Battery Stamina - How long without use?

[SD1too]

Originally Posted by Randyjim

My ZT190 was left stood for about 3 weeks recently and when I came back to it the battery was flat.

It needs charging Jim. Car batteries like to be fully charged at all times and few are. Buy a smart maintenance charger (I recommend the C-tek range) to ensure that it is and do so immediately. If you leave it in a semi discharged state the chances of terminal failure increase as time passes.

Its normally used as my daily ...

Think about how it's used daily:

• Do you travel short distances frequently, i.e. lots of starter motor use?
• Do you start the engine just to move it on and off a drive?
• Below 10 degrees ambient temperature, do you cancel the automatic heated rear window timer as soon as it activates if not needed?

The above will contribute to any battery's level of charge steadily decreasing until one day .....

To answer your original question clearly, a fully charged battery will last three weeks.

Simon

[Rp61973]

After 3 days standing last week due to illness (off work). The battery could only make the starter motor click and the indicators flash a dark amber. The car had been cranking slowly for some time, so the battery (at least 5 years old) was on borrowed time.

A nice new Varta ordered from Tayna last week and she now starts nice and swiftly.

[bigd]

from flat battery to jump leads and then 450 mile drive AND after 10 days of standing its dead again ,recharged and battery checked voltage standing 12.4 volts ,charging at 14,4 volts battery drop test ok satnav lights and boot light going off too when ignition off

Has anybody got any clues before I pull things apart

[HarryM1BYT]

Originally Posted by bigd

from flat battery to jump leads and then 450 mile drive AND after 10 days of standing its dead again ,recharged and battery checked voltage standing 12.4 volts ,charging at 14,4 volts battery drop test ok satnav lights and boot light going off too when ignition off

Has anybody got any clues before I pull things apart

You need to check to see what the discharge rate is, when the car is parked up and after being stood around 15 minutes. Those voltages are meaningless unless you state how you have measured them, the dash reading will always be low, because of volts drop.



10 days suggests either a dud battery which is not holding its charge, or an excessive discharge whilst it is parked.

[bigd]

Ok I will check again tomorrow cheers Derek

[tourer]

Originally Posted by bigd

from flat battery to jump leads and then 450 mile drive AND after 10 days of standing its dead again ,recharged and battery checked voltage standing 12.4 volts ,charging at 14,4 volts battery drop test ok satnav lights and boot light going off too when ignition off

Has anybody got any clues before I pull things apart

You didn't mention charging the battery after the 450 mile run and before standing for 10 days.
I have been led to believe in the last couple of years that an alternator will not fully charge a flat battery no matter how long it's run for, it will only maintain the level of charge.
I am hoping the gurus on here will put me right if I am wrong, as it contradicts my previous assumption.
Thanks.

[bigd]

Ok guys the battery was fully charged the other day and I have now checked the voltage it is still the same as previuos said and also the currant drain has been checked by removing negative lead from battery and the meter coupled between battery lead and negative terminal post on battery resulting in the following reading 2.85 then after around 30 seconds or so it falls to 0,01 which is no drain ,

So now I am going to moniter battery voltage for a week and see how much it falls

unless anyone has other ideas

[HarryM1BYT]

Originally Posted by tourer

You didn't mention charging the battery after the 450 mile run and before standing for 10 days.
I have been led to believe in the last couple of years that an alternator will not fully charge a flat battery no matter how long it's run for, it will only maintain the level of charge.
I am hoping the gurus on here will put me right if I am wrong, as it contradicts my previous assumption.
Thanks.

A car alternator should be able to fully charge a battery and certainly a 450 mile run should leave a battery in a fully charged condition. A short run of a few miles is not an effective way of charging a flat battery, except when there is no better way. 24 hours on a charger should recharge most batteries up to full capacity.

[HarryM1BYT]

Originally Posted by bigd

Ok guys the battery was fully charged the other day and I have now checked the voltage it is still the same as previuos said and also the currant drain has been checked by removing negative lead from battery and the meter coupled between battery lead and negative terminal post on battery resulting in the following reading 2.85 then after around 30 seconds or so it falls to 0,01 which is no drain ,

So now I am going to moniter battery voltage for a week and see how much it falls

unless anyone has other ideas

The 0.010 is a nonsense reading - you cannot rely on a reading being sufficiently accurate at such a poor meter resolution. It does though suggest 10mA which is promising, but surprisingly low - I would expect somewhere between 20 and 60mA depending on the cars spec.



All modern cars, including the 75 draw some current when parked and locked, to backup their systems - radios, satnavs, ECU's and alarm systems all draw some current. So four to six weeks unused, means the 75's battery will be seriously discharged.

[COLVERT]

Originally Posted by tourer

You didn't mention charging the battery after the 450 mile run and before standing for 10 days.
I have been led to believe in the last couple of years that an alternator will not fully charge a flat battery no matter how long it's run for, it will only maintain the level of charge.
I am hoping the gurus on here will put me right if I am wrong, as it contradicts my previous assumption.
Thanks.

You won't charge a flat battery on a 450 mile run.

Lets say you averaged 50 mph on that run. This would mean that the best you could hope for is 9 hours on charge.
( 450 divided by 50. )

The regulator in the alternator would limit the charge going into your battery at about 5 amps. ( about the same as your average charger. )

You need at LEAST 24 hours on a charger to get your battery anywhere near fully charged. So your 9 hours running would just not cut it.