Using a dynamo hub to charge a battery

Stringcat · Post by **Stringcat** » 17 Nov 2016, 4:00pm

Hi. I've just read the recent threads about dynamo hubs and lighting. Personally, I'm leaning towards keeping my lights separate and using the hub (probably a Son28) to charge a stand-alone battery so that I have juice for iPhone, iPad, etc. So, any recommendations for:

1) How to wire the hub to other components
2) Whether the output from the hub will sufficiently charge a Lithium battery pack (e.g. enough current? Will it trickle charge at any output?)
3) Any other tips from anyone using a setup like this. (I'd love to get it set up properly first time.)

I've done plenty of touring but I'm a newbie with this sort of kit.

Thanks. Andrew.

meic · Post by **meic** » 17 Nov 2016, 4:16pm

[XAP]Bob on this forum has done something along these lines.
I am not quite sure what though, I just remember talk of having to have something left on or an overvoltage protector or the electronics of various things could be overloaded.
viewtopic.php?f=5&t=94376&p=869439&hilit=dynamo+battery#p869439

Heltor Chasca · Post by **Heltor Chasca** » 17 Nov 2016, 4:19pm

Why not integrate? I'm very happy with my B&M which has a USB port. While you are riding in the day, it's charging up your kit.

Stringcat · Post by **Stringcat** » 17 Nov 2016, 5:06pm

Heltor Chasca wrote:Why not integrate? I'm very happy with my B&M which has a USB port. While you are riding in the day, it's charging up your kit.

I meant keep the lights as battery-operated LEDs, in case I didn't make sense! So it would just be the electrics for charging during the day.

Heltor Chasca · Post by **Heltor Chasca** » 17 Nov 2016, 6:18pm

Ok. Sure. [emoji106] The stem-cap ones look nifty and the tidy routing of cables is attractive, but I did hear a couple of years ago there were issues. Hopefully Son have resolved those. Wonder if there are reviews out there yet?

andrew_s · Post by **andrew_s** » 17 Nov 2016, 7:41pm

I use a SON 28 and B+M eWerk, a set up which predates the availability of the B+M USB-Werk or Luxos U.

The eWerk has piggy-back connectors on its cable, and if the eWerk is on the bike, the light cables plug into the piggyback spades, and directly into the hub if it's not.

Mostly, I use the eWerk set to 5.6V and charge things via a regular USB lead (phone, kindle, Anker battery).

However, it is possible to charge Li-ion batteries by setting it to a multiple of 4.2V, with a suitably low current limit, and CJ has charged his camera battery that way. It's probably unwise to try to get to completely full, but a top up is fine. The main problem is acquiring a suitable battery holder with contacts in the right place.

If you are using iThings, it's probably necessary that you use the official Apple cables.

Stringcat · Post by **Stringcat** » 13 Jan 2017, 6:52pm

andrew_s wrote:I use a SON 28 and B+M eWerk, a set up which predates the availability of the B+M USB-Werk or Luxos U.

The eWerk has piggy-back connectors on its cable, and if the eWerk is on the bike, the light cables plug into the piggyback spades, and directly into the hub if it's not.

Mostly, I use the eWerk set to 5.6V and charge things via a regular USB lead (phone, kindle, Anker battery).

However, it is possible to charge Li-ion batteries by setting it to a multiple of 4.2V, with a suitably low current limit, and CJ has charged his camera battery that way. It's probably unwise to try to get to completely full, but a top up is fine. The main problem is acquiring a suitable battery holder with contacts in the right place.

If you are using iThings, it's probably necessary that you use the official Apple cables.

Thanks. Really useful info. (Sorry, I haven't been here for a while and only just seen this reply.) A friend just recommmended the USB-werk as well. And I see Ortlieb (who have got my dry clothes through many downpours!) now do a bar bag with integrated electrics to connect to this kit. Great stuff. I might even ditch my paper maps for the occasional tour...

[XAP]Bob · Post by **[XAP]Bob** » 13 Jan 2017, 11:49pm

I picked up a biologic reecharge on offer a while back.

I leave the rear light always plugged in, since open circuit dynamos can reach silly voltages and the reecharge doesn't have over voltage protection.

It's done very well, I have a uSB power port which is always available...

I do have to query the sanity of running a dynamo and carrying battery lights....

Stringcat · Post by **Stringcat** » 14 Jan 2017, 7:41am

[XAP]Bob wrote:I picked up a biologic reecharge on offer a while back.

I leave the rear light always plugged in, since open circuit dynamos can reach silly voltages and the reecharge doesn't have over voltage protection.

It's done very well, I have a uSB power port which is always available...

I do have to query the sanity of running a dynamo and carrying battery lights....

