Electrics Planning - Opinions

[Ann3x]

I'm planning the 1st fix of electrics for a Kombi to Camper conversion and thought I'd put the plans down here to see if I'm making any major mistakes and see if anyone can answer a few questions i have.

Base Van:

• T6 T32 Kombi 4motion
• Factory Leisure Battery (think this is a 75Ah AGM)
• Factory Parking Heater
• MFU

My Aims:

• a DC-DC charger (as its a Euro6 van)
• a Solar Panel for offgrid use
• Capable of running a 12V fridge 24/7, a few 12v sockets (mostly overnight keeping phones alive), internal LED lights, Webasto heater
• 240V Hookup (it'd be ideal if the hookup charged the leisure battery too) with 1 240v socket (no need for an inverter tho).
• As "fit & forget" as humanly possible (with some basic monitoring of battery levels in place for ease of mind)

Current plans:

• Redarc BCDC1240 mounted under the passenger seat besides the leisure battery. I like this because it has the battery limiter, solar MPPT & DCDC all in one unit which I hope should make wiring / mounting simpler.
• 110Ah AGM Leisure battery (need to find one that fits under seat)
• 100-110W Flexible Solar panel mounted to poptop
• 240V Hookup hidden under rear light panel

The closest I can find to a wiring diagram for this setup is from the Redarc youtube video (screengrab below):


But it still leaves a few questions.

1/ How would I fit a mains hookup into this setup?
2/ Where would the RCDs sit (load side for fridge / lighting circuits I guess but where else) and is this as well as some of the fuses in the diagram or instead of?
3/ What relay to use (the RK1260 unit redarc recommend seems hard to find)?
4/ What gauge wiring to use?
5/ Any need for a diode in the solar panel wiring to prevent backflow or is that covered via the relay?
6/ How / where to integrate battery level monitoring?

I'm going to document my build in a thread in the camper conversions section so it's clearer for others in future but i reckon its always a good idea to check the plans actually make sense before I buy the stuff!

 

[Dellmassive]

A great list and a lot to look through.... so a more detailed answer for later...

But just for now I think you are going to need a second additional 110Ah leisure battery if you want to run that 12v fridge plus more extras for longer than 1 day on just battery power alone...


Edit: more info added below.


1- there are various ways:

like this . . .



and like this:



2- as above.

3- This is the relay they recommend . . .

https://cdn.accentuate.io/12384363851/41536345035/RK1260 Instruction Sheet.pdf

you could substitute it for something like this.

https://www.amazon.co.uk/Ehdis-Truck-Normally-Socket-Automotive/dp/B01KHRQAYA/ref=sr_1_5?ie=UTF8&qid=1538037665&sr=8-5&keywords=12v+80a+relay+5pin&th=1






4- Premade cable kits are best, you can get a 4/8AWG (80A )Amplifier kit, or just use a purpose made DC-DC kit, like this one from Trvelvolts . . . just chose one above the required rating. so if the readarc was 60amp rated i would got for a 80A or 100A kit.

https://www.travelvolts.net/product-page/wiring-kit-extra-long





5- A decent panel would normally have a back-feed diode already fitted. but the instructions says
"The unit will accept an input directly from the solar panels and act as a MPPT Solar Regulator" so you could fit one, just make sure its rated above the max A and V.


REDARC BCDC1240-LV USER MANUAL Pdf Download.

https://docs.wixstatic.com/ugd/d959f6_bce9d79e040b4c72a73cb9e883b45929.pdf

6- you could use bluetooth battery monitors like these:

Ctek battery monitor:

CTX BATTERY SENSE

https://www.amazon.co.uk/CTEK-40-149-Battery-Sense/dp/B0188TGF6W

Redarc:

https://www.travelvolts.net/product-page/redarc-bcdc1240lv


or you could use current shunt monitors like the Victron ones . . .


Battery monitors - Victron Energy










some other things you might want to think about:

If you have the smart-alternator then look at the (-LV) (Lov-Voltage) Redarc units that are designed to deal with "smart alternators" we went for the
Redarc BCDC1240-LV (bluemotion compatible)

A mains inverter if you want to run any 240v kit when off grid.

a mains powered battery charger to top up leisure batteries when hooked up to shore power/hook up..



Dellmassive`s -- "how I Done It" -- Thread

.

