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PowerBug for Dynamo Hub, Phone Charging

Old 12-03-17, 11:15 AM
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James Colver
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PowerBug for Dynamo Hub, Phone Charging

I wanted to have a way to charge my phone from by dynamo hub and I was taken aback by how expensive some of controllers were. Most controllers are designed to mount in place of your cap for the fork tube. It's a convenient place, but the problem with this design was that water could easily get in when my cord was plugged in.

I found a nice controller called the PowerBug. It was A LOT less than the other models and I really like how it uses a nice long cord I can route to one of my waterproof bags. It was easy to put on and I use it to trickle charge a 15000mah backup usb power supply. So far it works really well.
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Old 12-03-17, 11:57 PM
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Perhaps you might consider offering a link so the good folks at home know what your promoting.
I'm a fan of the E-werk myself due to being able to access replacement cables so far easily so I haven't had to worry about corroded connections.
For me it appears Ze Germans have thought of everything.
Busch & Müller E-WERK Charger
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Old 12-04-17, 08:55 AM
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Looks to be similar to the Sinewave... In any case I have a Sinewave Revolution and a Forumslader. The Forumslader cost more but I freaking love it. The Sinewave is okay but definitely needs a cache battery when paired with an iPhone and isn't nearly as efficient as the Forumslader. I don't see much on the Powerbug so no comments there, sorry.

Rifraf, Best I can find it's from Poland and sold on Ebay, https://powerbug.pl

I hope the OP doesn't end up in the middle of another Ebay fiasco...
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Old 12-04-17, 09:12 AM
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Don't worry there hasn't been anymore "fiasco"s. The charger came in about a week. It was just as described.

According to the manufacturer it will generate about 2200mah. That means it is possible to completely charge my power supply in 1 day off of it. I need to be going at least 10mph for it to activate.

I thought other poeple might want to look at it because it's only $45.00. Most other products cost at least $100.00 and I'm not happy with their design.
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Old 12-04-17, 02:01 PM
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I want the Cycle2Charge V2. Unfortunately it isn't available in the US. It's also only ~$50.

Last edited by 3speed; 12-04-17 at 02:05 PM.
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Old 12-04-17, 03:15 PM
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Originally Posted by James Colver
...
According to the manufacturer it will generate about 2200mah. That means it is possible to completely charge my power supply in 1 day off of it. I need to be going at least 10mph for it to activate.
....
2200 mah is a rating on how much power was produced,but that does not say over what time.

On thier website there is a graph that indicates about 600 milliamps at about 20 km/hour, that is reasonably close to my average speed touring on the flat. This is the graph I was looking at:
https://www.powerbug.pl/wp-content/u...300_stroke.jpg

That is about the same power output as my Sinewave Revolution. I think that might be 10 or 20 percent better than my AXA Luxx 70 plus, but I am only guessing on that as I have no detailed performance curve for it. I can't tell how that compares to my Luxos U because that has a cache battery but I think it is close to comparable.

It would probably take 25 hours to charge a 15,000mah powerbank at typical touring speeds from empty to full. Or, about 300 miles if you were riding at 12 mph.
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Old 12-04-17, 03:27 PM
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Power in mA/hr should be suggesting milliamps per hour .. mah you have to ask that writer. milli=thousandth

or 2.2 amps per hr?
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Old 12-04-17, 03:30 PM
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By the way Top of the heap at Ortlieb is a handle bar bag and separable electrical connector equipped bar bag mount.
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Old 12-04-17, 04:21 PM
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Originally Posted by Tourist in MSN
2200 mah is a rating on how much power was produced,but that does not say over what time.

On thier website there is a graph that indicates about 600 milliamps at about 20 km/hour
And to complicate matters a bit more, not entirely clear at what voltage we should apply those mA. 12v? 6v? 5.1v?

A better performance unit would be Watts.
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Old 12-04-17, 06:48 PM
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Originally Posted by gauvins
And to complicate matters a bit more, not entirely clear at what voltage we should apply those mA. 12v? 6v? 5.1v?

A better performance unit would be Watts.
I assumed that performance curve was based on USB output, thus somewhere around 5 volts. Some of my devices that can draw more amperage than a charger will deliver will draw the voltage lower than 5, but I always assume 5 unless I have a meter hooked up.

I think most powerbanks are also rated in amperage at USB voltage, not amperage at the Li Ion battery voltage.

***

I was in a rush to get out the door when I wrote that posting, I should have elaborated further. When I made my comment on 25 hours or 300 miles, that really is not a realistic measure because everybody will start out a trip with their batteries topped up. And if you are in charging mode starting on day two for the rest of the trip, worst case scenario is that your big powerbank will slowly lose power if you are using power faster than you can generate it. But sometime on the trip if you have a chance to plug it into an outlet overnight to top things up again, you are essentially starting over.

