Electric Cargo Bikes Powered by a Solar Charging Station

Here's an experiment put together by the staff at Greentech Renewables in San Francisco and Splendid Cycles in Portland, OR. The perfect combination of a cargo bike and an electric motor, recharged by the sun. The kit was put together from off-the-shelf components.

• The Objective

We wanted to end up with transportation that could recharge from a small solar array - not just a golf cart that's plugged into the grid to recharge overnight under off-peak meter rates. Plus, it had to be fun and much less expensive than a car. Also, it had to be able to carry 80 pounds of groceries and/or a small child up a modest hill without excessive effort. Here's a recent article on Cargo Bikes in the NW.

• The Bike

• Powder-painted in black
• Hardened aluminium frame
• Stainless steel and aluminium nuts, bolts and washers
• Complete Shimano XT series Drivetrain and Brakes
• Front and rear hydraulic brakes
• Puncture-proof Schwalbe-tires
• length = 96 inches
• width =  19 inches
• weight. = 48 pounds
• cargo capacity = 400 pounds
• Lockable/Waterproof Alloy box = 8500 cubic inches.
• Other cargo options also available

The platform we chose was the un-beatable Larry vs Harry Bullitt cargo Bike. This is not the heavy iron Long John work bike of Dutch fame. The basic bike is sturdy hydo-formed aluminum and weighs less than 50 pounds, and it's really fun to ride. Click the picture above for a short video from the NY Times.

• The Fuel

Using available components (listed on this page under related items) from the Greentech Renewables catalog, we built up what is basically and off-grid power pack of about 72Ah at 12Vdc. The power pack itself is completely self contained and can plug into any PV DC source up to 150 Voc, since it uses the Morningstar MPPT Sunsaver controller. It also fits nicely into a Pelican Case for loading onto the cargo bike. Instead of charging directly from the battery, we opted to go through a 1000W inverter, then into the 36 VDC LiOn Charger for the bike. This is less efficient, but has two benefits: One is that we have a nice source of emergency power for any small AC appliance, the other is that the bike charge remains unchanged and can plug into another AC source if it needs to.

• The Motor

• hi-torque motor for heavier duty use
• Battery = 10 amp hours
• Weight with BionX e-assist = 67 pounds
• average range per battery charge-15-20 miles
• average cost per battery charge-5-6 cents

The motor we chose is the 350W Bionx Hub Motor. There are a number of hub motors available up to 1000W, but the Bionx seems to be the most highly evolved in terms of firmware. The most critical feature for us was the variable assist. The controller can be set to sense the rider'd effort and then multiply that effort (almost seamlessly) by 100% to 400%. The 400% is a eye-opening kick-in-the-pants. It's like having an invisible team of (silent) Jack Russell terriers in harness. I know this because I have tried it with real Jack Russells.  The 100% to 200% are the best settings - they save battery life and they just seem to remove the weight of the bike and cargo - it's disconcerting to get on a regular bike afterwards.

• The Reasoning...

According to AAA, here's the cost of driving a car.

To spare you the reading, AAA calculates the cost of owning a "small sedan" at about $5600 per 10,000 miles. $5600 can go a long way towards a cargo bike that will make smug Prius owners ride the bus of shame. And, of course, since this is not in any way a scientific project, the main reason is just because a Solar Powered Cargo Bike is Cool!

• The Film

Just to prove that this did happen, we've compiled a compelling music documentary. Test Pilot Suzanne Fuoco rides the bike from food cart to food cart throughout Portland (this is because no documentary is complete without a mention of Portland food carts nowadays) to the music of Scissors for Lefty performing "Ghetto Ways". Unless you want co-workers peering into your cubicle, remember to turn down the sound.