Flat Battery question

Captain_Fishy

My car has been off the road and garaged for well over a year now, as I currently do not need to use it, and its market value is low if I wished to sell, but its a good car owned from new.

It has a flat battery and so I usually every three months or so give it a jump start from another car and run it for thirty minutes or so whilst it has a wash and turn the wheels up and down our drive.

However today when I tried to do this I could not get any life from it whatsover so I checked and adjusted the jump leads tried again but same result....its as dead as a dodo!!!

My question is can a car battery get so flat that it will not accept even a jump start from another car? Does anyone have any advice for me other than buying a new battery.....which no doubt will slowly drain as my car will still not get any regualr use for the forseeable future....

thanks in advance

custardy

yes a battery will die in the end with the scenario you explain
if it isnt sealed,check the fluid levels
then if alls good,get it on a trickle charge from a battery charger
since its on the drive,i would start it more often

Hammyman

Captain_Fishy wrote: »

My question is can a car battery get so flat that it will not accept even a jump start from another car? Does anyone have any advice for me other than buying a new battery.....which no doubt will slowly drain as my car will still not get any regualr use for the forseeable future....

thanks in advance

No but what can happen is that all the power being transferred from the "jump starter" ends up going into the battery.

The best way to do it is to disconnect the earth terminal from the battery, jump start the car and then once its running, put the earth terminal back on.

Now somebody will no doubt jump in and harp on about the sparks from putting back the earth terminal causing the battery to explode due to the gases but as its as dead as a dodo, this won't happen.

FYI, unless you sit there with your foot on the accelerator holding it at 3000RPM for 30 minutes, leaving it on tickover will put barely enough charge into the battery to make it worthwhile bothering.

Also after you have "charged it", do you disconnect the earth terminal in order to stop the battery being drained by the clock etc? If not, do so.

TiTheRev

...but that will of course mean that you'll lose the radio code, the time will always be 00:00, and depending on the age/model of the car it may mess with the ECU memory. I'd just start it more often and leave the battery as is!

ziggyman99

Don't be tempted to run your engine at 3000 rpm for 30 mins without a load on it... it will f**k your engine.
Buy a new battery. It will be knackered. No need to disconnect your battery. The load caused by a clock is miniscule compared with the capacity of a car battery and the self discharge rate of 4 to 20% per month. If your battery has been left that long sulphation will have occured. You could try trickle charging but I reckon it's had it. I certainly wouldn't want to rely on it.

somech

or connect jump leads leave for 15 mins

car will then start dont be too hasty when jumping cars as you can spike the ecu

Cool_Username

I'm no mechanic but can't you buy a 'trickle charger' that keeps the battery topped up when the car isn't being used for weeks on end?

skiddlydiddly

I have a similar situation, except with a quite expensive dry cell race battery.I took it back to the place I bought it in the hope that they could breath some life back into it.They did several full charge/discharge cycles on it and it looked like it was going to come back form the dead but ultimately it wouldn't make enough voltage to crank the car and I have had to bite the bullet and order a new one(after 1 week of charge/discharge cycles).

johnnyroper

the problem is when a battery drains down it never fully recovers,if it has been flat only a short period then they can normally be charged back up although do lose some of its CCA capacity.
if it has been left a long time dead or only had minimal charge briefly over short periods then the battery will no longer accept a charge,the lead plates get a build up of sulphur on the plates.

only thing to do is replace battery and get a trickle charger to keep battery level good.

note to titherev if the battery is that dead the clock and radio code will be lost anyway,also extremely unlikely the ecu will be affected,if this was the case how do garages change batteries??

gilbert_and_sullivan

Best to buy a CTEK smart charger that you can leave connected permanently, one of these may also revitalise the old battery.
Lidl (no doubt Aldi too) sometimes have very similar smart chargers on offer at something like a third of CTEK's price, i have a CTEK and a Lidl jobbie and they both work similarly.

May be old wives take but i've heard it's worth removing the present battery and (safely) giving it a vigorous shake and gently bumping it on the ground a few times...this is supposed to loosen the sulphated crud that will have enveloped the lead cells and can give it a new lease of life, can'y do any harm anyway.

Mankysteve

don't forget to add some additive to the fuel to stop it going stagnant can't remember the name of the stuff.