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Wood frame for Aricxi tarp tent

April 25, 2021 — BarryK

I posted about erecting the Aricxi tarp tent in my back yard:

The tarp is 15D silnylon and just over 300g. I like it, but the inner mesh bivi that it came with is tiny, and also very awkward to get in and out of when underneath the tarp.

I purchased both together, but Aricxi also sell them separately.

Forever seeking that "perfect tent", a new project has commenced. I decided to use the Aricxi tarp as the starting point, and sew my own mesh inner tent. I have a sewing machine, and can sew, just barely. So this will be an interesting experience -- will be sewing 10D silnylon, silicone-coated both sides, so incredibly thin and slippery. Will also be sewing thin no-see-um nylon mesh.

Did some planning with SpaceSolver, however, ran into limitations with the 3D modelling. Decided that it would be good to erect the tarp and then take measurements on the real thing. This is like a dressmaker's dummy, except I am doing it with the tarp.

Today, bought three 30x15x2700mm painted pine from Bunnings, and built this:


Setup inside, can drape the tarp over it The frame is 123cm high at the front, 55.5cm high at the back, and that ridge piece is 221.5cm long.

So, will be able to work on this project inside, out of the weather. Now impatiently waiting for the 10D silnylon to arrive from China. Very difficult to source this lightweight fabric. Want nylon with silicone coating both sides -- not the breathable kind, waterproof. There are vendors in the USA and the UK, but China is the main source. is one place where the manufacturer's sell their goods, and they even sell small samples, but need to be a registered business to register with However, I found one vendor on, ordered from them.  

Tags: light

Accurate test of CLAITE 10W 5V solar panel

April 14, 2021 — BarryK

I tested the panel recently, and got a strangely-large short-circuit current:

I have had this anomaly before. What is happening is that the pulses from the switching regulator are confusing the digital multimeter. At the higher load, the output filtering capacitor is not smoothing the pulses as effectively, and the pulses are upsetting the multimeter. So that over-2A short-circuit current is wrong.

Today was sunny, at least in the morning, and tested the panel with the switching regulator removed, directly connected to resistance loads. Today is April 14, 2021, Perth Western Australia, bright blue Autumn sky. Test conducted from 10.45am to 10.50am.

Solar irradiance (intensity) measured at start was 870W/m2, at end 880W/m2. Ambient temperature was 24degC. Negligible breeze.

The panel was sitting in the sun about 5 minutes prior to testing. About midway through the test, took a reading of the temperature at front of panel, IR reader held about 100mm away, reading was 47degC.

Here are the readings, and a plot:



I estimate peak power point is about 4.8V @ 0.84A, which is 4.05W.

So, if you reckon the vendors are cheats, advertising the panel as 10 watts, you would be right.

Note however, that they are claiming 10W with a cell temperature of 25degC and solar irradiance of 1000W/m2. Power output drops as temperature rises, and if I guess -0.3% per degC rise, then the rise from 25degC to 47degC will cause a power loss of 7%.

Then there is the irradiance. If I assume power output will climb linearly with increase of irradiance, then that 4.05W would become 4.6W. Then factor in the cell temperature, and we get the power output at 1000W/m2 irradiance and 25degC as 4.97W.

Just about half what the vendor claims!

It does make it hard for those vendors on eBay and Aliexpress that do the right thing and publish correct power output.  

However, they are good photovoltaic cells, more efficient than those in my SE05 panel. So the panel is a good choice for hiking, where we are chasing lighter weight.

What the vendor does not say, is what coating is used on top of the cells. As I understand it, the cheapest is epoxy-resin, then there is PET, then better still ETFE. The cheap option, the coating will perish in the sun, whereas ETFE will give you 10 years lifetime (I think, from memory).

For someone who will take the panel hiking, perhaps perched on top of their backpack, it probably won't matter what coating is used, as hikers are only going to be out there occasionally.

However, something to think about is the switching regulator. That will be sitting on top of your backpack, right near your head. It oscillates at about 300KHz and radiates much higher frequency components. It is, effectively, a radio transmitter.

There you are, out in the pristine wilderness, living a natural life. yet you have this thing on your backpack radiating RF into your head!

It might not be doing any harm, but for me it really does not fit with being back to nature. That is one of the reasons that I intend to replace the regulator with a linear regulator. Look at earlier blog posts for my design, and soon I intend to post a design that will handle up to 2A. My regulator is small, efficient, and replaces the switching regulator, and does not radiate any RF. Watch my blog, new regulator design expected soon! Note, I found a vendor who sells a raw panel without regulator, and has PET coating, so have ordered that and will report back.   

