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Another beach cart project

I'm looking to finish my 24v beach cart project. I would like to build this cart extra heavy duty. I have already some parts, but i would like to see if you could guide me in the right direction. I would like for the cart to be able to move 400lbs in beach sand with some incline as you might find at a beach. I have 15 x 6.50 wheels that will be used. I would like to go with a belt instead of chain because of the beach sand. I would need to know what wattage motor, motor controller, throttle and what amp hr batteries I would need? Thank you for your assistance.
3 people like this idea
The gear motors that we carry have chain sprockets that are factory installed on them and we are not able to get belt cogs that fit these motors, so if the beach cart will be belt drive then the belt cog for the motor will need to be custom machined or modified to fit the motor.

I ran a gear ratio calculation for chain sprockets and marked the outside diameter sizes of the chain sprockets which you can use as a guide for the outside diameter of the belt cogs to install. This calculation is using or MOT-36600G 36 Volt 600 Watt gear motor. Here is the calculation.

image


If you are planning for the beach cart to travel at walking speed then a 600 Watt gear motor will have enough power and the right amount of gear reduction for the conditions that you described. A controller for brushed motors rated at 600 Watts or higher will be compatible with this motor. We have full length and half length twist throttles and thumb throttles that could be used. We also have reverse relays and switches if you want the beach cart to have reverse.

The Ah rating of the batteries depends on how much run time that you want the cart to have. I can run some calculations to figure out the battery pack size. If the cart is traveling at a walking speed of 3 MPH then for a 3 mile round trip the run time would need to be 60 minutes. Do you know how many minutes of run time that you would like for the cart to have?
Thank you for getting back with me. I would like to get a run time of 1.5hr, if it's within reason. The machining of the pulleys/cog would not be an issue. I have access to a machine shop for said work. I'm not to interested in reverse I would prefer a free wheel option so I can maneuver it in and out of elevators. What size batteries do I need and is the free wheel an option?
A 1.5 hour run time is easily obtainable with the right size battery pack. I ran a run time calculation and discovered that a battery pack made from three 12 Volt 24Ah batteries is estimated to provide a 90 minute run time at full throttle. Operating the beach cart at less than full throttle during any of its travel would increase the run time over this estimate.

image


We do not carry 12 Volt 24Ah batteries however we do carry 12 Volt 22Ah and 26Ah batteries so the estimated run time could be lowered or raised a little depending on which battery size is selected. 
https://electricscooterparts.com/batteries2.html


We carry freewheels and freewheel axle adapters so having a freewheel in the drivetrain is definitely an option. Our axle adapters are available for all common axle sizes such as 1", 3/4", 5/8", 15mm, and 20mm.



These freewheels and axle adapters are available on these pages:

https://electricscooterparts.com/freewheelclutches.html

https://electricscooterparts.com/freewheel-to-axle-adapters.html


All of the parts could be purchased individually or we could make a kit out of them. The advantage of buying a kit is that we install matching and labeled connectors on all of the parts so they are plug-and-play right out of the box.

I used your calculator to get the following information about battery amp hr. I would rather have a 24v system unless you can advise me otherwise. I'm trying to keep weight down and I also have space restrictions. The calc said that I could use (2) 12v 36ah batteries to accomplish the same goal. What about brakes? Do you think I would need them?

The factory that we get our gear motors from does not make a 24 Volt 600 Watt gear motor and only produces a 36 Volt 600 Watt version. However we do carry a 24 Volt 450 Watt gear motor which is our item # MOT-24450G.


This 24 Volt 450 Watt gear motor is designed for electric bicycles so it does not have a flat mounting base like the 36 Volt 600 Watt gear motor does, so a mounting base would need to be fabricated for it. This 24 Volt 450 Watt gear motor of course has less power than the 600 Watt gear motor does but it also has other limitations over the 600 Watt gear motor such as having a smaller non- ventilated case which heats up quicker and hold heat longer than the 600 Watt motor's case does, and also having smaller less robust gears and a smaller diameter output shaft.


If you need to use a 24 Volt system and the 450 Watt motor is not powerful enough then two of these 450 Watt motors could be used to increase the power output to 900 Watts. These 450 Watt gear motors have fairly short shafts though so machining a belt cog to fit it might be a challenge.


Another option which will be available next week is a 48 Volt 1000 Watt gear motor. We will be receiving these motors and adding then to our site in the next week or two. They will be our most powerful gear motor and will open up a whole new level of power to our beach wagon kits.


Regarding brakes they may or may not be needed depending on the terrain that the beach cart will be driven on and parked on. With a gear ratio that provides a top speed of around 3 MPH there will be a significant amount of motor braking when the throttle is released. The more weight that the cart is loaded with and the steeper incline that it is traveling down will lower the amount of braking that the motor will provide. The motor braking tends to be strong but gradual. Motor braking will not completely stop the cart on downhill terrain so the final power to stop the cart when traveling downhill will need to be provided by hand or with a mechanical brake.


If you want to be able to stop the cart quickly and completely for safety reasons when traveling downhill without stopping and holding it by hand then adding a mechanical brake would be necessary.


You could build the cart and take it out for a test run to see if the motor braking is sufficient, and if it is not then add a mechanical brake to the cart later.

Could you work me up a quote including the 36v 600 watt motor and all the components that we've discussed?
Yes of course. I just need to ask a few questions to narrow down which parts to include in the quote.

What size (Ah rating) of batteries would you like included with the kit?

Do you know what type of throttle you would like to use?

Would you like a panel mount toggle switch, panel mount key switch, or handlebar mount switch for the power on/off switch?
I would like the 26ah batteries. Could you attach images of the switches you're talking about? I'm unclear as to how the free wheel works. It does free wheel in both directions, right? Like a neutral?

 Here are photos of the different switch options.


image


A freewheel only disengages the wheel from the sprocket in one direction and does not act like a neutral gear in a transmission. Freewheels are always in the same state and can not be switched on or off. 


The freewheel allow the driven wheel(s) to roll freely without drag from the chain and motor in the direction that the motor powers the wheels in. This allows the beach cart to be pushed forward by hand without any resistance from the motor. Without a freewheel the cart would be difficult to push by hand when the motor was off. The freewheel allows the beach cart to coast when traveling downhill. If there is no freewheel in the drivetrain then the motor acts as a brake when going downhill.

I'm that case no free wheel. Is there a thumb throttle with forward, reverse and a on/off switch?
We do not have any thumb throttles with two switches on them, they are only available with one switch. We do have separate handlebar mount switches available though, so there could be both a forward/reverse switch and an on/off switch on the handlebars.
Ok. Lets go with the thumb throttle that includes a switch for forward/reverse. Also include a switch that can be used for on/off. Thanks
For some reason my 3 other posts have not attached to this blog. Can we go the the thumb throttle with integrated forward/reverse and also include a separate on/off switch. Thanks
I went ahead and made a kit for your project. It is item number KIT-148-C. Here is a link to it: 
https://cart.electricscooterparts.com/36-volt-600-watt-beach-wagon-power-kit-with-reverse-KIT-148-C

Please have a look at all of the parts in the kit to make sure that it includes everything that you want. I can make changes to the kit so please let me know if there is anything that you would like to be changed.

Please let us know if you have any questions.
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