Heavy Duty Bike Trailers

George S.

Well-Known Member
I noticed this heavy duty bike trailer on LifeEdited. If you figure a normal rider is putting out 100 watts (no athlete), that's actually OK with a trailer that easily handles 300 pounds, but only on a flat. It's manageable, costing maybe 3 mph.

On a 5% grade, 100 watts output from a rider is like, uh, fuggedaboutit. Not fast enough to stay stable. On the other hand, the typical ebike in the US is around 500 watts. Add those 500 watts to the 100 watts from the rider, and you can get up the hill closer to 10 mph, a decent pace.

nyk-hauling-mattresses.jpg

Basically, you could bring home a washer or a refrigerator. The site shows some interesting uses, and there are several models.
 

Court

Administrator
Staff member
Wow! This is so awesome George, I can imagine the days when moving stuff with bikes will be more efficient than cars. Even today, thinking about New York City with all of the crowds and parking issues, someone with a trailer like this on an electric bike could provide a great moving service.

heavy-duty-bicycle-trailers.jpg

The prices seem fairly reasonable as well ranging from ~$600 up to ~$1,000. If you used something like this regularly it would be a good deal. Maybe it could be shared around with friends or possibly rented in the future as more ebikes become popular and people use them more frequently :)
 

George S.

Well-Known Member
Wow! This is so awesome George, I can imagine the days when moving stuff with bikes will be more efficient than cars. Even today, thinking about New York City with all of the crowds and parking issues, someone with a trailer like this on an electric bike could provide a great moving service.

View attachment 1432

The prices seem fairly reasonable as well ranging from ~$600 up to ~$1,000. If you used something like this regularly it would be a good deal. Maybe it could be shared around with friends or possibly rented in the future as more ebikes become popular and people use them more frequently :)

Court,

I studied their website in detail. I'm surprised they are not more ebike oriented. The problem may be that they need a certain kind of mounting area, or a mounting area with some real strength, for the hitch. Most ebikes are probably going to have components where their hitch is designed to go. One of the optional hitches might work. You need a lot of energy (watts) to move a real load up a hill. You'd need really good brakes coming down a hill with a lot of weight.

Sharing would make a lot of sense, and renting would work. I think if you used one for shopping it would be worth the cost of the smaller one. They build the trailers around tubs that have tight covers. It is pretty well thought out.

I could see the smaller trailer working for ebike explorers. The trailer is large enough to carry a few of these solar panels. These panels are light and bendable. They produce enough energy to recharge an ebike battery in a few hours. You could probably configure these panels on top of the trailer (with the tubs for equipment and food) to get power as you rode. (The panels are cheaper on the company website).

There is nothing like a well engineered and practical product that makes you see what is possible (to do). I'd rather use a trailer than buy a bike that is one big basket on a super heavy frame. Not that hauling a trailer is likely to be fun. I haul a trailer around and the best part is always unhitching it from my truck.:)
 

Court

Administrator
Staff member
Court,

I studied their website in detail. I'm surprised they are not more ebike oriented. The problem may be that they need a certain kind of mounting area, or a mounting area with some real strength, for the hitch. Most ebikes are probably going to have components where their hitch is designed to go. One of the optional hitches might work. You need a lot of energy (watts) to move a real load up a hill. You'd need really good brakes coming down a hill with a lot of weight.

Sharing would make a lot of sense, and renting would work. I think if you used one for shopping it would be worth the cost of the smaller one. They build the trailers around tubs that have tight covers. It is pretty well thought out.

I could see the smaller trailer working for ebike explorers. The trailer is large enough to carry a few of these solar panels. These panels are light and bendable. They produce enough energy to recharge an ebike battery in a few hours. You could probably configure these panels on top of the trailer (with the tubs for equipment and food) to get power as you rode. (The panels are cheaper on the company website).

There is nothing like a well engineered and practical product that makes you see what is possible (to do). I'd rather use a trailer than buy a bike that is one big basket on a super heavy frame. Not that hauling a trailer is likely to be fun. I haul a trailer around and the best part is always unhitching it from my truck.:)
I love the idea of a solar charger trailer for an ebike. Thanks for sharing the idea and link George, the one thing that eludes me is how to take the power coming from that panel and convert it into a port that I can plug my ebike charger into and then into the bike? Most of the smaller solar chargers I've seen are part charger and part battery so you then have to transfer from one battery to your actual device battery... I'm open to all suggestions here but would ideally like to know how to get 120v out of a solar panel so I don't have to void my warranty trying to go directly into my battery.
 

George S.

Well-Known Member
Court,

The short answer is that you convert DC to AC with an inverter. Hooking an inverter to the output of some solar panels would give you 120 V AC. Then you could plug your standard charger into the inverter. This is problematic because the sun is going to go behind a cloud at some point, the output of DC current will drop, and the inverter will probably shut down. It's not a good system because the inverter is really looking for DC output from a battery, which is relatively stable. This system will cycle too much, straining all the components, without a battery buffer.

So the next layer to add is a 12v battery. Now the panels go to the battery and the inverter goes to the battery, and it is more stable. Inverters are sold into the auto and RV markets, where 12V batteries are standard. The question is how much of a battery is needed, and since a lead acid battery works quite well for solar charging, assume some weight to add this battery. A good AGM battery with maybe a 30 AH rating will take the charge as the inverter draws it off. Adding this storage battery has a big advantage. If there is no sun, there is still a charging battery left to charge the Ebike battery. The cost is maybe $120 and 20 pounds of weight.