My two week tour this past February, I was self sufficient, never needed to plug anything into an outlet.

But that has not always been the case. In the photo I am topping up two powerbanks and four AA batteries at a construction project where the campground owner left a power supply for me to plug into over night.
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Old 12-05-17, 03:04 AM
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Do you find that if you have your phone charging in while you ride for the day, it'll charge up all the way, assuming almost dead from use the night before?
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Old 12-05-17, 08:28 AM
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Originally Posted by 3speed
Do you find that if you have your phone charging in while you ride for the day, it'll charge up all the way, assuming almost dead from use the night before?
Depends.

I can travel weeks on end navigating with a smartphone (always on) strictly powered by a dynamo hub. Now, it may require "power management". i.e. if the terrain is hilly such that average speed drops to, say, less than 10mph (16kmh), it may be wise to turn off the phone display to reduce power consumption, and turn it on just before reaching the next waypoint. Which is why I ride with a small/cheap bike computer to independently keep track of distance.

Another way to answer is: a fully charged phone, display on, consumes roughly 3.5 Watts. My rig (Shimano XT dynamo hub + Forumslader USB charger) produces that amount of energy at 12 kmh.
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Old 12-05-17, 09:14 AM
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Originally Posted by Tourist in MSN
I assumed that performance curve was based on USB output, thus somewhere around 5 volts.
Makes sense. That would translate into 3W.

Question for you. USB charger brand A delivers 3W@20kmh. USB charger brand B delivers 6W@20kmh. Do you think that wheel drag is the same in both cases or that if B produces more it means that the circuitry creates more drag in the generator?

If the answer were B (more output means more drag), what would be your opinion on the merits of B? Could be a good thing -- once you've recharged your batteries, drag falls to almost zero, the sooner the better.
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Old 12-05-17, 11:33 AM
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Originally Posted by 3speed
Do you find that if you have your phone charging in while you ride for the day, it'll charge up all the way, assuming almost dead from use the night before?
My phone is off except when I want to call someone. So, quite frankly I can't remember ever charging my phone on any bike tours. And my old flip phone was so old that you could not even charge it with a USB cable so I could not even charge it on a dynohub if I wanted to. My old flip phone was with Virgin Mobile, they canceled my plan because at $80 a year I was not profitable enough, thus had to go shopping for a new phone plan and phone. I have only had a smartphone that actually had a SIM card for the past 8 months. But I still leave the new smartphone turned off on a bike tour, my five day tour this past May I think I made two phone calls but otherwise it was always turned off.

I have on some tours carried a 7 inch tablet for wifi only. Or a smart phone that had no SIM card in it, so it was essentially a 4.7 inch tablet for wifi use only. Those were turned off except when I had wifi, and when I had wifi I usually could plug into an outlet. My two week tour this past February I was curious to see if I could be self sustaining on dynohub only, so I never plugged into an outlet on that trip. But my smart phone (with no SIM card in it) was only used for weather forecasts where I had wifi, so it had very limited use. I do not recall if I ever charged it on that trip or not.

My heaviest power drains are
  • My GPS (Garmin 64) that is on when I am rolling, uses two AA batteries. It also functions as a AA battery charger.
  • Taillights that I often use during daytime, two AAA batteries, can charge them in GPS with AAA to AA adapters.
  • Camera batteries (Li Ion). Use a Li Ion charger powered by USB.

I think that I probably get an average of 2.5 watts out of my USB charger while rolling, more at steady speeds but with hills and stop lights that cuts output. I think my phone battery is about 8 to 9 watt hours, so I likely could charge it up with a day of riding. My phone does not take a constant charge, it cycles from a high draw to lower draw rate so it takes longer to charge than you would otherwise expect based solely on battery capacity.
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Old 12-05-17, 11:51 AM
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Originally Posted by gauvins
...
Question for you. USB charger brand A delivers 3W@20kmh. USB charger brand B delivers 6W@20kmh. Do you think that wheel drag is the same in both cases or that if B produces more it means that the circuitry creates more drag in the generator?

If the answer were B (more output means more drag), what would be your opinion on the merits of B? Could be a good thing -- once you've recharged your batteries, drag falls to almost zero, the sooner the better.
I am most certain that when you draw 6 watts out of a hub instead of 3 watts, the drag (rolling reistance) will increase, probably double. I assume you are talking about your Forumslager (spell?) charger.

While I can't feel rolling resistance when I ride with the light on or USB charger in use at roughly 3 watts, I know that there is resistance. When I am off the bike, if I lift the front wheel off the ground and give it a spin it will keep spinning much longer if my light is turned off than if the light is turned on. That resistance is too small for me to feel when pedaling, but it is obviously there when I spin the wheel by hand.

