Sandcastle lesson vehicle

Spidennis

100 µW
Joined
Aug 10, 2022
Messages
9
New guy here, Dennis, from South Padre Island, Texas.
And yes, I give sandcastle lessons on the beach.
I encounter a few problems with my journey to the beach with my setup and I think I could use some ebike help, initially with a front wheel hub drive. Needless to say I have many questions!
So I want to diy this myself and I see kits on eBay and Amazon but what exactly do I want? Certainly inexpensive for starters. But hit has to survive the salt and sand environment too.
I usually take the pavement to class but ride the beach back, and our constant breeze it tough to deal with when I have to go against it. Plus I have to get thru the deep soft and hot sand between the parking lot and the hard pack sand. It would be nice to have a bit of ebike assistance here too.
I’m thinking a thumb throttle on the left side would be good as I drag the whole bike and cart using mostly my right hand to drag it all.
First technical question. 36v or 48v?
What I’m thinking for batteries is using power tool packs, so I can also use it for my tools. It would make charging easy too.
Comments, suggestions, thoughts? Thanks.
 

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It appears your cart already has large diameter balloon tires but I certainly would not try to drag it around by hand while riding. I am not usually a fan of Fat Tire Bikes (electrified or otherwise) but they are the best way to deal soft, sandy terrain. If you are not able to start with a "fat tire frame" then at least get the widest wheel and tire combination that you can find that fits your existing frame. I think that a large diameter direct drive rear hub motor might be the most appropriate starting point. Definitely 48 volts over 36. You do not always have to use that additional 12 volts but it good to have if/when you need it.
 
And river rocks large and the small soft gravel too, also less moving parts for less repairs on a rigid fatty with air cushioning over menial punk cracks on pathway.
 
Go with a direct drive rear wheel hub motor kit, not so much for its the best, but the best economical. 48v 1000w kit.

Buy a good quality battery for it, if you go with a tool battery, then you need at least a larger mower battery, such as the ego or similar 5 ah pack. Expect to spend at least thou on it all.

For the salt, the hub motor is pretty well sealed, but will need annual cleaning inside it. Put the controller and all the connectors to it inside a small plastic toolbox with homemade vents. It will at least keep direct spray off it. Electronic grease on all the plug contacts should help slow corrosion. Battery in some kind of saddle bag, or mid frame bag. Keep everything dry as possible, and out of the invisible salt spray humidity.

Don't ride on the wet sand when the waves will get near you, try for low tide, or slog through dry sand. Park the bike high on the beach, then drag the trailer to the surf line by hand.

Best bet though, would be expensive. Fat tire bike with mid drive motor.
 
I’ve watched some videos on tool batteries. 36 is an even number, two 18v batteries in series. 48v? No combination works.
Mid drive motor, for this application, would be a mess of sand. Pedals get full of sand from my sandals. A motor next to the pedals is asking for trouble.
Rear instead of front hub? I get off the bike in the deep sand and pull the trailer and push the bike. The rear wheel would not get any traction but the front would. And with a thumb drive on the left could help me power thru the sand?
A fat tire bike is not in the budget.
The cart tires in the pic I will replace with my 4” wide fat tire ones once I re lace up spokes on them. Maybe I should power the cart?
 
Spidennis said:
I’ve watched some videos on tool batteries. 36 is an even number, two 18v batteries in series. 48v? No combination works.
Mid drive motor, for this application, would be a mess of sand. Pedals get full of sand from my sandals. A motor next to the pedals is asking for trouble.
Rear instead of front hub? I get off the bike in the deep sand and pull the trailer and push the bike. The rear wheel would not get any traction but the front would. And with a thumb drive on the left could help me power thru the sand?
A fat tire bike is not in the budget.
The cart tires in the pic I will replace with my 4” wide fat tire ones once I re lace up spokes on them. Maybe I should power the cart?
First one needs to understand Lithium-Ion Cell technology. In common use there are many various chemistries but most of these fall within two distinct groups:
Lithium-Cobalt: nominal voltage=3.6 volts, fully charged voltage=4.2 volts, low voltage cutoff=3.0 volts
Lithium-IronPhosphate: nominal voltage=3.2 volts, fully charged voltage=3.7 volts, low voltage cutoff=2.5 volts
Actually all rechargeable Lithium batteries use Cobalt but electrode compounds vary. Most of the cells used in power tools as well as e-Bikes are going to be a variation of the former because they have a higher power density.

While most E-bike manufacturers and DIY (Do It Yourself) rate batteries according nominal voltage, tool vendors frequently rate their batteries according to the maximum charge voltage. Twelve volt tool batteries are typically 3S (three cell in series). We would rate these as 10.5 Volt batteries. Eighteen volt batteries are 5S (five cells in series). We would rare these as 18.5 volt batteries while tool vendors frequently call them 20 volt batteries.

The 48 volt batteries for e-bikes are 14S (fourteen cells in series). However most 48 Volt ebike systems can be run on 15S (fifteen cells in series) batteries. That is 54 volts or the equivalent of three 18 volt tool batteries in series. You will likely see frequent references to 52 volt systems ... those are 15S systems. The limit is the electronic components in the motor-controller which are most often rated at 60 or 64 volts. At maximum charge you are looking at 63 volts. People frequently limit their chargers to 4.0 or 4.1 volts per cell which is why they are called 52 volt rather than 54 volt systems. My personal preference is 16 LiFePO4 cell strings in series for a nominal 52 volts ... but I am a bit of an odd duck.

My point is that you can get a quality 48/52 volt motor and controller to use three 18 volt tool batteries in series.
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You may have a valid point about the weight distribution if you are actually pushing the bike/cart through deep sand. Front wheel hub motors are arguably the easiest install. Many controllers have a walk mode (about 4-6 KPH).
 
Ok, ordering another battery!
Thing is I can always use them!
 

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