This is what I used, just remember it’s upside down, so invert it in the config.txt, and using this will also make the spi on the robot hat not usable. I covered the robot hat’s spi pins with a blank femal gpio header, and the upper battery pack mounts to it.
The 2S 21700 battery pack will fit in the same space as the Sunfounder original battery on the robot, however you have to install the battery by removing the two vertical spacers between the upper and lower body, squeeze it in and replace the spacers.
OH ONE LAST THING, CHECK POLARITY THE SUNFOUNDER BATTERY CONNECTORS ARE BACKWARD FROM NORMAL BATTERIES! If you build your own battery pack from 21700 batteries, and you wire it normally it will fry the board. You have to take a multimeter and make sure you get the positive and negative leads correct. Balance lead of course goes in the middle.
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Which parts did you buy for the battery pack like BMS, nickel strips. I keep picking out parts but I don’t know if they will work together
So the Sunfounder Robot HAT’s handle the BMS and charging. The sunfounder batteries, are not only wired backwards, they are unprotected, and wont work with anything other than sunfounder prodects. Most companies do this, make their gear only work with their products. So, to make an exact copy all you are doing is putting wiring then in series with .2mm pure nickel strips. I went with 20awg solid copper wiring, (Silicon stranded is fine too) and you have 3 wires coming out of the battery: + mid - If you build the power upgrade make sure you label it just for the Sunfounder Robot HAT, it will not work in other devices, and may even cause a fire. Only charge the battery using the Robot HAT, unless you build yourself a custom charging unit just for this. Here is a pic of a charger unit I made to charge the battery pack seperate from the hat: A 20 amp BMS, ans a 2S 2A c-type charge module. The 3 leads on the bms go to the JST-XH 3 pin connector. Connect the battery, and a C-type power source, and it will have a red LED for charging, an a blue LED when full.
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I see you have usb wireless on that rig. did you have any trouble getting it to work with the picrawler?
I’m having trouble with my picar-x, the provided software has issues using usb wifi. pretty sure the issue is the software is assuming the wireless is wlan0 and the usb wifi is wlan1
P.S. Those are some cool mods you got on that thing.