Trailer Socket 12v EHU (x 2!)

[z1ts]

Following on from several things in this here forum, specifically @roadtripper 's excellent how-to here:- www.t6forum.com/threads/trailer-socket-12v-ehu-how-I've-done-it.45009 and my own findings regarding the behaviour of the trailer socket electrics etc here:- www.t6forum.com/threads/ignition-live-under-passenger-seat-30-amp-another-way-to-do-it.49156 I have decided to produce my own variant of @roadtripper 's 12v EHU!

So let's start with the why:-

1. My EcoFlow Delta mini is my leisure battery, charges quite slowly when engine on and I have a few always-on peripherals in my van and the BMS of the Delta is surprisingly power heavy! So with all that in mind I am losing around 20% capacity of my EF from 17:00 in the evening & 06:00 the next morning. My am & pm commutes don't replace this, so add in a weekend when the van might not get used, my EF is flaaaaat!
2. I don't want to drill any holes in my van (yet)
3. Solar whilst potentially the best route long-term and probably what I'd do from the get-go next time (will there be one I wonder? - can't see myself driving a Transhitporter...) is too much effort right here and now for my quite low requirements
4. I would like a solution to charge my EF without running 240v through an open window (wet passenger seat last Saturday - oops sorry love!)

Which brings us neatly on to the solution I am planning to implement here:-

1. Broadly stealing the how-to mentioned above I intend to charge my EF from a 12v PSU
2. Also implementing an option to charge my SB if/when needed
3. All hopefully achieved from the 13pin factory trailer socket...

What I'm using:-

1. 240v extension lead 2 gang www.amazon.co.uk/gp/product/B07MDL99NL £13.92
2. 13 pin trailer plug https://www.amazon.co.uk/gp/product/B09RQZ8ZYC £8.99
3. 12 core cable from 13 pin plug to my waterproof box Pardon our interruption... £5.95
4. Halfords battery charger 'quick-connect' doodah
5. 12v 10A 120W PSU www.amazon.co.uk/gp/product/B0CR5VX5PC £15.26
6. Grain of Wheat bulbs https://www.ebay.co.uk/itm/256760241468 £3.99
7. Wago connectors (got a bundle in me toolbag!)
8. Wagobox www.amazon.co.uk/gp/product/B0CDPYP1FH £4.23
9. Waterproof Electrical box thing www.amazon.co.uk/gp/product/B00B0X8CYC £10.41
10. Halfords battery charger/maintainer

So total outlay so far £62.75

I already possess a Halfords battery charger/maintainer since discontinued but was £47.99 which I haven't included in the above prices.

All items shown in their raw form (some adaptations made already like removing the plug from the 12 PSU etc!) here:-

(Numbers correspond with list above ^)


So what am I going to do?! Well briefly the following:-

1. Terminate the 12 core cable into the 13 pin plug following conventional wiring & colours etc.
2. Terminate the other end of the 12 core cable in the following manner:-
   1. Pins 1, 4 5 & 7 to positive of GoW bulbs
   2. Pin 3 to negative of GoW bulb
   3. Pin 10 to positive of 12v PSU
   4. Pin 11 to negative of 12v PSU
   5. Pin 9 to positive of battery charger/maintainer
   6. Pin 13 to negative of battery charger/maintainer
3. Put the 240v extension lead in the waterproof box
4. Plug the battery charger into the extension lead
5. Plug the 12v PSU into the extension lead
6. Plug in & enjoy 12v trickle charge to my EcoFlow and starter battery maintenance/charge

The Build

Pic of assembled unit open with battery charger in:-



Pic of assembled unit open giving more detailed look at cable routing etc:-



Pic of assembled unit closed:-



Now then - what does this give me? A very neat single plug (well 2 actually - one into 240v exterior socket on my garage & a 13 pin trailer plug) solution to charge my LB and SB at the same time!

Final testing:-

Plugged in to 240v external waterproof socket:-



Plugged into van via trailer socket:-



Confirmation that my EcoFlow is indeed being charged:-



To idiot-proof things when in use (cap from 13pin plug attached to steering wheel!):-



Thoughts and considerations:-

• Is it perfect? Possibly not, but it's pretty good for my requirements.
• Is it for everyone? Absolutely not! But it works for me.
• Why did I put the GoW bulbs in the waterproof box not in the 13 pin connector? Because I am using more cores (4 at minimum) and I had the opportunity to connect everything in the waterproof box I thought, why not!
• Doing it with GoW bulbs to give the vehicle trailer detection means that when the vehicle is locked and it is unplugged the alarm goes off and I get an alert via the VW app on my phone!

 

[roadtripper]

Nice, glad it was an inspiration. I'm still trying to find the time to do a solar version.

One thing to keep in mind with those style of boxes is that the waterproofness of the lid isn't perfect over a long period. If it's a week or two it's fine but if it's out long term as a maintainer like mine is I found it best to ensure the box has a drain hole punched out and is oriented so any water that gets in can get out. I suspect sometimes it's just an accumulation of condensation from damp air being sucked in as the box cools.