USB charging from dynamo or solar

[321up]

Hi folks,

I have previously been using a SON 28 hub with the apparently now discontinued Luxos U.  Now looking to setup another bike with a new (different) dynamo hub wheel and a charger for a USB powerbank (it's not practical to charge the camera directly whilst riding).  It needs to work at low speed (e.g. cycle camping) and I'd like to keep the cost down.  Any recommendations for alternative dyno hubs & chargers which will give a good output at low speed?

Does anyone have a good DIY 6V dynamo to 5V DC circuit design?  Many years ago I built a simple circuit with a bridge rectifier, capacitor, large zener diode (for over voltage protection) & low dropout linear regulator but I suspect it wasn't not very efficient (and ineffective in part because the phone screen kept coming on every time the usb power went off/on and negated the charging).

Do modern USB powerbanks require pull-up/pull-down resisters on the USB signal lines to identify the capability of the USB input power supply?  Which?  Or do they need more surfisticated signalling?  Any recommendations for USB powerbanks that will charge well from a dynamo powered circuit?

Many years ago a tired a Maplin USB powerbank with integral solar charging but I didn't get enough solar power to be useful.  Is there any viable lightweight solar charging devices available now?

Thanks.
A.

[L CC]

We (unhelpfully) have one of these https://www.bikeradar.com/news/axa-nano-50-plus-first-look/ which is still going strong 9 years later.

However it also appears to be no longer available. It doesn't look like they do an updated version.
We also have A4 ish sized solar panels that don't really give enough charge for 2 phones.

[ElyDave]

USB Werk?

[andrewc]

I've also got the AXA light with USB output.  It works but I suspect there are better options available now.


SJS have a selection. https://www.sjscycles.co.uk/dynamos-charging-devices/


There are some discussions/reviews on various devices on the Thorn forum. http://thorncyclesforum.co.uk/index.php?PHPSESSID=qvbumavi7dcovpdiobsdg9irf4&board=32.0

[Kim]

I have an e-Werk, which werks well enough with an Anker battery pack.  It's probably not the best option out there now, unless you particularly value the ability to output arbitrary voltages and currents (it can, for example, charge NiMH batteries directly).  Powering a phone from it directly is a good way to discharge the battery on your phone.

As for solar, I have a long-since-discontinued 15W thing from Portapow.  Three panels of a bit less than A4 size that unfold.  This will happily provide the best part of 2A at 5V when pointed at the sun on a clear day, and a respectable half an amp or so in summer overcast conditions.  As such, it's much easier to get a useful amount of energy out of than the dynamo at loaded touring speeds^[1], assuming you're hanging around on a campsite and can tweak its alignment at regular intervals to track the sun.  It should go without saying that solar performance is greatly degraded if not aligned with the sun.  Lying it flat, or worse strapping it across a rear rack is going to be a recipe for disappointment.

I find a USB power meter (something with an LCD and a non-volatile memory of cumulative Ah delivered) is useful to keep track of what you're using, confirming that the dynamo charging setup is actually working, and makes aligning a solar panel for optimum performance much easier.

And of course, quality time spent with a mains socket beats either option hands down.  A battery pack that can charge at higher wattages using QC or PD standards, combined with a suitable wall-wart is well worth it to make the most of limited access to mains power over lunch or on a train or whatever.


_{[1] The only real distinction between standard 3W hub dynamos is what size wheel they're designed for.  For this application you definitely want to avoid the audaxer trick of building a dynamo designed for small wheels into a full size wheel.  Indeed, the reverse is probably beneficial.}

[grams]

Solar chargers are great if they have (a) sufficient surface area and (b) sufficient direct sunlight or lots of time or preferably both. The ones integrated into power banks are gimmicks that are barely big enough to light the charging LED.

Are you asking for something that works better than the Luxos U did, or just equivalent? Because a dynamo’s power output is pretty fixed and you can’t get something for nothing, and the Luxos U does a pretty good job of extracting what’s there.

[321up]

Solar chargers are great if they have (a) sufficient surface area and (b) sufficient direct sunlight or lots of time or preferably both. The ones integrated into power banks are gimmicks that are barely big enough to light the charging LED.

Are you asking for something that works better than the Luxos U did, or just equivalent? Because a dynamo’s power output is pretty fixed and you can’t get something for nothing, and the Luxos U does a pretty good job of extracting what’s there.

I really like the Luxos U & Son 28 dynamo, it's great for Audax.  I'm hoping to find a less expensive USB charging setup for another bike that is broadly comparable.  For cycle camping trips I have older more basic LED dynamo headlights that are adequate, it's the USB charging becomes more important when out in the wild places for days at a time.  I suppose a solar panel and USB powerbank could be left cached somewhere remote and out of sight for a day or so.

