Dead battery

[kelvo]

Originally Posted by Terryf

Due to my age and covid my car has only had 3 very short trips since early March.
I do have a solar charger on my garage roof which normally keeps everything charged up without problems.
However I went to the car yesterday as I had a doctors appointment and all I got was the dreaded headlight flash. I made two checks, solar charger output voltage 14.7volts and battery voltage 10.1 volts and that was on a dull overcast day.
Is the absence of runs likely to cause the problem even though a regular charge was available or do batteries sometimes just give up for no apparent reason.
Just curious, new battery to be fitted on Friday.
Terry

yes, modern batteries do have a tendency to just suddenly fail. I've had it twice, funnily enough both with my MGs. In one case, only left the car a couple of hours, went out, turned the key and all sorts of flashing lights going on. Couldn't even jump start the car as it dragged the jumper car down as well.

2nd time it had been in the station car park whilst I been at work, came home and exactly the same. Cue a walk home to pick up my other car to drive to Halfords to get another battery to fit.

[FrattonEnder]

Originally Posted by macafee2

aldi and lidil chargers are cheap as chips but seem to work well except of a very flat battery. If very flat then an old fashioned charger is needed to start the charging process and then swop.

macafee2

I've got a Lidl smart charger and it managed to fully charge both my 'steamroller flat' Bosch but also my original Hankook which I thought was well past it. Only hadn't binned it because of travel restrictions.



If you leave the charger connected and switched on for around 12 hours plus, then disconnect and leave the battery for about a day and reconnect, you can fool them into thinking it's a motorcycle battery and then a car battery.


Bit of a faff, I admit, but it's saved me forking out on new batteries and both now seem to be fighting fit and fully charged. No drop off in charge after about 6 weeks of storage on the Bosch and the original Hankook is firing up the ZT diesel on the button every time I use her.

[COLVERT]

Originally Posted by FrattonEnder

I've got a Lidl smart charger and it managed to fully charge both my 'steamroller flat' Bosch but also my original Hankook which I thought was well past it. Only hadn't binned it because of travel restrictions.



If you leave the charger connected and switched on for around 12 hours plus, then disconnect and leave the battery for about a day and reconnect, you can fool them into thinking it's a motorcycle battery and then a car battery.


Bit of a faff, I admit, but it's saved me forking out on new batteries and both now seem to be fighting fit and fully charged. No drop off in charge after about 6 weeks of storage on the Bosch and the original Hankook is firing up the ZT diesel on the button every time I use her.

Interesting post.

Part one.--If the plates in a battery are sound and not HARD SULPHATED up the battery will take a charge.

Part two.--The only difference between a motorcycle battery and a car battery is the capacity.

Part three.--There's very little way a private person can tell if a battery is fully charged or not. ( Voltage is not the answer )
The best way---the specific gravity of the sulphuric acid content or second, a garage Drop-Tester.

Part four.--All batteries in storage will lose capacity until they become completely discharged.--Standing for over six months or so will require the battery to have urgent attention.

PS. A 1/4 charged battery will start an engine in the same way a 3/4 charged battery will.---This is not a way to assess the condition of a batteries charge.

[SD1too]

Originally Posted by kelvo

yes, modern batteries do have a tendency to just suddenly fail.

Hi Kelvin,

Your experiences are quite common but it's not a sudden, unexplained failure of your battery. The likely explanation is that the battery's level of charge has been slowly but consistently reducing over a long period. The owner won't notice this, so long as it operates the starter motor they're happy.

Before the advent of electronics and computer software we would get early warning of a battery in need of external charging as the starter motor slowed down. That doesn't happen any more. One day it spins merrily, the next day we get the flashing headlights and nothing. Oh, the battery has suddenly failed we might think, but no. It's been failing for weeks and months but we have had no way of knowing.

There is a solution to this. If you don't make regular journeys of, say 30 miles at cruising speed, then periodically connect your smart charger. If it shows 100% charge within an hour then you're doing well. If it's still charging after half a day then it needed it!

