bwgride

I've been testing a Biologic Reecharge Dynamo Kit/Charger ($30) this week. Link:

ReeCharge Dynamo Kit with Micro-USB Cable | BioLogic Bicycle Accessories and Bike Gear

Mine is a bit older version from 2014, so looks a somewhat different from current model. Not sure of any other changes beside appearance.

I have been charging my phone directly. Phone is Nexus 5 (~2300 mAh battery). When in airplane mode, but with GPS on and tracking my ride with Map My Ride, I find that I recharge a little better than 1% per mile. Today I charged from 72% to 93% with 18.7 miles of riding (12 to 13 mph).

In a previous ride I left the screen on the phone and found that it charged about 1% per 2 miles.

I also have tested recharging a large battery bank (Limefuel 15000 mAh). Cannot recall specifics, but looks like between 5% and 8% charge for about 15 miles of riding. It takes about 20% charge from this battery to fully recharge my phone.

This dynamo power converter seems to work well, and the price is one of the lowest I have seen of any commercially available dynamo power converters.

I read that the Limefuel battery is capable of pass-through charging, i.e., one can charge the battery bank from the dynamo hub while the battery bank charges another device. I tried this once, and it seems that the battery bank would not take a charge while it was charging my phone. However, once I removed the phone, the battery bank recharged 5% very quickly from the dynamo, so there may have been some odd recharge or display behavior.

In summary, while the pass-through charging may not work with my combination of devices, the Biologic Reecharge converter seems to work well recharging my Android phone and battery bank.

350htrr

Well, I guess you need to ride 50 to 70 miles per day to recharge every day...

bwgride

That is one interpretation, another is that since it gains in charge while I ride, it will stay charged most of the day so not necessary to charge the phone during the entire ride. This means I am generating enough power to charge the battery bank for some time (e.g. first half of ride), then during second half of ride switch to charge phone via dynamo to recharge whatever power was lost while charging battery bank. So it is a bit better than your interpretation which suggest a break even scenario.

P.S. If charging the phone while off, the recharge will be much better than the 1% quoted above. So in stretches where not needed, turn off phone to enhance charge rate.

350htrr

Fine, it would work... BUT: IF you actually want to keep track of your travels by GPS (something like, ride with GPS) the phone needs to be on...

edthesped

Ride with GPS seems like a nice program, installed it and am looking at it while at work. Will it let me continue to use it without an account? I really don't want to share my rides or have someone else marketing my riding habits.

350htrr

Yes you can use it free, and you can use it in airplane mode and double or even triple battery life of the phone...

Saving power is easier than making power IMO...

bwgride

Not sure why you post in this thread. Your posts seemed purposed to denigrate dynamo usage, and your posts seem to be without much thought.

My purpose was to inform users of dynamos of the performance of one power converter that is on the market. This particular converter is the least expensive by a large factor, so if it functions similarly to those that cost $100 to $200, then this knowledge might help those who use dynamo hubs.

Wheels turn as one rides, so one both makes and consumes power. With dynamo hubs one can capture some of the power that is made and direct it toward batteries for later usage.

Perhaps you are thinking - if you gave it thought - that dynamo hubs require more energy to turn than they generate, so power is lost and therefore a dynamo is a poor choice. This thought is wrong, but rather than direct you to studies showing the benefits of dynamo hubs and the relatively low friction involved with dynamo hubs compared with other factors on a bike, I'll instead let you search for those if interested. Given your current posts here, it seems you are uninterested in learning about the facts of such hubs and instead wish offer snide posts.

350htrr

Sorry, I guess my low opinion of making enough useful power with dynamos shines through...

EDIT; When I do the numbers that you quoted, I come up with one needing to ride 95 miles every day to keep the phone on in airplane mode to use it in GPS mode and keep it fully charged, well in my book that's a fail. Sure you can turn the phone off totally and fully charge it in 1/2 the distance... but that is still a fail, why? because then, you don't get the use of your phone to track your progress via GPS... Sorry again, but I have yet to see a dynamo set up that would work in a real world situation like we have today with all the modern gadgets, they can certainly work great for keeping the lights on while riding and that is what they were designed to do... so yea, they are perfect for that...

bwgride

It's not the fail you exclaim as I show below. Things to consider here: differences in calculations and expectations

Calculations --

My calculations show a more promising outcome; I think you may have miscalculated or misused one of the figures (an easy mistake with something like this).

In past rides I have noticed that my phone uses about 6% of battery per hour when not being recharged to track a ride while in airplane mode and with the screen off. In case I am wrong here, I will assume it is more power hungry and uses 8% per hour.

Lets say I plan to record a ride for 8 hours. If the phone starts at 100% charge, then the battery will be reduced by 8*8 = 64% percentage points, so 36% of the battery remains after an 8 hour ride without providing any charge to the battery.