This is the cheapest charging option from this supplier ...
https://www.sjscycles.co.uk/dynamos/cycle2charge-v3-plus-usb-dynamo-powered-charging-device/
... but has no reviews on their webpage.  The Sinewave Cycles Revolution has good reviews but is it significantly better?

A budget dynamo could be something like the Shimano Alfine DH-S501 but would it be adequate?

[quixoticgeek]

Gonna suggest a different approach.

Don't fuck about with dynamo to usb charging. It's not worth it.

If you have a 3w dynamo, the realistic amount of power you're gonna put into a battery pack is 2Wh, if you ride for 10 hours that's 20Wh per day. An iPhone 14 has a battery of just under 12Wh. A wahoo bolt is ~6Wh. That's most of your 20Wh gone there.

By comparison, Anker make a 26800mAH battery which is 98Wh (so as to be under the 100Wh max allowed on an aircraft). This has a pair of 2.4A inputs, which at 5v allows you to put in that same 20Wh in about an hour plugged into a cafe's wall outlet. Or if fully empty, in under 6 hours plugged into a hotel power outlet while you sleep.

This is going to be quicker, easier to use, and not cause you to put 5w of your own energy into charging you gadgets.

Unless you are going somewhere really off the beaten track where you'll be more than 5 days without access to a power socket. I don't think it's worth trying a dynamo to usb charging setup.

And solar is even more variable, it's better to just use the same weight in lipo packs.

J

[morbihan]

I'd concur with QG to a degree, but why not both?
If you are camping for a few days and only making occasional stops where grid power is accessible it would help minimise the stress of running out of juice.
Some of the small cafe stop in France and the like don't always have an outlet to hook in to, for example.

[quixoticgeek]

I'd concur with QG to a degree, but why not both?
If you are camping for a few days and only making occasional stops where grid power is accessible it would help minimise the stress of running out of juice.
Some of the small cafe stop in France and the like don't always have an outlet to hook in to, for example.

The ~5W loss can be significant for many riders. Esp over a whole trip.

J

[Kim]

Unless you are going somewhere really off the beaten track where you'll be more than 5 days without access to a power socket. I don't think it's worth trying a dynamo to usb charging setup.

I'm inclined to agree.  At the start of the month I used my e-Werk for the first time in ages:  I rode from Birmingham to Canterbury and back over a week, with no access to a mains socket.  Off the top of my head, the figures were something like:

Day 1: Full 14Ah^[1] battery pack, so didn't use e-Werk or bother getting the solar panel out.  Used maybe 2Ah into my eTrex batteries and phone.
Day 2: Connected e-Werk, put about 0.5Ah into the battery due to a combination of slow riding and the plug working loose, and something like 0.3Ah into it from the solar panel from the setting sun.  Used maybe 2Ah charging my eTrex batteries and phone.
Day 3: Shorter day, with a lot of off-road.  Maybe another 2Ah from the eWerk.  Didn't get the solar panel out as it had clouded over when I reached site.  Recharged the eTrex batteries, phone and head torch, maybe another 3Ah.
Day 4: Sun came out in the morning, and I completely recharged the battery pack from solar in a few hours before going for a shorter ride (no e-Werk).  Recharged my phone, maybe 1Ah.
Day 5: Short slow social ride, didn't bother with the eWerk.  Topped up my eTrex and head torch batteries when I got back to the site early-afternoon, then completely recharged the battery pack from solar again (wasn't paying attention to how long that took).  Used the phone a fair bit that evening, and recharged it from the battery pack.
Day 6: Got about 3Ah from the e-Werk, likely limited by the battery pack being full.  Used about 2.5Ah recharging my eTrex batteries and phone.  Cloudy by the time I pitched up, so didn't bother with solar.
Day 7: e-Werk worked well, but don't remember the figures, didn't bother with solar.  Used about 3Ah recharging my eTrex batteries and phone.
Day 8: Last day, so didn't bother with the e-Werk.  Got home with the battery pack approximately (by the 4-blinkenlight meter) half full, my phone at about 70% and some unknown amount of charge in the eTrex batteries.

ETA: Actually, the power meter hasn't reset.  It reports a total of 9.3Ah from the e-Werk and 12.6Ah from the solar panel over the course of the trip.

So yeah.  The e-Werk wasn't a complete waste of time, but it's still underwhelming unless you're doing a lot of faster riding.  A bigger battery pack would have been more predictable and less faff.  Solar (assuming a 15W panel like this, rather than the usual homeopathic rubbish) works well if you're hanging around a campsite (or indeed stopped somewhere suitable for lunch), but it's no use if you're spending all the sunny hours riding.  I have the e-Werk and it's fairly small and light, so I might as well use it.  Would I buy one today?  Probably not; I don't normally cover so many miles in a day when touring, which skews in favour of the solar panel (or a bigger battery).


