Dynamo > EWERK > Power Bank - Question

[TrustAllisOK]

I'm looking for a mobile power solution for my Blackberry, GoPro and Garmin 705 during tours. I couldn’t find this specific set of items I think might work with the search. I do NOT have a dynamo hub and have great wheels with Hope Disc hubs and TK540’s that are fine so no new front wheel in the plans… yet.

I’m not looking to charge devices on the road (or am I?), only a power bank that I can use at camp every couple of days on different devices. I figured with the bottle dynamo I could engage it only when I needed to refill the power bank, unless that turns out to be all the time with this size of power bank. I have no idea how the math works on these 3 devices together at say 11-13mph average for 5-7 hrs. rolling time a day.

I was thinking about running this bottle dynamo: http://www.peterwhitecycles.com/dymotec.asp

To this EWERK(transformer?): http://www.peterwhitecycles.com/ewerk.asp

To this 6000 mAh power bank with - input : 5VDC, 500mA-1.8A and USB Output: 5VDC, 1A: http://www.mychargepower.com/tablet-extended-batteries/portable-power-bank-6000.html

Does the B&M AC dynamo and EWERK device allow for DC charging? I’m only an architect so the extent of my small electronic device knowledge is about zippo to none. I’d bet there are lots of guys here who will have a dissertation on this subject and my question and those I’m not experienced enough to think to ask so please enlighten me gentlemen.

Thanks for your help.

[Joe B]

The ewerk is a very pricey solution to a problem that really does not exist anymore. It was designed to output various voltages at various amperage to be able to adapt to all devices. This problem has been minimized by the ubiquitous USB cable, if your devices can be charged by USB you only require 5vdc at 500 mAh for them  ( iPad excepted).

A quality rechargable NiMH AA Battery  is about 2000-2200 mAh in capacity. The 6000 mAh powerpack will be about 3x better than 4AA's . For reference 2AA batteries will charge a iPod Touch to about 70%.  I do not know how much the GoPro or Garmin use/store so I can't make a guess as to how often you would need to charge.

Simple way to compare different battery storage is:

AA @ 2000mAh (2a) x 1.2v = 2.4
4 AA = 2.4 x 4 = 9.6

PowerPack @6000mAh (6a) x 5v = 30.0

30/9.6 = 3.12 times more "work"

The links are to the most relevant pages of my blog where I have addressed exactly how I handle charging and device management on the road, there are other pages of the blog that have additional pictures and info but these 2 are the basics. 

http://joesride.wordpress.com/2011/11/09/electrical-chores-today-2/

http://joesride.wordpress.com/2012/01/20/final-electrical-installation-part-2/

I run a SON generator hub , the 6v Ac it outputs is converted to DC through a bridge rectifier and charges 4 (completely dead) AA NiMH batteries in exactly the time/speed you quoted, 10-12mph x 5-7 hrs. If the Power Pack does 3x more work than the AA's it stands to reason that it will take 3x as much to fully recharge it.
The electronic boxes you see on my bike will work with any 6v  bottle generator as well.

I could explain this for another 10 paragraphs but I will spare you ... If you have any questions after you see what I did please just ask, I'd be happy to expound on any topic you  like. If you want specific directions on how to make the  Gen to USB box I have a parts list, or I could make one for you ,free assembly for ACA members  they have about 40 - 45 $ in parts in em' .

NOTE: I'm currently on a Anacortes to Key West to Boston tour so I may not reply immediately based on WiFi access.

[Pat Lamb]

A retro-grouch in training question, if I may.

Joe, you're in touch sporadically via wifi, according to your post.  My question then is simply, how much of this is necessary?  When you have wifi access, how frequently do you not also have access to a power outlet that can charge the many devices with rechargeable batteries?

[TrustAllisOK]

Joe,

Wow, thanks for your prompt help and insight. It clarified a lot of things for me but now I think maybe I can go this simpler route listed below and use a wall charger every 10-12 days based on 2 of  the 3 devices needing charged every other day and the Garmin every 4-5.  Your math helped along with a little digging on the mAh of each device battery.

I could even buy 2 at this price and stretch out a month of no external power needs if I watch my picture and video taking.  Where I travel I can find power far more ofthen that that.

http://richardsolo.com/portablepowermax16000mahbackupbattery.aspx

You think that's a decent option?

[Joe B]

When you have wifi access, how frequently do you not also have access to a power outlet that can charge the many devices with rechargeable batteries?

It's about not having to rely on it for me. The times , like today's off day where I have WiFi and a/c, its no issue.  The biggest benefit to me is the ability to run my iPod for 10-12 hours a day. It is my cycling computer giving me distance, speed, cadence, heart rate etc... I also have all of my ACA map sections loaded into it panel by panel for evening convenience ( I still use the paper one on the road). It is just not possible to run it that long without constant USB power .
 
A headlight is a must have to me (makes a nice camp light as well). Charging batteries for my other devices ( camera, steri-pen water purifier) is a extra benefit of choosing this one.

I do carry a netbook ( or these posts would be a lot shorter ! ) and for that I am tethered to the wall plugs. That is the only 110v wall wart left in my kit. I am looking at the new ASUS Transformer notebook/tablet that DOES charge from USB ! Review to follow if I get it soon.

Now this is all relevant to touring in the US. When touring internationally the availability of WiFi or even line current electricity has been as much as weeks apart.

[Joe B]

I could even buy 2 at this price and stretch out a month of no external power needs if I watch my picture and video taking.  Where I travel I can find power far more ofthen that that.

http://richardsolo.com/portablepowermax16000mahbackupbattery.aspx

You think that's a decent option?

I had not seen this particular unit yet. Thanks for the link. Looks really nice !