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External Battery or Dynamo?

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Old 03-07-18, 12:19 PM
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gif4445
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External Battery or Dynamo?

I currently use an external battery (Gopuck 5x) for my rides. Works well thus far, as the longest Brevet I have been on was a 360K (Flèche). Looking at doing some longer ones this year and wondering if a dynamo would be worth looking at? I'm charging an iPhone 6s plus, garmin touring, maybe my jaybird (have hardwire backups) and possibly lights, although I think my lights can go at least a couple nights without charge. Just thinking that even on the long distance ones, I would be sleeping somewhere (maybe) for at least a few hours and could get things charged up. Assuming an outlet is available of course. I also carry a few USB wall plugs, as well as the 3 different charging cables. In my experiences thus far, I get about 2 charges (+/-) on my iPhone out of the go puck. Depending upon how new the iPhone is and how much navigation I need done, this will last me a couple days. When I did the Flèche, the Garmin ran out of battery about the 20 hour mark. I did get my phone recharged during a 2 hour "nap" at the Post office. Those that have been there and done that, please give me your opinion. Thanks.
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Old 03-07-18, 05:04 PM
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Originally Posted by gif4445 View Post
I currently use an external battery (Gopuck 5x) for my rides. ... I'm charging an iPhone 6s plus, garmin touring, maybe my jaybird (have hardwire backups) and possibly lights, although I think my lights can go at least a couple nights without charge.

With that list of loads, have you considered towing a Honda generator on a trailer? I can't see any way you're going to be able to charge all of that with a dyno.
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Old 03-07-18, 05:17 PM
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That is a bunch of stuff. I'm gradually freeing myself from battery lights using dynohubs and am really enjoying that change. Assuming you don't need to be using your Garmin and phone and whatever a jaybird is every minute of the ride, there's a good chance you could use the dynohub to help keep things topped off during the day.

Maybe you could attach one of those old-style bottle dynos to the rear wheel to help the cause.
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Old 03-07-18, 05:50 PM
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There was a very recent long winded thread on the folding bike forum on this exact topic, but for different types of riding and primarily for folding bikes.
Rechargeable Light Vs. Dynamo Powered

I often use a taillight during daytime while I am charging batteries with my dynohub. Thus, I have for several years been using AAA powered taillights and dynohub powered headlamp.

Initially I did that because my first dynohub was on an S&S coupled bike and I did not want to deal with the taillight wiring on that type of a bike.

I recently bought a fender mount wired taillight to use with my dynohub on a non-S&S bike, but I will always carry battery powered taillight(s) for daytime use so I can use the USB charger and a taillight simultaneously.
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Old 03-07-18, 08:31 PM
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A small common single cell (18650) USB battery should get any Garmin through the night. Use a double cell if you need more ... but I think those huge batteries that’ll charge an iPad a couple times kill the rando experience.

Use a USB battery that can be charged and provide power simultaneously and you should be able to keep everything topped off during the day with the dynamo and switch to the device’s own batteries during the night — supplement with the USB battery as needed.
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Old 03-07-18, 08:44 PM
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And with my Garmin I figure I’ll get around 15 hours (even if it says low battery at 10), so if I expect the ride to be longer than that I’ll start the ride with the Garmin running on a USB battery, and then once I get to ~15 hours remaining, I’ll stow the battery/cable. Easier to put the battery away than dig it out.

If there is a sleep stop, or some extended time off the bike, I’ll dig the charger out and charge the Garmin/phone then, and stow the battery/cable when I resume.

If the ride is long enough that that battery isn’t enough, then the USB battery gets charged with a USB-Werk on day two.
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Old 03-08-18, 12:20 AM
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Thanks for the replies thus far. Even Mr. Helpy Helperton and his Honda generator suggestion. Obviously a dynamo is not a silver bullet. I’ll just stick with the gopuck and off-bike charging until my distance/ circumstances point a different direction.
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Old 03-08-18, 12:45 AM
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I use the dynamo for front and rear light which I run both day and night for extra visibility in traffic (so I don't think there'd be much power to spare for charging the phone) and a spare battery for charging the phone which doubles as a bike computer, GPS, camera and, well, phone if need be.

