Solar panels for marine use (which is mostly for trickle charging the marine batteries) HAD that problem in the past (discharging at night). Most of them now are wired with a simple diode that prevents current flow the discharging way.

You may wish to look for these.

Although I have a dynohub, I decided to go with just a battery-powered taillight for the rare (I hope) case of riding on roads near dusk or during a dark storm while I look for somewhere to shelter. Similarly, I have a removable, USB-rechargeable headlight for lighting off-road trails and camp sites (allowing me to leave my small headlamp at home). The plan is to use the dynohub to charge one or two power banks, which in turn can recharge my headlight, Edge 25, iPad Mini (offline maps and wifi phone calls), and Nook (reading).

I have been contemplating purchasing a solar panel to use when I set up base camps in southern Utah, and perhaps farther south if I decide to keep going next winter. So far, I haven't been very impressed by reviews of different portable solar panels; most seem to suffer from one or more of the following faults: expensive, heavy, low efficiency, problems charging with intermittent clouds, weatherproofing, reliability, etc.

Of course, I am extremely interested in others experiences with different solar panels in the field.

Other than what I stated earlier (that looks resolvable) I find them useful. I was on a sailboat with one and had no other options. They do work and I have one that folds up like a wallet (small and easy to carry). However, they are slower to recharge than outlets and of course you need good sunlight and need to stay in one place for awhile (unless you can position it on the bicycle while you ride - not as easy as it might appear). I'd consider one as a backup, and as primary if I had no access to outlets (like on my sailboat or hiking in the backwoods).

I also use battery taillight when I have a dynohub. I either am using the USB port to charge, or using the headlight, but can't use both at the same time. If I wired in a taillight it would only function with the headlamp on. And I often want to have the taillight on while using USB to charge things. There are other charger setups that would get around that problem, but I am quite happy with the battery taillights so not changing a thing.

I bought two solar panels a couple years ago, but they do not appear to be available any more. Each one has a USB port and in bright sun will supply 500ma through the USB port. I have not used them on bike tours and have no such plans since I have a dynohub to serve those needs. I got the panels for kayak trips.

Im gonna say that you are right about the pin being shorted, standard USB is 4 pins (2 for power and 2 for data), if you look at a micro USB you will note 5 connections at the micro-USB end. Lets use a tablet as an example, if you plug it into a USB power source it will accept incoming power as a charge, if you have a OTG cable or device attached to the tablet it will SUPPLY power to that device (think usb stick) , the tablets know to give power by sensing the 5th pin is connected . Using a otg cable can allow you to use your tablet as a external battery for your phone or other devices if needed. I use one to supply power to a MiFi cell modem which has a pitifully small battery time as compared to my tablet. Not all devices can sense OTG however so check with the mfg or there are apps you can run to see if your device is compatable.

I think you were correct and the device went into supply power (OTG) mode.

**OTG= On The Go**

Thanks, that helps explain it.

AAA's are pretty small & light, kinda sucks that most lights & devices now use proprietary batteries.

Quit buying stuff that needs charging?

Yes, but don't the proprietary batteries charge with a cable using a USB port or power point connection?

I've just bought a solar power charger that on bench testing with my cell phone and GPS tracking device (Soleus) appears to be working quite well. It doesn't need full sunlight to charge its own internal battery, which is rated at 8000 mAH, and has two USB outputs.

I bought it essentially to recharge GPS tracking devices -- which will likely be my cell phone -- on randonnees.

I will be putting it to practical use on a short overnight trip we have planned to an island national park in two weekends' time. I will report back then on how it performs recharging phone, cameras and GPS devices in varying light conditions.

I'm considering the same device and I'll be watching for your report.

All I carry that needs charging is my iPhone (it's my GPS, Camera, blogging, texting, email, flashlight, phone) and an external 15,600mAh battery. I charge both at the same time from AC via dual USB outlet thingy. I don't ever plan night riding but do have front & rear AAA powered lights for safety/emergency.

The 15,600mAh battery has dual USB out (1A & 2.1A) weighs 9.9 ounces and only costs $18. I'm looking forward to the time when a lightweight solar pack will do the recharging but until then juicing-up at outlets every few days works for me.

http://ziligy.com/photos/posts/15600...nalBattery.jpg

BTW: My total electronics kit: iPhone (in waterproof case), battery, charging cables, & AC connecter comes in at 18.2 ounces.

That should be the same as the maximum charge capacity of the Son28, i.e., 0.5 amps. Have you had any experience charging larger, say 10k+, power banks? I had read in some review of the Son28 that larger power banks could be problematic, but no explanation was given in the review. Of course, I realize that it would take much longer and, apparently, it is exponentially more time consuming to reach full capacity for all of these power banks.

Sure, plus proprietary batteries easier to fit into small devices. My compact camera uses proprietary but at least it's easy to swap in a spare if necessary. Just seems simpler if most devices could use the same battery. But it's great to have the forum for info since things can get complicated with all the possible combinations of devices/batteries/chargers etc.

A few years ago one could read how fuel-cells (using methanol IIRC) were the wave of the future for phones & laptops etc but they've made little headway into the market. Seems like they'd be very convenient--no charging, light weight etc.

SON 28 and almost all of the other dynohubs are built for the same German standard for lighting, thus almost all are 3 watt, 6 volt. A few are lower wattage (2.4 is common), but if you want to charge stuff, don't consider the low watt hubs. This link has an electrical output graph that shows that at higher speeds they can out slightly more power than 3 watts, but not too much more. http://www.ctc.org.uk/file/public/fe...ub-dynamos.pdf

Unfortunately I have not seen any comparisons of USB chargers for dynohubs. Some apparently cut out at higher speeds. Mine will put out a bit over 500milliamps at a bit over 5 volts, that is about 2.5 watts. If there are any other USB chargers for dynohubs out there that can put out more power, I am unaware of them. Ideally, at higher speed a charger would be able to draw any extra power from the hub that the hub can deliver, but my charger does not work that way. It will deliver about the same current out of the USB at all speeds over about 8 MPH.

I did not plan to use any power banks, but I eventually changed my mind and got a couple cheap little ones. I do not use them to charge up a dead phone, I only got them because some of my devices do not draw a constant amperage load, but fluctuate the amount of current draw. The little power banks I got can absorb power while those other devices are not, that is the only reason I got them.

Every thing I have can be charged at 500 milliamps, so the low power is not a problem for me. I understand that some Apple products won't charge at that low rate, they need the big power banks. So you can charge the bank, then use that to charge the Apple device.

A bit late, I know, but...

The charger is fine for juicing up my cell phone (Samsung Core Prime), for several cycles, but the real issue is the slowness of the PV cells to get the charge back into the batteries again. There are four lights that show level of charge, and, while in Queensland recently (one of the sunniest places in Australia), I left the pack to recharge for almost an entire day, and it only moved the lights from one to two in that time -- I had pretty well exhausted the battery pack before this).

One thing that does slow down PV cells is heat and while leaving the pack out in the sun is what has to happen, the trade-off is that on hot days, the efficiency level goes down. It does seem to continue recharging in lower-light conditions, however. Even with full sun power, I suspect it would take three or four days to bring the batteries back to full charge.

Conversely, plugging the charger pack into my computer had the pack up to full charge in several hours.

I will keep using the pack to recharge my phone while riding in extended events such as randonnees, but I will rely more on connection to the mains with a USB adapter or to my computer than sunlight to restore power to it.