Tags: light

Some considerations for 5V solar charging

April 08, 2021 — BarryK

A couple of days ago, I posted a comparison of two small 5V solar panels:

And I am looking at replacing the switching regulator in the CLAITE "10W" regulator with my own design linear regulator, similar to the one I constructed in 2016:

For that regulator, I used a LM2940 LDO (Low Drop Out) regulator, 5V at 1A maximum output. This time, I would like the design to handle higher current. Not that I really need to handle higher current, as that "10W" panel is so pathetic -- I did a quick test of it today, bypassing the regulator, to find out what it is really capable of, and only got about 0.7A at the peak power point, however, sky was a bit misty and solar intensity was only 815W/m2.

Even if I can get solar intensity up to around 1000W/m2, it looks like won't be getting 1A out of that panel. Which will be under 5 watts, probably well under.

Anyway, would like to construct a linear regulator that can handle about 5V @ 1.2A. Altronics sell an LDO that is rated at 5A:

...HOWEVER, it is not suitable. The voltage drop from input to output is at least 0.8V, which is too high. Dredging back into my memory, I see from the internal circuitry, that the high voltage drop is due to the darlington transistor configuration. Also, it does not have reverse current protection, and a schottky diode would be required to prevent current flow back into the panel -- which will cause more power loss when charging current is flowing.

Found this one, L4940V5, rated at 1.5A max., pretty much the same design circuitry as the LM2940, with even lower voltage drop, around 0.3 to 0.4V. Meaning, that if 1A is flowing through the transistor, 1x0.4 is 0.4W -- no heatsink required. It is that PNP transistor configuration that achieves the low voltage drop. Ordered it from eBay:

Also available from other vendors, such as:


In the above link to tests done in 2016, I mentioned how the Chinese phones determine if a charger is limited to 0.5A or is capable of up to 1.7A. Simply by shorting D+ and D- together marks the charger as capable of the higher current. This article explains:

...what is also very interesting in that article, is it shows details of the circuitry inside a phone.

Actually, that detail of connected D+ and D- together is a USB standard: also mentions how the requirements for Apple phone is different.

The above article contains links to PDFs that show charging circuits, and it does look possible to satisfy both Android and Apple high-current determination, with three resistors.   

Tags: light

Comparison of CLAITE 10W and SE05 5W solar panels

April 05, 2021 — BarryK

I tested the SE05 "5W" 5V solar panel in 2016:

I recently purchased the CLAITE "10W" 5V solar panel:

It has been cloudy recently, but today the clouds cleared, just a bit of faint mistiness, so did a quick comparison of these two panels.

Date is April 5, 2021, 1.00pm, fairly clear sunny sky, solar intensity reading is 830W/m2, ambient temperature is 30 degC -- Autumn, but quite a warm day. Negligible breeze.

I used resistances to place different loads on the panels, and plotted voltage-current graphs. Here is the CLAITE "10W" panel:


Here is the graph of the SE05 "5W" panel:

img1 the latter graph, see the foldback effect, which I think is a very good feature.

For the SE05, the peak power point is about 4.78V @ 0.59A, which is 2.8W. For the CLAITE panel, peak power is only about 4.86V @ 0.6A, which is 2.9W. You see why I am putting those "5W" and "10W" ratings in quotes!

Hmmm, it seems that the CLAITE panel is throttling its output. It has a short-circuit current of 2.16A, which is an indicator that this panel potentially has a much higher peak power point.

I did a quick test connecting the CLAITE panel to two Android phones, and got 0.52A and 0.57A. My 2016 post explains D+ and D- pin connections required for Android phones. Shorting D+ and D- together made no difference.

Measuring the resistances between the GND, D+, D- and 5V pin on the USB socket, there are resistors connected to D+ and D-, indicating this panel is designed to charge Apple devices, not Android devices. Here is information for Apple devices:

Anyway, connections of the D+ and D- pins does not matter when just applying resistance loads, as I did for the above graphs. The regulator in the CLAITE panel is throttling the output. It should not be doing that.

It looks like I will have to sacrifice this panel, see if can open up that regulator, maybe replace with my own that I built in 2016 -- see link at top of this post.