I would rather ride at a 3 watt drag all day than a 6 watt drag for half the day. I might not feel the difference, but I still think it is better to have a more constant effort. That said, I have had some long days where the sun is getting really low on the horizon late in the day and I wished the ground was all downhill.
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Old 12-05-17, 03:48 PM
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Originally Posted by Tourist in MSN
assume you are talking about your Forumslager (spell?) charger.
Yes (ForumSlader).

I'll ask and eventually report. For now, just saying that I'd never thought that USB out is proportional to dyno drag. My simplistic assumption being that increased output meant more efficient circuitry.
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Old 12-05-17, 06:27 PM
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Originally Posted by gauvins
Yes (ForumSlader).

I'll ask and eventually report. For now, just saying that I'd never thought that USB out is proportional to dyno drag. My simplistic assumption being that increased output meant more efficient circuitry.
The drag caused by the alternator can be quantified in watts. If you can get more watts out of your charger than the drag caused by the hub, you have invented the perpetual motion machine that would have power to spare.

There used to be an article on the internet that unfortunately is no longer posted. Article title Shining Examples, December/January 2012-2013, Cycle, CTC.ORG.UK, Pg 58 to 64. They had graphs comparing different dynohubs for power output, drag with and without a headlamp, etc. Their drag graph was quantified in watts. I would attach a PDF here but that might be in violation of copyright rules, so I am hesitant to do so.

That article was one of the reasons I bought the SP hub in April 2013, at that time there were no distributors for that hub in USA, I had to order it from Asia.
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Old 12-05-17, 10:52 PM
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Yes I understand that you'll incur a drag penalty that is at least as large as the charger's output. What's not clear, however, is the magnitude of the penalty. It may be constant across chargers or depend on their respective wizardry.

To rephrase, charger A output is 3W, charger B is 6W. If the drag from A is equivalent to 6W and the drag from B is 12W, that's one thing. If both produce a drag of 8W, it is a different story.
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Old 12-06-17, 10:00 AM
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That article I cited above in post 17, I just looked at the drag graph. At 20 km/hour with light turned off drag was 1 watt, with light turned on drag was at about 5.4 watts. I am citing drag numbers for the PV-8 because that is the hub I use. (They did not measure drag of a non-dynohub wheel for comparison, so I have no clue if that 1 watt is actual additional drag increase for the dynamo or not, perhaps a regular hub has a 1 watt drag?)

They say that drag of 5.4 watts at 20 km/hour was equivalent to climbing 6 feet of elevation per mile. I am not sure what weight of rider and bike they are using for that calculation. But assuming that is accurate, at 20 km/hour, that is a bit over a foot of elevation gain per minute of extra effort. If you double that for your Forumslager, I probably would not notice that additional drag either.

The text in that article text:

"Electrical output is monitored with a 12 ohm resistance, since
that’s how it’s always been done, as bulbs are also
resistors. But LEDs are diodes, and alternators naturally
perform much better with those, especially if both
components play to their strengths. Actual power
output may therefore be significantly greater when a
generator is used with matching lamps."


I would take that to mean that drag is going to be proportional to hub output, but with some extra inefficiencies added in here and there.

Send me a private message with your home e-mail address and I will e-mail that article to you.
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Old 12-06-17, 10:49 AM
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Originally Posted by gauvins
Yes I understand that you'll incur a drag penalty that is at least as large as the charger's output. What's not clear, however, is the magnitude of the penalty. It may be constant across chargers or depend on their respective wizardry.

To rephrase, charger A output is 3W, charger B is 6W. If the drag from A is equivalent to 6W and the drag from B is 12W, that's one thing. If both produce a drag of 8W, it is a different story.
The drag is proportional to the number of magnets they have spinning around in there.
I believe the term is "reluctance", if memory serves.
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Old 12-06-17, 11:29 AM
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Originally Posted by boomhauer
The drag is proportional to the number of magnets they have spinning around in there.
I believe the term is "reluctance", if memory serves.
Load plays a major role.

Stumbled across this interesting post. Looks like chargers' efficiencies are very similar. The difference is in the maximum output curve. Most chargers deliver a max output of something close to 3W@20kmh, whereas the Forumslader can deliver 5W@20kmh. The maximum drag of most chargers is 3.5W@20kmh vs 6.3W for the Forumslader.

One perspective is to say the higher output levels add (potentially) unnecessary drag. Maybe. My perspective is that since efficiencies are essentially the same, total drag is the same, whether you have a high vs low output charger. It is only a matter of how drag will be distributed over the day. In my experience, batteries were fully charged within a couple of hours on a typical day, meaning that the charger had to deliver whatever wattage my phone would consume once fully charged, i.e. < 2W, A high power charger is more forgiving wrt power management. And drag wattage is very low anyway, and becomes meaningless when your speed goes down, climbing, and you want all of your few leg-generated watts to propel you up that nasty hill...
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Old 12-06-17, 04:20 PM
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Originally Posted by boomhauer
The drag is proportional to the number of magnets they have spinning around in there.
I believe the term is "reluctance", if memory serves.
No. When I said the following, that pretty much proves that if more power is consumed, then the drag is increased.

