I’m actually in the process of doing away with the 24v pack for the wheelchair motors and consolidating on the 52v (13s) pack for both blades and wheelchair motors. The Sealed Led Acid SLA batteries I’m using for 24V aren’t performing very well. I upgraded to a roboclaw high voltage, 60v controller to drive those same motors. I figure I can run the wheelchair motors at 52v and 50% duty cycle and get about the same life out of them. Time will tell.
On the deck I starting by wiring a simple 5k potentiometer to manually set throttle position on the Alltrax. I manually turn the pot to start the blades before each run. I’m running it at 100% power which comes to about 50 amps (and about 2200 motor RPM producing 2600 blade RPM because the motor pulley is slightly larger than the blade pulleys…). My battery pack for the blades is a 13S lipo pack, 100Ah (52v, 5.2kwh) and I’m getting about 1.5-1.7 hours runtime. I like the elithion BMS I have very much.
On my to-do list is changing the blade speed/Alltrax inputs to be software-controlled (using an onboard raspberryPi) - the benefits of this will be able to set and maintain a particular RPM, and also the ability to turn the blade off when I don’t need it (which is, by my rough estimate, about 30-40% of the time! - time spent maneuvering u-turns at the end of each strip). I may also implement the blade control as a LUA script.
At the moment however I’m working on the ardusimple GPS. Hoping to get heading from 2 onboard GPS receivers using the RELPOSNED message. This will enable me to ditch the 4’ tall mast whose sole purpose is to keep the magnetic compass away from all of the EMF interference. This will enable me to mow closer to some trees that have low hanging branches.
While I’m at it I’m also changing my source of GPS corrections to not use mission planner, and instead use an onboard data modem to source corrections directly over the internet onto the mower, and feed the GPS corrections direclty to the GPSs. This will enable me to ditch my laptop whenever I’m running. All control will be from an onboard RPi with a touchscreen.