EDIT 2021-04-06:
Today, just after 11am, I noticed that the clouds had cleared, just some wispy clouds off to the sides, but quite intense blue overhead. Did a very quick test with the CLAITE panel, time 11.30am, April 6, 2021, Perth, Western Australia, sun intensity 885w/m2, ambient temperature 27 degC. Negligible breeze.

I did this very quickly, didn't allow the panel to completely warm up in the sun. Just brought it out from inside, aimed it at the sun, running through an inline voltage-current digital meter, and wrote down the readings.

Charging my Huawei phone, a 2019 model that I actually purchased early 2020 (so I escaped the Google embargo), battery was at 93% and the charging was 4.90V @ 0.78A, which is 3.82W.

Then plugged in my Voltaic V15 battery bank, which is approximately 50% charged, and read 5.05V @ 0.62A, which is 3.13W.

I expected better with the stronger sunlight, but those reading are nowhere near the claimed 10W!

I need to find out what the panel is actually capable of, without the regulator getting in the way. I used a serrated kitchen knife to cut the plastic covering, exposing the regulator:

img1 the bottom are the two tabs from the panel, so I should be able to remove the regulator and solder directly to those tabs. The glue is flexible, probably a silicone sealant, so should be able to pry the board off.

The main chip is "XL1410E1" and on the next line "01103". Would be interesting to find the specs on it. 

EDIT 2021-04-14:
Here is a more accurate test of the CLAITE "10W" solar panel:

...hikers, note the comment about the switching regulator!   

Tags: light

Portable bidet for hikers

March 25, 2021 — BarryK

I posted recently about a small titanium trowel for digging "cat holes" while hiking:

In that post, posted a link to a video by "Paul the backpacker", showing how to use a portable bidet instead of toilet paper. Consequently, I ordered one off eBay, not the same ones that Paul mentioned, just one that I discovered while searching for "portable bidet" and "travel bidet" on eBay:

...that is stocked in Australia, so was fast delivery for me, but if you want, you can get it cheaper from China, for example:

It arrived yesterday, and had the first opportunity to test it today.

Firstly though, a bit of background. I first visited India in 1980, and most places I stayed at had squat toilets. Indians use a small bowl, known as a "lota", filled with water, and the left hand to wash the bum.

I adopted this with some trepidation, but ended up becoming a fan of this method. Prior to that, I often had an "itchy bum", but after adopting washing the bum, the itchiness went away totally.

When you wipe the bum with toilet paper, as Paul explains, all that you are doing is smearing the shit around on the skin. This can lead to various skin conditions, including infections.

One Indian person told me that they thought foreigners are "dirty" because they don't wash their posteriors when go to the toilet. This was a totally new viewpoint for me.

In Western toilets, some with-it people have installed bidets, which is great for them. I think that the Japanese have bidets in most homes.

In a normal Western-style toilet, a lota can be used, though a bit awkward. This is what I do. Some people use the bathtub -- which is very awkward, as you have to move from the toilet seat across to the bathtub. Some people have a shower every time after going to the toilet.

Today, on my Western-style toilet, got the first opportunity to test the portable bidet. I plugged it onto a 600ml mineral water bottle:


I used about 120ml of water, but this was being cautious and could probably have used less. I have a special towel to pat the bum dry afterwards, and confirmed that it got the posterior (and left hand) completely clean.

But then, I have years of experience with this kind of cleaning. Someone who has only ever used toilet paper might find it needs practice.

Paul gives excellent advice in his video. One tip he gives is to squirt some water before doing your business, which greatly aids in washing it off. Here is his video:

I know that some people find this kind of topic to be embarrassing. Well, at least I haven't posted any demonstration photos! Seriously though, it is an important topic...

Apart from personal cleanliness with using a bidet, toilet paper is a disaster from the environmental viewpoint. Yeah, all those trees getting cut down, but a more immediate problem is that buried toilet paper often ends up not-buried, as animals dig it up. This can spoil otherwise pristine scenic locations.

I have ordered another one of those bidets, one to use at home, the other for hiking. Still not sure which is best, lota or bidet. Probably the bidet, as the water is focussed -- with the lota, water can get splashed all over the place.
One good thing when hiking, you could use any water, from rainwater tank, stream, pond, whatever.   

