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Wiring

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Warning

This is not advice, merely a reference to myself. Do not use this as a guide. Page is generally very messy.

Initial Wiring Diagram

Analog wiring diagram here. Missing wire sizes, colours, and doesn't include all parts of system. TODO add 12V main wiring, LV cutoff circuitry, digitise. Need inline fuse on the LV cutoff too, also on the fairy lights. Need to work out solution to plug in socket externally so that we don't have issues with trickle charge. Correct 17mm cable to 17A cable on fuse box.

Digitised Wiring Diagram

I'm currently trying to digitise this diagram using qelectrotech, mainly as an exercise to myself. The project file is here, with the latest schematics here.

Current Wiring

Fusebox in the kitchen cupboard at the back. This fusebox has some tails which connect out to various circuits. In addition to the fusebox, there is the split charge relay, which is connected out to the front of the van and is on a voltage sensing relay. There are two isolator switches. The first isolates the leisure battery from the circuit, the other isolates the split charge aspect of the system.

To de-energise the system, both have to be disconnected.

The fusebox connects to the aux power on the side of the kitchen cupboard, the diesel heater, the lights, and the aux power at the back. It also connects through to the inverter. The inverter is a 250/500W peak, so would have current spikes of 41A at 12V. The spec sheet didn't say the sizing of the cable required. The calculator here said a CSA of 8.37mm2 would be needed.

Currently this is a paralleled twin and earth just using the L/N of the wire. This needs replacing with flexi cable. Also not earthed.

Inverter has a single plug atm, want to wire it up to have multiple plugs in the van. Need to replace solid core twin and earth runs with flexi. Lights on twin and earth and also on a twin switch circuit with no conduit so cannot easily be replaced. Run from the cupboard to back aux also currently on mains twin and earth, so need a 12V DC to the back, then

Mains Wiring

Inverter can do 500W peak at 230V, or 2.17A. Mains cable needs to be able to handle this AWG25 or 26 ideally 0.16mm2 CSA. Can put one at the back of the van next to current aux power, one next to the aux power up front, then maybe a small spur that goes to a free floating plug in the front for running wiring outside the van. Could also just wire a plug next to a socket on the underside of the van. This would then allow the mains to passthrough the van?

Low Voltage Cutoff

  • Currently looking like Victron do a decent BatteryProtect product
    • This cuts off at a configurable voltage
    • Can connect to the phone for programming and display
    • Can sound an alarm and has reasonable times for things
  • Connect this with their smart shunt product to get good state of charge reporting on the battery
  • Instead of SmartShunt could also use the BMV which would show SoC on a display in the van.
  • BMV ranges some have a port for aux sensor or relay shutoff, but most don't
  • Only the most expensive one has Bluetooth built in, otherwise need a VE.Direct to Bluetooth or VE.Direct to USB
  • Don't think you can get a network bus-based version of this.
  • Final setup would likely be the batteryprotect for all non-inverter, then take the inverter apart to add some sort of cutoff switch to the switch itself, then use the smartshunt to get current state of charge

  • would probably make for a good blog post once installed

  • 100A cable should be 26mm2

STILL TO BUY 2x BatteryProtects Also cable lugs And maybe dielectric grease https://www.youtube.com/watch?v=pSXv8RHa22I https://www.victronenergy.com/upload/documents/Smart_BatteryProtect_12V_24V/114439-Smart_BatteryProtect-pdf-en.pdf

Plan of Action

  • Replace doubled up 1mm2 mains cable for positive and negative currently going through the fusebox with a run from a busbar.
  • Negative can go

Shopping List

Nice to have

  • 18AWG or better red and black sheathed ideally to run into the back, approx 5m? Cig lighter can draw 16A and current tails for 18AWG
  • Lugs to crimp with
  • Crimping tool
  • Label Maker
  • Fish wire
  • Pull cord
  • More conduit
  • Gland for mains flexi? Maybe not bother
  • 12V light for cupboard to come on with main lights, maybe wire it so it is a switched spur on the main lighting
  • small 12v switch
  • Trickle charger
  • 16A plug and socket for external mounting
  • 12V 100A relay with lowish hold current

Low Voltage Cutoff

After killing two AGM batteries, I have made the decision that investment in a low voltage cutoff system for the van is an essential way to prevent further costs and protect the battery.

Through research, I have established that there are two main ways to do this: use a voltage sensitive relay, which switches a relay to cut loads in and out; or a 'smart' transistor device, which switches a transistor to allow current to flow. The former is the simpler and cheaper option, but suffers from relay sizing requirements (as the relay has to be able to switch high currents without getting stuck), and the quiescent current of holding the relay open.

From a basic Amazon search, the quiescent current of a suitable relay is about 5W, which would drain my fully charged 95Ah @ 12V leisure battery to 50% SoC in 144 hours, or 6 days. The alternative to consider is a product like the Victron Smart BatteryProtect 12/14-Volt 100A which can switch up to 100A through a transistor, with a quiescent current of 1.5mA/0.6mA @ 12V = 0.018mW, draining by leisure battery much slower. Whilst I normally try and shy away from Victron kit, I thought this was a good investment, as it's something I should be able to take with me from van to van and should last a long time if installed correctly.

There is a gotcha using a transistor-based system as opposed to a simple relay. Due to the way a transistor works, loads can only flow one way through the system, and they don't handle things like capacitors very well. Therefore, this has to be connected between the main battery and the fusebox for loads, and can't simply go between the battery terminal and all other circuits. I've installed mine downstream of the main leisure battery disconnect so that once that's off the entire BatteryProtect system is also off.

The battery protect has two 8mm posts, through which I can connect some 16mm2 cable. At the same time as installing this system, I needed to update the wiring on the inverter. As the inverter is a capacitive load, it cannot be connected downstream of the BatteryProtect system. Most of the Victron inverters have a remote switch which controls the power state of the inverter. My inverter doesn't have this switch, so I need to include a

Eventual Electrical Upgrades

  • Transfer switch and mains charging to allow van to plug in
  • Input and output 16A sockets externally

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