# First Test - DIY RC Lawnmower



## CalgaryPT (Jan 29, 2020)

Fired it up for the first time after completing some shop tests. Not much grass to test on yet though.

It's just temporarily wired for now. Next step is to write the Arduino code for the tilt and strike sensors, test those and tweak the code. After that comes a complete tear down and painting, then final wiring where I can make things neat with split loom, etc. Lastly, I just need to wire in the mower blade motor to the relay and adjust the deck height.

I may build a solar powered parking garage for it so I can recharge the batteries automatically, but we will see. Can't find a 24 VDC solar charger so I got a honking big solar panel that I'll alternate across my two 12V batteries with some circuitry.

Video of it actually running is here (the rattling sound is the electronics box I didn't have bolted down yet):


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## PeterT (Jan 29, 2020)

Nice job PT. I can tell that represents a lot of work.

I don't quite comprehend the inner workings of RC chargers, but I know they 'step up' input voltage to charge/output batteries at higher voltages. Just as example I bought this charger a while back when I was charging 6S lipos, decent watts per channel. I think the power supply I got at the time 24V but I think the charger itself can accept a range of input voltage, charging time will vary. RC guys are always in a hurry to recycle packs at the field but sounds like you would be more trickling in between sessions.
https://www.progressiverc.com/icharger-406duo.html


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## CalgaryPT (Jan 29, 2020)

Nor do I but I will have to learn. I use a lithium pack for the TX but the real charging issue is the mower and power units themselves. The power unit uses two 24V AGM (scooter) batteries in series to drive two 250 Watt 24V motors. I have a 24V battery tender for that, but eventually want to solar charge these batteries with a 12VDC 15W solar panel I have. I'm thinking about building a circuit that will first charge one battery @12V, then switch over and charge the other. Then it will alternate back and forth to trickle them at 12V, so when I reconnect them again I'll have 24V to power the drive unit. My calculations show I should get 60-90 mins of drive time from these two 35 AH batteries. They are the weak point in the project, but that is still more than enough time to mow my small yard.

The mower motor for the blade uses a separate 40V lithium power pack. I need to learn more about these so I can build a replacement pack as I am sure in a few years I won't be able to find one.


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## YotaBota (Jan 30, 2020)

All it needs now is a seat for pooch.
https://duckduckgo.com/?q=dog+driving+tractor&t=canonical&ia=images&iax=images


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## CalgaryPT (Jan 30, 2020)

That's too funny.


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## DPittman (Jan 30, 2020)

CalgaryPT said:


> Nor do I but I will have to learn. I use a lithium pack for the TX but the real charging issue is the mower and power units themselves. The power unit uses two 24V AGM (scooter) batteries in series to drive two 250 Watt 24V motors. I have a 24V battery tender for that, but eventually want to solar charge these batteries with a 12VDC 15W solar panel I have. I'm thinking about building a circuit that will first charge one battery @12V, then switch over and charge the other. Then it will alternate back and forth to trickle them at 12V, so when I reconnect them again I'll have 24V to power the drive unit. My calculations show I should get 60-90 mins of drive time from these two 35 AH batteries. They are the weak point in the project, but that is still more than enough time to mow my small yard.
> 
> The mower motor for the blade uses a separate 40V lithium power pack. I need to learn more about these so I can build a replacement pack as I am sure in a few years I won't be able to find one.


Looking good!


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