In one and a half years on the road, our electrical system has seen some major upgrades. We have changed almost every key component in the system. We upgraded our solar panel and replaced broken batteries and a solar charge controller that was also lost in action. While the considerations and evaluations in our original article on expedition vehicle electrics are still true, here is our March 2018 update:
What went wrong?
Everything, as usual! No, that is not true either. But a couple of things that promoted each others unfavorable behavior. While the demand calculation from our original article is true for mild and sunny weather, we realized that the fridge draws a lot more power when it is hot. Talking about 35/27 °C day/night temperature ranges. Then, our fridge would run two thirds of the time during daytime and half the time at night. Leaving only an amp or two from our solar panel to recharge the battery, while substantially draining it at night, as well. We were left with the one conclusion: we need more solar power!
Another thing we noticed just a couple of miles down the road: the voltages our solar charge controller delivers are not quite the ones our battery needed. So if you install a new setup, make sure the voltage ranges of these two components match!
Eventually, both, starter and auxiliary battery died in Ulaanbaatar. After some cold nights, the auxiliary battery’s voltage was only 10 V, a few days later, the starter battery joined it. Sounds suspicious and I can understand the battery company blaming my wiring. But we double checked that and did not find any faults.
We came up with another explanation, though. The voltage of 10 V indicates that one internal cell of each battery has gone bad. We think that all the vibrations from those bumpy roads had caused internal mechanical damage, with sub-zero temperatures finally pushing them over the edge. Well, we learned that cheap batteries do not pay off in the end. Would not buy the Winner brand again.
Last but not least, our solar charge regulator refused to work, too. That one we consider bad luck only.
More often than we would have liked, we experienced that you have to take what you can get when you are traveling Asia. We literally spent days shopping for solar panels and know all the battery brands that are on offer in Mongolia.
Second solar panel
After an endless search for solar panels in bazaars all over Pakistan, we realized that swapping the existing panel with a more powerful one is not an option. New panels get more power per area, but there were no sizes available that would fit the space on the roof. Our friend Harald came up with the idea to place a second panel on the bonnet and so we did in Mumbai.
With a total of 200 watts of solar power, we now have more than enough electrical energy to power all our devices and keep the battery charged at the same time.
We mounted it in a way that it comes of easily, giving us the opportunity of aligning it with the sun. At home we would have chosen a way of mounting that would not have required to drill through the bonnet. But that was way out of reach in India..
Usually, our battery is now fully charged by noon on a sunny day, leaving a whole lot excess energy to charge laptops and stuff in the afternoon. 150 watt of solar power is the absolute minimum, we would go with in the future. But if you have the space, a few extra watts are a good idea, especially since solar panels are quite affordable these days!
A step forward in battery technology
Heiner is a nerd when it comes to these things. After many hours of thinking, we decided to go for a 100 Ah LiFePo battery. If you just go through the numbers, it is a no-brainer. Half the weight, three times the usable energy, ten times the cycle life of a liquid acid battery with the same amp-hours. But it is also three to four times as expensive. An investment that pays off if you plan to use it often and for a long time.
Another down-side was that we had to find a space in the back of the car. Lithium batteries do not like the heat in the engine bay. It is now up and running for roughly two months. And by how long it usually needs to charge, we can say that it was never drained by more than 20 Ah.
We are expecting it to life long in these conditions. Ten years of constant use should be the absolute minimum. Plus, it is a good feeling to know that we are running our power with a big buffer.
Another thing we appreciate is the negligible voltage drop under load or during discharge. There is always enough power!
A minor tweak: a new relay
We also replaced the battery combiner relay with a voltage sensitive one. We opted for a quality product from Victron, as we found a good deal on it. This part is a bit more intelligent than a relay that just switches whenever the alternator is running. It connects based on the battery voltages, only when one of the batteries is being charged. Effectively preventing one battery to drain into the other one.
The solar charge regulator
We thought we had bought a piece of quality equipment with the Steca controller. It is made in Germany, after all! Maybe it was just bad luck. Anyway, for availability reasons, we bought a MPPT controller from Jaycar, a big Australian electronics retailer. At least it is a technological step forward compared to the PWM Steca one, too. The MPPT technology manages to squeeze up to 12 amps out of our solar panels, whereas the Steca usually topped out around ten. That’s a 20% increase!
As you can see, there were quite a lot of things, we had to learn on the road. We hope that our new setup is now built to last and hope that this update has helped you seeing things clearer when it comes to your overland vehicle’s electrics!