 

[Phil_G]

I'd suggest the newer Redarc 'D' dual input version, the older one shown in your diagram with the single switched input for both alternator and solar is a bit crude!
With the 'D' you dont need that relay, its much neater.

 

[Dellmassive]

Re: @Phil_G suggestion . . .

Dual Input 40A In-vehicle DC Battery Charger

https://www.redarc.com.au/Content/Images/uploaded/Manuals/BCDC Dual Input Instruction Manual.pdf

unsure yet how it would deal with the "Low-Voltage" on a smart alternator setup.

 

[Ann3x]

I'd suggest the newer Redarc 'D' dual input version, the older one shown in your diagram with the single switched input for both alternator and solar is a bit crude!
With the 'D' you dont need that relay, its much neater.

Great suggestion. I will do that as the extra relay was a headache.

A great list and a lot to look through.... so a more detailed answer for later...

Edit: more info added below.

Thanks so much for the detailed answers. I'll factor all of that into my plans. Super helpful!

On the battery capacity point I calculate as follows:

Consumption needs:

• 12V Fridge = 50W (constant)
• Phone x4 = 6*4W = 24W (intermittent use - assume 50% >> 12W)
• LED lights = 50W (6m of 5w/m LED strips + couple of spots) (intermittent use - assume 25% >> 12.5W)
• Webasto = 15W (intermittent use - assume 25% usage >> 4W)

Calculation:

• Total Power Usage= 50+12+12+4 = 78W
• Av. Current Draw = 78/12 = 6.5A
• Time to draw 88A (ie run battery to 20%l) = 88/6.5= 13.5h
• So the Leisure Battery would run ~15h without any charging

Factoring a solar trickle into this (even with UK cloud) and I reckon a single 110Ah battery would give me 2-4d+ off grid depending on the weather. With a young family, frankly 2-4d+ is plenty for now! I guess if my needs change i could add another battery in future right?

 

[Dellmassive]

Yes, you can add additional batteries anytime . . . . but might be best to cable for it now and set aside a location for one..

dont forget that if you leisure battery does run your kit for 15hrs . . . . . . . at that point it will be totally flat . . . . .

and with a 240vac purpose charger that could take 20hrs or more to charge back up..

charging through the factory relay smart alternator will only ever charge to about 80%. and that would take a very long drive indeed.

just might be better to factor in some extra Ah now before you finish the build.

 

[Phil_G]

Is it a proper compressor fridge?
If so its not 50w constant, as the thermostat cuts in & out. Thats why their consumption is measured in the very obscure unit 'watt-hours per day'. Once its down to temp and its 'coasting' the consumption is very low, especially overnight when you're not opening the door.
Thats why the 'average' consumption needs to be measured over a long period of time, ie over many thermostatically-controlled on/off cycles.
If its a Peltier fridge, they do tend to be constantly on although you can get thermostat ones, or its easy to add your own thermostat.

 

[Pete C]

I was going to say the same thing as Phil_G above about the fridge.
What fridge do you have planned ?

Pete

 

[Ann3x]

Is it a proper compressor fridge?
If so its not 50w constant, as the thermostat cuts in & out. Thats why their consumption is measured in the very obscure unit 'watt-hours per day'. Once its down to temp and its 'coasting' the consumption is very low, especially overnight when you're not opening the door.
Thats why the 'average' consumption needs to be measured over a long period of time, ie over many thermostatically-controlled on/off cycles.
If its a Peltier fridge, they do tend to be constantly on although you can get thermostat ones, or its easy to add your own thermostat.

Tbh I havent decided so I looked at figures for a 50l Waeco and planned from that using worst case numbers.

Definitely a 12v compressor tho.

 

[Ann3x]

Yes, you can add additional batteries anytime . . . . but might be best to cable for it now and set aside a location for one..

dont forget that if you leisure battery does run your kit for 15hrs . . . . . . . at that point it will be totally flat . . . . .

and with a 240vac purpose charger that could take 20hrs or more to charge back up..

charging through the factory relay smart alternator will only ever charge to about 80%. and that would take a very long drive indeed.

just might be better to factor in some extra Ah now before you finish the build.

It'd be the same problem (just delayed) with 2 batteries tho right? Is there a way to artifically limit the amount the system discharges perhaps?

I might take your advice on the pre-wiring plan tho. I guess I'd just leave the dummy leads in place unconnected (with ends insulated ofc)?