_{[1] All measurements at USB 5V.}

[quixoticgeek]

I'm inclined to agree.  At the start of the month I used my e-Werk for the first time in ages:  I rode from Birmingham to Canterbury and back over a week, with no access to a mains socket.  Off the top of my head, the figures were something like:


So yeah.  The e-Werk wasn't a complete waste of time, but it's still underwhelming unless you're doing a lot of faster riding.  A bigger battery pack would have been more predictable and less faff.  Solar (assuming a 15W panel like this, rather than the usual homeopathic rubbish) works well if you're hanging around a campsite (or indeed stopped somewhere suitable for lunch), but it's no use if you're spending all the sunny hours riding.  I have the e-Werk and it's fairly small and light, so I might as well use it.  Would I buy one today?  Probably not; I don't normally cover so many miles in a day when touring, which skews in favour of the solar panel (or a bigger battery).


_{[1] All measurements at USB 5V.}

How much does the solar panel weigh?

Cos adding a 26800 Anker pack is ~500g.

J

[Kim]

How much does the solar panel weigh?

Who cares, a battery is obviously going to be lighter and - more importantly - a less annoying shape and less faff.

It made more sense when I was carrying a fondleslab as well as a phone, but phones got better and the fondleslab got crufty.

What would have made more sense for the above trip would be some sort of lightweight racing 16A Ceeform plug...

[grams]

By comparison, Anker make a 26800mAH battery which is 98Wh (so as to be under the 100Wh max allowed on an aircraft). This has a pair of 2.4A inputs, which at 5v allows you to put in that same 20Wh in about an hour plugged into a cafe's wall outlet. Or if fully empty, in under 6 hours plugged into a hotel power outlet while you sleep.

These days you can buy 65W and even 100W USB C power banks and chargers of similar size that will charge from full to empty in about an hour. Or put another way will get you the same amount of power as an hour of solid riding on a dynamo in 2-3 minutes plugged in.

[Kim]

I'm still a big fan of dynamos, but mostly because they mean you don't have to think about bike lights.  They're just there when you switch them on, irrespective of your other gadgetry.

[quixoticgeek]

I'm still a big fan of dynamos, but mostly because they mean you don't have to think about bike lights.  They're just there when you switch them on, irrespective of your other gadgetry.

Oh totally. For lighting they are brilliant. But trying to charge your life off one seems optimistic.

J

[Lightning Phil]

By comparison, Anker make a 26800mAH battery which is 98Wh (so as to be under the 100Wh max allowed on an aircraft). This has a pair of 2.4A inputs, which at 5v allows you to put in that same 20Wh in about an hour plugged into a cafe's wall outlet. Or if fully empty, in under 6 hours plugged into a hotel power outlet while you sleep.

These days you can buy 65W and even 100W USB C power banks and chargers of similar size that will charge from full to empty in about an hour.

I’d rather have one that charged from empty to full.

I have a 20,000 mAh power bank when cycling.  The main drain is clearly the phone.  Putting the phone in aeroplane mode or switching off whilst riding, depending on your usage, means you should be able to last several days without external power, if mostly keeping a GPS charged. If truly remote, the phone signal is likely to be weak anyway, thus it’s the trying to maintain 4G killing the phone.

[quixoticgeek]

I’d rather have one that charged from empty to full.

I have a 20,000 mAh power bank when cycling.  The main drain is clearly the phone.  Putting the phone in aeroplane mode or switching off whilst riding, depending on your usage, means you should be able to last several days without external power, if mostly keeping a GPS charged. If truly remote, the phone signal is likely to be weak anyway, thus it’s the trying to maintain 4G killing the phone.

This rather assumes that a phone is only to be used for communication.

When I'm riding my phone is usually being used to play podcasts in my ear. I keep the phone signal on, but generally turn off 4g so as to reduce battery usage.

It's very common for riders to use a phone as a media player while cycling.

J

[Lightning Phil]

Which depending on usage covers. You put it in aeroplane mode, and continue to listen to podcasts.

[321up]

Thanks Kim for your usage stats.  One of those USB power meters is now on my wish list.

I don't expect USB charging from a dynamo to provide sufficient power for everything indefinitely, but it does extend the time things can be kept running away from mains, and enable the most important devices to be kept in a usable state or potentially the chance to bring something back to life after everything has run flat.  Us each having a dynamo with a USB charger is perhaps more significant to keeping one set of devices charged than a single dynamo.

Yes it would be sensible to upgrade our two powerpacks with something newer and larger capacity.  When mains power is available for short periods charging two in parallel is likely to accumulate more charge depending on the power rating of the 5V mains adaptor(s).  For short/intermediate length trips dynamo USB charging might not be necessary, but might come in handy if one of the powerpacks die or discharge for some reason.

