I built a robot mower using a new cub cadet swivel mower and added two invacare motors to the rear with a 24v 40 amp alternator. I'm using a sabertooth 2x25 controller and powered by two 18ah batteries. My problem is that the batteries are getting hot and don't last long at all. I was really hoping to keep the smaller batteries with the alt picking up the load. This doesn't seem to happen and the alt I would have hoped would have powered say 3/4 of the energy needed to run. The alternator is a 24v delco si10 1 wire and the positive lead goes to the positive terminal on the battery and the neg is grounded to the frame. I'm using 10awg wire for everything. I can see the volts increase on the batteries when idling but I would have thought the alternator would have loaded the motor when demand increased. That doesn't seem to be the case. I would love to hear what others have done and how they wired it.
I have 90% of the mower complete and have done test cuts with success other than I can't finish the front in one charge. This has been a fun project but my ignorance is getting the best of me and this build.
What is the actual current draw of your motors under load?
What are you using for a regulator on your alternator?
What is the actual voltage across your batteries at idle vs when mowing?
For the batteries to be getting hot, either there is too much of a load placed on them, or, the charge voltage / current is too high.
If you look at my robot “Jazzy”, I too am using wheelchair motors but mine draw less than 6 amps under full load. I too am using a Sabertooth controller, 12AH gell cells, and a solar charge controller for power distribution. One upgrade in the works is using a DC/DC up-verter to convert my 12VDC battery power to 20VDC for the motors. Since they were originally designed as 24V motors, they are not quite fast enough at 12V, even with the larger diameter wheels.
I need to find current draw. I live on a hilly yard so I figure I’m spiking a little.
The alternator is supposed to have an internal regulator and it seems to be pushing 28volts. I was hoping the motors would pull 5-7 amps. I have to try and find out. I’m really new to this and learning as I go.
Well I seemed to have figured it out. I was able to cut my yard and still have power. I rewired the mower and added a negative wire from the alt to the battery. My first attempt was to add a wire to the chassis.
I just need to make a box to hold the controller and receiver plus add a solenoid to kill the mower, and this project is done!
I need to read up on stepping the power down and adding the solenoids (all new stuff to me ha)
