Trying to google this but to be honest I’m just confusing myself.

Essentially I’m wondering if you can get a dynamo for the bike to charge a phone on a daily basis. And how long you would need to cycle for (at a low speed I might at probably averaging 6 to 10 mph word obviously go faster but curious to use low speeds as a base number).

Anything exist that wouldnt be a pain to run, in the sense of dynamo resistance and weight of the dynamo and battery unit.

Surely it wouldn’t take much to charge a phone with a 2100mah battery? Or would it? That’s the only device in interested in charging. So wondering about the spec to search for to do this?

I’ve seen the hub dynamo idea that’s out as I eckon too expensive.

Not the answer you are asking for, but solar solutions may work better. Remember it keeps on working when you stop for a rest 🙂

I have a device that goes from my front hub dynamo and terminates in the top cap as a USB port. Charges my phone fine at anything over about 9-10 mph. Not really an option though if you’re already balking at the cost of a £50 shimano dynamo hub unfortunately!

Loads of options!

Dynamo hub >

Dynamo light with usb out (rose bikes sell a few)
Or
Sinewave revolution
Or
Lightcharge
Or
Plug 2
Or
Dahon Biologic ReeCharge (optional battery)
Or
Kemo 172
Or
B&M USB Werk (inc battery pack)

Use an Anker or 7Dayshop power bank to act as a buffer to receive the charge and output a steady 5v.

Surely USB charging anything with a LiPo battery will result in damaged to the cell caused by the on/off nature of Dynamo?

Cool. Anyone got a simple answer for the numbers I’m looking for as I say I’m just wanting to be able to say charge a phone from a 20/30 mile peddle? So don’t need excess power generation.

Regarding solar. Consider we have 99% cloud coverage in Scotland I’m rather dubious. A wind turbine would probably give me more confidence! 😆

I’ve seen the hub dynamo idea that’s out as I eckon too expensive.

None of the solutions I’ve seen are cheap.

Tbh if you just want to charge a phone, get a USB battery pack. I’ve got one that uses 6AA batteries and it’ll charge the phone twice from dead.

SP Dynamo PV8 will do the job for the hub, and a Supernova “the Plug” is on of the neatest charging solutions I’ve seen.

I’ve used a PowerMonkey/SolarMonkey combo to recharge a Garmin Edge 705 daily whilst touring Scotland. I don’t know how that compares to a 2100 mAh battery though.

(My phone gets very little use when I am touring).

I use a Shimano Dynohub + Biologic Reecharge to avoid campsites on cycle tour (I like bothies and wild camping). I can produce enough juice on maybe 80km a day to run a Garmin 305 + a HTC Desire S that I use once a day to update the wife.

Recently got a Garmin 510 which I reckon will use more electrons, yet to field test, fingers crossed!

Hmm the solar monkey does sound interesting a reasonably light. Something the think over. I’ll investigate that further as an option, just watched a wee video looks as if solar tech has came on a bit.

To decide if a 30 mile ride will charge your phone…..

1. what mAH rating is your phone wall charger and how does it compare to your dynamo device?
2. How long does that wall charger take to charge your phone
3. How long do you take to ride 30 miles?
4. What will your phone be doing?

If you’ve got a modern smartphone with a 1000mAH wall charger a steady 350mAH from a lightcharge for example is going to take 3x as long to charge.

I use shimano hub and B&M USBWerk. The USBWerk has a cache battery that yr dynamo charges first, so it regulates the output and carries on charging for a while when you stop. Haven’t used it in anger yet but my guess is a good few hours at a clip to get a decent charge. It’s OK to top up, ideal for long tours but for day rides I’d go with a simple already charged usb battery pack or charging case. Had powermonkey explorer also but again it can takes ages in the UK for a small solar panel to charge a smartphone. I inadvertently killed the powermonkey battery unit by hanging it in a tree upside down and it rained into the connector. Am massively into renewables and sustainable solutions but in honesty I should just go riding with a basic emergency phone, one of those nokias with weeks of standby!

For an absoute emergency a wind up torch/phone charger?

Wouldn’t it make far far more sense to just buy multiple batteries ? they’re about a fiver a pop, charge them up and then whenever they die, replace a bad with a good. Surely there’s time every 2-3 days for charging the others that are now down ?

IF your phone has a user replacable battery.

Or…buy one these: £4.99. Stick your SIM card in it, the battery lasts about two weeks.

Pretty easy to make, uses the panels from a solar charger – Maplin L09BK. Also a low loss 5v regulator and optional resisters to indicate to the phone it’s a high-current USB charger. Caps are usually a good idea to reduce noise on circuits. Charges a 1500mah battery in about 2 hours of direct light.

I also suspect you could use the charger intact and use 4 batteries in it as a cache then attach the USB Reg to the output port you can see in the below pic, [though this would be heavier by a long way].

Another option with a dynamo hub is to make the USB charger – last time I looked it was less that a tenner’s worth of components (rectifier, regulator and 3 capacitors, plus USB socket), and that was at Maplin’s prices.

That’s pretty much just swapping the panels above out for a rectifier and an extra cap 🙂

I have an SP hub (2 actually) and a Kemo usb adaptor. Provides enough power to keep the phone fully charged and running with gps and screen on.

On the cheaper side, I also have a solar powered external battery that will fully charge the phone and will charge itself up even on a cloudy day. Cost about £10 from ebay.

Tbh after loads of googling I actually reckon there’s not really much advantage over just buying a hi capacity external battery say 10,000 mah that will charge the phone 4 or 5 times for my type of riding, although if I every did something really long like out for a few weeks in the wilderness it may be something to revisit.. Cheers all for the input though. It was just a wee investigation to see what’s out there.

When I emailed exposure, they said that the output line from a revo would charge a garmin or a phone as long as the light isn’t running.

I found out last year that the newer/better NiMH cells reach about 1.3V when charged (and stay above 1.2V for quite a while under load). So you can just link 4 AA cells to a 6V solar panel (cheap on ebay) and tie it to the top of your pannier/rucksack all day and use the battery pack to power a USB port when charged. I didn’t quite get round to building this up though, as I ran out of a need for it.

The output direct out of a revo will bugger your electrics good and proper. The exposure battery lights smart port does a nice 5v output to use with the boost cable. The power direct from the hub or the rear light port is not regulated!