Question on Dynamo hub

[toolonglegs]

If any of you have a Dynamo setup can you share your thoughts please.
Thinking of ordering a Son hub to fit to 29’er wheels. Plan is to let it charge a power pack during the day ( to recharge iPhone, GPS and head lamp ) and let it run light at night.
Is this feasible? Be on a MTB on at times a very hilly off road route, so at times won’t be moving fast. Aiming for 175 kms per day, about 13 days in total.
Any advise and setups would be appreciated.

[RonK]

That is what I do when I'm bikepacking. I have an SP hub and a Sinewave Beacon light. The Beacon is not the most powerful light but it has the charger integrated into it and can either charge or be powered by the power pack.
This is the best approach because many devices such as phones do not charge when the voltage drops at lower speeds but the power pack will keep charging as long as there is output from the dynamo hub.
I run the light during the day as well but the Beacon prioritises charging when the power pack is connected to the charging circuit.

[ironhanglider]

Hi TLL, I don't know much about the charging bit, so others can comment on that. However the lights that I have used (B&M and Hermans) have always come into full effect at pretty low speeds, about 10-15km/h.

Cheers,

Cameron

[Tim]

Dynamo hubs are actually alternators pumping out an AC current.
To recharge devices you'll need a rectifier to convert to DC, most likely 5V/0.5-1.0A, equivalent to standard USB charging.
Lights such as Ron's do this for you. In my case I use an E-Work converter to charge a power pack then recharge the phone and GPS later.
https://www.sjscycles.co.uk/dynamos/bus ... k/?geoc=AU

This thread is dated but still reasonably current.
https://www.bicycles.net.au/forums/view ... amo+device

[Aushiker]

In my experience, bikepacking on my Salsa Mukluk versus road touring on my Surly LHT I don't get anywhere as much charge from the SON on the Mukluk because the speeds drop below the magical 15 km/h quite a lot more than I anticipated.

I also turn off the lights so the dynamo is focused 100% on charging my battery.

My interface is an early prototype of what is now the K-Lite DUAL USB charger. See https://www.klite.com.au/product-page/k ... v2-charger

[toolonglegs]

Thanks guys. I was thinking of using a Sinewave Revolution to convert AC/DC but what your saying Ron gives me food for thought. I won’t need to run the light during the day as I will be 80% off road or on very small roads. Like Andrew says my speed will be very slow at times but hopefully 50% of my day will be quicker.
From what I understand you need to be careful on what battery packs you buy? Need one with “through” power. Able to charge and be charged at the same time? Also better to have two smaller capacity ones than trying to charge one big one?
Still in planning stages so have plenty of time.

[robbo mcs]

If you haven't looked at it already, you should have a look a Alee Denham'ss excellent website

https://www.cyclingabout.com/

here is the section on dynamos and charging

https://www.cyclingabout.com/category/e ... nt/dynamo/

this will answer all the questions you have, and many questions you haven't yet thought of

[RonK]

Thanks guys. I was thinking of using a Sinewave Revolution to convert AC/DC but what your saying Ron gives me food for thought. I won’t need to run the light during the day as I will be 80% off road or on very small roads. Like Andrew says my speed will be very slow at times but hopefully 50% of my day will be quicker.
From what I understand you need to be careful on what battery packs you buy? Need one with “through” power. Able to charge and be charged at the same time? Also better to have two smaller capacity ones than trying to charge one big one?
Still in planning stages so have plenty of time.

Yes, It's best to use a power pack with pass-through charging capability. This lets you connect the power pack to the charger and your device to the power pack, so the device will continue to charge even when your speed is low. I use a xiaomi mi power bank.
Of course it's a good idea to take any opportunity to charge using mains power. So I have an Anker 6-port charger. This lets me charge all my devices - power pack, phone, camera, bike computer from one power point.

[Cycleops70]

I've recently had a dyno wheel set up built.
I've only managed 1 bikepacking trip so far, but a few rides on it on a Sunday morning.

It's a son28 with sinewave beacon light, & a small rear light (can't remember what make).

I charge my phone with a small power bank in line with the output as a kind of buffer. Seems to work quite well.

You might find off road you can't generate enough at lower speeds to make it viable. Particularly with larger wheels like a 29er.
My use is predominantly road, but I did use in on a section of the Munda Biddi & the light was good enough to see where I was going.

[toolonglegs]

Good info thanks, will check out those links. Great idea about charging everything from one battery.
Pretty sure a lot of the time my speeds will be too slow to charge but the main ride is in August so my days will be long here, at least 14 hours daylight. Not sure how much I will need the light each night, but will be good to have the option to push on into the dark if I feel up to it. I am planning on a hotel every three or four nights so will be able to charge everything to 100 percent reasonably often.

