Battery Life When Laid-up

[chumley]

Due to circumstances beyond my control (!) my Chim 500 has been laid up for 2 weeks and is likely to be unused for another 6-8.

I've heard of batteries going flat and am wondering whether it is likely to last this long or whether I should arrange for someone to take it for a run every week to keep it charged up.

[Steve_T]

It won't last that long. I'd say two weeks and then you need to top it up, ideally every week. An Optimate charger is ideal for this. Worth getting the engine started every week or so too, to prevent the oil from draining from it. Worth rolling the car every now and then to avoid flat spots on the tyres.

Steve.

[Incorrigible]

It "should" be OK for as long as a couple of months but, as you've heard, mysterious current drains can and do happen

Mine draws about 0.1-0.2 amps when it's all switched off that's about 5,000 hours to completely flatten the battery

Optimate cheaper and much less of a pain than a new battery though

[nc3]

Purely from an 'electrics' perspective you shouldn't regularly let the battery discharge so it will 'only just' start the engine, or worse, it damages the chemistry inside the battery and will shorten its life or let you down! If it is fully charged, you could disconnect the battery for the 6-8 weeks, but you'd do better to fit a 'trickle' charger to keep it topped up. You can get these almost anywhere, I use a Halfords charger that is an actual charger, that switches to trickle mode when the battery is fully charged. Remember that if you disconnect the battery, or let it go flat the engine will run lumpy for a while while it re-calibrates itself.

[kojak69]

My cerbera is laid up waiting for a clutch.
Just bought a Leven battery charger/conditioner for £45. It charges then keeps it topped up.

[chumley]

Cheers folks. I decided to add my dad onto the insurance so he can give it a spin once every couple of weeks whilst I’m laid up. He wasn't looking forward to it and I think it's the first time I've actually seen him genuinely nervous!

Anyway, it started first time after being sat for two and a half weeks and ran perfectly (apart from him stalling it at the bottom of the road!). After a few tentative miles (during which he remained near-silent apart from the odd "jeesus!" and "not bad this") he was soon enjoying himself. We ended up having a nice blast into North Yorks and by the end of the run he'd offered to take it for a spin back home once a week to give it a clean until I get back on two feet - and this from a man known to have a severe phobia of cleaning cars!

He took it out again at the weekend and we're off out again tonight. The rate we’re going he’ll be “just giving it a quick spin” every other day - I can’t wait to get behind the wheel again but reckon I’m gonna have to wrestle him for the keys now!

[Nickccc]

I took mine back to the dealer as it would constantly go flat even over night. After talking to one of the mechanics I now know that if the door is not completly closed shut (whilst in locked garage) then the relay for the rear light still pulls a current, even when interior light is off. Anyway doors closed batery full and not discharging. Hope this helps.

[malloryn]

Just a point -

What do the battery suppliers / autofactors do if the batteries discharge so quick. They must have them on the shelves for weeks.
Even places like Halfords must have less popular batteries sitting on their shelves for more than a couple of weeks.

Makes you think, what sort of condition a new battery is in when you buy it.

[K4TRV]

malloryn said:

Just a point - What do the battery suppliers / autofactors do if the batteries discharge so quick. They must have them on the shelves for weeks. Even places like Halfords must have less popular batteries sitting on their shelves for more than a couple of weeks. Makes you think, what sort of condition a new battery is in when you buy it.

Batteries at Garages/Shops are stored charged, but DRY from suppliers. Believe they have long sleve life in that condition and why, when you add acid, you need to do a full cycle of charge before proper use. The battery life, once acid is added, it is the long slope to Sulphation and death !! ;-))

Trev McM

[the dodger]

Couple of thing of noteworthiness. First, something I know from old and that is that car batteries are supplied to the motor factors dry-charged. They have extremely long shelf-life in this condition. The factors add the correct electrolyte mix and put them on display. For Months!. Secondly, something I've learned recently. We then buy them, put them in a TVR and they're flat in two weeks. I can also confirm that by not closing the doors fully on the battery will be flat in about a week. Totally flat. I know.