Simon

[kelvo]

Originally Posted by SD1too

Hi Kelvin,

Your experiences are quite common but it's not a sudden, unexplained failure of your battery. The likely explanation is that the battery's level of charge has been slowly but consistently reducing over a long period. The owner won't notice this, so long as it operates the starter motor they're happy.

Before the advent of electronics and computer software we would get early warning of a battery in need of external charging as the starter motor slowed down. That doesn't happen any more. One day it spins merrily, the next day we get the flashing headlights and nothing. Oh, the battery has suddenly failed we might think, but no. It's been failing for weeks and months but we have had no way of knowing.

There is a solution to this. If you don't make regular journeys of, say 30 miles at cruising speed, then periodically connect your smart charger. If it shows 100% charge within an hour then you're doing well. If it's still charging after half a day then it needed it!

Simon

Possible I suppose, in the first instance the car was perfectly normal 2 hours beforehand. Odd in the 30 odd years that I have had cars and been driving, the only two times it has happened to me is with my ZTs

[bl52krz]

Batteries can ‘go down’ in minutes. Had that happen many years ago with a Ford Thames van I had. Only left it for around ten minutes and came out of my mothers and it was flat, nothing, not even a glimmer.

[Terryf]

Thanks for all the interest, I was correct battery kaput.
With regard to trickle chargers, I do have one. Unfortunately to use it means trailing a mains lead across my neighbour's back gate, so can only use in daylight.
Another thing I have just realised, I have a power pack (think that's what it is called) to start the car if battery flat. Problem is my car just fits my garage and is positioned in top left corner. So I have no chance of using the power pack.
Must get my old brain in gear and devise a solution. Like running a good thick cable through to the boot or something like that.
Terry

[SD1too]

Originally Posted by kelvo

Odd in the 30 odd years that I have had cars and been driving, the only two times it has happened to me is with my ZTs

Same with me Kelvin! I have a second modern car with multiplex electronics but only with the 75 have I experienced the unexpected flat battery syndrome. However I recently investigated in some detail the current drawn whilst the 75's software was "asleep" and I believe this could be the reason. One precaution that I take at this time of year is immediately to cancel the automatic operation of the heated rear window unless it's really needed.

Simon

[bendrick]

Originally Posted by SD1too

Same with me Kelvin! I have a second modern car with multiplex electronics but only with the 75 have I experienced the unexpected flat battery syndrome. However I recently investigated in some detail the current drawn whilst the 75's software was "asleep" and I believe this could be the reason. One precaution that I take at this time of year is immediately to cancel the automatic operation of the heated rear window unless it's really needed.

Simon

Me too, only twice have I had a battery pack up overnight revealing that they were U/S after testing by mechanics, one on each of the 75s that I've owned.

In the old days as mentioned above one way of knowing that your battery wasn't up to scratch charge or general condition wise was the increasingly slow turn over of the starter motor/ engine now if the voltage drops just slightly there's nothing but a click and no starting.

[COLVERT]

There are two ways that a cell in a battery can fail quite quickly.

1/ Almost instantaneously is when the lead plates in a cell become detached at the tag that links the cells together.
Plates are roughly rectangular with a tag at one of the corners. According to the batteries rated capacity the number of plates in a cell varies, from about 5 to 9 for cars.
When the block of plates is placed in one of the 6 compartments in the case the tags stick upwards in a row.
The positive plate tags to one side and the negative tags to the other
A lead link is melted on to the tags fusing them all together. ( pos to pos, Neg to neg. )

These links are then joined together so that the total voltage along the length of the battery is approximately 12.6 volts.
( Each cell being close to 2.1 volts.--Six cells. )


2/ The second way a cell can die is when, due to vibration over several years of use on the car, some of the paste from the plate grid falls to the bottom of the cell and causes a short circuit across the negative and positive plates, rendering them useless.
If checked with a volt meter the reading across the battery will show around 10 volts.