Are cheap USB dynamo chargers any good?

[niggle]

For someone like me with no electronics know how and poor DIY soldering skills, are any of the now readily available cheaper dynamo USB charging devices any good?

E.g.

http://www.laxzo.com/universal-usb-powe ... 1004-p.asp

http://www.ebay.co.uk/itm/380854368541? ... .S2.R1.TR2

http://www.halfords.com/cycling/cycling ... 0wodzYkJ5Q

https://www.reichelt.com/?LANGUAGE=EN&C ... Gwod8bIAUQ

Also re the Shimano SM-DH10 overvoltage protector- would this have a role in making these safe in case their own overvoltage protection is ineffective or non-existent?

[fatboy]

The latter definitely needs over voltage protection. I know this because I bust one very quickly!

[PH]

i asked about the velocharger a while back, having seen it at York rally where it was getting a lot of interest. Only one user review, seems to be a good buy, I'm still undecided, not on how good it is but if I really need any:
viewtopic.php?f=5&t=107024

[niggle]

The latter definitely needs over voltage protection. I know this because I bust one very quickly!

Useful to know!

I wonder if they or anything else can recharge a 4x18650 battery as used with a Magicshine lamp?

Things I have at my disposal to play with:

Novatech EDH-2 dynamo hub with overvoltage diode disconnected, built into 700C rim

Shimano SM-DH10 overvoltage protector

Magicshine XML-T6 LED lamp with 'freznel' style, but single axis, diffuser lense thingy, which produces a more useful spread-out beam if aligned to do this horizontally

Magicshine rubber shrouded 4x18650 LI battery pack

Various mains chargers for the Magicshine battery including a couple of two pin non UK ones

A cheap Union StVZO approved dynamo front lamp, which would make a good 'dipped beam'.

Edit: one of the chargers does not plug directly in the wall, it has a typical two pin mains appliance lead with 'foreign' plug at the end which could easily be adapted to connect to anything you want, but it is rated as AC100-240V 50/60Hz input, DC8.4V 1.8A output so I suppose not likely to be much use...

[hamster]

Worth considering the Axa Luxx 70 Plus front lamp, which has the charger circuitry and USB socket built into the lamp. I've used it for a year now, seems to work well.

[Norman H]

Without having details of the design of the electronics its hard to form an opinion.

The failing with some of the earlier designs was that they had no over voltage protection and the device itself could be destroyed on fast downhill descents. Running with a load, such as lights, in parallel can prevent this but at best charging won't be as fast and some devices wont work at all with lights switched on. There is also the distinct possibility that if you hit a bump and the the lights temporarily go open circuit you will fry the electronics. The Halfords unit quotes an input voltage of 0-50V but doesn't say whether it's protected above 50V.

The Velocharger specifically states bottle dynamo. That doesn't mean that it wont work on a hub generator but, if the circuit is optimised for a bottle dynamo, it may be less efficient.

Another consideration is charging current. Modern phones and tablets tend to be quite power hungry and have large capacity batteries. Consider 500mA as a minimum charging current. Better still 1000mA.

I have the Axa Luxx 70plus front light that hamster mentions. It has USB charging at 500 mA and it's been totally reliable for the last 4 years. I believe some B+M lights will charge at 1000mA.

Finally don't expect any of these to work with Apple devices.

[PH]

The Velocharger specifically states bottle dynamo. That doesn't mean that it wont work on a hub generator but, if the circuit is optimised for a bottle dynamo, it may be less efficient.

There is a hub dynamo version, though it's considerable dearer.
http://www.adeptelectronics.co.uk/velohub.html

[niggle]

I have a standard Axa Luxx 70 on another bike, it is OK but for this experiment I want to use a Magicshine 'high beam' , which I know is superior for descending at high speed, with the cheap front lamp I also have (Union Hilux 35 lux) as a low beam. I realised my error with the Velocharger earlier...

