I’m still not 100% sure how much energy I managed to capture today but it looks like around 30W which should give me enough time to post without too much worry.

I stopped at about 10:45 and set up my solar collection point, ate my breakfast and waited. And waited. And got a bit bored! I managed to hold out until 1400 and then went for it. Nearly all the way up to Koblenz. Total distance for the day was about 61km which is really good and way ahead of schedule. I can now plan a rest day. Or rather another solar collection day!

I’m going to finish this entry now and make sure its posted before the battery runs out although right now its looking good.

Or thereabouts. It was a long hard day and ill write a bit more about it later. I’ve updated the map and am just off to have some food.

I’ve finally decided on the start and end points of the tour and I’m 90% sure that its going to cover 500km from Strasbourg to Duesseldorf along the Rhein. The route will take me through Karlsruhe and Mannheim, Mainz, Koblenz, Bonn, Koeln (Cologne) and will end on the Rheinufer (Rhein promenade) in Duesseldorf with a very large beer although I do reserve the right to spend more time working and therefore less time on the bike! If big news breaks, the main aim will be to work and test out the UMPC ‘office’ to its limits.

The planned start date is within the 3-day window 9th to 12th June and the end date will be between the 19th and 21st June.

I’ve been checking maps and comparing them to the ‘netzabdeckung’ (coverage map) from Vodafone Germany. Apart from a few GSM-only areas (which I guess will at least get me GPRS coverage) on the first stages of the tour, most of the route is well covered with 3G services. I really can’t imagine having any connectivity problems on the way. If there’s no signal I’ll just pick up my office and cycle to the next cafe!

Detailed dates will really depend on the weather which will start to come in range within the next few days. The current 14-day forecast via RTL Wetter (paid service) is looking good with a big change coming in the middle of next week. It might make sense to go as early as possible and that means I need to be ready! I’ve still got lots of items on the todo list although I heard to day that the tent and solar panel have been dispatched.  

I’m quite lucky to have been able to test a lot of UMPCs out over the last year. Most have been good in their own target markets but only some have been good for me. One of my favorites, the Kohjinsha SA1, an AMD based device is also one of the most-power efficient too and I took it to CeBIT this year where I used it exclusively for 5 days. It worked well and it demonstrated to me how much I might use a PC in one day. During the daytimes I was able to get by with a single charge – 4 hours. In the evening I was using it for another 2 hours, minimum! OK. CeBIT was a worst-case scenario. There was breaking news all over the place and there was one point where I was walking to a meeting with Intel and trying to edit and post a news entry at the same time. I don’t expect to be doing that on the bike! I do expect to be stopping 2-3 times per day for 30-60 minutes at a time though. Primarily to update my location, photos and geotags and to make quick reports here and also to work on any news that’s breaking. In the evening I expect to do a small amount of video editing, uploading and maybe a longer post, chat, IM etc etc. 2 hours is what i’ll give myself in the evening depending on the forecast for the next day.

At 9W drain (hopefully less in evening with low backlight and careful control of HSDPA and WiFi) that’s about 36W per day.

In addition to the UMPC I will have:

Mobile Phone. This is a Nokia 6380 with the 3.3v 900mah battery. 3watts. I will use this as my email and quick blog news checker using the gmail java app and the opera mini browser with bloglines mobile. These are combinations of applications that I’ve found very efficient and there’s really no need to turn on the UMPC to read email and RSS text. I can even do short emails on the phone too. If something interesting comes up then i’ll take the UMPC out of hibernate and do further reading, research or even email or blog. If I throw an hour or so of MP3 or FM radio in, I estimate that one charge per day on the 6280 will see me through. That will take about 5W of power from the power bank or I might be able to charge it in the early/late part of the day when the suns power falls below 70%.

Camera. This takes 4 x AA batteries. I use 2300mah 1.2v rechargeable batteries that should (if I use the camera carefully) last up to two days. That’s again, 5W per day. Charging will have to come from the solar panel during the day. Hopefully this can be done for an hour earlier or later in the day. Testing and research into different types of chargers needed. Smaller capacity batteries could also be useful.

GPS logger. This takes 2 x AA batteries every 15 hours. I hope that 2 batteries lasts me 2 days so that’s 2.5W per day. I will take a Bluetooth GPS device in case the logger fails. I think it lasts 10 hours on a 3W battery and can be charged from a USB port so its much the same in terms of power.

Lamp. This will be a very efficient LED lamp. Its possible to get ones that are solar powered or hand-cranked. I expect this to be a negligible drain. I will even take a few candles just in case. Bear in mind that it will be light until 2200 and will get light again at 0500. I don’t expect to be awake much during these hours!

Finally, something I haven’t mentioned yet, a backup PC. Well its more of a web tablet really. Its the Nokia N800 and it will run for 3-5 hours on a 5W battery. That’s very efficient and could serve as an email tool, IM tool and, at a pinch, blogging tool (although i’ll have to look into a mini keyboard solution for it.) This will only be used if the worst happens. I.e. I run out of power or the main UMPC breaks. Otherwise I won’t use it and it will stay packed away.

Total daily usage:

UMPC: 36W

Mobile Phone: 5W

AA batteries for camera: 5W

AA batteries for GPS logger: 2.5W

Total daily power usage: 48.5W

In the previous post I estimated I could average 48W solar power collection and storage per day. Bingo! Now, did I forget anything?

The other luxury I will give myself is a fully charged set of batteries before I go. I don’t think its unreasonable as anyone in their right mind would ensure that their batteries were charged before they went. Here’s the battery power that I will take with me:

• Powerbank: 56W
• Extended battery: 60W
• 2nd extended battery. Empty 
• 8xAA batteries for rotating through camera. 20W
• 4xAA batteries for rotating through GPS. 10W
• Phone charged. 3.5W
• Emergency UMPC charged. 5W

Total starting power: about 150W.

