The LoRa.Net board has a Lipo charger with load sharing: excellent choice of MCP73831. Does anyone know what’s the best for a always working node with Lipo/Charger and Solar? I had this question in mind for long time.
I have both of them, I just need to cable then and put node device monitoring their Lipo bat and solar level and send them to emoncms. Do you have connected vsolar (from solar panel) and vbat (brom battery) to a CPU analog input (using voltage divider of course) to be able to check them ? could be interesting
I’ve done this last year with a seedstudio basic Lipo Rider charger (no load sharing or MPPT) results were interesting, as you can see Solar goes to 6V (on day) but not when charging at the beginning of the day because charge (500mA asked) must load the solar panel and thus create a voltage dropout (On the night node was sending using lipo power so needed to charge) until charger decided that the Lipo was charged and stop charging it.
I can’t remember if I had flashed node with sleep mode between send and I think charger was charging (no way to change that due to all 403 CMS resistors too close from each other)
Here the whole thing, as you can see chinese solar don’t like outdoor humidity, I stopped measure because was unable to solder back red wire to the solar panel
two voltage divider on a solder board to measure Solar- and Battery power
–> https://thingspeak.com/channels/137976
The final construction should base on a RN2483 in case for the RFM9x there is no sleep implemented in the actual library
It is not in the library but you could easily put the ATMega in sleep mode when receiving the event EV_TXCOMPLETE, it is what I do for my GPS tracker.
By the way I ordered cheap lipo charger and was wondering if it is enough to charge a 18650 cell : there is no MPPT or clever use of the solar panel but those chargers can be set to use weak currents, so weak charge on solar panel. My boards use 3.5 µA in sleep mode (without power regulator, need to check that) so I think it might be achievable.
Does somebody tried ? If not I’ll do when I receive my chargers and post the results
it won’t work as expected, because your solar panel output in clouded conditions is fluctuating to much.
put something like this in the middle to keep the input of the charger module constant and replace a resistor on the charge module to lower the current.
oh, and not all 18650’s are equal (forget the chinese ultra fires! )
@BoRRoZ is right about vooltage (I didn’t even thought about this point, thanks), and we must take into account some points:
Solar panels don’t deliver same voltage, mine are approx 6V, some are more, some less, so may be a module with step up AND down may to the trick. @rob notified me about excellent and cheap pololu ones. Chose the output voltage in the range of the one needed by your charger.
solar panel don’t deliver enough power also, trying to charge at 1A is on my point of view too much and create a voltage drop on the solar (look at the 1st graph, 4.5V instead of 6V when charging), I would try with 100mA, since a day is approx 10H long, it should be large enough to charge. But it depends on your power needs. I’m pretty sure a Node with sleep mode could survive with small 400mAH lipo and 100mA charging.
All of this need to be tested, I’m trying a node revival to test these, I’ll keep this posted here
We are doing a node revival as well. We have a lot of Roofnet-style nodes in the field that we are going to retrofit with TTN… we have to “roll a truck” anyhow to reclaim / reposition the dead nodes so this is an opportunity to upgrade as well.
lipo’s tend suffer from a capacity drop under a certain temp (I still have to test in my freezer. )
but because you have a buck/boost converter in between I don’t think you will notice… well, there is not much/enough sun in the winter anyway.
Humm, a well designed PCB with WeMos and RN2483 could fit right out of the box
No Charles, don’t open Eagle CAD, this is an addicting software!!!
@BoRRoZ, would you mind post a picture of the electronic board or if you know it, the chip used to charge and step up/down boost ? It’s a 2nd Generation, right ?
I think they mean by ‘second generation’ that there is now a pir inside.
The ‘first’ generation had a condensor mike and reacted to sound to switch on the LED’s
Also they make clever use of the solar panel itself to detect day/night, so it don’t switch on the LED’s during daylight hours.
I’ll try to make a close up of the guts …
@BoRRoZ
you won, I’ll have now my cash reduced by 30€, I just bought 3 for 30€ free shipping from amazon and the good news, is that I should have them to play in few days instead in 1 month from China
And this is all your fault, admins should ban your account here
Something fancy in the spécifications Li-ion battery span life: 500 circles => if charge always happen on day it’s 1 year and 5 month, hope charging occurs only at certain step of discharge
Specification
Solar panel: 0.55W, 17% efficiency
Li-ion battery: 3.7V 800mAh
Switch inside for saving power during shipment
LED: 16pcs, SMD3528
Lumens: 100lm
LED span life: 50,000 hours
Solar charging time: 8 hours
Lighting mode: Dark/bright; Bright: motion activate for lighting
Auto identify day or night
Safety Features: Over charging, over discharging, over current, short circuit
Li-ion battery span life: 500 circles
Solar panel span life: more than 5 years
Yes there is a hidden switch, so in the package you’ll find a needle to switch the unit on, don’t forget it like me… after days in the sun still no power
also if you are impatient (and you are ) it is clever to mount a separate TP4056 charge module, because when your package arrives and there’s no or a little sun …
close up of model-1 electronics, the type number is sanded off.
Thanks for sharing, I have some JST lipo connector, can see there place to connect on PCB, I’ll change this then it will be easy to change/charge. After this it’s easier for maintaining and testing, I like plug/unplug
(forget the chinese ultra fires! )
. )