[toolonglegs]

Got my quote for the wheels today. I am pretty happy with it but will throw it out there for you guys if you have any thoughts.
- Jante DT SWISS XM421 29er 32T
- Moyeu SON 28 110x15mm Noir 6T
- Moyeu AR DT SWISS 350 148/12
- Rayons Sapim Strong
Thinking I will run Maxxis Ikon 2.35’s ... actually have thought about running 2.6’s but I haven’t got room in the back.
I have read that even with a Son28 I maybe struggling to charge the battery during the day as average speeds can be pretty low especially in the 2nd half of the route. But if they can run my lights ( haven’t 100% decided on them yet ) I will be happy.
I will run a helmet lamp as well which on low power should do me at least 3 nights on the trot. Maybe a hotel or two along the route to top everything up to 100%
I don’t know if I am even capable of doing this yet mentally / physically but I am aiming for 12 days max. Still 6 months off but having watched my little sis prepare for the Tour Aeoteroa I realize how quickly 6 months can pass!
I have no hols apart from this week until August so testing things once it warms up will require innovation!

[RonK]

Yes, those components should build up to a good solid wheelset.
I suggest you consider also Vittoria Mezcals - I have them on two bikes, they are an excellent fast-rolling all-rounder for mixed surfaces. And it's not uncommon to run a wider front tyre so you could run a 2.6/2.35 combination if you prefer.
My personal choice for a long ride such as you are planning is for 29x2.1 Mezcals - wider tyres are heavier and harder to push so better not to choose bigger than really needed.

[find_bruce]

It looks like a good build to me.

As for speed, a hub dynamos produces what is effectively a constant current (~0.5A) however the voltage they can produce increases with speed. Dynamos have a very funky characteristic referred to as load matching. At a particular load for a given speed you can get a dynamo to produce way more than 0.5A - almost double. At slow speeds there is a limit to how much you can achieve.

The easiest way to get a low speed boost is the Forumslader V5. (How good is your german?)

Aushiker refers to power sharply dropping off below 15 km/h - the forumslader gets you that power at around 10 or 11 km/h, but as you can see from these graphs you're still not getting much power below that.

via List of Hub Dynamo USB Chargers and Charging Systems for Electronic Devices

[toolonglegs]

Thanks Ron, I had seen the Vittoria’s but was thinking if I did run 2.1’s I would go with the Rene Herse Endurance tire... they seem to get very good reviews too. My problem will be lack of time to test them all. My thinking for the bigger tires is there seems to a fair bit of rough and rocky terrain. Punctures seem to be a big issue. But also the comfort side of things improving with the bigger tires. Still with around 30% on the road that is over 600km on tarmac. Saying all that until a few weeks ago I had never ridden more than a 26inch MTB with 2.1 tires!
As to the Forumslader Bruce... is that a USB buffer battery? Aim was to run a setup like Ron suggest before. But I am only organizing the wheel so far. Was thinking maybe a Sinewave into a battery.
I have no idea of my average speed while riding. Hoping for at least 15km av... which probably means a lot of time under 10 when climbing / pushing. I should have a least 14 hours daylight each day... hoping 11-12 hours ride time during daylight hours will be enough to keep everything charged even at the a lower average.

[RonK]

Mezcals are available in most sizes including 2.6. sounds like you should fit the widest tyres you frame can accommodate, a wider front will certainly contribute to a more comfortable ride.
I have 2.1 Mecals on my bikepacking bike and 2.6 Mecals on my MTB. I've been running them mounted tubeless for several years, yet to get a puncture or any other problem.

[find_bruce]

As to the Forumslader Bruce... is that a USB buffer battery? Aim was to run a setup like Ron suggest before. But I am only organizing the wheel so far. Was thinking maybe a Sinewave into a battery.
I have no idea of my average speed while riding. Hoping for at least 15km av... which probably means a lot of time under 10 when climbing / pushing. I should have a least 14 hours daylight each day... hoping 11-12 hours ride time during daylight hours will be enough to keep everything charged even at the a lower average.

Sinewave is a good product - it generates 2.5w at 17kph. The forumslader is a bit more "bloke in a shed" build than others, but you can get it with a buffer battery (2100 mAh). The reason I suggested it is that it generates 2.5w @13 kph & should help make sure everything gets charged.

