Adventure Cycling Association Forum

Bicycle Travel => Gear Talk => Topic started by: onebadcat on March 07, 2014, 12:01:50 am

Title: Schmidt Dynamos for charging batteries… HELP!
Post by: onebadcat on March 07, 2014, 12:01:50 am
I have been devouring information for weeks trying to figure out if a Schmidt Dynamo will provide me with what I need on tour. Oddly enough I don't care about lights or a phone or my iPod losing charge. My main concern is camera batteries. I admit up front that I know very little about electricity. I do know (now) that a straight USB connection is not going to do the trick. Have been focusing on the Busch & Müller e-Werk as a converter but am not sure what I am looking at for voltage and current needs. I am shooting with a Olympus PEN E-P5 which takes a 7.6V battery and has a two-prong wall charger. Excuse my ignorance but can I just get a female plug, tie it into the system and go?

Other converters? Cache batteries?

Any light you can shed would be greatly appreciated. Need to order my parts ASAP but wondering if this is going to be a viable solution? Stressing me out.

Thanks in advance!

Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: Old Guy New Hobby on March 07, 2014, 08:33:33 am
You seem to have put a lot of work into this, so I'll skip the discussion of alternatives.

The camera's battery has a capacity of 1800 mA Hours. The hub will generate enough energy to keep it charged. As you have already stated, the problem is that there doesn't seem to be a charger that accepts power from a USB hub. However, there are chargers that accept power from a car adapter. They often include a spare battery, so you can keep one charged while using the other. For example: (

You will want to set the e-Werk to it's maximum voltage output. The power outlet from a car is typically a little over 14 volts, but 13 volts should work fine. Positive voltage goes to the center connector of the adapter, negative voltage to the outside ring.

If you want to know more about charging hubs, I wrote a post here: (
Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: onebadcat on March 07, 2014, 11:59:20 am
Thank you. Your write up was very informative. Not sure why I hadn't found that in my previous searches?

Again, I have to apologize for my ignorance when it comes to electricity but with the option that you provided would I simply take the wire from the car charger and splice it with one of the provided Ewerk cables with 'free ends'?

My worry with the camera batteries is that we will be camping 95% of the time and I just don't see us having enough time around power to recharge all of our batteries or I would simply buy 4 batteries for the camera and fully charge them when possible. Each battery seems to take nearly 3 hours to charge and can shoot about a day and a half on each in warm weather. This would mean once a week we would have to have access to a wall plug for at least 12 hours. That has me feeling restricted and nervous as I really do like to shoot photos.

I really appreciate your help. Most information I have found has either been too engineering oriented (read: over my head) or are simply reviews of how products worked for folks (mostly USB-based).

Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: Mark_BC on March 08, 2014, 01:39:27 am
Old Guy New Hobby, I can only find specs for the SON 28 hub that show it produces 6 V (AC I presume), with one reference to a 12 V hub being produced in the future. Will the E-Work be able to still produce 13 VDC with a 6 VAC input?

Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: Old Guy New Hobby on March 08, 2014, 07:27:18 am
Good catch, Mark. How did I missed that? There is the B & M Dymotec S12. If it's still for sale, it's pretty expensive. This doesn't look very promising.  :-\

I guess it's finding a power outlet at the camp site, or packing lots of batteries.
Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: bogiesan on March 09, 2014, 10:00:54 pm
There is a point of diminishing returns when the mass of the generator and the effort, however slight, to spin it and the cost of the devices overcome carrying spare batteries.
There are many other ways to charge camera and phone/tablet batteries including solar and thermocouples and using an auxiliary large capacity battery that is recharged as possible but provides charging current for smaller devices. Again, add the mass/cost/hassle and you can throw up your hands in despair.

Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: zerodish on March 11, 2014, 09:42:20 am
Charging lithium batteries is not basic electricity. They must be charged slow and for a two cell battery the maximum voltage needs to be 8.4 volts. First thing you should do is get a coin cell battery and open it up with pliers. Lithium has a distinct smell you need to recognize. This will not kill you. Lithium batteries will vent if they are abused if you smell this with one of your rigged chargers stop what you are doing and disconnect the charger. Lithium batteries catch on fire. There are generally two types of camera batteries those that charge the cells individually and those that charge them together. If you have the type that charges individually like Sony then you can forget trying to rig something up you have to provide precise voltage to all three terminals. Even with a 12 volt camera battery charger this probably will not work. The computer in these batteries will shut down the battery. If you have the other type you only need to provide voltage to two terminals. You can try this by using a 9 volt wall charger or put 5 AA batteries in a paper tube and hold the wires on with a rubber band. Wall chargers have an icon on them a half circle with a dot that tells you the polarity. Charge the battery by hocking up the positive voltage from the source to the positive terminal on the battery. I recommend 15 minutes. if this works then buy a universal camera battery charger. Universal camera battery chargers are available that take 12 volts. Some of these even charge AA and AAA batteries. These cost $20 to $40. And they will regulate any voltage in and out and alert you if the polarity is wrong.
Title: Re: Schmidt Dynamos for charging batteries… HELP!
Post by: onebadcat on March 13, 2014, 03:06:19 am
Well after more research I have gone from the SON to solar and back to the SON. My solution, for the time being, will be to purchase the PowerMonkey Extreme 12V which is the only USB chargeable 12V out cache battery I have found. I can charge the battery while riding and top off with the small included solar panel when at camp. Unfortunately I haven't found many reviews on that system. If you have experience with that product or have seen it reviewed let me know. Also, if you know of another USB in/12V out cache battery I would be all ears.

Thanks to everyone for their input.