Voltage falls about a volt on unlock

[Samro]

I have been using my van as a mobile lounge for the last 3 weeks due it being more comfortable to sit on a car seat than any other chair in my house!

I've not been driving the vehicle and so the starter battery hadn't received any juice over the last couple of weeks or so. The voltage fell pretty low yesterday, so I got my wife to take me for a day out to recover a volt or so.

This morning I noted that when I unlock the van, my battery monitor shows that there is a drop in voltage for a few minutes, indicating a load on the starter battery. This load doesn't last long.

The regular locking and unlocking without driving has been slowly draining my starter battery, but I don't know why.

The load which I refer to isn't the unfolding of mirrors, interior lights or show me home lighting, so I assume it must be fuel pump or some other preparatory function that VW seem necessary.

I will charge the battery when I get a chance, but is there a clever way of avoiding this load on the starter battery at the time of unlocking?

Here is the monitor showing good voltage of 12.37V and then you can clearly see the voltage dip for 3-4 minutes when unlocked at 9:40 this morning.

 

[Dellmassive]

When you unlock the van all the modules power up in preparation for an engine start.

 

[Samro]

What about unlocking with a key. Does that stop it?

 

[Dellmassive]

No same happen s.

Every time you unlock the van the BCM wakes up.....

This poweres The van up, light's,locks, pumps,relays, etc etc.

The interior lights and front light's are the main power drain.

You can code the front light to be off when the handbreak is on, very handy for camping.

You need to look at fitting a battery maintainer that will keep the starter topped up from you leisure battery for extended long parking durations.

The AMT12-2 is recommended and programmable...
( That's provided you have a decent leisure battery setup)

More info...

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

[Guide] Battery Maintainer (for Starter battery) -- How I Done It -- Right so its that time of year again . . . . . . . . Winter & (Lockdown 2020) The van might be layed up not being used, which will lead to a flat battery in around 3 weeks. The cold weather doesn't help the battery's...

www.t6forum.com

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[Dellmassive]

The 50w folding dash panel I have that plugs into the dash socket might help you here? .... Most of the year except winter.

 

[Samro]

Thanks for the good advice @Dellmassive.
It is unusual for the vehicle to sit and not be used, but you're right about the Ablemail being the best solution.

Do you use any regulation for the output of your 50W panel into dash socket?

 

[Dellmassive]

oh yes . . . 100% need a solar regulator.

have a look here what i done.

50W folding panel with PWM controller, then fitted a 12v plug.

[Guide] Mobile Solar Panels ? . . . - How I Did It -

Mobile Solar Panels ? . . . - How I Did It - There is loads of background to this . . . . . but for now here is a vid for you all. =] Just remember W = V*A and as a general rule a good 100W panel will give you up to 6A charge with good sun. 25w = 1.5A 50W = 3A 100w = 6A 200w = 12A 300w = 18A...

www.t6forum.com

 

[Dellmassive]

FYI . .

this is the current version . . .

BlueFusion Folding Solar Panel 50W/100W/120W, 12V/24V Lithium Battery Charger | eBay

Flex Power Portable Solar Panels 50W, 100W, 120W. Peak Power (Pmax): 50W 100W 120W. Premium Solar Panels and Accessory for Leisure and Marine Applications. Battery not included. Cells: High Efficiency, Grade A Monocrystalline solar cell.

rover.ebay.com

 

[Samro]

oh yes . . . 100% need a solar regulator.

have a look here what i done.

50W folding panel with PWM controller, then fitted a 12v plug.

[Guide] Mobile Solar Panels ? . . . - How I Did It -

Mobile Solar Panels ? . . . - How I Did It - There is loads of background to this . . . . . but for now here is a vid for you all. =] Just remember W = V*A and as a general rule a good 100W panel will give you up to 6A charge with good sun. 25w = 1.5A 50W = 3A 100w = 6A 200w = 12A 300w = 18A...

www.t6forum.com

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Nice.
I am thinking the ablemail is the way ahead for me.
Thanks for your input.

 

[Dellmassive]

Yes.... If you have a good LB.

The ablemail will work.

Programmable too....

 

[BoroBoy]

I have had an Ablemail AMT 12-2 fitted for over a year now and had no low voltage problems since.

 

[Samro]

I have had an Ablemail AMT 12-2 fitted for over a year now and had no low voltage problems since.

I've ordered one and am keeping fingers crossed that it will be a simple fit. (Fairly serious lack of space under the drivers seat where i will need to install it to save running cables!)

@Dellmassive & @BoroBoy - Did you put anything more sophisticated than a BM2 for monitoring the 100% charge/condition of your starter batteries? I will all ready be able to see what power leaves/arrives at my leisure battery as the AMT12-2 will be grounded to my Smartshunt, but other than seeing the starter battery voltage, I wont be able to view much detail for the starter battery. I guess monitoring has to end somewhere!

 

[BoroBoy]

I use the BM2 on my starter battery and monitor the voltage and charge via the app. I can see when the AMT 12-2 kicks in as required.

 

[Samro]

I use the BM2 on my starter battery and monitor the voltage and charge via the app. I can see when the AMT 12-2 kicks in as required.

Sorry about the (non) English of my last post. Posted without reading it!

Do you have some sort of shunt for your BM2? How does it know what flows in and out of it?

 

[BoroBoy]

I don't know what a shunt does, but I know there is one on the starter battety. BM2 is connected to + terminal on the battery and an earth point on the van body near the battery.

 

[Samro]

I don't know what a shunt does, but I know there is one on the starter battety. BM2 is connected to + terminal on the battery and an earth point on the van body near the battery.

It is magic! I shall get one and see how I get on.

 

[Dellmassive]

I just use BM2, you will see the voltage rise on the graph.....

 

[Samro]

I just use BM2, you will see the voltage rise on the graph.....

I can already see the voltage on a graph on the VRM, but that is all i can see.
The BM|2 is cheap enough, so I've ordered one anyway. Be interested to see if it brings anything useful to my install.

 

[Dellmassive]

i use two BM2 units on the van.

one on starter,

one on leisure battery.

them use the BM3 APP to see both together on the same plot / screen.

the BM3 APP allows 4x simultaneous BM2 units to be viewed at once.






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[Dellmassive]

more info here:

Battery Monitoring -- How I Done It --

Battery Monitoring -- How I Done It -- Part #1 Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends...

www.t6forum.com

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