Jolla Solar Half prototype
 

I remembered last night that I had solar panel in my scrap box. The size was perfect for Jolla and a quick test proved that it can be used to charge Jolla too:

- voltage is about 6 V (measured with multimeter)
- panel outputs 40-80 mA under a lamp (measured with multimeter)

I haven't seen sun in a month or so here in Finland so the test was performed under 70 W halogen, distance ~10 cm.

http://relativity.fi/jolla_solar_toh/solar_toh7.JPG

More pictures:

http://relativity.fi/jolla_solar_toh/

Today I modeled new other half for the panel and printed the new model. The panel fits nicely. I dit not take yet pictures from the inside, but I soldered some wire to the panel outputs and glued wires so that they are in contact with Jolla power pogo pins.

UPDATE: Jolla's CSD tool shows charging current of -10 mA (at winter in Finland). This means the panel outputs about 100-110 mA at winter in Finland (the idle discharge current is about 100 mA). There's still room for 60-70 mA more, but this can be tested here when the sun is shining a bit higher at summer.

Under the 70W lamp CSD tool shows +50-60 mA, so the panel is giving about 50 mA out but the battery is still discharging. The phone still says that charger is connected.
UPDATE END

I have to test the Solar Half more, but it indeed seems to be working rather nicely :cool:

EDIT: .stl file available here: https://github.com/skvark/TheOtherHa...esolarhalf.stl
EDIT2: I misinterpreted the CSD tool. Yes, the phone says it's charging and yes, the CSD tool says "Charging" but under a lamp the panel is just limiting the disharge current. If the battery is actually getting more juice, the current is shown as negative value. However, the original 70-100 mA is still realistic.

Re: Jolla Solar Half prototype
 

wow amazing other-half :D

I imagine your 70W lamp is really lower than the direct sun exposition ?

Re: Jolla Solar Half prototype
 

What a coincidence that your solar panel from your scrap box was a perfect fit for Jolla :D

I'd love to see something like this commercialized.

Say...how much did you pay for that solar panel? (just a rough guess, I understand if you can't remember exactly)

Thanks in advance.

~Chinoman10.

Re: Jolla Solar Half prototype
 

I'd imagine so. Direct sun exposure is about 1kW per square metre. At high noon, with the receiver exactly perpendicular to the incoming sunlight.

By my VERY approximate calculations, his solar panel received about 5W from his 70W lamp. Most of it in the wrong wavelenght. So getting 360-480mW out of it (6V x 60-80mA) is actually not too bad a result.

Re: Jolla Solar Half prototype
 

Next Jolla phone should have audios tech on the touch screen. That would eliminate need for a solar other half.

Re: Jolla Solar Half prototype
 

I bought the panel from Adafruit (if I remember right) over a year ago. And yes, it was perfect :D

I think it was 10 USD. Panel: http://www.parallax.com/product/750-00030

So it outputs in direct sunlight max. ~167 mA.

Jolla Solar Half ProtoType 6V-2W (130mm-71mm)
 

Try to contact with some Solar Panel Factories to send you some test samples in the same size but with higher efficiency panels with specs such us 6V - 3W.
I already use 6V - 2W Solar Panel for my mobile phone Nokia 1020 (130mm*71mm).
I measure in direct sunlight at 14:00 about 220mAh.
Cost me 25 euros.

Re: Jolla Solar Half prototype
 

hmm.. seems that this is available in many places, though parallax is out of stock. e.g. Mouser.. Need to get one :)

just google "Solar Panel 6V @ 1W, 125 x 63 mm"

Re: Jolla Solar Half prototype
 

so, no components between the panel and the phone? so the phone has regulator that limits current for preserving 5v?

Re: Jolla Solar Half prototype
 

Looking at what rainisto said in the other thread about wireless chargers ( http://talk.maemo.org/showpost.php?p...2&postcount=42 ) a 'dumb' 5V source should be the best option.

Re: Jolla Solar Half prototype
 

No other components than the panel and wire. And yes, I think there's regulator (because the connectivity & TOH i2c specs are still missing can't be sure) :rolleyes: There's more information about the power input in wireless charging thread: http://talk.maemo.org/showthread.php?t=92059

EDIT: And you have to glue a plastic pin like in official TOH's to the panel next to the battery so the microswitch will trigger. Won't charge without it.

Actually that's not true. It charges without the pin too. Hmm..

Re: Jolla Solar Half prototype
 

microswitch, good to know!!

Re: Jolla Solar Half prototype
 

so what happens if you plug the phone into the wall charger with this toh and pput it under the sun at the same time?

Re: Jolla Solar Half prototype
 

I don't know, but I hope there's some circuitry or logic which selects only one of the inputs when they both are available.

Re: Jolla Solar Half prototype
 

maybe check dbus messages and see if you can differentiate between the two different power sources. if it is distinguishable, there might be hope.

Re: Jolla Solar Half prototype
 

I expect bad things to happen if you plug in a wall charger and do not put the solar panel under the sun at the same time. Or even without the charger, depending on how it is wired.

The reason is that the photovoltaic cells suffer when subjected to reverse voltage. Which means, if you connect the panel to a voltage source higher than the voltage produced by the panel itself.

So some sort of protection is essential. At least a diode if nothing else. This has been mentioned a number of times, for example here. Of course, your solar panel may have a diode built in, but I somehow doubt it.

Re: Jolla Solar Half prototype
 

Answer from #jollamobile:

13:48 < skvark> does someone know how jolla reacts if there are 2 chargers connected, another to the usb an another to the back power pins?
13:50 < Jonni> skvark: back power pins are disabled when usb cable is connected.
13:51 < Jonni> (and yes, I've tested it with my wireless charger toh)

And I'll add a diode there to be sure that nothing bad happens if the voltage gets reversed.

Edit: If there is a reverse protection already in Jolla, then the diode would be useless?

Re: Jolla Solar Half prototype
 

excellent! the pins are disabled when USB is connected. aaaaaaaah.

slightly off topic question: if the back power pins are disabled, will a TOH with a spare battery be impossible to charge when you plug in the wall charger? or is the reference in IRC only for input power pins?

Re: Jolla Solar Half prototype
 

How about printing the 2ndhalf so that there's an overhanging flap that covers the USB port when the solar kit is in use :D

Re: Jolla Solar Half prototype
 

You would naturally build the extra-battery-capacity 2ndhalf so that it connects to the battery terminals of the device.
(of course you need to design it so that it does not add to the existing battery but replaces it)

Re: Jolla Solar Half prototype
 

The answer from IRC only covers the wireless charger + usb cable test so I don't know. This is why we really need the official specs from Jolla.

Edit: juiceme has the answer for you :)

Re: Jolla Solar Half prototype
 

Actually that's not true. It charges without the pin too (took it off to test again). Hmm..

Re: Jolla Solar Half prototype
 

This is brilliant stuff! I'm really impressed and excited by this!
@skvark - I downloaded and printed a copy of your 'other half', it came out really nice, but sadly, it doesn't quite fit the phone in the length.
It was that tight that it started to bow the phone so off it came!
I used Netfabb Basic to cut a section from the lower half of the model and stitched it back together in Blender.
I'm going to my friends tomorrow to print it off, hopefully it won't be so tight!, perhaps we have some settings wrong on my mates printer, but when we measured the model the dimensions were as you set them.
Has anyone else experienced the same thing?, I've added 1mm to the length of the model to compensate but I will also check the software for the printer again.
Any info appreciated.
Regards
Mark

Re: Jolla Solar Half prototype
 

I'll look into this, but it seems there's about 0,4 mm error in the model length and PLA (if you used it) tends to shrink max. 1%. I'll keep you updated.

Re: Jolla Solar Half prototype
 

Thanks for replying. Yes, PLA was used and I understand what you're saying about shrinkage/tolerances.

I will post back later tomorrow after another printing session! :)

Re: Jolla Solar Half prototype
 

I did some measuring with the CSD tool (= phone is in airplane mode and I have turned the tohd.service off). Charging current under the 70 W lamp stabilized to 50-60 mA and some spikes go to 70-80 mA. If the CSD tool can be trusted (and the panel is actually charging the phone, like the phone and the tool says), there should be about 1% more battery every ~30 mins. To confirm this, I ran a short test:

I started testing at 18:00 (battery level was 85 %). Strange thing is that the UI does not update the battery level without a reboot (bug?). So I rebooted the device couple of times during the loading period. After every reboot there's was always 1% more battery level. Reboots were at 18:45 and 19:45. After the second reboot device reports battery level of 87 %. So getting 1% takes more than 30 mins.

Some conclusions:

- the 1W (125x36mm) panel is enough to upkeep the battery level and to charge the phone very very slowly (under a lamp, sunlight it would be maybe 2-3 times faster)
- for faster charging more efficient panel is needed

Re: Jolla Solar Half prototype
 

Or not but the reboot sucks some juice. Not sure about Jolla but on N900 a reboot always does.

125x36mm = 0.0045 m2. At full sumlight that should receive about 5W of energy. The best solar panels have about 20% efficiency. So it is not even theoretically possible to get more than 1W from a solar panel of that size without revolutionary technology advances. Sorry.

Re: Jolla Solar Half prototype
 

very cool stuff

Re: Jolla Solar Half prototype
 

Reboot propably sucks some juice yes. I was referring to this post: http://talk.maemo.org/showpost.php?p...78&postcount=7

The panel size is actually 125x63 (made a typo, not 36mm), so it gets close to 2W.

Re: Jolla Solar Half prototype
 

Just for imformation:

http://www.adafruit.com/products/1485#Technical_Details

http://www.adafruit.com/images/medium/1485_MED.jpg

This one is only 0,77 mm thick! :D

.

Re: Jolla Solar Half prototype
 

Sunny day today :) It seems that the CSD tool is showing negative current when the battery is loading even though there's is text "Charging" when it's positive too (I should have noticed this earlier...). The tool shows now -10 - +10 mA current when the phone is in sun (there's some snow in the air).

So the earlier results are ok but they have been just limiting the discharge current (though I don't still get how the battery can go from 85 to 87 % in 2 hours during the last test when it should have been going down to 83% :confused: (EDIT: this is because the phone was most of the time in stanby though I'm not sure did I have the NFC bug workaround in use during testing). So the panel gives at winter in Finland about 100-110 mA output, which is still 60-70 mA short from the max ouput. If the phone discharges at ~100 mA in idle (EDIT: Idle as in "screen on" and no software running. Standby current is about 10 mA when screen is of) , ~160-170 mA from the panel should result in 60-70 mA loading current. Better and a bit bigger panel should get to over 100 mA easily.

EDIT: Of course if the phone is shut down you'll get the ~100-110 mA more juice per hour.

Re: Jolla Solar Half prototype
 

Hi skvark,
I have a solar panel prized out of a solar charger and as I don't have a soldering iron (yet), I'm using copper tape to 'replace' wires.
My main confusion and question, is which of the GPIO pins am I to connect to on the rear of the phone?, I first thought it was the GROUND and 5V+ (which are side by side), am I right or wrong here?, I feel I'm so close to getting this working but am a little afraid of damaging the phone due to lack of 'electronics' knowledge - any info gratefully received,
Regards,

Re: Jolla Solar Half prototype
 

Yeah, connect the solar panel's '+' to 5V DC input and '-' to GND. Take a look at the page 14 in TOH technical specification. I'm myself just a SW dev with limited knowlegde about electronics :)

Re: Jolla Solar Half prototype
 

Thanks Skvark,
that is how I have it connected, but the CSD tool isn't indicating that any charge is being created.
The panel is definitely working, as I have a very powerful high intensity discharge lamp to work with (400 watts), which send my multimeter off the scale!, but I don't know what the specifications of the panel actually are.
I think perhaps I should find a different way to hook up to the inputs/outputs.
How have you made your connections?
Regards,

Re: Jolla Solar Half prototype
 

What's the voltage of the panel?
Do you have the panel datasheet or link to manufacturer page? Are you sure the connection to the pogo pins is ok (there's voltage in the copper tape, usually only the other side of the tape is conductive because there's glue at the other side)?