In theory, that lot will give me a 1 day buffer which means at some point in the tour, I can have a day of bad weather and continue as normal.

I will talk to select solar next week to see what they think of my estimates and if they give it the thumbs-up Ill start real testing – assuming the sun comes out!

The weather is still bad here in Germany and there’s no chance of getting reasonable testing done on a solar panel at the moment. The forecast is also bad so I’ve decided to send the test P3 panel back. In the very short time I was able to test it I was able to learn a lot though and its given me some thoughts about how I will move forward. This post goes over some of the stats, figures and calculations so its not exactly the most interesting post for the average reader. For those that are thinking about doing a similar thing though, this could be a very interesting post for you!

A very important lesson was learnt on the first day – the charging system doesn’t even start working until the sun reaches 70% of full power. This is due to the Li-ion charging system on the powerbank. It wont trickle charge so only kicks into life when there’s enough power to drive it. This renders about 8 hours sunlight per day as unuseable with this set-up.

The second thing learnt is that the charging system doesn’t work faster if there’s more power available. It seems that the power bank needs 12W to charge and will not take any more power if, say, 15W is available.  Thinking back to my basic electronics, I guess this makes sense! This means more waste though and requires balancing the charging requirements with the power available if i’m to use this set-up.

One very nice feature of the P3 panel was that it was able to charge the TabletKiosk powerbank directly, without voltage conversion. That helps a lot because the other solar panels i’ve looked at only drive 12V. That would mean converting voltage up to 19V and losing power in the process. Taking a few of the figures learnt, there’s a simple equation gives me the theoretical power possible per day.

Power available (W/hr per day) = Powerhrs x ChR

Powerhrs is the number of hours per day when the sun is over 70% power. (taken from sun power records. June. Bonn, Germany) This is about 7 hours in May, June and July.

ChR is the charge rate of the power-bank (must be about 0.7 of solar panel rating for best efficiency.) = 12W

This assumes a sunny day. No cloud cover. No shadows and the panel facing the sun. The changes of that happening are slim. I have the advantage that I’ll only leave the house if the 6-day forecast is good so I can reduce this risk to a minimal amount but I think I’ll lose another 20% through shadows and positioning while I’m moving. If cycling around becomes a problem with shadows and sun positioning I might have to carefuly plan my stops in order to maximise solar panel positioning. Maybe a stop at 10-11 and again at 3-4 would help get the best out of the early and late light.

So lets plug the figures into the equation and see what we get with the P3 solar panel and the TabletKiosk MP3400 power bank.

7  x 12 = 84W/hr energy per day assuming 15W from panel at max sun power.

Now for the second part of the equation:

1. There’s no such thing as a perfectly sunny day. Especially when you’re cycling. I’ve been advised to use a figure of 4 hours per day for sun. In my tests, on two sunny periods, I managed to load a 56W/hr battery in about 8 hours so the equation seems to be roughly OK. At a 12W load rate, that’s about 4 full hours of sun so I agree with the 4 hours rule.  
2. You can not charge and use the bank at the same time. This means that a second power source is needed for the daytime. In the evening its fine because I run from the powerbank. I could use the battery on the device UMPC in the daytime of course but what happens when its empty? Can I charge it from the solar panel (that’s stupid because I would need a second UMPC just to charge the battery – the solar panel will not be able to run AND charge a UMPC. Also, if there’s not enough voltage or current protection on the UMPC I would risk killing the UMPC) There’s is the possibility of topping up the UMPC overnight from the power-bank but If I do that, I have to consider the following…
3. To charge other devices from the bank, there is something like 20% power loss through the charging circuitry.

There’s one other point too. The powerbank can only store 56W/hr of power. Taking point 1)  into account brings me down to 48W/hrs on a sunny day which I guess solves the problem of limited powerbank capacity!

I think the best solution for point 2) is to use a second power bank. This also has the advantage of giving me a spare powerbank should one fail, and, being able to fill a second device should I find myself with sun and nothing to charge! It also reduces the risk of killing the UMPC and avoids the wastage of 3)

So we’re now at 48W/hrs per day. Its incredibly poor considering the power of the sun. In theory, the suns power is equivalent to 1Kw of energy for every m2 and that makes solar energy capture and storage horribly horribly inefficient. Consider that in 4 hours, about 2KW/hr of energy will be hitting the solar cells on the panel I tested. Yes 2000W/hrs. Enough energy to power a small UMPC for 1 month at 8 hours per day! The efficiency is a crazy 48/2000. Just over 2%.

How can this be improved? One thing I could do is to find a lower-power charging solution. That is, start storing energy before the sun reaches 70%. If you can start storing energy when the sun is at 50%, you have a few more hours per day and if you can start gathering energy at 30% power, you can even get some when its cloudy!

The second variable is the power-loss on charging. This is generally because the Li-ion batteries need a fairly strict charging voltage and current and there’s a fair bit of circuitry there to protect them. Lead-acid batteries could be better but, wow, the weight! To store just 70W/hr of energy you’re looking at 2.5KG. The 56W Li-Ion power-bank I have is just 500grams. 

The third option is to get a panel with more efficient solar cells.

Having said all that though, this is an off-the-shelf system that appears to work. I didn’t need to make any modifications at all and I like the idea that this project could go ahead with off-the-shelf equipment. It makes it easier for others to replicate it.

The big question now is, will 48W per sunny day be enough? If so, I don’t have to worry about the terrible efficiency and high cost. It will be enough to provide me with power where I can’t get it. I’ll be analyzing the power requirements in the next post to see if 48W per sunny day is enough. If it isn’t, i’ll have to go back and look at other options.