Ridefreemc

I am considering a cross USA ride with my Big Dummy soon. It currently has a Bionx system on it, but I can easily take that system off and put my stock rear wheel on. My initial thoughts were to go without the electric assist, but now I am rethinking that idea. One of the drawbacks with going electric is the range with pedaling of 50 miles or so (less than I plan to travel each day) and the lack of places to recharge in some areas. I will take some remote roads and trails and may go without access to electricity for a few days.

I thought of taking a second battery too, but again, with lack of access to electricity and the extra weight (7 pounds for the 48v battery that I have x 2) I am thinking otherwise. However, I thought I might be able to charge one battery while using the other, and at least be able to extend my range a bit.

So, is there a way for me to do this? I have two panels already that I use to charge my GPS and phone, but I am clueless on the charging from solar instead of from 120 volt AC. Would I get much out of this (i.e., extra range/power recharge)? The Big Dummy has a large rear rack area so I could put two panels across the back.

Any ideas?

350htrr

I would say most solar panels just wouldn't work, for at least two reasons, big & bulky, and usually not enough output... But the good news is that there are some, that most certainly would work... But the price ... Parts and Accessories - Solar Power Systems - Hi-Power Cycles

Ridefreemc

Ouch! For that price I could hire someone to do the peddling for me

I have two panels now: one flexible and the other a folder, but I'll have to check the wattage. Like you say, the output, especially after going through an inverter, may not be much help at all. I did find this as a potential inverter:

https://www.amazon.com/inverter-black...GBK3CFTRW7NB0T

I also spoke to Bionx and they said it could be done on an idle battery (not while using the battery), but we didn't get into the feasibility or practicality of it.

350htrr

The beauty of the HPC folding solar panel is 200watts+, small but folds out big, and they will put a converter on it to directly charge the 48v battery, (26v input actually) so that when you stop anywhere you can directly plug in the solar panel with no losses... 2 to 3 Hrs and your battery is full charged from empty and you can charge an Hr here or there when you stop during the day... Like you say the only other way is an idle battery, but then the solar panel is a problem needing to be facing the sun all day, not practical...

corrado33

Solar panels may be hard. They're heavy, big, and well...expensive. A much easier way to do it would have a detachable dynamo that can charge the battery when you're cruising down a hill or just pedaling in general.

Allen

Doesn't work like that. You use less energy just pedaling. No system is 100% efficient, therefore you have to put more energy in to run the dynamo than you would get out of it. If that energy is coming from your effort and not an outside source (wall plug, solar panel, etc.) you are better off without the drag.

Bionix is correct, solar is ok for an idle battery/bike but impractical for a moving bike. The amount of air resistance from a deployed panel (no to mention the weight and drag of the structure to hold it in place) is going to surpass the energy it delivers.

CliffordK

You don't need the inverter for the solar panel unless you have 110V accessories you wish to power. It would be maximally inefficient to power an inverter off of a solar panel to power your battery charger.

You would be much better to find a MPPT controller matched to your solar array and battery pack. Or... if you aren't risking overcharging your battery pack, then you might even try charging without a controller. But the MPPT may gain enough efficiency to justify the additional electronics.

The highest power "portable" solar panels would be the semi-flexible solar panels, and perhaps the Sunpower Brand semi-flexible solar panels.

Semi Flexible 150 Watt Solar Panel High Efficiency Sunpower Marine Rated | eBay

This one is 150 watts for 52" x 26.5". It might work on a bike trailer if you're carrying camping gear and etc.

What is the power consumption of your electronic assist bike?
The capacity of your battery pack?

350htrr

The problems with trying to charge a battery while moving with a solar panel,

1; It has a big area, not conducive to biking even on a trailer.
2; It ends up not facing the sun at the optimum angle a lot of the time.
3; It ends up in the shade often, a lot of on/off (at least around here).
4; It is expensive once you get the better ones.
5; It doesn't work well on cloudy days.
6;

fietsbob

Size Matters.. in solar panels .. smaller takes More time ..
Think instead Of A Carport sized Panel you Park Under .. that will offer the needed surface ..

Metal Man

Something like this.
I couldn't give you the math to back it up, but in general terms alternative energy costs many times more than people think and delivers a fraction of what they expect.

CliffordK

You also really only get peak power for a few hours a day, say in the summer, you might do ok from 10 AM to 2 PM (excluding daylight savings time).

Perhaps you could arrange your trip to get a nice early start.
Stop around 10:00... and expand your solar array to several times your road capacity with solar tracking.
Take a nice long noon siesta.
Then get back on the road at 2:00 with charged batteries... assuming you have the charging capacity.

350htrr

I have gone on 2 trips using my E-Assist bike, 650Km and 850KM tours and never plugged into a wall outlet, just used my 75watt solar panel on my truck & camper set up... So, short answer is yes, a solar panel can supply all the power you would need to go for months without plugging in anywhere... YeHa... And I could have done the same without the camper set up, BUT it would have cost me over $2,000 for the type of solar panel that would have allowed me to do the same thing on a bike only set up...

BUT, YES it's certainly & easily doable with todays technology, it just costs a bit more than most can afford...

slo

A solar panel big enough to power up your ebike charger will be too big to fit on your bike and ride across country with. And expensive.

A couple 5w marine panels should fit on top of your rack and be durable enough (semi-flexible, no glass) for a bike trip.
Marine Solar Panels | Chargers | Marine Electrical | West Marine

The downside to small panels is you'll need a separate storage battery to power up your ebike charger.

If you could tow a BOB-type trailer you could carry a 12v marine-type battery for solar storage. Some people also put a motor in the Bob wheel for more push.

In the pic you can see what i'm talking about, the ebike is charging off the marine battery through an inverter while the panels are charging.


Another consideration is that ebike chargers don't travel well. Commuters usually buy a 2nd charger to leave at work, for instance, rather than carry a charger in the saddlebag bouncing along on the daily commute. good luck

CliffordK

Ok,
Here is some data on E-Assist bikes I'm seeing for sale.

250W to 750W
51.2V x 12AH (614 WH)
38.4 x 9 AH (345.6 WH)
33 x 9.3 AH (306.9 WH)

A little 5W panel won't do much, although every little bit helps. Say 5W x 5Hours = 25 WH. Not even 1/10 of a charge on the smallest assist battery.

However, a 100W panel charging at near max for 5 hours would give 500W, and fully charge all but the largest of the battery packs above.

350htrr

I agree with your assessment on the 5W panel except I would go further, basically useless is how I would put it, not worth the effort at all...

I agree with your assessment on the 100W panel except I suspect it would keep falling behind a bit every day and eventually fail to produce the power needed to charge the battery fully. My experience tells me the minimum you can get away with is 120W, but 240W is what I would get...

350htrr

Long distance solar powered biking can be done, 38 days and 1 Hr 7,500KMs. Just takes big $$$... Vulcan | Minimalist Business Template 4