Outdoor #ESP826 ?
How are folks powering their outdoor / remote IoT devices? I’m not about to spend $20-30 on a 3 watt solar panel, charge controller and battery system to power a $2 wireless sensor node (or any sensor node for that matter.)
The $10-15 solar power bank things are a laugh with their 0.5 to 1.0 watt panels, I doubt the solar barely overcomes the current for the management circuity.
This is a good question, hope we get some good answers. Yes I agree small panels are probably very bad due to the overhead of the charger… so if cost is not crazy its best to over design the solar end 
Looking into rolling my own right now Parts list: 5/6 pin Li+ pulse charger, ~3 watt solar panel for under $10, inexpensive li-poly pack with integrated protection and a 3.3v ldo regulator. Should be able to fit these things on a small carrier board with room for an esp-07/12
For my nodes I’m using a couple of AA batteries. With alkalines and a reports every 5 minutes the nodes run for about 2 months. I’m planning on changing the report rate to once every 15 minutes which will get ~6 months. I’m using the ESP-12.
http://sensornodeinfo.rockingdlabs.com/component/tlnode/
@JERRY_DUNMIRE that is great to hear! I assume you’re using the deep sleep function? Something I haven’t experimented with yet. One question, lots of websites talk about GPIO16 to REST for deep sleep… is REST still pulled to Vcc through a resistor?
Yes, deep sleep is the key. The reset pin should be pulled up and you probably want a capacitor to minimize accidental resets. Check out the schematic for the T&L Node.
@Gordon_McLellan Any progress or specs on the panel you’re using here Gordon. I’m not too familiar with solar panels and could use some advice.
@Stefan_Nordlander I was just shopping ebay for panels, there’s a bunch in the ~3 watt range advertised as USB solar panels… never bought anything. What is your application, charging a battery or directly powering an ESP?
@Gordon_McLellan I’ve got both an ESP-12 module and one with an integrated LiPo battery charger (charges via micro USB) so I guess the simplest initial solution would be to use the Huzzah Feather which has the on board charger and just connect a panel to it.
Will that “just work”? I mean, can I simply connect a 5V solarpanel to the LiPo charger or will the irregular charge from the panel damage the battery over time?
Adafruit doesn’t list what chip they’re using to charge the Lipo. Off the cuff, I’d say you’re OK as long as you stick with a very small panel. Open circuit voltage is what could be the problem, if the chip is a strict USB charging chip, it might not tolerate more than 5.5v on its input. While the battery is dead, that’s fine, it will load down the panell, lowering the voltage. once the battery is full, the charging chip will see the panel’s open circuit voltage (charging transistor is off). For that matter, the 3.3v regulator on the board might not handle more than 5.5-6v as well.
My plan was to use a lithium ion pulse charger, like the MAX1879… as I recall it accepts up to 20 volts input.
@Gordon_McLellan Thanks for the info. Nor sure I’ll risk it though. It seems Adafruit has special chargers for sale for solarpanels.
If you’re able to determine the chips, you can know exactly. I didn’t look to see if there was a schematic published for that board or not. Another option is to put a 7805 regulator across the solar panel. You’ll lose some power, but keep the voltage safe.