Evans also sell the same unit as Halfords (Tigra Sport BikeCharge Power Converter) plus both sites have one sensible looking positive review for it. The fact that two large retailers are selling it encouraged me to look up the manufacturer's website for more info:

https://www.evanscycles.com/tigra-sport ... r-EV203986

http://www.tigrasporteurope.com/en/bike ... 02247.html

Description:

- Works with most common hub dynamos in the market
- Low speed efficiency: typically starts output at 5-6kmh and reaches maximum at 18-20kmh (on 26" wheels)
- SMART circuitry: if light and USB devices are both connected, light will always be given priority with light intensity unaffected
- SMART circuitry: USB port can charge most common smartphones and USB-powered devices*
- 3 lighting modes to choose from: 1. Light ON; 2. Light AUTO (light will switch on only if ambient ligh is dim); 3. Light OFF (all power goes to USB)
- High speed protection triggered at above 40kmh
- Input: AC 0-50V
- Output: DC 5V (USB compatible) 600mAh max.
- Waterproof
- Weight: 87g
- Package includes Power Converter, zip ties
* Due to the unsteady nature of power output from pedalling, it may have issues with some smartphones equipped with power management systems (eg. iPhone). Users are recommended to use this Power Converter to charge a battery pack which in turn charges the phone

Data Sheet:

ACTIVITY Bike
SPECIFICATION Power Solution;Waterproof IPX4

I have just ordered a power bank, thinking I can always use something like that anyway, even without dynamo charging for it. If I do get a USB dynamo charger it will probably be the Tigra Sport one.

[Norman H]

The Tigra unit looks to be worth a punt. It seems well made and has most bases covered.

Charging a powerbank is a pretty reliable way of using these chargers, if not the most efficient. Some devices don't like it when the the charging current falls or even drops momentarily to zero as your speed varies. You may even be able to use the powerbank as a cache battery and simultaneously charge your device from the powerbank whilst charging the powerbank from the dynamo.

[Sweep]

Anyone got any practical experience of the above mentioned Tigra Sport?

Seems to be on sale at Evans at the mo for under £20.

I would be using the converter to feed into a powerbank , nott a device.

[hjd10]

Anyone got any practical experience of the above mentioned Tigra Sport?

Seems to be on sale at Evans at the mo for under £20.

I would be using the converter to feed into a powerbank , nott a device.

Hi,
I've been using one of these for a few rides and it seems to work perfectly. With the lights turned on I charged a powerbank in a similar way, which in turn powered my GPS and IPhone.

Cheers,

[crazydave789]

Anyone got any practical experience of the above mentioned Tigra Sport?

Seems to be on sale at Evans at the mo for under £20.

I would be using the converter to feed into a powerbank , nott a device.

I've just wired a tigra into a sanyo NH rim dynamo, the dynamo is rated 6v 3w and the tigra can take up to a 50v input so overvoltage or solar panels will work okay with it. it only chucks out 5v 500ma though which is enough for a light or low charge usb devices/devices that can remain turned off, so I'm patching it via a cache battery as most phones now require higher charge rates or they run down devices faster than you can charge them because they try to turn themselves on whenever they get a bit of charge.

I got some zendure A1C batteries from amazon, all zendure stuff has pass through charging which is what usually makes powerbanks expensive.

https://zendure.com/products/a1-portabl ... mah-silver

I need to test it with a meter to see how its output varies, I don't know if putting a voltage doubler on the feed in would make any difference when pedalling at a pathetic rate at the end of a long day.

[Sweep]

Thanks for the replies.

I use this anker powerbank.

https://www.anker.com/products/variant/ ... h/A1271012

They quote 10 to 12 hours to recharge it from a 2 amp charger.(I use a quality 2 amp Anker unit rather than a cheap 1 Amp I have) which should, should it not?, mean that it will take up to 48 hours to recharge the powerbank fully from the Tigra?

Seems like a hell of a long time of course but I'm thinking that that might not be a great problem if it's just sat there gently charging all the time as I pedal. And since the powerbank has a high capacity and can recharge my 7 inch tablet a fair few times I reckon I should still be putting charge into the powerbank faster than I'm taking it out. If there's any fault in my thinking, folk feel free to point it out.

Could the 500mA output actually be kinder to my powerbank than a higher charge? My NiMH AAs are always charged at 200mAH unless I am in a particular rush as this is kinder for the batteries.

Again, critiques of this thinking welcome.

The other thing I'm thinking is that in practice the pedalling charging of the powerbank will be supplemented by mains power charging now and again. So we could have a goer.

I like the cheapness of the Tigra Sport ( ) and also its apparent simplicity.

edit: note that the Anker does not appear to support pass-through charging but that isn't necessarily a problem for me.

[Sweep]

PS.

It appears that the Tigra Sport is now a discontinued model.

Anyone got any ideas about whether this reflects at all on its quality?