The headtube & top cap version looks neat when installed
,

The hidden electronics

(image from Rodgerbiltit in this thread

If you get the handlebar bag, at €110 instead of €227, you get

The three purple cylinders are the batteries,

The sinewave revolution is a much more professional looking package

[Aushiker]

Aushiker refers to power sharply dropping off below 15 km/h - the forumslader gets you that power at around 10 or 11 km/h, but as you can see from these graphs you're still not getting much power below that.

This is very interesting Bruce. Off to look into the forumslader. If my translation/reading is correct, you need to put this together yourself. Also, I could not find any purchasing options. Does anyone have more specific details?

Edit: Found the price list at http://www.forumslader.de/fileadmin/use ... nglish.pdf

[find_bruce]

Aushiker refers to power sharply dropping off below 15 km/h - the forumslader gets you that power at around 10 or 11 km/h, but as you can see from these graphs you're still not getting much power below that.

This is very interesting Bruce. Off to look into the forumslader. If my translation/reading is correct, you need to put this together yourself. Also, I could not find any purchasing options. Does anyone have more specific details?

Edit: Found the price list at http://www.forumslader.de/fileadmin/use ... nglish.pdf

They used to only come in kit form, but he will also assemble it for you - for what looks like a fairly modest fee of course - the downside is that it looks like it adds 3 months to the availability. The price list is dated 2017 so I'm not sure if it is current. I believe ordering is via email: info ((AT)) forumslader (dot) de so that would be the best way to confirm current prices etc

I don't own one, but I like the design because of its low speed boost. I know TrevTassie has owned one for a few years now, so he can probably point you in the right direction

[toolonglegs]

Getting to 2,5w at 13 instead of 17 makes it very interesting! Stupid question but at aforementioned 2,5w how long do you have to ride at the corresponding speed to charge everything? I expect to have GPS ( plus a spare ) ... iPhone and head lamp.
Thanks Ron, I will look into them... I know I have a habit ( love ) of bombing techie downhill sections, will have to reign that in as I also have a habit of damaging sidewalls!
So much new stuff to figure out!

[find_bruce]

People throwing watts & amps etc can still be confusing, but phone makers seem to make it deliberately obscure.

Iphones are somewhere between 7-15 watt hours, so if your phone was completely flat, you would need to ride for 2.8 to 6 hours (AT) 2.5A to fully charge. Most GPS unit use less than 500 mAh, so maybe 1.5 hour. No idea about your particular headlamp, but I'm guessing around 3 hours if completely flat. Worst case scenario would be something like 10.5 hours.

BUT - if you're on the bike for 11-12 hours you're unlikely to have flattened your phone - when they talk of a phone having an 11 hour battery life, that's with the screen on, loading a web page every 30 secs. Similarly you probably won't be staying up late reading.

Plus it's really speed dependent - anytime you are doing 20km/h or more, you're looking at more than 5w with a forumslader, so basically halve those times

[Aushiker]

Thanks, Bruce. I sort of got a handle on it all after posting. In the meantime, I came across this post in the Thorn forum which goes some way to explaining I think what how the Forumslade achieves what it achieves.

[RonK]

Getting to 2,5w at 13 instead of 17 makes it very interesting! Stupid question but at aforementioned 2,5w how long do you have to ride at the corresponding speed to charge everything? I expect to have GPS ( plus a spare ) ... iPhone and head lamp.
Thanks Ron, I will look into them... I know I have a habit ( love ) of bombing techie downhill sections, will have to reign that in as I also have a habit of damaging sidewalls!
So much new stuff to figure out!

The problem with charging the iPhone is that its charging circuitry senses when the current drops and disconnects - this is to protect the phone from accidental discharge if you happen to plug it in to an unpowered USB port. It won't resume charging until the input stabilises, so when your speed is fluctuating close to the threshold it won't charge much at all. This why you need a power pack with pass through charging - to keep the iPhone charging continuously. In practice it's usually better to charge only the power pack then use it to recharge your devices once stop for the night.

[Aushiker]

On the subject of tyres this look at the rolling resistance of different rim widths might be of interest.

[toolonglegs]

Definitely going to run everything off a power pack. I may run the phone flat! I love audiobooks and podcasts! Lol. But I need a new phone do least battery will be better than the one I have now which is dying in the cold!
Head torch I am thinking Supernova Airstream 2... should get 2 to 3 nights out of that on low power.
GPS will probably be a 1030+ ... the track can be tricky, looking at previous years traces there can be a lot of hunting around for the correct route. Organizers are really strict with penalties.
25mm internal width rims should be good I hope!

[Aushiker]

On the subject of the Forumslader it appears that the graph Bruce provided early is provided by Forumslader. Assuming I have that correct does anyone any links to independent data or reviews? I am not having much luck finding anything.