On a multi-day ride I'd carry a charger for the USB battery and recharge it during stops. I'd just rationalize the amount of electronic gizmos with me. However, using a dynamo to recharge the USB battery during the day, with lights off, would work fine, too.
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Old 03-08-18, 02:20 PM
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I have 5 "lipstick" batteries and a Zenduro usb battery. I figure that will get me through a 1200k. I used to use a Luxos U, but I never figured out how to get the charger function to work for me. The cache battery isn't big enough to keep a garmin 800 charging without fairly frequent "external power lost" warnings, which are annoying in that context
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Old 03-09-18, 07:22 AM
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Headlights tend to draw a lot more power than anything else, if you want to have a decent amount of light out in the countryside and away from streetlights, so to me it makes sense to treat that one as special.

On both bikes I use the dynamo hub for lighting only and a beefy USB battery for recharging the GPS and the phones.

In the past I tried several different USB adapters that can run off the dynamo hub, but between the problems introduced by start/stop (mobile devices turn on the power-hungry screen whenever external power goes away or comes back), the challenge of avoiding over-voltages on fast descents (I fried one phone and one buffer battery) and the trade-off of adapter weight vs. battery weight I really couldn't make a good case for the USB adapter route over the less costly and simpler USB battery route.
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Old 03-09-18, 09:40 AM
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Originally Posted by gif4445 View Post
Assuming an outlet is available of course.
Not everything goes according to plan.....

As for me, I use dynamo but not for charging. A Gomadic AA external charger keeps my Edge 500 going for navigation, and I keep my phone on airplane mode/low brightness/etc. to keep the battery going as long as possible. I generally don't ever need to access my phone during rides beyond sending a check-in text at controles, and having to pull it out to look at a map during a ride is a horrific thought. A checked-over cue sheet works great in tandem with my Garmin.

I guess the bottom line is for me, my strategy involves minimizing the use of things that *need* charging during a ride. I do carry a phone charger on long brevets, and I will leave my battery charger in my drop bag for things like helmet-mounted headlamp, Gomadic batteries, etc. However, juggling keeping all my electronics alive is not an added task I'd like to take on, when my primary mission is to keep myself alive and get through the ride!
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Old 03-09-18, 12:49 PM
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I used to turn my phone off during rides. I was 23 hours into a ride, riding along at 3 a.m. and the alarm went off, scaring the crap out of me. Turns out the alarm on that phone would turn it back on, and I had set the alarm to go off every day. My current phone will do pretty well on battery life as long as I turn off location services, bluetooth and wifi, so I just leave it on. Probably not going to last through a 1200k though.
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Old 03-10-18, 06:26 AM
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Originally Posted by unterhausen View Post
...Probably not going to last through a 1200k though.
All of the GRs in the US provide overnight stops so you can charge your phone every night if you need to.
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Old 03-10-18, 05:41 PM
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I've got a Serfas True 350 for a headlight. Also a spare battery for it. Seems pretty bright on its lower settings. Should get 6 hours on each fully charged battery. Ran all night on one battery the last time I used it. I need to see what the actual time is for both charging and run-down. Rear lights are regular old battery type and will go for a long time. I carry a spare battery for those. So I feel pretty good about the lighting end of things. Probably just re-access how/when I use my phone and Garmin. Should be good thru a 600K with what I'm doing now. The 1000k in May should educate me.
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Old 03-10-18, 10:21 PM
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eWerk. I am considering seriously getting one for me and Machka. We use our cell phones for Strava and other stuff on the bike. Audax rules here require a back-up headlight, and the new generations of small ones are pretty good (even if the beams aren't as refined as the German/EU dyno ones).

