Any Autosparks in the room ??

[michael king]

Long standing issue on my VW Transporter T4. First noticed under 'lockdown'. Battery drains flat if stood more that 3 - 4 days. Industrial spark's myself so set Fluke to Amps dc and sure enough a few 'beans' flowing between battery and battery clamp when disconnected and ignition turned off. So disconnected all the separate cables bolted to the clamp expecting to find just one with drain but they all have amps flowing, all slightly different amounts . Next port of call was the fuse box, with the Fluke in the circuit between the removed clamp and the battery post i pulled all the fuses one by one , no change .
Question is ,,, as it needs deeper investigation which i'd rather wait for a bit warmer weather to do for i'm looking for a work around. My plan is to install a 12V 100A isolator in line in the cab as a temp work around to stop the drain when it's stood, but unsure if it will take the starting currents ?.
Any ideas / suggestions all welcome and much appreciated.
Cheers.
Mike.

 

[plugsandsparks]

The standard battery isolator with the red toggle handle are designed for 100A continuous (check the specs) and are used in motorsport, the starting current is OK for short periods.

 

[UNG]

So my first question would be how old is the battery the cold weather is good at finding weak batteries after that I would be checking the earthing points on the body and engine

 

[michael king]

Thanks very much for yr input Ung but as a sparks that was first port of call. First noticed the issue under lockdown when she didn't move much and i've replaced the battery with a brand new one since, but no change. Also recently installed new engine and redone engine earth strap as it looked old. I did think about 'general earthing ' points but tbh i wouldn't know where to start looking for them, also i dont think we are looking for a 'bad earth' the issue is a circuit partly still made while everything is off so not sure how a bad earth could cause constant leakage, but I'm always ready to learn something new

plugandsparks cheers pal ,that's exactly the one i have my eye on . The battery is rated at 85AH but also says 800A(EN) . So knowing how Industrial motor starting currents can be 20 x initially settling to 4 x after initial movement is achieved i was half wondering if i need a bigger isolator. But from what you say It sounds like the start surge is not present for long enough to matter so long as it's rated for 100A continuous load.

I am very grateful for the input from you both. It always amazes me how easy it is to obtain good info with forums, It's like tapping in to the collective world knowledge on any topic you choose. Love it

 

[UNG]

Thanks very much for yr input Ung but as a sparks that was first port of call. First noticed the issue under lockdown when she didn't move much and i've replaced the battery with a brand new one since, but no change. Also recently installed new engine and redone engine earth strap as it looked old. I did think about 'general earthing ' points but tbh i wouldn't know where to start looking for them, also i dont think we are looking for a 'bad earth' the issue is a circuit partly still made while everything is off so not sure how a bad earth could cause constant leakage, but I'm always ready to learn something new

The problem with vehicles is the number of earthing points to the body / chassis they have in some obscure places, when an earth point is not connecting properly you often find a circuit will try to find a connection by a different route through another current using item, you don't see it that often these days but the rear lights were always a problem area the lights would all be fine until you put the indicators on and you could end up with allsorts of problems from dim lights, flashing brake lights to some lights going off completely with vehicles it is not easy to apply normal electrical logic and discount things as they will always prove you wrong

 

[mainline]

Long standing issue on my VW Transporter T4. First noticed under 'lockdown'. Battery drains flat if stood more that 3 - 4 days. Industrial spark's myself so set Fluke to Amps dc and sure enough a few 'beans' flowing between battery and battery clamp when disconnected and ignition turned off. So disconnected all the separate cables bolted to the clamp expecting to find just one with drain but they all have amps flowing, all slightly different amounts . Next port of call was the fuse box, with the Fluke in the circuit between the removed clamp and the battery post i pulled all the fuses one by one , no change .
Question is ,,, as it needs deeper investigation which i'd rather wait for a bit warmer weather to do for i'm looking for a work around. My plan is to install a 12V 100A isolator in line in the cab as a temp work around to stop the drain when it's stood, but unsure if it will take the starting currents ?.
Any ideas / suggestions all welcome and much appreciated.
Cheers.
Mike.

Some common items to drain batteries are Radio, Alternator, alarm, Bsi.
Max current when everything is sleeping should be less than 50ma.
When checking for current draw make sure all doors are closed and allow time for any modules to goto sleep.

 

[plugsandsparks]

Thanks very much for yr input Ung but as a sparks that was first port of call. First noticed the issue under lockdown when she didn't move much and i've replaced the battery with a brand new one since, but no change. Also recently installed new engine and redone engine earth strap as it looked old. I did think about 'general earthing ' points but tbh i wouldn't know where to start looking for them, also i dont think we are looking for a 'bad earth' the issue is a circuit partly still made while everything is off so not sure how a bad earth could cause constant leakage, but I'm always ready to learn something new

plugandsparks cheers pal ,that's exactly the one i have my eye on . The battery is rated at 85AH but also says 800A(EN) . So knowing how Industrial motor starting currents can be 20 x initially settling to 4 x after initial movement is achieved i was half wondering if i need a bigger isolator. But from what you say It sounds like the start surge is not present for long enough to matter so long as it's rated for 100A continuous load.

I am very grateful for the input from you both. It always amazes me how easy it is to obtain good info with forums, It's like tapping in to the collective world knowledge on any topic you choose. Love it

I use an electronic one for motorsport, it has a giant mosfet which cuts the main earth connection. Sadly i had to restart the engine in a rush and had 100A of accessories running at the same time and it blew up, lol
The one you have looked at will be fine, as long as you dont do what i did.....

 

[LukeD]

Couple of issues facing car owners is "sleep drain" when the car has a new multi function HU that sings and dances .Those buggers kill a battery quick of they are set to only "sleep" . Mine is FULL OFF and the boot up time is less than 10 seconds more . Next will always be bad earths . been a real car hifi guy in my days .First was to always add new ground points . This saved so many issues