Luck would have it, I am doing a similar build to what you’re trying to achieve. I just finished installing the second hub with controller and throttle today. However, I’m looking to do more than you are with my cart. I’m using a heavily modified rubbermaid cart that weighs a ton and I’m looking to put a seat on it and ride it around as well.
Here is my build
2 Wheels
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2 Controllers
Find many great new & used options and get the best deals for 36V 48V Universal Brushless Controller Thumb Throttle fo Scooter E-bike ATV Quad at the best online prices at eBay! Free shipping for many products!
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4 battery adapters (2/wheel)
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Battery gauges (ETA Saturday)
2 Pieces DC 12V 24V 36V 48V 72V Battery Meter with Alarm, Front Setting and Switch Key, Battery Capacity Voltage Indicator Battery Gauge Monitors -Acid and Lithium ion Battery Indicator (Blue)
https://a.co/d/hHMH3CT
Mechanical Brakes (ETA Saturday)
Lomodo 4 Pieces Bicycle Brake Accessories Including 2 Pack Aluminium Alloy Brake Levers Handle Bars and 2 Pack Brake Wire (Front and Rear Brake Cable) for Mountain/Road/MTB Bike(Black)
https://a.co/d/hLLMxWS
Toggle Switch Panel 3 Gang...
https://www.amazon.com/dp/B09P3FZCYL?ref=ppx_pop_mob_ap_share
Car-ling 7Pin Rocker Switch DPDT...
https://www.amazon.com/dp/B0BRCQY2TK?ref=ppx_pop_mob_ap_share
Forward Reverse Rocker Switch For...
https://www.amazon.com/dp/B073V64N5W?ref=ppx_pop_mob_ap_share
It’s moving a medium sized rubbermaid cart that has knack cart armor on it and is lined with 3/4 plywood with shelving inside. It worked but struggled with only 1 hub installed but with 2 it’s got plenty of power. I haven’t wired up the speed selector or tried to figure out how to put in the reverse switch yet. That’s actually how I found your post lol
Here’s a video of the test from today