Is this battery FUBAR
Discussion
Been suffering with flat battery problems (had an earlier thread about it) the battery has run down 3-4 times but the garage thought they identified and fixed the parasitic drain as they followed the standard procedure & tested the draw as OK once fixed, however after this it did go flat once again - I was wondering if going so flat 3 times had ruined the new battery's ability to hold charge
So to test I fully charged the battery by putting it on conditioner for 48 hours and then driving it for 30 mins
I then disconnected my battery on Tuesday lunch time after fully charging it
Before I disconnected it I put the lights on for a few mins to get rid of any surface charge
I measured the voltage after removing surface charge it was: 12.98v
Today 3 days later it is 12.76v a drop of 0.22v
At that rate it would drop a volt in 12 days & be flat
Is it fair with that drop to assume the battery needs replacing? Or is it normal to discharge a little like this?
(It is a huge effort in my car to change battery so am more reluctant to do it than if it was drop in replacement)
So to test I fully charged the battery by putting it on conditioner for 48 hours and then driving it for 30 mins
I then disconnected my battery on Tuesday lunch time after fully charging it
Before I disconnected it I put the lights on for a few mins to get rid of any surface charge
I measured the voltage after removing surface charge it was: 12.98v
Today 3 days later it is 12.76v a drop of 0.22v
At that rate it would drop a volt in 12 days & be flat
Is it fair with that drop to assume the battery needs replacing? Or is it normal to discharge a little like this?
(It is a huge effort in my car to change battery so am more reluctant to do it than if it was drop in replacement)
12.4 is real minimum a battery should sit at, after charging and standing.
12.5 is real world average of most batteries (not new).
12.6 is ideal, and technically fully charged.
Above that is unusual and sounds like it is holding charge. It will lose charge down to a fixed point after any charging. Its tgat point, and how long it holds it that is important.
Why not get the battery load tested for a full test and opinion?
12.5 is real world average of most batteries (not new).
12.6 is ideal, and technically fully charged.
Above that is unusual and sounds like it is holding charge. It will lose charge down to a fixed point after any charging. Its tgat point, and how long it holds it that is important.
Why not get the battery load tested for a full test and opinion?
Deep discharging a lead-acid battery reduces its ability to take and hold a charge and its ability to output current. It does not cause a current drain but means that it has a lower capacity so it will discharge sooner for a given drain.
The voltage measurements you've taken don't show any problem. The battery should normally settle at about 12.6V if it is charged to capacity. If you see a reading above that, it suggests the battery hasn't settled yet. If it settles to a value below 12.6V after being fully charged (not taking a charge), it is faulty and needs replacing. If the voltage drops excessively when a load is applied (excessive internal resistance), it is faulty and needs replacing. If the voltage drops quicker than expected (reduced capacity) when a load is sustained, it is faulty and needs replacing.
You should check the charging system is working correctly and there isn't an excessive residual load before fitting a new battery. I think you have already checked the residual load.
The voltage measurements you've taken don't show any problem. The battery should normally settle at about 12.6V if it is charged to capacity. If you see a reading above that, it suggests the battery hasn't settled yet. If it settles to a value below 12.6V after being fully charged (not taking a charge), it is faulty and needs replacing. If the voltage drops excessively when a load is applied (excessive internal resistance), it is faulty and needs replacing. If the voltage drops quicker than expected (reduced capacity) when a load is sustained, it is faulty and needs replacing.
You should check the charging system is working correctly and there isn't an excessive residual load before fitting a new battery. I think you have already checked the residual load.
Edited by GreenV8S on Friday 8th March 22:09
Is it car you use every day or a weekend car? If you use it every day, it should be fine, given that the garage have identified and stopped the drain.
Your original post makes it difficult to appreciate the timescales involved. It may be helpful for more knowledgeable posters than me if you could say when the repairs were carried out and how long it was before the battery lost its charge again.
Your original post makes it difficult to appreciate the timescales involved. It may be helpful for more knowledgeable posters than me if you could say when the repairs were carried out and how long it was before the battery lost its charge again.
sunbeam alpine said:
Is it car you use every day or a weekend car? If you use it every day, it should be fine, given that the garage have identified and stopped the drain.
Your original post makes it difficult to appreciate the timescales involved. It may be helpful for more knowledgeable posters than me if you could say when the repairs were carried out and how long it was before the battery lost its charge again.
It's not a weekend car per se but it doesn't get daily use - I take one long drive a week (return trip of 50 miles each way roughly) and a few smaller tripsYour original post makes it difficult to appreciate the timescales involved. It may be helpful for more knowledgeable posters than me if you could say when the repairs were carried out and how long it was before the battery lost its charge again.
Has been mainly fine but if left for a week or longer the battery drains
Garage traced it to a dashcam that I had installed on a piggy back fuse that they said was causing the canbus to keep waking. So they gave it it's own circuit. Took the car home but a week later it was dead again.
I jump started it, took a long drive 40 mins+ and then unplugged all the stuff I installed, phone cradle etc.
Went on holiday for 8 days, came back and it's dead again.
Have just charged it up using a new conditioner, then disconnected the battery completely and it went from 12.98v, to 12.76v over 72 hours disconnected from the car. I've just reconnected it back to the car and it's immediately dropped to 12.5v and held that for 3 hours, will retest tomorrow
Just want to get it sorted really. I believe the garage identified and fixed the issue as they said they did a standby current draw test and it was well within acceptable limits
It's booked in for Tuesday
That doesn't seem normal. I've only one suggestion - based on what you've now posted - and that is to check your alternator is charging properly.
I had this with a classic Mini Cooper - the alternator produced just about enough charge to ensure that the charge light didn't come on!
The voltage drop over 72 hours seems to me (as a complete layman) acceptable.
ETA: On re-reading your post it would seem that there could still be some drain on the car electrics.
I had this with a classic Mini Cooper - the alternator produced just about enough charge to ensure that the charge light didn't come on!
The voltage drop over 72 hours seems to me (as a complete layman) acceptable.
ETA: On re-reading your post it would seem that there could still be some drain on the car electrics.
Got an update on this
Garage have done another parasitic drain test and identified the culprit. My aftermarket exhaust causes a current drain if I leave it in the valves closed position when parked. Obviously it closes something to the ground. If I leave it in ‘loud’ mode it doesn’t drain the battery.
Pretty hopeful that this has solved it
As I always put it in ‘quiet’ when I am near my house that explains why it drains at home. As I have it in ‘loud’ for the underground car park at work (it’s a bit of fun and I get there so early no one is about) that explains why it doesn’t drop at work
I’m keeping my fingers crossed now that this is solved! Thanks for all the comments
Garage have done another parasitic drain test and identified the culprit. My aftermarket exhaust causes a current drain if I leave it in the valves closed position when parked. Obviously it closes something to the ground. If I leave it in ‘loud’ mode it doesn’t drain the battery.
Pretty hopeful that this has solved it
As I always put it in ‘quiet’ when I am near my house that explains why it drains at home. As I have it in ‘loud’ for the underground car park at work (it’s a bit of fun and I get there so early no one is about) that explains why it doesn’t drop at work
I’m keeping my fingers crossed now that this is solved! Thanks for all the comments
Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff