solar power on a Pine64 tablet

[Little_Johnny]

im making a Pine64 tablet with a c4 labs screen case, i want to put a 5v solar panel with a 5v 2A voltage regulator on the back to charge the 3.7V Li ion battery, im thinking about using a usb plug from the voltage regulator to the pine64 board, my questions are is this possible and do i have the voltage and amps correct to charge?

[MarkHaysHarris777]

im making a Pine64 tablet with a c4 labs screen case, i want to put a 5v solar panel with a 5v 2A voltage regulator on the back to charge the 3.7V Li ion battery, im thinking about using a usb plug from the voltage regulator to the pine64 board, my questions are is this possible and do i have the voltage and amps correct to charge?

If your voltage is constant, and clean, then yes you may get away with it.  Better would be at least 2.5A (2500ma), @ 5.1v;   and this as long as you're connecting to the pine board's DCIN;  euler bus pin(4  +5v), pin(6  gnd).

The axp803 PMIC controls the charging, along with the ARISC. Don't try to charge your lipo directly with the 5v system!  (you will be sorry, but I spare you)

It might be better to have a 12v SLA system that powers the pine(s) via dc-dc converter;  have your solar system charge the 12v system, and allow the pine to run off the 12v feed via CPT or other dc-dc.  (this is how my setup works)  Be sure to have good filtering between the dc-dc converter and the pine(s), with plenty of decoupling caps. Its important to have the DCIN clean, and constant.

[pfeerick]

im making a Pine64 tablet with a c4 labs screen case, i want to put a 5v solar panel with a 5v 2A voltage regulator on the back to charge the 3.7V Li ion battery, im thinking about using a usb plug from the voltage regulator to the pine64 board, my questions are is this possible and do i have the voltage and amps correct to charge?

What sort of solar panel... is it one of these fold out ones with built in USB sockets? If so, skip the next paragraph, which focused on a self-build system. One of things you didn't explain though was what sort of useage was this tablet going to get, which will dictate how much charge it will need. If it's something like an hour or two of use a day, and it being off the rest of the time... then this might actually be practical, even on a cloudy day. 

Your volts and amps are indeed right to provide the 5v to the pine64 to power it and charge the battery via the microUSB port or DC_IN euler pins, but my question would be although you have a 2A capable regulator... what is the amperage of your solar panel, and will it provide say at least 1A at 5v. If you're cheating and using a voltage regulator instead of a proper solar management system, the solar panel needs to be a higher voltage, say a 9-12v panel, and your buck regulator able to accept that as the input voltage. Then you might have more luck. As things stand at the moment, you would be rely on the solar panel to be putting out more than 5v so the regulator has the overhead voltage it needs (to get 5v of a switching regulator, unless it is a hybrid linear/switching or passthrough capable regulator, it needs more than 5v in). 

As Macrus suggested, you would probably be better off with a 12v system... as you can get small 12v panels really cheap (20w should just about do it, although 40w would be better - more is better, especially for overcast days), and then use a charge controller and a SLA/car battery. Bigger and bulkier, but the best way if you want reliable solar power. But obviously won't be fitting onto the back of the pine64 case.

[Little_Johnny]

thank you heaps for the info guys, the tablet probably wouldn't get used a real lot, and would be used with android for music, games and net, i haven't selected any panel yet, im a bit of a noob to allot of this stuff but im learning fast and love it, i had a look on ebay and i seen this solar kit too, would it possibly work? http://www.ebay.com.au/itm/172668558091

[pfeerick]

would it possibly work? http://www.ebay.com.au/itm/172668558091

That is everything except for the internal battery which it needs. Once you add a battery to it (not the one in the pine, the solar power bank needs its own), as long as you consider that it may take that unit 2 or 3 days to fully charge between uses... it would probably be fine. However, I really, really, REALLY don't like those sorts of chargers... as lithium batteries do NOT like getting hot (it's one of the three quickest ways to kill/severely reduce the service life of a lithium battery). Plus the solar panels are pretty crappy, and don't charge them that fast at all... they're really there as a selling point and only good for cosmetic appearances... they might as well have just painted them on for all the good they really are. 

In all honesty, if you want the more portable route, you'd be better off with a 10,000mah-ish power bank (especially  if it supports passthrough charging so you can use it and charge it at the same time) ... I personally can't go past the Xiaomi powerbanks for quality and performance... and a folding solar panel like this (just an example... that one probably isn't the cheapest, but is a good brand and should be able to power the pine64+LCD and charge the pine64s battery in most conditions without any dramas). Then you'd also be able to use that setup with anything else you have that needs USB power / charging when you're not using it for the pine64 tablet combo. 

The only other option is to get some 6v (preferable tempered glass for longevity... the normal epoxy ones will probably only last you 6 months before the epoxy crazes) solar panels, 18650 batteries and holders, a solar charge controller, a 5v boost module, and protection circuitry for the 18650 batteries, but that will probably cost more than an off the shelf combo to be honest, especially if you don't get it right the first time.  But if you want to do it to learn, then great, all the better!

[Little_Johnny]

would it possibly work? http://www.ebay.com.au/itm/172668558091

That is everything except for the internal battery which it needs. Once you add a battery to it (not the one in the pine, the solar power bank needs its own), as long as you consider that it may take that unit 2 or 3 days to fully charge between uses... it would probably be fine. However, I really, really, REALLY don't like those sorts of chargers... as lithium batteries do NOT like getting hot (it's one of the three quickest ways to kill/severely reduce the service life of a lithium battery). Plus the solar panels are pretty crappy, and don't charge them that fast at all... they're really there as a selling point and only good for cosmetic appearances... they might as well have just painted them on for all the good they really are. 

In all honesty, if you want the more portable route, you'd be better off with a 10,000mah-ish power bank (especially  if it supports passthrough charging so you can use it and charge it at the same time) ... I personally can't go past the Xiaomi powerbanks for quality and performance... and a folding solar panel like this (just an example... that one probably isn't the cheapest, but is a good brand and should be able to power the pine64+LCD and charge the pine64s battery in most conditions without any dramas). Then you'd also be able to use that setup with anything else you have that needs USB power / charging when you're not using it for the pine64 tablet combo. 

The only other option is to get some 6v (preferable tempered glass for longevity... the normal epoxy ones will probably only last you 6 months before the epoxy crazes) solar panels, 18650 batteries and holders, a solar charge controller, a 5v boost module, and protection circuitry for the 18650 batteries, but that will probably cost more than an off the shelf combo to be honest, especially if you don't get it right the first time.  But if you want to do it to learn, then great, all the better!

iv'e been working on this for several weeks now, ill upload pics later, i have a 7mm thick 4000mah li-on battery with the thermister trick, my pine seems to charge too slow, is there any way to boost charging time

[Little_Johnny]

would it possibly work? http://www.ebay.com.au/itm/172668558091

That is everything except for the internal battery which it needs. Once you add a battery to it (not the one in the pine, the solar power bank needs its own), as long as you consider that it may take that unit 2 or 3 days to fully charge between uses... it would probably be fine. However, I really, really, REALLY don't like those sorts of chargers... as lithium batteries do NOT like getting hot (it's one of the three quickest ways to kill/severely reduce the service life of a lithium battery). Plus the solar panels are pretty crappy, and don't charge them that fast at all... they're really there as a selling point and only good for cosmetic appearances... they might as well have just painted them on for all the good they really are. 

In all honesty, if you want the more portable route, you'd be better off with a 10,000mah-ish power bank (especially  if it supports passthrough charging so you can use it and charge it at the same time) ... I personally can't go past the Xiaomi powerbanks for quality and performance... and a folding solar panel like this (just an example... that one probably isn't the cheapest, but is a good brand and should be able to power the pine64+LCD and charge the pine64s battery in most conditions without any dramas). Then you'd also be able to use that setup with anything else you have that needs USB power / charging when you're not using it for the pine64 tablet combo. 

The only other option is to get some 6v (preferable tempered glass for longevity... the normal epoxy ones will probably only last you 6 months before the epoxy crazes) solar panels, 18650 batteries and holders, a solar charge controller, a 5v boost module, and protection circuitry for the 18650 batteries, but that will probably cost more than an off the shelf combo to be honest, especially if you don't get it right the first time.  But if you want to do it to learn, then great, all the better!

iv'e been working on this for several weeks now, ill upload pics later, i have a 7mm thick 4000mah li-on battery with the thermister trick, my pine seems to charge too slow, is there any way to boost charging time

my battery seems to be lasting around 6 hours on idle with android 5.5 and the thermister trick, it takes about 6 hours to charge on ac this doesent seem right, will it charge faster with a battery that has a thermister, the pine is also telling me its a 2850mah battery and its ment to be 4000mah

[Madhuwesly]

Hello,

I am Madhuwesly, working on a Carrier Board based on SOPine A64 SOM module.

Q1:

It is mentioned in AXP803 data-sheet that "AXP803 features an IPS circuit to transparently select power path among DCIN/USB(VBUS)/Li-Battery to system load", What I want to do is in-place of USB(VBUS) supply option I want to provide 6V Solar panel supply directly to the VUSB pins, will there be any issues with this kind of configuration?

Q2:

It is also mentioned that "If the current is still insufficient, charge current will be reduced to zero, and battery is used for one of the power sources", so whenever the current is insufficient from Solar panel, will it consider automatically the battery power source as one of the power source??

Thanks & regards,

[pfeerick]

@Little_Johnny Sorry for not responding earlier. As far as the capacity goes, IIRC it is not indicative of the actual capacity of the battery - it is a static number hard-coded in, so just ignore it. And unfortunately, yes, due to some misconfiguration of the PMIC charge registers, it does not charge anywhere as fast as it could, pretty sure it is around the 500ma-600ma charge mark, so six hours does sound about right...

@Madhuwesly Maximum voltage for VBUS for the AXP803 is 11v, so the 6-7v it'll see from the solar panel sounds like it should be fine. I'd just check the schematic for the sopine compute module to make there is no 5v logic in the VBUS/ACIN path... From the quick look I had at the schematic, it looks like it should be fine - I can't see anything else sharing the DCIN/ACIN voltage lines. http://files.pine64.org/doc/SOPINE-A64/S...er-0.9.pdf

And yes, if a battery is present, the AXP803 will act like a UPS... if there is enough current to run or charge, it will run from the VBUS/ACIN, else it will run from the battery. Or, I should say, that is how the pine64 and pinebook, which are basically the same hardware (A64 processor, AXP803 PMIC, etc) operate.

[Little_Johnny]

im still playing around with the solar, i got it to charge off a solar power bank kit, that way was using 2 separate battery's, and not enough solar input, the solar power bank usb port was going to the euler bus pins 4 & 6, im going to have a play around with it over the next few months, so i can use 1 battery charged by solar or charged by the pine64