beach cart

purehavoc81

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Dec 3, 2021
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I am building a beach/fishing cart to help move everything from the parking lot to the waves. I already have the cart and a set of 48v geared hub drives motors that i am working on the controllers for. this will be a heavy cart (400# plus loaded) that requires low speed 3.5-4 mph for walking with. i would have rather run a chain drive system, bit clearance from a 13" tire chain drive in the sand limit that. current motors on hand are 600w 48v geared hub (5-1) 13" "wheelbarrow" motor/tires w/100nm torque. current max speed is around 8 mph (200rpm). i need to cut that in half to around 3.8-4 mph. would i be better served to run a 24v battery system or try to slow down the 48v system? i want to keep as much torque as possible to start the cart in soft sand. battery life is always an issue, but 1.5 miles is a max day for me
 
You're best off using 24V with higher amp controllers. You can probably use up to twice the amps that your motors are nominally rated for, but half the voltage. This will result in problems if you stall the motors or drag them down to the low end of their RPM range at high load, but if you avoid that situation the motors should quickly spin up to their cruising speed and run relatively cool at high efficiency.
 
I am interested too. Have you modelled the motors on grins ebikes.ca site? Asking because i used similar to build a slow speed mobility quad for my son. The 48v controller will modify the voltage wave so the motor "thinks" it has less voltage and therefore slower speed when you apply less throttle. Your issue in sand will more likely be lack of traction from the wheelbarrow tread versus the torque those wheelbarrow motors can put out. Sorry if you know all this. My next build is a beach fishing cart too but using two bafang fat front g60.750 48v on 20" rims at front and balloon wheels on the rear. Better to pull from front to avoid wheels digging in (same as manual push vs pull on beach). For you with 13" wheels if you also use balloon wheels for the other end you should distribute weight more over those to float more of the weight and therefore less torque needed to drive it. For +400lbs nothing stopping you putting dual axle balloons on the other end (6x2 monster) I am planning to use my 60L camping compressor cooler fully loaded plus tackle and rods so about 150kg plus weight of trolley. Likely close to your weight.
 
Well I was wrong about my two g60.750 fat geared hub motors on 20" rims - modelled it on ebikes.ca today and not enough torque before motor overheats.
 
JB in TH said:
Well I was wrong about my two g60.750 fat geared hub motors on 20" rims - modelled it on ebikes.ca today and not enough torque before motor overheats.

What voltage did you assume?
 
As stated above, a 24V system can be designed to work well for this.

However, due to the large selection if small inverters that will convert 48V to 220V AC, I would recommend considering 48V as an option, even if it would require an additional stage of chain/sprocket reduction.
 
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