If I wish to end the day with 100% charge on the phone, then the question is how long can I go without charging the phone before I need to begin charging via the dynamo hub.

As noted in a previous post, the phone recharges at a slightly better than 1% rate (in airplane mode, tracking ride, screen off) per mile.

Assume I ride at a 10 mph pace on tour when fully loaded. I actually ride a bit faster, but most folks report this is a typical pace when touring, so I will use this figure.

Hour 1: distance traveled 10 miles, phone battery level with no charging = 92%
Hour 2: distance traveled 20 miles, phone battery level with no charging = 84%
Hour 3: distance traveled 30 miles, phone battery level with no charging = 72%
Hour 4: distance traveled 40 miles, phone battery level with no charging = 64%

At the half-way point, I switch from charging my battery bank, if it needs it, and I now I begin charging my phone via the dynamo hub.

Hour 5: distance traveled 50 miles, phone battery level with charge = 74% (1% per mile)
Hour 6: distance traveled 60 miles, phone battery level with charge = 84% (1% per mile)
Hour 7: distance traveled 70 miles, phone battery level with charge = 94% (1% per mile)
Hour 8: phone is at 100% (well, 99% due to constant use) at mile 76 and will stay at this level for the remainder of the ride if still attached to dynamo hub.

The point of the above is to show that I only need to recharge my phone at about the half-way point to have a phone fully charged at the end of the ride. So if I ride only 4 hours (~40 miles) during the day, I need to charge the phone only during the last half of the ride, 20 miles, to recharge to nearly 100%.

If my phone is less power hungry using 6% instead of 8% per hour, I could go longer than half-way before I needed to begin charging my phone.

In short, one does not have to ride 95 miles to fully recharge the phone (unless one is starting with the phone at 0%). Instead, one only has to begin charging the phone at about the half-way point during the ride to recharge to nearly 100% each day. Or, one can begin recharging the phone at the half-way point to recharge to the same, or a little better, starting charge level before the ride begins.

So, during the first half of the ride, power generated from the dynamo could be used to recharge something else such as a battery bank, or not used at all.

Expectations --

I hope this information shows that a dynamo hub is not the fail you exclaim above. While not everyone sees the need for a dynamo hub, and certainly in the US very few use a dynamo hub, it is useful on some tours.

For example, soon I will be touring on the Blue Ridge Parkway. There is very limited electrical recharging options on that route unless one wishes to pay extra for an electric-equipped campsite at one of the national park campgrounds, or one wishes to stop and wait at visitor centers while the phone charges. The dynamo hub offers a good option for keeping phone and other gadgets recharged on this trip.

As another example, many bikers on the Great Divide route use dynamo hubs. Here is one blog that discusses recharging an iPhone via dynamo exactly as I outlined above. Quotation:

"I was able to charge my phone within about half a day of riding."

Schmidt's SON 28 15 Generator Hub Review ? Small Tomatoes

That quotation fits squarely with my calculations above. This is useful information because it shows that my findings are consistent with this blogger's findings despite using different dynamo hubs and different power converters.

A Google search also shows many others on the Great Divide using dynamos to charge phones, GPS units, and batteries.

350htrr

You are correct it depends on your expectations, if you use your phone less you need to charge it less. Thus my main point which was, it's easier to save power than to make power, as I said in previous posts.... Thus for you it works, but most people want to use their phone and other gadgets way more during the day, thus, relying on a dynamo would be a fail for most people, IMO

bwgride

Ok, thanks for your thoughtful and insightful post.

edthesped

I use a Shutter Precision dynamo coupled with a Sinewave Revolution USB charger and my normal riding speeds are between 12 and 17 mph. My ancient MOTOX running Urban Biker, and yesterday afternoon Ride With GPS, charges at around 15% per hour. Yesterday's average speed for my 15.2 mi commute home was 13.5 mph and the charge on my phone went from 76% to 93%, for me the dynamo is a keeper. One observation I can make is that the 15% per hour seems pretty constant regardless as to whether I'm running a gps app in the background or not. I'm not sure how often the screen comes on but do know it comes on every time the charging state changes, i.e. starts and stops, which I do very frequently during my commute.

I was a bit skeptical going to a dynamo hub a month or so ago but in hind sight my only regret is not getting one sooner. Also, I don't really notice any change in my average riding speed so I'd say the loss of riding efficiency is next to 0 or at least low enough as to be imperceptible.

I realize this isn't a dynamo luv fest thread but figured I'd add my experience.

I was close to buying the biologic but chickened out in the end and went with something tried and true.

bwgride

Thanks for posting edthesped; it seems our charge rates are similar, and are similar to other reported recharge rates for phones via USB converters and dynamo hubs.