Kaley is equipped with enough power to run a small village. Seriously. And she can carry enough fresh water to last a week off the grid for a family of 4.
The power system was designed by an electrician/engineer with over 10 years experience in living off the grid in his own bus. It is designed to be 100% off the grid, and run an array of appliances for regular living. In nearly 3 years of living in the bus the only times we had to plug in / run the generator, were when we had almost a week solid of dark rainy weather, or were parked under trees and didn’t get any sun on the solar panels.
Kaley is equipped with 8 x 200W solar panels, giving a total of 1600W solar power (shown below). The panels have been raised between 50mm and 100mm off the roof of the bus, to allow for cooling and air-flow while driving. This ensures the panels run as close to their optimum temperature as possible. The panels are also set on an angle to ensure good water drainage.
On a typical sunny day with typical usage, the system would generate around 4-5 kilowatts of power, and the batteries were usually back to 100% full by about 11am.
SOLAR CHARGE CONTROLLER & INVERTER CHARGER
The solar panels connect to a Victron BlueSolar MPPT 150V/70A Solar Charge Controller. This device takes as much current as possible from the solar panels on the roof, and re-shapes the power to better suit what the batteries need and can use. This is the most efficient way of charging batteries from solar panels, and Victron gear is widely regarded as some of the best in the business.
The Inverter Charger is a Victron Quattro 24V/3000W/70A, and it does a few different jobs with the power system. Firstly, it converts the 24V power from the batteries into 240V AC power for use in regular power sockets for things like computers, blenders, TVs, and so on.
The Inverter Charger also has two extra power inputs – one from the onboard Generator, and one from a mains plug (e.g. a 15A outlet in a caravan park). It takes those power inputs and converts/shapes it to charge the batteries while also delivering power to the 240V sockets throughout the bus.
Finally, the Inverter is smart enough to bypass the power conversion for high power devices like air conditioning, and simply pass-through the power from mains / generator to aircon.
BATTERIES & GENERATOR
The whole bus runs off 6 x 210Amp-hours 12V sealed AGM batteries. Big blue boxes shown on the right side of the image below.
The batteries are wired in series/parallel, which results in 630Ah of power at 24V. This works out at roughly 15,000 Watts, so for example if you use something that draws 1000W of power, you’ll be able to run it solidly for 15 hours before the batteries are fully drained. NOT that you would want to do that… you’ll trash the batteries.
In short, there is so much battery power on board that you can run a 220L fridge, a 100L chest freezer set to -18 degrees C, all the lights, power, and other gadgets you want, and you’ll make it through each night only using around 15-20% of the power capacity of the batteries. In other words, the battery monitor will show 80% in the morning.
The batteries don’t need any maintenance, and are weather proof. Regarding charge levels, they have been carefully looked after, and never been drained beyond around 65%. This ensures they’ll have a very long life for many years to come.
We even managed to run the Air Conditioner directly off the batteries for around 1-2 hours on hot nights, as long as we were certain of re-charging the batteries with solar the following day. The combination of an inverter A/C unit, plus the great Victron Inverter Charger meant that this didn’t kill the batteries.
Shown in the photo above next to the batteries, the big green box is an Onan MicroQuiet 3600 (3.6KVA) generator. It runs on unleaded petrol (the silver tank immediately to the left of the generator in the next bay) and has a remote panel in the cabin to start / manage it. (This is shown in the next section below “Power Monitors”.)
Onan generators are supremely powerful, and very high quality. This one hasn’t missed a beat, and was barely used while on the road. It started every time – except when we ran out of fuel, or the starter battery died cos we didn’t need to use it very much!
The bulkhead of the bus includes a full array of monitors to ensure the power system is working as intended. There are four main control panels, although after we got used to the system, we barely looked at them. It just ran itself!
The four panels are:
Victron Color Control Panel
This one shows ALL of the system working together. You can see how much power is coming from the Solar Panels, or the Generator/Shore Power (mains plug). It shows the current state of charge of the batteries, the amount of DC power being used by the system, and the amount of AC power being used through the Inverter. It also shows whether the Inverter is “inverting” (changing power from 24V to 240V) or “charging” (filling up the batteries)
Victron Inverter Control Panel
Specific to the Inverter, this panel lets you switch the inverter on and off, and into charger-only mode. It also lets you control the current limit on the inverter, to ensure you don’t overload your power circuits or your batteries. Lastly it shows warnings for low battery, overload, or temperature alarms. This panel connects directly to the Color Control panel and feeds into the overall system status.
Victron BMV 702 Battery Monitor
This panel is the definitive guide to the state of charge of the batteries. It has many other features, but honestly we simply used it to check battery charge level at a glance. It is also needed because it connects directly to the Color Control panel and feeds in its data for the overall system status.
Cummins Onan Generator Remote Control
This panel starts, stops, and manages the generator remotely. It is all push-button driven, meaning you don’t need to yank on starter cords to kick over the generator… it just works!
12V/240V POWER OUTLETS
Kaley is filled with power outlets. There is nothing we tried to run but couldn’t run, and we had maximum flexibility of power outlets in every possible location. (It drove our electrician slightly bonkers during the build…)
There are double 12V cigarette-lighter sockets alongside double 240V power sockets throughout the bus, in the following locations:
- Front of the bus
- Dining Tables (both sides)
- Kitchen (both sides)
- Both bunks
- Master Bedroom (both sides)
- Plus in each side bin
The bus is fitted throughout the interior, side bins, rear boot/trunk, and passenger side with 12V high efficiency, high brightness LED lights. You could literally run ALL of the lights ALL of the time, and barely make a dent in the batteries. The light switches are all easy to access, and positioned in sensible, intuitive locations.
Kaley is fitted with 3 water tanks. 2 fresh water tanks, which hold a total of around 600L of fresh drinking water, and 1 grey water tank which holds around 240L.
The bus water system is plumbed using common John Guest fittings for fresh water (hot and cold) and simple flex pipe for waste water. This means that any repairs or maintenance jobs are super easy and simple to do.
The first photo above shows one of the stainless steel water tanks, plus the 12V water pump (orange/white/black device on left) and an easy-access tap for washing or cleaning outside the bus. The blue hoses are cold fresh water, and the “Y” shaped black hose is an example of the simple plumbing waste hosts.
In the bottom right of the second photo, the black panel is the hot water heater – a Suburban 20L gas/electric hot water service. This is more than enough for several brief showers, and only takes around 15-20 mins to reheat. The middle of the photo shows the two tank filler hose fittings (front = front tank, back = back tank). The top left of the photo shows the toilet cassette hatch where the cassette can be removed/replaced for emptying and cleaning.
The water capacity is enough for a family of 4 to live off the grid for a week at a time. There are several ways of using the water – front tank only, back tank only, both tanks combined – and there are clear hoses attached to each tank for easy level checking. There are also digital gauges shown below in the top middle of the fuse board, which is in the cupboard above the fridge. This panel also has an isolator switch / reset switch for the hot water service, and the on/off switch for the water pump.