Generating 4500 mAh/day
 

[UPDATE]
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I took to the general advice and installed a dynamo hub + a forumslader USB charger. This combo generates something in the neighbourhood of 6W at 20kmh. It can easily run a smartphone used as a bike computer, that will be fully charged at the end of the day. (my S5 consumes 1W screen of, 2-3W screen on and 7W+ when charging).

I've also tested the solar panel, installed on my rear rack and hooked to a tablet that was turned off. On a sunny day, with the spring sun still fairly low on the horizon, the 10W nominal panel increased the charge by 50% over the course of 6 hours. A back of the envelope calculation suggests that this is roughly equivalent to 7Wh, i.e. barely 10% efficiency.

Our strategy will be to use the USB charger to charge the phone and tablet, and to carry a battery bank and wall charger as a backup.

[end of update]
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(planning a self supported tour)

The short version is: how many mAh/day do you generate with a dynamo or solar panel?

The longer version goes like this:

We must process work-related mails and documents while under way. My estimate is that we can probably survive on 4500 mAh per day. In the past we've been able to recharge a battery pack at night in most campgrounds' sanitary facilities, but this Summer we will travel in places where this may not be an option. So we must think about alternative means. Either a dynamo hub or a solar panel.

1. As we plan to average 80kms/day or so, a 3W dynamo (.5A) might be part of the solution (riding 6 hours would generate close to 2 500 mAh net (a back-of-the-envelope estimate confirmed by customer support at Sinewave). We could stretch a 10 000 mAh battery bank to four days or so. It is, however, horribly expensive when you add the price of the dynamo, wheel building and AC->DC converter. I'd say 350$ ballpark. And the worst part is that if we cannot find an outlet on the fourth day, we have to significantly scale back our Internet usage.

2. Riding with a 10W (2A nominal) solar panel strapped on top of the rear rack/panniers. Experience suggests that we can probably hope to generate 6 000+ mAh when the sun shines reasonably. We already have such a panel, or we could spend 60$ to get a larger, 20W unit. On the plus side, no drag (the 3W generated by dynamos require 5W of pedal power) and it is much cheaper. On the other hand, if the weather doesn't cooperate, the panels' output drops to almost nothing... and even if it is perfectly sunny, tree cover may greatly reduce their efficiency.

So... if you have war stories to tell, I'd like to hear them.

(looks like a trade-off between an assured 2 500 mAh/day at $350 (dynamo) vs a probable 6 000 mAh/day at $50 (solar panel).

So isn't a major point of bicycle touring a way of getting away from it all. i.e. getting away from suburban America. Get out there find yourself, and other people. Please don't bring a BOB trailer and a 100 ft. extension cord so you can be comfortable. The bit of discomfort is part of the growth process. IMHO.
Live well!!

We count ourselves quite lucky to be able to get away from it most :)

I think your dynohub math is about right. My USB port usually pumps out about 500 milliamps from my dynohub. But, you never get as many milliamps out of a battery pack as you put into it. Think about it, when you use your tablet or computer the battery gets warm. And when you charge your battery later, it again gets warm. That heat is wasted energy. I have no idea how much of the energy is wasted. My point is that you might need more power than your calculations to make up for other losses. Also, the rectifier and voltage conversions will consume some power too.

I assume your power requirements are rated as output from the USB port, not the Li Ion battery ratings since the Li Ion batteries would have different voltage.

If you want more ways you can spend some money, besides the dynohub you could also use a rim driven alternator or two. They are not cheap and you would probably have to order from Germany. And since you can't take AC current from multiple sources and feed it into a single USB charger, you would need multiple USB chargers.
VELOGICAL RIM-DYNAMO

I suspect you will hope for sunny days.

Last tour I did not bring my dynohub, big mistake. Our plans were to motel it roughly twice a week, so I expected to charge everything about every 3 or 4 days. But, we had outstanding camping weather so we almost always camped, only once during five weeks did we stay in a motel. Whenever I stopped at a restaurant, I tried to sit near an outlet. And at the hiker biker campsites, usually tried to find a place to plug into. It was a hassle that I could have avoided if I brought a 26 inch touring bike (my dynohub is on a 26 inch wheel) instead of my 700c touring bike.