We already have the dynohubs (I think around 10 these days), that run headlights, and it makes sense to add the eWerk to the system to charge the power bank for the extra light and the phone and whatever else.

Here, the eWerks are $180 each, are fairly discreet on the bike, and seem to make use of down time on the dynohub.
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Old 03-11-18, 09:56 AM
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The discussions of electronics (dynamo, GPS, whatever) starts to remind me of the discussions of saddles after a while, and then again, almost every other discussion of equipment. Nothing wrong with that, of course.

It seems to me that a dynamo hub is a no-brainer. It's basically a free source of power. The question is: what's the best use of that power?

The problem I've encountered is that I form habits and forget about them. We start a 200k a little after dawn, with batteries charged, which is enough to last the whole ride, so I just leave my lights on all day; unnecessary but it's extra safety at no cost. And since most of my rides are 200k's, this is habit forming.

On longer rides, we start a little before dawn, when lights are absolutely necessary. So the correct thing to do, I believe, is to turn the lights off sometime after dawn and use the dynamo to keep the cell phone and/or GPS charged. But (so far) I haven't remembered to make the switch.

What I'm planning to do, this season, is leave my headlight (B&M something or other, senso-plus, premium, gibberish) on the automatic setting so it cuts out in daylight and comes on as darkness falls; and I'll charge phone or GPS all the time.
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Old 03-11-18, 10:34 AM
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Originally Posted by rhm View Post
It seems to me that a dynamo hub is a no-brainer.
Sort of. The electronics system I have used until now uses nothing but AA batteries, and I can complete a 600k with 9 batteries never recharging anything. I got a dynamo hub this year mostly so I can run my headlight all night on high power, which will save me the hassles of carrying 4 extra AA batteries on a non-stop 600k. Could be a slightly bigger deal on a 1200k, but not really even then since there is potentially less riding in the dark and the opportunity to recharge stuff at night compared to a non-stop 600k.
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Old 03-11-18, 09:28 PM
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you must ride 1200k's faster than I do. My last 1200k featured 6 hours of sleep. But if you are riding a 600k on 9 batteries with your system, it isn't much of a problem to use 18 batteries on a 1200. To me, the thing that makes a dyno a no-brainer is the taillight. Because it's always on and the batteries never die without warning.
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Old 03-11-18, 10:03 PM
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I'm a no-brainer after 400k or so. The fewer parts of my bike that I need to mess with to keep things working, the better.
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Old 03-12-18, 07:22 AM
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Originally Posted by unterhausen View Post
you must ride 1200k's faster than I do. My last 1200k featured 6 hours of sleep.
My first 1200k attempt is this season, so we'll see how much sleep I'm able to get. I'm not especially fast or slow, normally average around 15 mph on the bike and reasonably efficient at the controls, so I'm expecting to get at least few hours of sleep every night.

Originally Posted by unterhausen View Post
But if you are riding a 600k on 9 batteries with your system, it isn't much of a problem to use 18 batteries on a 1200. To me, the thing that makes a dyno a no-brainer is the taillight. Because it's always on and the batteries never die without warning.
Funny how differently people look at things. I didn't even attach the taillight to the dynamo. I have a B&M toplight line senseo that runs 40 hours on a single AA battery so I didn't really see the point of running the wire even though I bought the dynamo version of the same light. I may hook it up later this season, we'll see.
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Old 03-12-18, 08:37 AM
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I also have a battery light, and I usually carry a spare. The fall series I did last year started out in a big pack every time, and there was always one or two riders had their battery lights off at the start. One of them had to stop for batteries. I have had my battery light go dead on me a number of times. It was through my own negligence, but I didn't expect it. Now all my bikes have a dyno tail light. So when a battery dies, it doesn't make me happy, but it's a non-event. The annoying thing is that if the battery is nearly flat, turning it off and letting the battery recover will allow the taillight to function just long enough that you aren't paying attention when it goes off again.

