Will an '09 Viano accept charge via a solar panel into the front 12v socket?

[duncan-09-viano]

Our much loved and slightly abused Viano - "Bob" - was sat with a 60w solar panel in the windscreen in full sunlight for @8hrs on Sunday. After a 120 mile journey on Friday night and then sat stationary all Saturday - (truck racing weekend at Thruxton). Panel was showing 30-35w output and had previously powered my mahossive camping battery pack to 60% the previous day. However with the kids opening the rear doors over the course of the weekend when we came to leave... turn the key and... zilch... nada... Camping neighbour started Bob with a jump and we came home, no bother.

We have had this issue before when camping so I made sure headlights weren't set to auto, all fans off, all interior lights off, nothing charging from the van's own 12v's. Surely that amount of solar charge should have added something or was I using the wrong socket or do the viano electrics just not work that way. I'm fairly technically minded but definitely not a mechanic so a little help/guidance would be appreciated.

 

[V6Matty]

Our much loved and slightly abused Viano - "Bob" - was sat with a 60w solar panel in the windscreen in full sunlight for @8hrs on Sunday. After a 120 mile journey on Friday night and then sat stationary all Saturday - (truck racing weekend at Thruxton). Panel was showing 30-35w output and had previously powered my mahossive camping battery pack to 60% the previous day. However with the kids opening the rear doors over the course of the weekend when we came to leave... turn the key and... zilch... nada... Camping neighbour started Bob with a jump and we came home, no bother.

We have had this issue before when camping so I made sure headlights weren't set to auto, all fans off, all interior lights off, nothing charging from the van's own 12v's. Surely that amount of solar charge should have added something or was I using the wrong socket or do the viano electrics just not work that way. I'm fairly technically minded but definitely not a mechanic so a little help/guidance would be appreciated.

Nope afraid it won’t charge from that socket, you could try one of the others but you may find it easier to buy a replacement socket from eBay and wire it directly to the battery then just make sure you you get one with an inline fuse

 

[Blobcat]

Most 12V sockets switch off with the ignition key.... so you can put as much juice into it as you'd like but it won't do anything...

Get to the back of the radio - find the 12V permanent supply and piggy-back into that - My friend has a 5W panel that keeps the SLK battery happy and that't not used for a couple of weeks at a time

 

[M80]

As above the dash socket is only connected with the ignition on.
The rear socket by the tailgate is permanently connected.

 

[duncan-09-viano]

Most 12V sockets switch off with the ignition key.... so you can put as much juice into it as you'd like but it won't do anything...

Get to the back of the radio - find the 12V permanent supply and piggy-back into that - My friend has a 5W panel that keeps the SLK battery happy and that't not used for a couple of weeks at a time

Aaaah... there are sockets in the rear that are permanently 'live' so best to use those. I shall experiment!

 

[MinionBob]

The 12v socket in the rear, RHS, near the boot is permanently live for sure. Not sure about the ones 'around' the rear passenger area (there are some under the drivers seats too.

I have found, and I can only assume this is due to the voltage drop over ~5m that if you connect a smart charger to the rear 12v is never registers the battery as being charged.

 

[M80]

I have found, and I can only assume this is due to the voltage drop over ~5m that if you connect a smart charger to the rear 12v is never registers the battery as being charged.

When attempting to charge at a high rate the volt drop would be a 'choke' on the charge rate for sure.

Volt drop is a product of cable resistance, voltage, and more relevant here the current flowing.
Small cables will choke more.
Low voltage, as is 12 volts, will see a higher % of voltage reduction.
But these are multiplied as the current in the circuit increases.

A low charge battery, by comparison to the charge voltage, will draw a higher current if the charger can deliver. That would reduce the possible charge rate.
But as battery charge increases and the voltage of the battery voltage rises toward the charger voltage then the volt drop in the circuit is reduced.
To confuse a little more chargers under load, unless big chargers, will drop their output voltage. A large battery might cause a small charger to struggle on delivery as it causes a drop in charger output voltage.

A 60 watt solar charger is a pretty big unit. I imagine it would do ok plugged in at the back. Worth a try.