The idea of sending solar power to a charge controller and then into an inverter, and back into another battery is not efficient. We are converting DC to AC so we can convert it back into DC. But, this lets you use the regular charger. Any solar panel that is hooked to a battery is a stable source of DC. With the DC and an inverter you have 120V AC. The question now is one of sine wave versus modified sine wave, and that is a cost issue. In general, power supplies will work with the cheaper inverters. You might ask the ebike manufacturer about this. It should have come up.

A more direct way would be to have a second Ebike battery and simply charge it from the solar system. You basically have to figure out where the circuits are that protect the cells. If the battery is designed to be charged off the bike, it is a pretty good bet that all the charger unit is doing is supplying a specific DC voltage. That is easy. DC-DC converters are cheap and precise. The battery should be very happy, as happy as it would be with the regular charger. If the battery charges on the bike, or is not accessible, this is not going to work.

The output on my PT X3 is specified on the charging unit at 43V. You would expect the output voltage for charging to be maybe 20% above the rated voltage of the battery, often 24v, 36v, or 48v. As long as you match that voltage, nothing has changed. But there are sophisticated electronics that go with any lithium battery. I assume the battery charger is just a power supply, but there may be other functions on board. They seem to put the circuitry in the battery case, but who knows.

If you can charge a second (bike) battery, off the bike, by supplying the current specified by the charger (or by measuring it) all you need is the battery connector. You need an upconverting DC-DC variable power supply, which the Chinese seem happy to supply on Ebay for very little money. You still might want to buffer the output from the solar panel with a small battery, say 10AH. That way the output won't be dropping off. But this second battery requires a charge controller. Every circuit and every battery has a cost. It depends on how robust your system is, how much wattage you get from the solar panels relative to what you need. If you need every watt, you need peak efficiency.

To summarize the second system: The solar panel produces maybe 16 volts and 5 amps with full sun. You can convert this 16 volts to 43 volts with a DC - DC converter. These are relatively simple and efficient. Now the solar panel produces 1.6A at 43 volts, steadily, depending on the sun. If the 43 volts is all you need to regulate, charge, and make the battery happy, you are done. You need the plug that goes into the battery.

Second batteries for ebikes are not cheap. If someone has a serious need for unplugged travel, a system can be designed, swapping two batteries. I think the idea behind these trailers is that there is more capacity, and part of that might have to be used to have more power, better options. Having a decent 12V storage battery might be very useful, along with an inverter. The first system gives you a nice source of AC power for any need. And you just plug the basic ebike charger into the 120 outlet, and the sun refuels the source battery when it can.

I can see where someone who would be utilizing a trailer all the time could just design a bike and integrate the bike power to a battery system that integrated solar. That's not where the buyers of ebikes are going, right now. But solar has just gotten so cheap that the kinds of power that any ebike uses represents a rather tiny investment in solar panels. What you can't do is easily keep the panels in the sun. You basically need a real trailer to carry the panels, because of the size, but if you can carry them, the sun will provide the power, at least while parked. For $400 buy two 100W panels (the heavy kind), a basic charge controller, a 500 W inverter, and a 30 AH AGM battery. You have to figure out how to carry it. The lighter panels add $250.

A lot of this stuff is more complicated because there are more sophisticated options. For example, to charge a 12V battery from a solar panel you can either just clamp the voltage and protect the battery from too much voltage from the panel. Or you can use a MPPT controller that converts the voltage down to a safe charging voltage, conserving the overall watts from the panel. People don't need to know 'too much' but there are a lot of paths to the same goal of solar charging and creating 120VAC from a 12V DC battery.

I'm not real sure about riding the bike and charging the battery on the bike at the same time. You'd have to ask...
 

Court

Administrator
Staff member
Awesome information @George S., thanks for taking the time to help explain this to me. Admittedly it's still a bit foggy with so many options but this is a start if I or anyone else decides to pursue solar charging electric bike batteries :)
 

FitzChivalry

Active Member
BikesAtWork was specifically recommended by Practical Cycle, where I bought my City Commuter, when I asked about doing a Burley Travoy (which they didn't recommend due to needing special hardware to hook it up). I'm definitely interested in getting one of these someday.
 

Ravi Kempaiah

Well-Known Member
I noticed this heavy duty bike trailer on LifeEdited. If you figure a normal rider is putting out 100 watts (no athlete), that's actually OK with a trailer that easily handles 300 pounds, but only on a flat. It's manageable, costing maybe 3 mph.
On a 5% grade, 100 watts output from a rider is like, uh, fuggedaboutit. Not fast enough to stay stable. On the other hand, the typical ebike in the US is around 500 watts. Add those 500 watts to the 100 watts from the rider, and you can get up the hill closer to 10 mph, a decent pace.

View attachment 1417
Basically, you could bring home a washer or a refrigerator. The site shows some interesting uses, and there are several models.

George,

How is your health?
I hope you're getting better.
 

George S.

Well-Known Member
George,

How is your health?
I hope you're getting better.

Hi Ravi,

Thanks for asking. Been doing better with the lung efficiency. It's nice to have an e-bike with a throttle to use as a scooter. E-bikes can be very therapeutic because you are out there in the world and you can avoid doing anything that would be a strain. So much of being really sick is that the world gets small and closes in around you.

I've carried an oxygen tank, which is safer if I want to get a work-out. But overall I can stay off the oxygen during the days and hope to get off it entirely. The mile high altitude is a constraint.

I wish I could find a group ride because I know some of the regular bikers are a bit hostile to ebikes. I figure they would cut some slack for the poor guy with an oxygen tank and cannula.

Warmest regards,

George