Report your batteries

I'm using 2 X 18650 3200mAh batteries with my DIY Nybble. Mine are Tanuoyi brand purchased on Amazon. They work fine and seem to last ok but not great. When I start having weird behaviors I know it's time to swap them out and recharge them 😉 (go to Amazon and search for "TANUOYI 4 Pack Battery for 3.7v 20A 3200mah")

Does anyone have a current link to batteries that will work with Nybble? I have bought a couple different ones and they are still not right. I need a physical link to a buying page or some detailed buying info, with item numbers and/or prices or something…

Hi @Rongzhong Li ,

I have issue that looks similar (Servos move in calibration mode) but I have a dog with the original battery from you guys. Does it mean my battery is misbehaving?

I'm using the model XTAR 14500-800 (Li-Ion, 14500, 3,6 V, 800 mAh, Button Top) which can be ordered here:

https://www.reichelt.de/industriezelle-li-ion-14500-3-6-v-800-mah-button-top-xtar-14500-800-p253362.html?&nbc=1

It has a current protection at 4.5 A and is working fine with Nybble.

The power supply to the chip and RPI will always be regulated to 5V. It's separated from the servos powering network. Your powering option on the servo won't affect the chip so it's safe.

The documentation for the v0_2 board states the following:

NyBoard can accept 6~9V power inputs. Be careful with the polarity when connecting your power supply to NyBoard’s battery socket. There’s “+” and “-” besides the socket. Reversed connection may damage your NyBoard! • To isolate voltage fluctuation caused by servos’ movement, NyBoard provides two independent power management. One supplies a stable 5V power to the chips, the other supplies an adjustable voltage (4.5-7.5V) to suit most models of servos. To ensure safety during operation, please do not connect the servo to NyBoard first.Check the rated voltage of the servo, use a voltmeter to monitor the output for servos and adjust the potentiometer to obtain a desired voltage.

So it seems, by using the out-of-the-box voltage management of bypassing the potentiometer, I should get at least a stable 5 volts served to the servos and and RPi...

Further, under Features it states:

• Core processor: ATmega328P working at the frequency of 20MHz.

• Power input: DC 6-9V

• Power output: Two independent power supplies, 5V to chips (3A peak), 4.5-7.5V adjustable voltage to servos (5A peak). Dial counterclockwise will increase the voltage for servos. The stable voltage range will shift with different input voltage. Due to the resistance in chip, the maximum output will be lower than raw input. Stable 7.5V can only be achieved with 9V input. Try to use the lowest voltage that can complete your motion requirement, to reduce the wearing of your servo’s gears, and increase both circuit stability and battery life.

I'm tempted to use the adjustable voltage option to get the full 7.5v stability with the 9v input, but I may run the risk of damaging my RPi board since its max tolerance seems to be around 5v.

Incidentally, I ran Nybble for about 30 minutes today on and off and he seems to be running well, I didn't connect the RPi this time though. Nybble didn't seem to walk any faster than when I "air-walked" him using the board-resetting lithium 14500 batteries. I think the voltage regulation is supplying a steady 5v as per the documentation, but I don't have voltmeter to test voltage output.

An alternative I'm trying out is the Keenstone 9v PP3 Li-Ion 800mAh. This is because I wanted to power both Nybble and an RPi with a single, lightweight battery. The battery is protected and it also means changing the battery holder out, but so far it seems to work well powering Nybble and an RPi 3B+

I've only run Nybble for about 10 minutes and the RPi for about the same time plus a few minutes running in calibration mode, so need to run further tests to ensure no malfunctions occur as I did notice a slight stutter whilst Nybble was walking 9 minutes in...

I've tried SAFT 3.7v 14500 Li-SOCl2 which don't work well, looks like their too weak as they seem to run fine when Nybble is in the air, but when on the ground, Nybble keeps resetting.

Since we're on lock down I finally got the kitten built and running on one of these:

https://www.amainhobbies.com/eflite-2s-lipo-30c-battery-7.4v-800mah-eflb8002sj30/p147074

It works fine and has just enough duration for debugging. I'll want to install something bigger (more mAh) before I plug in my Pi, though.

Obs!!!!

This cell is a "flat top" type, that is it need's something to make the positive contact in the battery-holder.

Also be very aware to put positive to the right side as it is flat.

Regarding "flat top's"

http://uhomeshopping.blogspot.com/2013/10/about-18650-batteries-pt3-of-4-choosing.html

http://www.lygte-info.dk/info/Battery%20button%20or%20flat%20UK.html

Works fine for me,

Vapcell ICR14500 1000mAh - 3A,

https://eu.nkon.nl/rechargeable/vapcell-icr14500-1000mah-3a.html

Test of the cell,

http://budgetlightforum.com/node/64318

Im using GTF 14500 Li-ion 3,7 V 2800 mAh https://es.aliexpress.com/item/1000004324121.html?spm=a2g0s.9042311.0.0.469163c0uv9XO3 and now seems to work doing this on Nyboard v0.2: Connect the jumper wire SW3 between BATT and V_S.

I was wondering if there is any reason why the 14500 form factor is specified. In many batteries I have seen on the market I find that the cell capacity is limited to 800mA and in my case 2.3A (which is not enough for all motors, Ultrasonic sensor and RP, not to mention a future camera and IR light).

I would be interested to know if the Li Ion 18650 can be used. Specifically, the Samsung 25R (model INR18650-25R) is a 2500mA battery with a maximum continuous drain current of 20A. From the specs it can provide 5A for 30 minutes (Using 97% available capacity to residual voltage of 3.3V) (http://dalincom.ru/datasheet/SAMSUNG%20INR18650-25R.pdf).

Any comments or suggestions?

Best regards

D L

Klarus 14GT-80UR 3.7V 2.96Wh 4A 800 mAh 14500 Li-ion (Micro-USB Charging)

Works (most of the time).

Protected and fits the original batterie holder. AFAIK other Klarus batteries wont work due lower discharge limits, this is the only so far.

If you hit the 4A limit on heavy movements or if you run Nybble to long and the batteries gets hot Nybble just stops. A batterie holder on/off is then needed.

I think in consideration of safetyness its a good compromise to use this batterie and charging it directly through USB is really a killer feature at all! :D

Ordered it here (internatianal shipping, it took one month to Austria):

https://www.lightmalls.com/klarus-14gt-80ur-3-7v-2-96wh-4a-micro-usb-charging-high-discharge-800-mah-14500-li-ion-battery-1-pc

I've observed 4A average, 4.5A peak current through batteries when Nybble is in trot gait. When rest, the current will be some 50mA.

So far there're two major bottleneck in the power output. One is the battery, the other is the step down chip. You can check section 4.1.4 in the instruction doc.