattfield's post sums-up my understanding and he says it rather more eloquently than I put it.

Any doubt, and the sacrificial spare battery would also be a great help.

[8bit]

New Relic said:

Without any wish of appearing pedantic, jimattfield's post sums-up my understanding and he says it rather more eloquently than I put it.

Any doubt, and the sacrificial spare battery would also be a great help.

Sure, but I wasn't talking about starting the car and letting it sit idle, the engine will need to spin up a bit to generate enough power to cover the losses incurred in starting it, any drain placed by systems that require permanent power and then generate enough to add some charge. A ten or so mile run every week or so *should* be enough for that I'd have thought, at least barring any unknown drain on the battery and assuming it is in good condition.

An AGM type battery might not be the worst idea as they reportedly hold charge better than regular ones. Then if the OP desires, the old one could be charged up and taken on the trip to provide a backup if necessary.

[Dave.]

I wouldn't want a loose battery anywhere in the cabin in case of a rollover etc...

What about one of those li-ion jump starters?

Would probably be more useful in the future too, as opposed to having a spare car battery lying around.

[PH XKR]

The battery was replaced last year, the jag does seem to like to drink from the battery if it isn't used. The car is a private underground car park so no option for solar chargers etc (though I like the sound of them!).

I'll just take it for the occasional motorway charge up once a week to be on the safe side, jump leads are in the boot too