Battery Discharge

[alicat]

Techy question for electrical boffins

 

Currently having grief with our company cars and flat batteries. All the vehicles have trackers in them and lately everytime there is a flat battery the manufacturers say we must pay for the work as the tracker has drained the battery.

 

So I have pulled a unit out and the consumption is rated at 500ma, this being the case how long will they take to drain a typical car battery?

 

Thanks

 

Alicat

[Sheds Moderator]

A 7 batt is 30 Ah, IIRC. This means it will run 30 hours at 1A or 60 hours at 0.5A (500mA). A bigger battery in a tintop might be 50 Ah, so it will run for 100 hours or 4 days. This isn't long. A decent Easter weekend will kill it. You might find it useful to fit "heavy duty" batteries to cars not used daily, these will buy you a bit more time before the inevitable.

 

It is true that a fully discharged battery won't last long unless it is charged. However if the prob is simply "won't start" then get a few sets of jump leads or one of those booster boxes, off you go. Alternatively equip each car with those ciggy socket to ciggy socket jumpleads - these are idiotproof in operation and 5 mins with the engine running will get the second car battery charged enough to start it.

[alicat]

Thanks

 

I think we need to run the used cars instead of just parking them up.

 

Alicat

 

 

[jmalcol1]

I wondered why my 7 battery kept failing to turn the engine, I too have tracker fitted. John M

[Simos]

There are devices that you can get (never tested one) that attach to the batt and stop the current flow if the charge drops to a preset level that typically will start a car. This would stop your tracker working if they trailered it but if they hot wire it it will still track if you see what I mean.

However since it looks like your tracker will be dead anyhow there's not much of a loss really and you would be able to start the car.

 

Worth remembering that car batteries (and many others) are not meant to be deep discharged. A few full discharge cycles is enough to damage them significantly, more so if they are left discharged for a while.

You are then on a slippery slope...

 

On my old VW when I killed the batt I went to the local motor shop and bought the biggest batt that would fit in the space. There were a whole series of batteries the same width that would fit in the clamp but were different lengths and capacities. The one I got was a for a big diesel beastie with nearly double the capacity specced by VW for the petrol passat and it never gave me any grief ever again :-) (cost £<30, maybe £5 extra and boy did it turn the engine over !) ended a whole string of not starting incidents including a RAC callout to a remote location. best £30 I ever spent on the car.

[Anton]

I have a tracker in my 7. Had the same problem - flattened battery if car not used over weekend, but had it cured in a very simple fashion. The tracker was originally set for a 14-hour 'active' period after the ignition was turned off, so I had this shortened, as the power drawn when it is 'asleep' is far less. The tracker will return to 'active' if the car is moved or the engine started. Check with your tracker supplier.........