In combination with the lack of sensibility that comes from being on a long ride, I want to make sure my taillight is on no matter what my mental state.
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Old 03-20-18, 04:56 PM
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Originally Posted by rhm View Post
...

It seems to me that a dynamo hub is a no-brainer. It's basically a free source of power...
Is it? A dyno hub is also expensive, not light, introduces mechanical drag, is platform-specific (not plug&play across bikes), and its output is rather meager relative to cost, wiring complexity and modern electronics needs.
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Old 03-20-18, 05:16 PM
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Originally Posted by Abu Mahendra View Post
Is it? A dyno hub is also expensive, not light, introduces mechanical drag, is platform-specific (not plug&play across bikes), and its output is rather meager relative to cost, wiring complexity and modern electronics needs.
I realize some people don't like them, for the reasons you cite. True believers (like myself) find ways to rationalize them anyway.

I mean... cost? It's a one time cost (and you don't have to buy the most expensive one; the $40 Sanyo is quite nice). People who rely on batteries are always buying batteries (which is good for the battery industry, but not for the environment), and the cost adds up. I don't buy batteries, and don't throw them in the landfill. (Well, not many anyway )

Mechanical drag? I don't believe there is any mechanical drag.

Meager power? I find the power adequate; but the important thing is: the power is always available. Charge the devices during the day, light up the night.

Heavy? Well, the weight doesn't bother me. It's just part of the deal.

Now I'm not saying this is the right view and everyone else is wrong; but to me, yes, it really is a no-brainer.
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Old 03-20-18, 06:01 PM
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Originally Posted by rhm View Post
...
Mechanical drag? I don't believe there is any mechanical drag.
....
The drag is not perceptible when riding, but there is drag.

If I lift my front wheel off the ground and give it a spin by hand with my light off, the dynohub (SP PV8) wheel will spin about the same as a normal wheel. But if I turn on the light and give the wheel a spin, it will slow down much faster due to the extra drag from the light consuming electricity.

I often leave my light on when riding, just because I do not think it will slow me enough to worry about it. I saw a good article about six years ago where several hubs were tested in a lab. They concluded that most better dynohubs will have the same drag as gaining about 5 or 6 feet per mile. To me that is not perceptible, but it is measurable.

If I was riding a timed event, I might turn my light off in daytime to gain those few extra feet, but otherwise I would not worry about it.
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Old 03-20-18, 06:28 PM
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Originally Posted by Tourist in MSN View Post
The drag is not perceptible when riding, but there is drag.

If I lift my front wheel off the ground and give it a spin by hand with my light off, the dynohub (SP PV8) wheel will spin about the same as a normal wheel. But if I turn on the light and give the wheel a spin, it will slow down much faster due to the extra drag from the light consuming electricity.

I often leave my light on when riding, just because I do not think it will slow me enough to worry about it. I saw a good article about six years ago where several hubs were tested in a lab. They concluded that most better dynohubs will have the same drag as gaining about 5 or 6 feet per mile. To me that is not perceptible, but it is measurable.

If I was riding a timed event, I might turn my light off in daytime to gain those few extra feet, but otherwise I would not worry about it.
Yes, all of that is true.

But is that what we mean by "mechanical drag"? I mean, I hope we all understand that a dynamo is a device that turns some mechanical energy into electrical energy, so the LED can turn it into light energy, and that with each conversion some small amount is inevitably lost. The energy that is converted to another form of energy is not helping power the bicycle, and what is lost is lost; but is that mechanical drag?

I am probably confused about the terms. But when I say there is no mechanical drag, I mean the dynamo hub does not have parts rubbing together causing drag any more than any other hub. People unfamiliar with a dynamo hub will spin the axle with their fingers and invariably say "but I can feel the drag! It's hard to turn the axle!" And yes they can feel it; but what they feel is not mechanical drag, but rather magnetic resistance. Likewise riders can feel the pulsing of the dynamo as the wheel turns, and it feels like friction. But no; just because you can feel it doesn't mean it's slowing you down.
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