Dynamo charging data

[Retiredtester]

Questions seem to pop up here quite regularly regarding how effective dynamo and usb charger combos are at recharging bits and bobs, so my inner nerd thought it might be useful to compare our own 'in the field' tests. I was really impressed with what my own combo put out on my commute this morning. Feel free to add your own -

Ride duration - 1h10
Av speed - 30kph
Device - wahoo bolt v2
Battery size - 1600 mAh
Dynamo - Shimano XT 8000 series
USB charger - Velocharger MK2
Battery %age added - from 19% to 75%

[Lazarus]

If it was winter i would be able to help[ but its not on the bike at the minute]
sinewave beacon
Exposure Dynamo [ rebranded SP]

Think mine did 10% per hour to the phone 3500mah battery iirc @ 12mph average - its a shared use path so large parts were quite slow due to walkers and their dogs.

[ripio]

Questions seem to pop up here quite regularly regarding how effective dynamo and usb charger combos are at recharging bits and bobs, so my inner nerd thought it might be useful to compare our own 'in the field' tests. I was really impressed with what my own combo put out on my commute this morning. Feel free to add your own -

Ride duration - 1h10
Av speed - 30kph
Device - wahoo bolt v2
Battery size - 1600 mAh
Dynamo - Shimano XT 8000 series
USB charger - Velocharger MK2
Battery %age added - from 19% to 75%

Sounds great, but nobody's going to be averaging 30kph or only charging a 1600mAh battery, when they are bikepacking.

[whitestone]

I posted it on my blog about when Cath and I were touring/bikepacking through Brittany http://bobwightman.blogspot.com/search/ ... namo%20hub I was able to keep a Garmin Oregon and an iPhone (probably a 5 series) charged.

I'd charge a powerbank during the day then charge up the devices at night. You do lose about 10% due to that intermediate step but Garmin devices (and Apple ones!) don't like intermittent external charging so I figured it was a price worth paying.

In general you need to know both your kit in its power consumption and the route profile and how suitable it is for dynamo hubs.

[Alpinum]

From my recent trip with my fatbike across Iceland in March.

Average speeds across the Highlands about 5 - 7 km/h thanks to snow, ice and slush.
Device - various (phone, GPS, internal buffer battery of charger) but for this example I'll take the phone
Battery size - 3800 mAh
Dynamo - SON 28 (150 mm)
USB charger - "Forumslader" version as of autumn 2019 - split cable (charger/light).
I constantly got about 1.3 % charged for 1 km ridden.
Off the Highlands I rode more like 20 km/h and got about 2 %/km.
This was without discharging the buffer battery of the Forumslader and the phone battery always between 20 - 80 %, where charging is most effective.

[Retiredtester]

Sounds great, but nobody's going to be averaging 30kph or only charging a 1600mAh battery, when they are bikepacking.

Fair point on the speed, but I'm not sure how linear the relationship is between speed and output. I'm doing a long audax this weekend and anticipate a moving average of 22-24kph - my usb charger kicks in at about 6kph and I don't know how much more power is generated at 22kph or 30kph.

And regards the battery, when I go bikepacking I mix and match between charging a power pack and charging the wahoo direct.

[ripio]

Fair point on the speed, but I'm not sure how linear the relationship is between speed and output. I'm doing a long audax this weekend and anticipate a moving average of 22-24kph - my usb charger kicks in at about 6kph and I don't know how much more power is generated at 22kph or 30kph.

And regards the battery, when I go bikepacking I mix and match between charging a power pack and charging the wahoo direct.

The output is fairly linear in relation to speed.
https://www.cyclingabout.com/dynamo-hub ... n-shimano/

[Alpinum]

The output is fairly linear in relation to speed.
https://www.cyclingabout.com/dynamo-hub ... n-shimano/

This is correct for the dyno, but not for the charger.

[whitestone]

Sounds great, but nobody's going to be averaging 30kph or only charging a 1600mAh battery, when they are bikepacking.

Fair point on the speed, but I'm not sure how linear the relationship is between speed and output. I'm doing a long audax this weekend and anticipate a moving average of 22-24kph - my usb charger kicks in at about 6kph and I don't know how much more power is generated at 22kph or 30kph.

And regards the battery, when I go bikepacking I mix and match between charging a power pack and charging the wahoo direct.

Get yourself one of those USB meters, just a few quid on Amazon. Ride at a steady pace for say ten or fifteen minutes and see how much current has passed through. Reset the meter and repeat for different speeds. That way you can characterise your setup. Might not be 100% accurate but it will be close enough to work with.

As Gian notes, the output isn’t linear across the whole speed range, more of an S-curve with the middle bit being linear, maybe between 10 and 30km/h or something like that.

[Retiredtester]

Great idea! I'll give that a bash.

[Alpinum]

As Gian notes, the output isn’t linear across the whole speed range, more of an S-curve with the middle bit being linear, maybe between 10 and 30km/h or something like that.

Depends on charger. Eg the latest Forumslader (think it's V5) has 4 stages of output which are automatically adjusted depending on dyno input. This way it's linear across a very wide range of typical riding speeds for cycle tourers/bikepackers. Not sure it's the only one that behaves like that.