How long should battery hold a charge ?

Mogodon · 16th November 2023, 16:14

I've been unable to drive for for 3½ weeks due to a retinal tear in my left eye meaning the Zed has sat untouched on the drive for the same amount of time.

Can now drive again 🥳, went to start the Zed and not enough battery to start, just a click and headlamps came on. Charged battery for 4hrs and away she went as normal.

Battery is a mid range Hyundai fitted January 2020.

Should a battery still be able to start a car after sitting idle for nearly a month ????,

macafee2 · 16th November 2023, 17:10

yes.
It may not have enough puff because it is faulty or because there is a drain on it. Even in a UK winter I'd expect it to still start a car.

macafee2

MSS · 16th November 2023, 17:57

Quote:

Originally Posted by Mogodon

Should a battery still be able to start a car after sitting idle for nearly a month ????,

A major factor is how much energy was stored in the battery in the first place before the car was parked up. It is never safe to assume that the battery was fully charged. On a fully charged battery in good condition three weeks would be perfectly fine for a CDT provided the only drain on the battery is the car's stated drain of 20mA to 30mA.

Your first step should be to fully charge the battery and repeat the same conditions or measure the car's current drain with all systems in the idle state.

There's a post here by myself which gives a lot of detail as do posts by others.

bl52krz · 16th November 2023, 18:29

The battery on my sorned 2.5 Connie, is charged every three/four weeks. Checked it today, freezing cold, and it was down to 11.9 volts. It would still have started the car, but is very low at that point. Left it on charge for 4 hours, and it was upto 12.56 volts. I will put it on charge again tomorrow for 4/6 hours to bring it up in this cold weather. Will start the car this weekend for around 30/40 minutes to keep the oil circulated and the water.

Mogodon · 16th November 2023, 20:50

Quote:

Originally Posted by MSS

A major factor is how much energy was stored in the battery in the first place before the car was parked up. It is never safe to assume that the battery was fully charged. On a fully charged battery in good condition three weeks would be perfectly fine for a CDT provided the only drain on the battery is the car's stated drain of 20mA to 30mA.

Your first step should be to fully charge the battery and repeat the same conditions or measure the car's current drain with all systems in the idle state.

There's a post here by myself which gives a lot of detail as do posts by others.

Also, in the weeks it's been idle, it's been locked and unlocked a few times, and used a plug in tyre inflator twice to check tyres and keep one up (slow loss of pressure)

gozo ken · 22nd November 2023, 20:42

When I've not used my classic car for a while, I've used a cheap solar panel plugged into the cigarette lighter, or connected to battery. Also disconnecting the battery helps, as the immobiliser can sap some power over time.
Colder weather does impact on a poor battery though.

16th November 2023, 16:14	#1
Mogodon Gets stuck in Nisan Micra 1.4 SVE Auto. Join Date: Apr 2015 Location: Wellingborough, Northamptonshire. Posts: 838 Thanks: 196 Thanked 198 Times in 84 Posts	How long should battery hold a charge ? I've been unable to drive for for 3½ weeks due to a retinal tear in my left eye meaning the Zed has sat untouched on the drive for the same amount of time. Can now drive again 🥳, went to start the Zed and not enough battery to start, just a click and headlamps came on. Charged battery for 4hrs and away she went as normal. Battery is a mid range Hyundai fitted January 2020. Should a battery still be able to start a car after sitting idle for nearly a month ????,

16th November 2023, 18:29	#4
bl52krz This is my second home Rover 75 cdt club + Rover 2.5 KV6 Conni SE Join Date: May 2008 Location: Birmingham Posts: 11,440 Thanks: 6,587 Thanked 2,262 Times in 1,729 Posts	The battery on my sorned 2.5 Connie, is charged every three/four weeks. Checked it today, freezing cold, and it was down to 11.9 volts. It would still have started the car, but is very low at that point. Left it on charge for 4 hours, and it was upto 12.56 volts. I will put it on charge again tomorrow for 4/6 hours to bring it up in this cold weather. Will start the car this weekend for around 30/40 minutes to keep the oil circulated and the water. __________________ Great Barr, Birmingham.

16th November 2023, 17:10	#2
macafee2 This is my second home Rover 75 Saloon & Tourer Join Date: Sep 2012 Location: Lincoln Posts: 14,997 Thanks: 1,630 Thanked 3,032 Times in 2,181 Posts	yes. It may not have enough puff because it is faulty or because there is a drain on it. Even in a UK winter I'd expect it to still start a car. macafee2

22nd November 2023, 20:42	#6
gozo ken Avid contributor R75 SALOON Join Date: Feb 2013 Location: Lincolnshire Posts: 226 Thanks: 20 Thanked 57 Times in 44 Posts	When I've not used my classic car for a while, I've used a cheap solar panel plugged into the cigarette lighter, or connected to battery. Also disconnecting the battery helps, as the immobiliser can sap some power over time. Colder weather does impact on a poor battery though.