Different people like different ways of touring and staying connected.

If a solar panel is what it takes to travel, what's the problem? It's like saying "I'd never use chamois / I'd always use chamois". Whatever the preference.

Solar panels don't work while moving.

Basically at all.

We tried to use one, and every stray branch or tree or power line overhead cast a shadow and interrupted the charge. Every interruption caused our phone to turn on and off, sapping more power than the phone was getting from the panel. After 3 hours on a gorgeous sunny day on mostly open roads, we had lost 8% battery.

Yes, you are right - panels are finicky when connected to phones (which require stable voltage) but it is, or this is our experience, a different story if they are connected to a battery (which takes basically any voltage within a reasonable range). I hear that iPhones are particularly delicate. We took to the habit of recharging a battery pack such that if we'd forget it a the outlet, or lying on the grass attached to the panel it would be a minor loss.

But the truth is that we've never toured with a panel on a bike...

We'll have a shakedown ride a few weeks before our tribe gets under way so we'll probably test the panel, unless the consensus in this thread is strongly in favor of a dynamo in which case we may conclude that dynamo it will be, whatever the cost...

True. I too tried solar a few years back and it was a waste. That said, I'm hearing that the units are improving all the time so maybe in the next couple of years it will be viable.

Alternate point --> dynamos aren't improving tech wise from what I see. AND they only work while you're moving!

Thanks for the pointer. This might well be it.

The "problem" with solar panels is people buy cheap ones and expect them to work... :lol: Not... :rolleyes: There certainly are, solar panels that would do the job even on a cloudy day... All it takes is some big $$$... ;) I would buy something like a BRUNTON METAL electronics charger big enough to last you a few days between places where there is no plug in... :thumb: As for the dynamo, forget it for anything more than lights or maybe a phone... JMO

http://www.brunton.com/products/revolt-9000

A dyno hub through one of the various headlights with USB output will *just* keep a smart phone charged if it's running a GPS app like Strava or maps provided you don't stop to look at the scenery too much and keep going at a reasonable pace. If you are in a marginal service area the phone may go backwards as it tries to connect with towers, in that case you might need to switch to flight mode or switch it off. It'll put a little bit of charge into a battery pack but not a lot. Basically because we already have USB output on our lights we use the dynamos as bonus power, and depend on battery packs and fast chargers, like you have been doing, just to run a couple of mobile phones. You need to get a high amperage USB charger that puts out say 6 or 8 amps, so you can use a 2A USB lead to charge a large battery pack and charge everything else at the same time, so you utilise 2A to charge all your devices. I just bought one of these Original Xiaomi 16000mAh Mobile Power Bank Aluminium Alloy Material Charger-27.85 and Free Shipping| GearBest.com because of a report from this guy Review, Teardown: Xiaomi (Mi) NDY-02-AL 16000mAh Power Bank | Gough's Tech Zone but the hard thing is, even with a two amp input, it will take 9 or so hours to charge from flat. I was using 10000mAH Unifun packs from Amazon, but one died and they never really seemed to meet their rating. With a 8amp charger you can look at it this way, if you can use all it's output you get 8000mAH for every hour it's plugged in.
But I like the look of that Sinewave USB charger, hub dynamos can put out a lot more power than they are rated for, I've seen articles that talk about voltage doublers etc to get 12W out of them, so 1A would be very possible. That would change the equation of getting realistic power from a hub. From what I've read though you can overheat bottle dynamos with this output.

I understand the rugged quality but battery tech is moving quickly here's a battery 3x the power AND half the cost just double-baggy-it. I'm using this one (15,600mAh @ $18)...almost disposable.