Re: Jolla Solar Half prototype
 

Hi,
i'd like to ask if these panels would be suitable for solar TOH:

http://www.flexsolarcells.com/PowerF...Components.php

I'd probably used two SP3-37 - but they make 6V - could this damage the phone?

Would the voltage drop enough (to 5V) when the battery starts charging?

Would it be possible to cover part of the panel to drop the voltage to 5V?

Thanks!

Radek

Re: Jolla Solar Half prototype
 

Hi,
sorry for a late reply and thanks for getting back to me.

PANEL DETAILS - The panel was removed from a solar charger, of which I believe is; 5.5v 100mA http://www.paramountzone.com/solar-m...ne-charger.htm

POGO CONNECTION - As far as I am able to see, my strips of copper tape are in contact and aligned with the pogo pins and the polarity is also correct. Yes, you're right the copper tape has adhesive.
https://scontent-a-lhr.xx.fbcdn.net/...28313292_o.jpg

COPPER TAPE - As you can see, I have run the copper tape in one length strips to the corresponding pins.
I realise this is not the best way to make the conenction, but it's all I have at my disposal, for now.
The original wires that were soldered onto the solar panel had left quite a blob of solder behind, so I feel quite certain, coupled with meter readings, that voltage is being carried along the tape, not that the Sailfish CSD tool seems to show any changes in voltage supply.
Regards,

EDIT: It only bloody works!! (My connection, where the old blobs of solder are just not quite making contact), but with reasonable pressure on the panel, it connects and charges! Yay!

https://fbcdn-sphotos-f-a.akamaihd.n...84424932_o.jpg

What do you glean from the reading on the phone's screen, Skvark?, good, bad?
Regards,

Re: Jolla Solar Half prototype
 

You need to compare the reading without panel and then with panel. That reading in the picture indicates that your phone is still discharging at a rate of 136 mA.

That 136 mA is imho very high discharge rate for the phone. My phone gives about 100 mA when running the discharge tool without the solar panel.

With the panel CSD tool shows discharging rate of 50-60 mA (lamp) / 0 - -10 mA (sunlight) (= panel gives 40-50 mA (lamp) / 100-110 mA (sunlight)). Do you have multimeter to measure the panel real mA output?

Re: Jolla Solar Half prototype
 

I myself use a 6V panel (fluctuates between 5-6V depending on light source), but I think that a step-down converter to 5V is necessary for non-proto stuff. I'll have to check what the phone reports as the voltage, those are multimeter values. Covering the panel partly may be possible, I have to test that too.

EDIT:

cat /sys/devices/platform/msm_ssbi.0/pm8038-core/pm8xxx-adc/dcin

Result: 4522986 Raw: 32421

So phone says 4,52 V (cloudy sky). This may get a bit closer to 5 V if I make better connections :D Take this with a grain of salt but it seems to be safe to use 6 V panels.

Re: Jolla Solar Half prototype
 

Oh, okay, seems I misunderstand how these things work. I see what you are saying now, I think. A quick peak now at discharging rate, shows it is around 115mA without solar panel.

I do have a multimeter. I'm no expert at using it. With a 20 watt lamp over the panel, I get an output of around 5mA (again I maybe reading this wrong), or do I add a zero and it becomes 50mA?
My apologies for being a dickhead where this is concerned, I did all this at school, many. many, years ago and have forgotten ALL OF IT! :D :(
Thank you for your help so far :)