This is part 3 of our little 3 part series. In part 1, 100% Electric across Canada, I shared our plans on how to get across Canada without the extensive Supercharger network we’re used to from the US. In part 2, Solar Charging for Nerds, I provided tons of details on our solar panel and battery set up. To get the full scope of information, make sure you read those two before reading this post.
Charging the Camping Trailer’s Batteries
The trailer came, as usual, with a lead-acid battery, which I replaced with a Lithium-Iron-Phosphate (LiFePo) battery. I disconnected the original battery charger as the LiFePo batteries will always be charged from the solar panels. At the campgrounds, we will plug in our car for charging, not the trailer. What an innovative concept ;-)…
Follow the thick blue line: The power comes from the 8 solar panels to the MPPT controller, which converts the roughly 80V of the panels to the battery voltage. From the MPPT controller, the power goes through the charge fuse the high-voltage solenoid and the battery main fuse to the battery. The programmable voltmeter reads the battery voltage and opens the high-voltage-solenoid to stop charging, once the maximum battery voltage is reached. You can still see the 110V charger next to the MPPT solar controller. We can connect it in a pinch should we need to ever charge the trailer battery from a power outlet.
Charging the Electric Car’s Batteries
Now to the fun part: Charging the car from our stored sunshine. Granted, this will only provide a small percentage of our power requirements to drive across Canada, but it can help us out if we are in a pinch far away from any electrical outlet! On the other hand, who can make gasoline from sunshine in the wild?! 😉
I already had a 1500W true sine wave inverter from another project and that’s what we’re using at this point. It can charge our Tesla Model X at 6km/h. We tested it and it works perfectly. We can easily upgrade to a 220V-3000W inverter to charge the car at double the current rate, which would then be 12km per hour. All cabling has been sized for the higher power demands.
The trailer’s battery can store about 20km of range. Should we ever wake up in the morning and realize we do not have enough range, we can use the stored energy from the battery and the solar panel output to add about 30km of range to the car by early afternoon. That way, we might be delayed a little, but we certainly won’t get stuck! Following the thick blue line in the diagram below, our stored sunshine comes out of the battery, through the 400A fuse, and the low-voltage disconnect solenoid to the inverter. The inverter converts the 12V DC to 120V AC for charging the car. The programmable voltmeter will open the low-voltage disconnect solenoid, should the battery voltage be getting too low. No problem there, the sun will shine again and fill our battery soon.
(For more information on how we are planning to charge our electric car, please refer to our previous blog post ‘100% Electric across Canada‘.)
Powering the Trailer
We will lead a power-hungry life on this trip, as we will be running several laptops, computer screens, network equipment, a cellular data router and air-conditioning to keep up with our blogging and social media updates. The same inverter outlet we can charge the car from will be our plug-in for the trailer. So we simply connect the trailer cord to the inverter and run everything that is 12 V and 120V from the LiFePo batteries. Thus, we will be ‘dry’ camping 100% of the time, while the car enjoys the juice from the nearest, hopefully ‘green’ power plant.
Such Endless Opportunities
I just had one more idea! Gosh, the fun never ends – for an engineer that is! We can already run the AC from the battery using our inverter, but we still carry a propane bottle for cooking, the fridge and hot water heater. Would it be possible to replace all those functions with our solar panels and battery? Let’s try it! I took a portable induction cooker and hooked it up to the trailer’s battery. Filled a pot with water and switched on the induction cooker. Low and behold, it works! Within a few minutes the water was boiling.
In the end, though, we decided to not go that route. We love our induction cook top at home, but the pots are heavy and not stackable. For our trip, we want to go light weight and small volume. But, it would be doable!
This now concludes our 3 part series on charging, solar and batteries. We hope it gave you some valuable information and maybe a few new ideas. Do not hesitate to let me know if you have any questions.
As per special request, here are the three diagrams a little bigger: