Vehicle battery running down

[Mottie]

Hi R,
Someone was locked out of his Mercedes, with a flat battery.
I told him to use his key to open the boot, where the light would be on, and charged the battery through the light socket, I didn't find out if this worked?
C

He could have used the key to flip the plastic cover off of the passenger door handle where there will be a barrel to open the door with the key!

 

[camerart]

He could have used the key to flip the plastic cover off of the passenger door handle where there will be a barrel to open the door with the key!

Hi M,
That would have made it easier, if we'd know, maybe next time?
C

 

[ericmark]

A lead acid battery takes longer and longer to recharge the longer it is left discharged.

With a caravan battery, had it on charge for nearly two weeks before it started to accept charge then like ficking a switch, and taking a car for a run is simply too short of a time, looking at days on charge not hours.

I use a Lidi 3.8 amp smart charger, and it really needs to be on charge for at least a day. It is not amps or volts that is important, it's time.

 

[camerart]

Hi M,
That would have made it easier, if we'd known, maybe next time?
C

 

[camerart]

A lead acid battery takes longer and longer to recharge the longer it is left discharged.

With a caravan battery, had it on charge for nearly two weeks before it started to accept charge then like ficking a switch, and taking a car for a run is simply too short of a time, looking at days on charge not hours.

I use a Lidi 3.8 amp smart charger, and it really needs to be on charge for at least a day. It is not amps or volts that is important, it's time.

Hi E,
Yes, some batteries need a 'kick start' with a higher voltage, for them to start charging, but I agree, a good charger is best.
This is my mates car, and he has a good charger, thanks.

The problem is all of the standby stuff, that is a constant drain.
C

 

[ericmark]

Over the years I have tried chemicals in the top up hole, high voltages and many other methods, but that was before we could buy cheap smart battery chargers.

I have also fitted battery isolators but the coded radios stopped that, today I simply connect the smart charger and forget it.

 

[camerart]

Over the years I have tried chemicals in the top up hole, high voltages and many other methods, but that was before we could buy cheap smart battery chargers.

I have also fitted battery isolators View attachment 291219but the coded radios stopped that, today I simply connect the smart charger and forget it.

Hi E,
Yes, those chemicals!
I've all sorts of stuff.
Anyway on his last vehicle he added a cutout, and may do it in this new one too.
C

 

[Mottie]

Anyone remember these ? How would you add these to a modern battery?

 

[norseman]

Anyone remember these ? How would you add these to a modern battery?

With considerable difficulty

 

[camerart]

Anyone remember these ? How would you add these to a modern battery?

Hi M,
Yes, I've never used them though.
I also remember when you could cut out the top of the battery (tar) and wash it all out, and refill it with acid. (that you could buy then)
C

 

[Harry Bloomfield]

He has a clamp on amp meter, and will try that, to test for anything being left on.

Back in the day, when you switched off, and stopped the engine, the battery was disconnected entirely for all discharges. Modern cars have lots of electronics, which need some power to keep them going. They expect you will make some regular use of them, to keep the battery topped up, or another means needs to be used to top the battery up regularly. A clamp on meter is unlikely to show the tiny discharge, an in series with the battery lead meter is needed, to show the 20 to 60mA normal, whilst parked discharge.

On his last vehicle, he had a power switch fitted, to disconnect most of the current when not in use, apart from the alarm system etc.

Doing that, is dependent on how the vehicle is wired. My car spends lots of time parked in my garage - I have it on a dumb charger, which tops it up for 20 minutes per day, every day.

 

[Harry Bloomfield]

With considerable difficulty

I remember them, I got the idea they were mostly snake oil. If they didn't work, which they wouldn't, the seller could just say the battery was 'too far gone to recover'.

 

[camerart]

I remember when cars had to leave their lights on if parked on the road at night.
C

 

[Harry Bloomfield]

I remember when cars had to leave their lights on if parked on the road at night.
C

and the portable single bulb light, which clipped on a window, to avoid having to leave all the parking lights on.

 

[EFLImpudence]

A clamp on meter is unlikely to show the tiny discharge, an in series with the battery lead meter is needed, to show the 20 to 60mA normal, whilst parked discharge.

I have such a DC Amp clamp meter.