I’m a complete beginner when it comes to auto electrics so looking for some advice from this forum please regarding best way to connect my various boxes, or any resources I can go to to determine the correct cabling protocol for my setup.
I live in Australia and plan to travel to the goldfields of WA periodically throughout the year. The aim is to have a dual battery system to charge a portable fridge, camp lighting and charge various USB devices. I have a Toyota Hilux 2008 so will have a starter battery for the car and a second deep cycle battery for the devices. I will also have a 220w solar panel. I plan to put my controller boxes in the engine bay.
So far I have bought a second battery tray, a Victron orion tr smart 12/12-30 DC to DC charger and a Victron SmartSolar MPPT Charge Controller 100/30. I plan to buy my second battery when I have everything else setup, just in case it takes me longer than expected : )
I would keep both the solar controller and the DC-DC charger out of the engine bay entirely - they’re not rated for that type of installation like you may be used to in Redarc installations or that sort of component, and they are likely to quickly de-rate due to excessive heat.
The user and installation manuals of both the listed components will tell you most of what you need to know specific to them; for a crash course in electrical physics and theory itself, Victron’s free book “Wiring Unlimited” is a great place to start: Wiring Unlimited
I have been running a similar system in a Landcruiser 100 for many years and recently changed from CTEK to Victron charging equipment because it offered more flexibility for lithium battery charging, better monitoring options and a higher solar charging voltage (the CTEK D250 I had can only accept up to 25V and would not allow me to connect my 2x110V panels in series). Below some experiences earned the hard way.
Battery location. If you locate the 2nd battery in the engine bay you are limited to lead acid chemistry because LiFePo4 does not tolerate the high engine bay temperatures very well. Look for a good quality AGM (I’d recommend Optima or Discovery) but 1st prize is to locate the battery in a cooler, dry location.
Charging componentry. Two issues here : i) try to keep the cable length from DCDC and PV chargers to battery as short as possible and ii) don’t fit these in the engine bay because their internal circuitry will inhibit their performance at engine bay temperatures.
All cabling to follow sizing recommendations in the Victron manuals. When they talk about cable length they generally mean the full path length of the circuit ( positive + negative cable runs). If the cable will be sheathed, routed in trunking or bundled with other cables, its cooling will be affected so go up a size. Cables from the main battery to DCDC charger needs to be sized for minimal volt drop and not heating as the primary concern so these cables may end up quite large. For a dual battery system with a 12V 100Ah battery no less than 16 sq.mm and consider going up to 25 or 35 sq.mm if mounting the 2nd battery at the rear of the vehicle. All cable runs to be protected against short circuits by fuses/breakers as close to the two battery positive terminals as possible (preferably no more than 10cm).
ideally purchase bluetooth enabled Victron devices. They can be networked together so they share information and enable you to monitor everything from a smartphone app.
Adding a shunt to your system will enable more monitoring options and also helps to report the actual 2nd battery voltage to other devices via bluetooth networking.
Fitting all this together requires an investment in some specialised tools. A good cable cutter and a crimper suitable for heavy duty cable lugs will go a long way to ensuring good quality joints. Add a MC4 crimping tool if you will use those connectors for your solar panels.