Hi!

I dont know if this is the right forum to ask this question, but anyway...

Im wondering if it would be possible to charge a Anker Astro battery( https://www.ianker.com/product/79ANS1052-BA ) with a Voltaic solar panel ( https://www.voltaicsystems.com/6wattkit.php ) without damaging the battery?

Thank you!

If you get the appropriate connector adaptor it should work

Looks like the panel output is slightly higher than the USB standard of 5V 1A. But as long as the USB port on the panel does not go over voltage, should not be a problem. Once the battery is full, it should stop taking more power from the panel. Due to the higher rating, I would not directly connect an expensive smartphone to it, but I often needlessly get overly cautious about that sort of thing.

I recently bought two panels at 2.4 watts each that I plan to use to charge similar batteries.

I never had much luck charging USB batteries directly from my solar panel (GoalZero Namad 7). The panel's USB port only provides 5V in optimal conditions and with lower voltages most batteries won't charge. You're best off with a battery designed to charge off the solar panel like the Voltaic V39.Personally, I'd suggest a dynamo hub but if you go with solar make sure your batteries will accept a trickle charge.

Considering Voltaic V39 with either Voltaic 6w panel or the Goal Zero Nomad 7 panel. I don't suppose anyone has experience of using both together?

Thanks
Andrew

Agreed. Note that the Anker battery specs indicate that it's expecting an input at 5V, 1.5A; i.e. 7.5W whereas the solar panel is spec'd with an output of 6W - and that's probably under really optimum conditions (summer noon with the panel facing the sun and no haze). No idea what this particular battery pack will do if it doesn't get the full 7.5W. Some will just not charge at all while others might charge but at a slower rate. Unless you can do some tests or find a reliable review that has done some you're better off going with a battery pack that at least says it's designed for the variable power you get from a solar panel.

solar panels generally..
.. may have to sit in one place in clear sky and keep chasing the sun angle as it moves across the sky

moving the panel, to keep panel perpendicular to the sunlight.

To hope to achieve the watts in the panel specs.

This is so true. I was using a panel for about 2 month on my current trip, when I lost the connection that directly connects to my batteries. I was forced to use the USB side of things, and honestly unless you were in perfect light (never when riding a bike) nothing would charge. Usually things were discharging more than charging!

I have tested the Anker Astro 3e 10,000 mah on my hub dynamo. It appeared to be working with the lights blinking. But after 8 hours of biking it still did not have any charge within it. My USB adapter is 5v 1a. I have also tested the Mophie Juicepack 4,000mah, which didn't work.

Unsure how much charge I can produce within 8 hours though, 3,000 mah possibly? Maybe the Anker just needed another couple hours to get over the edge.

I hacked together a usb solar charger for about $70 using this instructables as a guide (link). I did swap out the LiPo charger they recommended with a new product (link) from SparkFun that's supposed to optimize your solar output in non-optimal conditions. If you can solder (anyone can) you can do this on the cheap. Parts I used:

0.45W Solar Cell (link)
Solar Charger (link)
2000 mAh LiPo battery (link)
MintyBoost Kit (link)

The Instructables says 20 hours to charge the battery with this setup. You can spend a little more money to get a larger solar panel that will significantly reduce charge times - anything that sparkfun sells will work. The Battery is roughly the same size as your typical smartphone battery.

I loke the Bushnell Solarwrap Mini. The battery doesn't have the capacity of the Anker but the solar panel is integrated and the whole thing makes a small package. In fact I carry two of them when touring, one being charged via the solar panel and one being charged from the dynamo hub through a converter while riding. Cabelas sells them for around $60.