August 8, 2012 | Power play
We have seen some rough weather in the past few days. Lots of clouds, lots of wind, some long rainfalls, and it got noticeably colder. Hopefully winter won’t set in very early this year!
We’ve still managed to adhere to schedule, but it has been challenging. Without enough sun, the solar panels do not generate enough electricity, and without engine power, it’s very hard to climb even small heights, since we carry so much extra weight. And heights there are aplenty: The terrain has changed noticeably since Novosibirsk, from very flat plains to rolling hills.
The only way we manage to keep up our speed is by rigorous energy management. For this, there are lots of factors to consider, some of whom we only discovered while already on the road. For example, the MTSE charge regulator only charges the batteries quickly when they are below a certain output voltage, which corresponds to 50% or so of their capacity. Above that, excess energy from Panasonic’s solar panel is simply lost, as the charger, in order to lengthen battery life, decides they may only slowly be charged. Thus, to get the solar panel to do useful work at all, we first have to drive for an hour or so – or climb hills early on.
Panasonic’s battery packs themselves add some complications, too. They clearly are excellent batteries: Great power output and great capacity, very low weight – we are very happy to have them! They also take the constant vibrations and heavy shocks they get from the unsuspended trailers in stride, without any noticeable negative effects. But, as with all batteries, they have a high output voltage when fully charged – which then goes down as they discharge. And their output voltage also depends on their momentary load: The more power the engine takes, the lower the battery voltage. Conversely, battery voltage goes up when we go downhill and the engine works as generator, or when the cells are being charged by the solar panel. As a consequence, the solar panel will generate next to no useful energy for us while the batteries are still charged half or more and we are going downhill, or while we are riding with nearly full batteries in flat terrain – not even under a blue high noon sky.
To alleviate this, we try to get up early and empty the batteries enough by midday so that the sun is used as well as possible. This is not always possible: Problems with the bikes seem to pop up in the morning much more often than in the evening, and we have to fix them right then lest they get worse. Even if there’s no major complication, there’s usually a screw loose somewhere, a flat tire, or some of the cargo not sitting correctly.
A further complication is that the angle of the panels is adjustable. This is, of course, a major plus – but actually not always a good idea to make use of. The reason is their air resistance – the panels can act both as a major drag and as a sail. Obviously, at those times when the generated energy is limited by the charger anyway, it makes no sense to adjust the panels – but there are lots of cases when we have to chose between less wind resistance and less power or more of both. Given that wind resistance goes up enormously with higher speed, it sometimes makes sense to go slower, and get more power, so that we can cover a longer distance overall. And in some cases, it might even be useful to adjust the panel orientation away from the sun: In strong winds, using the panels as sails can give us a bigger push than a clouded or evening sun could.
Still, all this said, we try – and so far usually succeed – to get the batteries fully recharged by grid power overnight. Certainly we would be less far along without good old Russian nuke power! This is not to say it would be impossible to do SiStour without: As mentioned above, we lose considerable sunlight due to the fact that the batteries are too full to make best use of it during the first part of the day – and without overnight charging, this problem would simply disappear. We’ll have ample opportunity to test this as we get further east, away from cafés or restaurants where we can set up our tent and recharge overnight.
Even with clouds and hills, on days without major problems, we regularly go for more than 200 km. This is good: We were a little behind schedule when we left Novosibirsk. Yesterday we left Krasnoyarsk, and we are on schedule again. In the meantime, we made new friends, lost a passport, and got a night-time guided tour through Krasnoyarsk – we’ll fill in the details in the next post!