 

[Phil_G]

It'd be the same problem (just delayed) with 2 batteries tho right

Thats right, rather than a bigger reservoir, the real answer is to keep the reservoir topped up.
For long off-grid periods use I would suggest a bigger panel - say a 250w panel like @Deaky and @andys have nicely documented on here.
Thinking About A Solar Panel? Look At This.....
My Roof Might Be Crap But The Solar Panel Is Ace
Solar Panel Fitting To Front Hinged Roof

Daylight (& sunshine when we're lucky) are free!

 

[Pauly]

I think larger solar would be the ideal, in your opening post you say a fridge 24/7, the only way to do that is to generate more power than you consume and the only way to do that is to either be permanently on hookup or utilise more solar power

 

[Ann3x]

I think larger solar would be the ideal, in your opening post you say a fridge 24/7, the only way to do that is to generate more power than you consume and the only way to do that is to either be permanently on hookup or utilise more solar power

I should clarify. By 24/7 i mean 24/7 whilst we are camping which is usually 3-5d at a time between hookups (cant do without civilisation for too long with young kids).

So if the battery is gradually discharging day by day (which would be the case if we had a 100W panel) - fine. As long as we have a fridge alive by the end of the time off grid.

 

[travelvolts]

I can confirm that the new Redarc BCDC1240D is also LV so totally suitable for the T6.

 

[Ann3x]

So now I'm a bit further down the line with my conversion so I'm back onto this topic as electrics will be the next job. Taking onboard some of the comments above my plans now look like this:

Initial Setup:

• Leisure Batteries: 2x Leoch Xtreme AGM 110AH Batteries
  • Low height - fit under seats, bit more headroom for off grid
  • Replacing the standard 90Ah VW leisure battery I currently have under passenger seat
• DCDC Charger: Redarc BCDC1240D
  • Integrated mppt, smart alt + LiFePO4 compat for future (I might go that way one day)
• Mains Charger: Victron Bluesmart IP65 12/15
  • low heat + efficient, Li compatible
• Battery Monitor: Victron BMV712 Battery monitor
  
• RCD & HUP
  • HUP either under bonnet or behind rear light cluster (preferably)
• Lighting:
  • LED strip lights already fitted in Hilo pelmets
• Wiring Kit
  • General DCDC loom kit from travelvolts
• Fusing & Isolation:
  • Main Leisure Fuse to protect whole leisure system
  • 12V Fuse box: lighting, fridge, webasto on separate circuits
  • Main Leisure Isolator Switch
    • To confirm everything fully off in car mode
  • Fridge Isolator Switch (for when we just need fridge off), possibly not required if fridge has dedicated switch

I would hope that the majority of the installation can sit under my 2 captains seats (with obvious exception of the BMS, RCDs & Isolators). Is that realistic?

Future Additions:

• Near future: Solar panel mounted to Hilo roof bars (to avoid sikaflexing to my nice carbon roof!)
  • Any issues with retrofitting this to my proposed setup? Would it just be plug n play or would I need to change settings on the DCDC / BMS significantly?
  • Anyone mounted a solar panel to roof bars? I know most just sikaflex to the roof
• Far future: Li battery replacing the AGM (far future when I've got use out of the AGMs) so I'd like most of my planning / kit to be capable of coping with this.

Please - critique my inept planning and/or total over optimism

 

[Dellmassive]

Some good qualty kit you have chosen there my man.

 

[Pete C]

I bought a 100W folding solar panel which we only take if we need it. It takes up limited space, and I made some simple bars which act as roof bars if we need to put it on the roof. We can’t drive with it up there, but it takes about 2 mins to put in place.
All the wiring is in place for it, with a simple connector to plug it in.

Pete

 

[Ann3x]

Some good qualty kit you have chosen there my man.

Yeah it didnt escape my notice that its very similar to your setup!

 

[Dellmassive]

I bought a 100W folding solar panel which we only take if we need it. It takes up limited space, and I made some simple bars which act as roof bars if we need to put it on the roof. We can’t drive with it up there, but it takes about 2 mins to put in place.
All the wiring is in place for it, with a simple connector to plug it in.

Pete

We now have 4x folding solar kits as we loved them so much.

We have the original Renogy 100w hard frame Suitcase, and now the new slim line 100w version. We have 2x cheapo wish.com 20watt dashboard sized units and a new 50watt slim folding unit from ACOPOWER which has a surprisingly good build quality.

Loving the solar so much, now looking to make the shed/garage solar with permenant panels.