Batteries,
First as a RC hobbyist and a flash-light one (you will be surprised what is out there :)) I will try to give some info. regarding Petoi Nybble's batteries.
It is very important to have the right cells for a successful operation of Petoi Nybble.
The reason is that the draw current is relatively big when several servos is in operation like when you let Nybble walk.
So,
You have 3 categories of 3,7V 14500 batteries.
The 14500 stands for the physical size, that is 14mm x 50mm, that is the same size as a "regular AA" battery with the main differences that instead of 1,5V or if a rechargeable like NiMH 1,2V the single lithium cell delivers 3.7V.
Categorises of 14500 3.7V:
Non rechargeable 3.7V cells (Saft LS14500, Li-SOCl2 - never put these in a charger!)
Rechargeable 3.7V cells with protection (Li-ion - discard cells if under ~2.7V, check data sheet)
Rechargeable 3.7V cells unprotected (Li-ion - discard cells if under ~2.7V, check data sheet)
No manufacture if I am correct do provide protected cells, but other companies add a small circuit at the end (makes the cell slightly longer) to prevent discharge to where the cells cease to work properly, that is when the cell gets a voltage lower than ~2.9V.
This small add-on do have it's limitation in possible draw current, and that is what causes problem with Nybble if used and why unprotected cells is needed.
The non rechargeable cells (Saft LS14500, Li-SOCl2) also have a relatively low draw current and will not work.
A good thing is that Nybble do have a voltage monitoring function which can be read about here in the second post in the thread,
https://www.petoi.com/forum/clinic/partially-alive
Generally me and many with me say do avoid 14500's with names containing "fire", "ultra", "ultra fire" there is a lot to read about this on the net.
And any 14500 with fantasy numbers of mAh that is anything above1000mAh should be avoided, there are some with fantasy mAh numbers out there.
So how to avoid getting scammed when buying a cell, and get something that actually delivers what is promised?
I really do recommend the forum I link to below that are for flash-light enthusiast, there you can search for the brand of cell/charger you are thinking about to buy and be reasonable sure there is a test/review of that particular brand with the actual mAh and discharge current tested/measured.
There are also some extensive tests and recommendations on cheap chargers which you probably also will need to be able to charge your cells.
I stress that I am not affiliated in any way with any brand or company, just a regular user there.
Link to the forum,
http://budgetlightforum.com/forum
Rechargeable Battery Reviews and Tests,
http://budgetlightforum.com/forum/batteries/rechargeable/reviews
Charger Reviews,
http://budgetlightforum.com/forum/batteries/chargers/reviews
Struggles problems you might experience when it is time for calibration,
I would recommend that you take your software installation and nyboard for a test run before mounting it into the cat to ensure functionality and verify your software installation.
If you have installed the Arduino package and the FTDI drivers the board by it self will run on the power provided only by the USB cable and you should be able to upload a sketch if it all works out.
Be super careful to insert the FTDI adapter the right way and not to have any metal stuff close to the board that accidentally can short out you Arduino board.
When you do load the "writeinstinc.ino" and have brought up the serial monitor to issue commands for the calibration it does not work. The first thing is to make sure that in the serial-monitor in the bottom part that you have the choice: "no line ending". If this is not the selected option it might take you a couple of steps but you will never reach "loading instincts" which is a must to be able to do the calibration. A typical run with something else than "no line ending" will end you with "Gotcha" and you will never see the "loading instincts".
Some empiric battery tests,
If you have the wrong batteries you might be able to do a bit of calibration, but when you load up the main sketch the remote might just take one command and then hang.
I did test with a couple of non chargeable (Saft LS14500, Li-SOCl2) that I had at home and I could barley do a calibration, and managed only to get Nybble to walk if I held it in the air with no physical load on the servos.
With protected cells I could not even calibrate Nybble, so get the right cells.
Flat top unprotected cell info. Important read!
Be aware that most unprotected cells do not have a top on the positive end, that means you have to put something onto it to make contact with positive in the battery-holder.
That also means that you have to be extra careful when put the cells in so they got in the right way.
I will quote some info from this site below that covers this and workarounds,
http://uhomeshopping.blogspot.com/2013/10/about-18650-batteries-pt3-of-4-choosing.html
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1. Button vs Flat Top;
2. First thing to note is the +ve end of the 18650 battery : Button or Flat Top. Here is a good article to read on;
3. http://www.lygte-info.dk/info/Battery%20button%20or%20flat%20UK.html
4. When you buy a 18650 battery, take note if it is a Button or Flat Top as some devices need a Button Top as in some torchlight while some High Drain devices need a Flat Top as a Button Top is too long to be inserted in. So buying the wrong type, it may not fit in your device. Of course one may buy a Button Top magnet to put on a Flat Top to solve the problem.
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Edit's in this the third post in the thread,
2020-02-09 - creation of post
2020-02-14 - an important addition to this post "Flat top unprotected cell info. Important read!"