Tags: light

Looking for collapsible bottle for dirty water

March 22, 2021 — BarryK

I posted about the Sawyer Mini water filter kit taken on the last hike:


That flat bottle can be filled with "dirty" water from stream or pond, or even from a rainwater tank, and filtered through the Sawyer Mini into another bottle.

However, it is difficult to open up internally, to fill from stream or pond. I have been hunting for an alternative bottle, and purchased this, 500ml size, as it has a 28mm thread:


It arrived today. Unfortunately, the thread does not fit the Sawyer Mini. Read a bit about threads, found this:

The thread looks very similar to that on the Sawyer bottle.

This bottle is made with TPU body, and is only 18g without the lid, 28g with. The previous TPU bottle I purchased is 57g.

I confirmed that this bottle is very easy to fill from a still pond surface. It's natural tendency is to be "open" internally, so just putting the bottle flat on the surface of the water -- as I tested in a sink -- the bottle completely fills in a matter of seconds.

Pity about that thread. Thinking might cut off the thread and glue the thread from the Sawyer bottle onto it. Selleys plastic glue that I have previously used for solar water distilling experiments, forms a very strong bond, and might do the job. See here:

Or, could test other inline filters. There are competitors to the Sawyer Mini.

EDIT 2021-03-23:
To experiment with different threads, have ordered these from China:



They are quite cheap. Interesting that I am consistently finding items on Aliexpress to be cheaper than on eBay. Also, "Aliexpress Standard Postage" to Australia is fast.  

Tags: light

Sleeping bag versus quilt

March 20, 2021 — BarryK

I am currently revising the hiking gear, an exercise to reduce weight when hiking with the Daylight lumbar pack.

A couple of weeks ago, posted about reducing weight of the shelter system:

The shelter system is an ongoing project. Heh heh, there are hikers who spend their whole life looking for that "perfect tent". I am the same, and confess to being a "tentaholic".

Anyway, this blog post is about the sleep system. Here is the report on gear used in the last hike:

The sleep system:

Sleeping bag (S2S Micro III, in compression bag)
Mattress (Nemo Tensor insulated short mummy)
Pillow (S2S inflatable)
Pump (S2S)

The pillow has developed a leak, and on the last hike had to improvise a pillow using the Daylight pack.

Rethinking the sleep system, and after considerable online reading, I have decided to go for a quilt rather than sleeping bag. These are a special kind of quilt designed for hikers.

This is a very good overview:

I am a side-sleeper, and turn from one side to the other 3 or 4 times during the night, even more when in a tent. My mummy sleeping bag ends up all twisted up, and often the head-section ends up on top. A quilt allows you to toss and turn.

However, there is one significant downside. That tossing and turning may result in air gaps on the sides, not so good in cold weather. This would probably be the number one reason why some people prefer a sleeping bag. One guy who uses a quilt and is a side-sleeper, reported that sometimes his bum would stick out and get cold.

Ideally, I would like to train myself to sleep on my back, not turn from side to side. Proper use of the straps would help. We shall see. I have ordered one from a guy here in Australia who makes them to-order. He is very popular, and currently has a backlog of about 6 weeks.

This is what his quilts look like:


...that one has a zippered footbox, so can be opened up completely, good for hot nights.

Usage of the straps is optional. Some hikers don't use them. Their purpose is to keep the sides down, so you don't get side draughts. They can go either under or over the mattress.

The one I have ordered has more down fill than the S2S Micro III, yet is much lighter. Here are the weights, the quilt is the "-8 regular" model with zippered footbox, 950-loft down and 10D fabric:

Stuff sack

I will post details on where it is ordered from, after it arrives. The chap is struggling with a backlog right now, so let him catch up a bit.

Some interesting developments with the pillow, but will post about that later. There will be a later post on the complete new light sleep system.

If you want to watch some videos:   

Tags: light

10W solar panel for USB charging

March 20, 2021 — BarryK

In 2016, tested some of these small panels: choice for hiking is the SE05 "5W" panel, which actually generates about 3.4W. I cut it down a bit, so weighs 92g:


The claimed cell efficiency of the SE05 panel is 17%. While browsing on Aliexpress a couple of days ago, noticed some panels claiming 24%. This "10W" panel claims 24%:

...dimensions are 24x14cm (not 26x14), claimed weight 138g.


Have ordered it. Very interested to find out how close to 10 watts will get out of it. I plan to plot the voltage-current output as did back in 2016. The brand name is given as "CLAITE", so that is how I will identify it ongoing.   

Tags: light