I wouldn't power it from battery. To consuming.
Had one powered with two AA batteries. It lasted for one week.
Changed the nano with a pro mini 3.3v and now it runs forever.

There is a new maintainer for the module in fhem. He implemented a lot of new stuff and also the smartsleep feature. For example nodes are now showing if they are sleeping.
Also messages to the node are delayed till it wakes up the next time.

If you want to force the ID for the Sensor node you can add

#define MY_NODE_ID 200

before

#include <MySensors.h>

This will overwrite the Node ID in the Arduino EEPROM. If the Unit is powered up and connected to the Gateway you can remove the define. The ID should now be stored in the EEPROM.

Nothing fancy. Got my new ts100 today and I pre-soldered some V10 easyPCBs with 3.3v Arduino pro minis.
The iron is pretty good. It is Louis Rossmann approved. Now I need a good 24V power source to drive this thing.

if (!isTransportReady())
      wait(MY_RECONNECT);

your node just needs to be awake to reconnect to the gateway.
I've set MY_RECONNECT to 5000 (5sec).
So far this works for my sleeping battery node.

isTransportReady could also be isTransportOK. depends on the version you are using.

I've found some typos on the serial api page.

S_DIMMER	4	Dimmable device of some kind	V_STATUS (on/off), V_DIMMER (dimmer level 0-100), V_WATT

V_DIMMER needs to be V_PERCENTAGE

S_HVAC	29	Thermostat/HVAC device	V_HVAC_SETPOINT_HEAT, V_HVAC_SETPOINT_COLD, V_HVAC_FLOW_STATE, V_HVAC_FLOW_MODE, V_HVAC_SPEED

V_HVAC_SETPOINT_COLD needs to be V_HVAC_SETPOINT_COOL

I bought the ender 3 (non pro) from gearbest. So far I'm very satisfied with it. For 180$ it is a very good printer.
The bed surface I upgraded for a PEI one. This thing is awesome. Very clean bottom surface and the prints are easy to remove.
Later I will add a bltouch for automatic bed leveling. Then I want to replace the board. In embedded stepper motor drivers are a bit to noisy. No need for in terms of quality. Mostly for silence reasons. Another great addition is a raspberry pi with octoprint. With this you can run your printer wirelessly over WiFi.
200$ is already very cheap. I wouldn't by a cheaper one than the ender 3.
If you need more build volume you might better go with the 10s from creality.

@Reza this is a #define MY_RECONNECT 5000
just put a time in ms into the wait function.

It might be possible to power the Arduino off the output pin. Since they are dirt cheap I would just test it.
But like the others I would suggest to use the interrupts of pin 2 and 3.
For my battery powered 3.3v pro mini I use 3.3v pir sensors without the voltage regulator. The standard 5v pir needs at least 4.5v just to step it down internally to 3.3V. On these I had problems with voltage stability because I stepped it up to 5V. Also the battery lifetime was poor.
With the 3.3v pir version this thing runs for months. With the solar panel on top maybe forever.

I bought this one:
US $24 47%OFF | RM109 Palm-size True-RMS Digital Multimeter 9999 counts Square Wave Backlight AC DC Voltage Ammeter Current Ohm Auto/Manual
AliExpress

It is Dave Jones approved and served me very well.
Here is his review:
Youtube, Dave jones, review

I bought the ender 3 (non pro) from gearbest. So far I'm very satisfied with it. For 180$ it is a very good printer.
The bed surface I upgraded for a PEI one. This thing is awesome. Very clean bottom surface and the prints are easy to remove.
Later I will add a bltouch for automatic bed leveling. Then I want to replace the board. In embedded stepper motor drivers are a bit to noisy. No need for in terms of quality. Mostly for silence reasons. Another great addition is a raspberry pi with octoprint. With this you can run your printer wirelessly over WiFi.
200$ is already very cheap. I wouldn't by a cheaper one than the ender 3.
If you need more build volume you might better go with the 10s from creality.

If you want to force the ID for the Sensor node you can add

#define MY_NODE_ID 200

before

#include <MySensors.h>

This will overwrite the Node ID in the Arduino EEPROM. If the Unit is powered up and connected to the Gateway you can remove the define. The ID should now be stored in the EEPROM.

Nothing fancy. Got my new ts100 today and I pre-soldered some V10 easyPCBs with 3.3v Arduino pro minis.
The iron is pretty good. It is Louis Rossmann approved. Now I need a good 24V power source to drive this thing.

@sullivan-buchs how did you get 7e1 mode on an uno working?
I have some Energy Meters working with Meter-Bus and the IEC1107 protocol. Couldn't find a proper working software lib for serial communication. I solved the problem using the hardware Serial ports on my Mega.

There is a new maintainer for the module in fhem. He implemented a lot of new stuff and also the smartsleep feature. For example nodes are now showing if they are sleeping.
Also messages to the node are delayed till it wakes up the next time.

@flyingdomotic thank you. I also had some problems with some nodes which worked very nice on 2.1.1. When I worked on some of the nodes and updated to 2.3.1 I noticed, that communication wasn't so great anymore.
On first glance this fix works on my plant sensor node. Hope it stays that way now.

Some people are saying with debug on it works and without it, it doesn't maybe the Debug line before the ce(low) does the same thing as your delay.

I wouldn't power it from battery. To consuming.
Had one powered with two AA batteries. It lasted for one week.
Changed the nano with a pro mini 3.3v and now it runs forever.