Originally Posted by Tourist in MSN
...
When I am off the bike, if I lift the front wheel off the ground and give it a spin it will keep spinning much longer if my light is turned off than if the light is turned on.....
The wheel spins for a shorter period of time when drag is increased, that drag is increased when the light is on.

*** ***

Originally Posted by gauvins
...
My perspective is that since efficiencies are essentially the same, total drag is the same, whether you have a high vs low output charger. It is only a matter of how drag will be distributed over the day. In my experience, batteries were fully charged within a couple of hours on a typical day, meaning that the charger had to deliver whatever wattage my phone would consume once fully charged, i.e. < 2W, A high power charger is more forgiving wrt power management. And drag wattage is very low anyway, and becomes meaningless when your speed goes down, climbing, and you want all of your few leg-generated watts to propel you up that nasty hill...
I pretty much agree with this.

I would add to that that if you had a lot of devices and a day of riding with most chargers was insufficient for your needs that your higher output charger might be beneficial.

I am talking in generalities here, there would of course be slight differences with different hardware, etc. (As an engineer, I of course have to add the disclaimer.)
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Old 12-07-17, 11:03 AM
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Originally Posted by Tourist in MSN
I would add to that that if you had a lot of devices and a day of riding with most chargers was insufficient for your needs that your higher output charger might be beneficial.

I am talking in generalities here, there would of course be slight differences with different hardware, etc. (As an engineer, I of course have to add the disclaimer.)
Trying to better understand what's at stake, for my own purposes, I've calculated the table below. It looks at the energy produced by high vs low output chargers (essentially the ForumSlader vs the rest) for a tourist like me, i.e. pedalling at 125W with a combined weight of 110Kgs (rider + bike + luggage) over courses of 100Kms. In my experience, terrain makes a BIG difference in speed (and therefore on energy produced), so I've calculated results for a variety of terrains : (1) flat, (2) and courses with gradients of +1% half of the length and -1% for the other half, and similarly for 3% and 5%.

Major takeaways, for me at least, are that:

(1) Barrelling down a mountain doesn't make it up for the hours you took to climb. The amount of electricity produced on a steep terrain is 40% to 50% of what you'll get on a flat terrain.

(2) If you rely on always on electronic navigation, you are likely to run into a deficit. It will generally be the case with a low output USB-charger. The Forumslader produces enough energy to feed a smartphone as long as the terrain is not too hilly (i.e. average gradient of 1% is OK). Otherwise you have to start managing power consumption, by turning off the display between turns.

(3) Drag differential is inconsequential for tourers, at a couple of minutes for the day.

(4) Not being en engineer, I am not required to add a disclaimer . I'll say that the numbers jive with my experience. So someone could use this calculator and the power and drag charts available here to compute relevant figures.

(if the table doesn't show, click here)

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Old 12-07-17, 12:23 PM
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Originally Posted by gauvins
Trying to better understand what's at stake, for my own purposes, I've calculated the table below. It looks at the energy produced by high vs low output chargers (essentially the ForumSlader vs the rest) for a tourist like me, i.e. pedalling at 125W with a combined weight of 110Kgs (rider + bike + luggage) over courses of 100Kms. ...
I mostly concur, but I found that I can travel self sustained for power with a GPS on when i am rolling.

1 - Fully agree, the amount of time you are producing high wattage is minimal compared to the amount of time climbing when you are producing minimal at best.

2 - I use a GPS, Garmin 64. It is not a cycling specific unit, powered by two AA batteries. But I can charge AA rechargeable batteries in it with my USB charger, and by using AA to AAA adapters can put AAA rechargeable batteries into it to charge up, I use AAA batteries in my taillights. I leave my phone off when I am not using it. If I had my phone on, they you are right in that I probably could not stay self sustained for power. The Garmin can't directly charge AA batteries, it has to be fooled into thinking that a Garmin branded battery pack is in it. I wrote up some comments on the Garmin 64 here, that page also has another link to some other comments I made.
https://www.bikeforums.net/19403692-post26.html

3 - Fully agree. The way I look at it is that dynohub drag might be equivalent to less than a one or two mph difference in headwind.

4 - I have nothing to add.

Photo is of my Garmin 64 on my Florida trip. I have a DIY bracket to mount it on my stem cap bolt on that bike.
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Old 12-08-17, 01:04 PM
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Originally Posted by 3speed
I want the Cycle2Charge V2. Unfortunately it isn't available in the US. It's also only ~$50.
I use the Cycle2Charge V2. I had my bike touring partner bring it from Germany. 50 Euro. Charges reliably, shell spins around to hide the socket, great product. Kind of looks like a mushroom above your stem.
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