A cheap power bank will waste 40% of its capacity, and expensive one only 20%

Anker and Xiaomi are the top brands when it comes to power banks

Yea, Mine is 3+ years old so there are/is much better stuff out there now, But it's the type of power/package I was pushing/advocating... The one thing I must also say is that my BRUNTON METAL crapped out after 3 years of use... and they sent me another one to replace it... ;) Three years after I got it and used it for three years.... No questions asked. :thumb:

EDIT; Some Warranties do/can make a difference in the price, IMO ...

Interesting. Do you have data source info to back this up?

I thought it was a well know fact, when ever a device generates heat, that heat is a waste byproduct (unless its a heater or an oven) the more heat generated the less efficient the device is.

For power banks:
"All portable chargers lose power through heat generated and voltage conversion during charging, so the advertised capacity will never be available to your mobile device. However, while the cheapest power banks average 65- to 70 percent efficiency, and some of the better models around 80 percent." http://www.pcadvisor.co.uk/review/batteries/anker-astro-mini-3200mah-power-bank-review-3593330/

More power will be lots on the phone/device , aswell as through the cable. Its a grimm world when it comes to electricity

The weight is 1.1 lb and the capacity 28,600 mAh. That's an outstanding solution. They're $49.99, get two or three.

Have a rummage through this guys site: Review, Teardown: Xiaomi (Mi) NDY-02-AL 16000mAh Power Bank | Gough's Tech Zone he gets off on pulling things to bits and testing them, very, very, very thoroughly . Very interesting technical stuff about charging algorithms and etc, and yes it does seem that cheaper ones aren't as good in terms of efficiency or charging speed because of the components used. The charging speed is also important, if you look at his article about charging curves, some of the less efficient ones can take 3 times as long to charge.

I thought you talking about $$ cost:



Wow, that is actually more than I need :)

Looks like the Busch and Muller E-werk might the best option for the most power from a dynamo hub. Can be adjusted to 5V 1.5A.

5 volts at 1.5 amps is 7.5 watts.

At this link, http://www.ctc.org.uk/file/public/fe...ub-dynamos.pdf
see the graph labeled electrical output. When most dynohubs at 50 km/hour (~~ 31 mph) put out less than 5 watts, I think that kind of power is unlikely. The voltage conversion and rectification in the USB charger will loose a little bit of power, not expand it.

Best you write to Sinewave, Busch and Mueller, and all the other manufacturers and tell them that they don't know what they are talking about then.
But before you do that have a look here Dynamo LED Light Systems for Bicycles (electronic circuits) to see what you can actually extract out of a hub by taking advantage of the fact that a hub is a constant current source, with the voltage getting up to 50V or more. The test used in the article you linked was very basic, using only a fixed resistance. With proper circuitry you can match the impedance of the load to the hub to extract maximum power.

If a family will be traveling, having charged batteries for some screen time to unwind and recharge the body's battery is a huge help.

I am unconvinced of your claim of 1.5 amps at touring speeds. I have at times run two headlamps in series for more light, but you had to be going faster to get enough voltage to provide enough power on them to give good light. Going up hill, the two lights were often darker than the single light because the voltage was too low. I am well aware that without any current that the voltage will climb, I measured 34 volts AC with only the multimeter on the dyno when I was going 25 mph. That was when I quit trying to make my own USB power circuits because that told me why I was blowing out capacitors, at that point I just bought a USB charger.

And, no I see no need to write to anyone.

Solar panels do work while moving ! Its your phone that is being recalcitrant. Use a small buffer battery, problem solved.

I use both these days, Dyno for the guaranteed power and solar for the off bike stuff, (keeps charging while I'm napping doing important maintenance) . I did a video on all this awhile back that is still relevant and I've refined my GenHub to USB box down to $5 in parts and added output displays so I know how much my devices are getting at any given time. I'm working on adding the solar panel to this so it can take the input from both sources though thats going to drive the price of parts to nearly $6 :eek:

As far as the OP's ? I find that if I "capture" all the GenHub output I very rarely need to supplement that with wall outlets. I also am a watt-miser in my usage where I can.

Bicycle365 page on : Electrical Matters

Original video here: Charging system walk through

http://www.bicycle365.com/postimages/newmeter.jpg