Cafe stops are a bonus for which we carry two of these so we can charge 4 devices from two mains sockets...
https://www.themu.co.uk/collections/uk-chargers/products/mu-british-duo
... but the availability of cafe's can't be relied upon (we might not pass one for days, it might be full with a queue out the door, there may be no available mains sockets, or it might be closed).  We would also make use of a mains socket for a quick boost in a shop whilst buying provisions.

Hotels/Hostels?  we got lucky once but other occasions we wanted shelter from approaching storms they were full (thankfully the tent has survived thus far).  One hostel we tried had gone up market, was full and wouldn't even let us pitch our tent in their sheltered garden overnight with an approaching storm (grubby outdoors types were not their target market).  On occasion we took refuge in a bothy but obviously no mains power there.  One storm was so bad going anywhere even on foot was not an option, thankfully it only lasted a day.  Having a working smartphone to get the weather forecast occasionally is very useful.  Sometimes there are other issues more important than charging stuff (such as finding drinkable water).

I still need to decide which dyno hub to buy, even if USB charging is an optional extra.  Even in the summer, when there's not much darkness, lights are sometimes required due to poor viability and dynamo lights in my experience are much more likely to continue working with prolonged exposure to pish weather.  We might choose to ride a section of route overnight when there is less traffic.

I think solar charging is potentially useful, particularly on long trips when walking is the main activity.

We sometimes keep one phone off so it's fully charged if we really need it - don't rely on this though as on one trip we found it had got itself switch on somehow and found it had run flat.  Otherwise they will be in flight mode until we find a place likely to have signal to pick up the weather forecast.

[chrisbainbridge]

Whilst I usually carry a battery pack the igaro d2 does give very efficient usage of any spare output from the dynamo. https://www.igaro.com/d2

[D.A.L.E.]

I find a USB power meter (something with an LCD and a non-volatile memory of cumulative Ah delivered) is useful to keep track of what you're using, confirming that the dynamo charging setup is actually working, and makes aligning a solar panel for optimum performance much easier.

Anything you'd recommend? I want to get a better understanding of what my dynamo/powerbank is doing as so far I've been less than impressed. Something like this? - https://uk.banggood.com/RIDEN-UM34-or-UM34C-For-APP-USB-3_0-Type-C-DC-Voltmeter-Ammeter-Voltage-Current-Meter-Battery-Charge-Measure-Cable-Resistance-Tester-p-1297185.html?imageAb=1&p=MA240439985285201910&ID=511646&cur_warehouse=CN&akmClientCountry=GB&a=1688037036.2033&akmClientCountry=GB

[Kim]

I find a USB power meter (something with an LCD and a non-volatile memory of cumulative Ah delivered) is useful to keep track of what you're using, confirming that the dynamo charging setup is actually working, and makes aligning a solar panel for optimum performance much easier.

Anything you'd recommend? I want to get a better understanding of what my dynamo/powerbank is doing as so far I've been less than impressed. Something like this? - https://uk.banggood.com/RIDEN-UM34-or-UM34C-For-APP-USB-3_0-Type-C-DC-Voltmeter-Ammeter-Voltage-Current-Meter-Battery-Charge-Measure-Cable-Resistance-Tester-p-1297185.html?imageAb=1&p=MA240439985285201910&ID=511646&cur_warehouse=CN&akmClientCountry=GB&a=1688037036.2033&akmClientCountry=GB

I've got something like that (the now legendary UM25C) for bench-testing things.  In my touring kit I have an older version of https://portablepowersupplies.co.uk/product/dual-usb-power-monitor

[D.A.L.E.]

I find a USB power meter (something with an LCD and a non-volatile memory of cumulative Ah delivered) is useful to keep track of what you're using, confirming that the dynamo charging setup is actually working, and makes aligning a solar panel for optimum performance much easier.

Anything you'd recommend? I want to get a better understanding of what my dynamo/powerbank is doing as so far I've been less than impressed. Something like this? - https://uk.banggood.com/RIDEN-UM34-or-UM34C-For-APP-USB-3_0-Type-C-DC-Voltmeter-Ammeter-Voltage-Current-Meter-Battery-Charge-Measure-Cable-Resistance-Tester-p-1297185.html?imageAb=1&p=MA240439985285201910&ID=511646&cur_warehouse=CN&akmClientCountry=GB&a=1688037036.2033&akmClientCountry=GB

I've got something like that (the now legendary UM25C) for bench-testing things.  In my touring kit I have an older version of https://portablepowersupplies.co.uk/product/dual-usb-power-monitor

Thanks, seems to be exactly what I'm after.

[ElyDave]

I went out for a ride the other day on the bike with the USB charging off the back of the B&M front light, took my Garmin from about 30% to >80% in under an hour, adn past experience is that it'll keep the Garmin topped up nicely when riding. Saves the BFO powerbank for other devices.