Thanks. Someone recommended the reecharge a while ago. I'll have another look.

'Sanity' is a bit strong? Well, my reasoning is:

Running lights during the day on a long tour will add to the drag on the dynamo - charging a USB device is already a sacrifice of efficiency, but hopefully as small as possible.
The USB-werk instructions say it operates at 0-70 volts and has a limiter for over 100v peak voltage.
The instructions also say it can result in up to 50% reduction in the lighting output.

I'm perfectly happy as I am, but just fancied the luxury of charging devices when camping for days on end. Maybe in the future I'll opt for connecting lights too. I rode in the USA for the whole summer of 2015 and didn't use my lights once, but camped in the middle of nowhere quite often!

hamster · Post by **hamster** » 14 Jan 2017, 11:59am

I use an AXA lamp with USB. You switch it either to lamp or charge. It works well but definitely better to charge a battery rather than the phone directly. The varying output kept powering up my phone screen which wasted charge. I cannot see why I would want a battery light with this setup beyond a small lamp to fix punctures at night.

Sweep · Post by **Sweep** » 14 Jan 2017, 1:03pm

Do you have a link for this light/USB charging combo hamster?

Don't have a dynamo set up at the moment though pretty sure I will end up going that way to charge tech.

andrew_s · Post by **andrew_s** » 14 Jan 2017, 1:07pm

It is in the nature of dynohubs that they try to put half an amp through whatever is connected to to them, and if they can't, will raise the voltage in an attempt to do so. Given enough speed, that can be up to 100 volts, which is enough to blow out many electrical components.
A poorly designed charger, like the Reecharge, can't cope, and can fail if there's nothing connected to the USB port to take current and you are going too fast.
If you have such a charger, you have to ensure that either you disconnect it from the hub when there's nothing connected to the USB port for the power to go, or you make sure there's always something taking power by connecting lights in parallel to the charger.The problem with lights is that they reduce the power available to whatever you are charging, so it takes longer.
With well designed chargers, such as those from B+M, Igaro, and Sinewave, you don't have to worry about not having anything plugged in, or the battery you do have plugged in reaching full.

Sanity:
If you have a dynohub on the bike, dynamo lights are lighter and considerably more reliable.
Battery lights are designed to be easily removeable, ànd will remove themselves on pothole impacts, get removed by other people when you park the bike, get removed by you and left behind, get turned on in the bag you put them in to keep them safe from other people and have flat batteries when you want them, have flat batteries because you forgot to charge them, have to be re-aimed every time you but them back on the bike, etc etc.
In contrast, dynamo lights are like car lights; you just flick the switch, or, these days, just let the automatics do that for you when it gets dark enough.

andrew_s · Post by **andrew_s** » 14 Jan 2017, 1:24pm

Sweep wrote:Do you have a link for this light/USB charging combo hamster?

Don't have a dynamo set up at the moment though pretty sure I will end up going that way to charge tech.

Either
B+M Luxos U: https://www.sjscycles.co.uk/lighting/bu ... b-dynamos/
or
Axa Luxx 70 plus: https://www.rosebikes.co.uk/article/axa ... aid:642351
(the Luxos is £105 + post from Rose)

The Luxos has a small cache battery that conitinues to supply power when you stop at traffic lights etc. Some items don't like interruptions to charging - for example, if you are running a Garmin with USB power and the power is lost, it will beep and ask whether to continue on battery power, and turn itself off if you don't say yes within 15 secs or so. A disadvantage of the cache can be that if you plug in something that wants more power than the hub will supply, such as a USB battery pack, the cache battery will supply the extra until it runs flat, at which point the Luxos stops supplying USB power and recharges the cache instead. The end result is that charging takes longer than if there was no cache.

I believe that tne Axa just has a switch to choose between lights and USB power.

Russell · Post by **Russell** » 14 Jan 2017, 1:40pm

Suggest you read this forum thread.

https://yacf.co.uk/forum/index.php?topic=100575.0

Should be what you want.

R

andrew_s · Post by **andrew_s** » 14 Jan 2017, 1:41pm

hamster wrote:I use an AXA lamp with USB. You switch it either to lamp or charge. It works well but definitely better to charge a battery rather than the phone directly. The varying output kept powering up my phone screen which wasted charge. I cannot see why I would want a battery light with this setup beyond a small lamp to fix punctures at night.

Charging a battery to charge the phone will waste considerably more power than the screen does. You have to put a fair bit more power into a rechargeable battery than you get out, plus there's lost power in extra stages of voltage converion.

I use a small USB chargeable head torch, which is considerably more convenient for puncture mending than a hand-held bike light would be.

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