Will disconnecting the battery save charge?

Will disconnecting the battery save charge?

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Discussion

ab5

Original Poster:

17 posts

70 months

Sunday 29th September 2019
quotequote all
Hi,
I haven't been using my car for a while and it is currently SORNed and on my drive but will soon need to move it somewhere else for a bit. Unsurprisingly I keep needing to charge the battery and as its been standing quite a long time now it needs charging quite often and I'm worried about the hassle of it not starting when it's further from home. I read that if you leave the battery disconnected it conserves the batterys charge, if I fully charged it before moving it and then disconnected it would it be likely to restart again if I did this?
Thanks smile

pozi

1,723 posts

194 months

Sunday 29th September 2019
quotequote all
It depends on if your battery is already knackered? Disconnecting it will stop any residual drain from alarms etc will but a battery will still self discharge and this only gets worse with age.

Andy 308GTB

2,963 posts

228 months

Sunday 29th September 2019
quotequote all
My car sits in the garage Oct/November right through to the Spring - I have a battery isolator switch and I disconnect the battery for the whole period. I've never had a problem (other than when I had a knackered battery per the previous poster)

ab5

Original Poster:

17 posts

70 months

Sunday 29th September 2019
quotequote all
Thanks for the replies, it is a pretty old battery but I'll try disconnecting it anyway and hope it's a bit better smile

Leveret

167 posts

165 months

Sunday 29th September 2019
quotequote all
I don't see why a battery will self-discharge more when it gets older. Although my TR7 is 'on the road' all the year round, in winter it's sometimes unused for a few weeks. I disconnect the positive terminal every time I use it. Never needs a spanner, a push and twist fit is good enough. The battery is over twelve years old, so I think it's a good idea to do this if a car is not used often.

GreenV8S

30,487 posts

291 months

Monday 30th September 2019
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Leveret said:
I don't see why a battery will self-discharge more when it gets older.
I suppose the older the battery is the more chances there were for the electrolyte to be contaminated. But failing that, the issues are more likely to be sulfation or plate distortion. Neither of those show up as self discharge.

tapkaJohnD

1,993 posts

211 months

Monday 30th September 2019
quotequote all
The Battery University estimates a lead acid battery will self discharge 5%/month a rate that as with all batteries increase with age and ambient temperature.
See: https://batteryuniversity.com/learn/article/elevat...

The OP might consider a battery reconditioning or "smart" charger.
John

ab5

Original Poster:

17 posts

70 months

Monday 30th September 2019
quotequote all
I've now put the newly charged battery in the car ready to move it and nothing's happening! I charged the battery up ready to move the car off my drive but when I replaced it and reconnected the negative terminal (after connecting the positive one) instead of the usual click when the door lock system switches on it sparked instead, and then when I turned the key to start the engine the dash lights came on for a split second and then absolutely nothing happened, it just went completely dead. The battery must have been working though as the electric door locking was still working, does anyone have any ideas about what might have happened?? I looked it up and it said it might be the ignition switch or starter motor, I'm not sure if I'm keeping the car to drive or not so don't want to take it to a garage without having some ideas of what the repairs would cost, or might it be something I can sort out myself?

GreenV8S

30,487 posts

291 months

Monday 30th September 2019
quotequote all
Double check the battery voltage at the connectors (not the battery posts) to make sure the battery is healthy and you have two good connections.

Have you disconnected the battery before? Sometimes you need to do things to reassure the alarm after everything has been powered down.

ab5

Original Poster:

17 posts

70 months

Tuesday 1st October 2019
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GreenV8S said:
Double check the battery voltage at the connectors (not the battery posts) to make sure the battery is healthy and you have two good connections.

Have you disconnected the battery before? Sometimes you need to do things to reassure the alarm after everything has been powered down.
I don't have anything to check the voltage but tried the headlights this morning which didn't work, then when I went to lock the car the locking system has stopped working as well, so I think I might just have to get a new battery, I'd charged it for 9-10 hours so think it should have been fully charged

GreenV8S

30,487 posts

291 months

Tuesday 1st October 2019
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ab5 said:
I'd charged it for 9-10 hours so think it should have been fully charged
All the symptoms suggest the opposite. Maybe the battery is dead or your charger isn't working.

A volt meter would make it easy for you you to find out what's actually happening.