Thanks all; saved me money and time.
The Olight Universal magnetic charger does work nicely though. I use that in my hiking solar kit. I would suggest spending your money on a decent powerbank, and a better and larger solar panel.
There are a few other threads here with members who also use portable USB solar panels.
I've used various portable solar panels for a while now.
My first was the ICP Global iSun Solar Charger 2.2W that I bought in 2002 (you could daisy chain so I used 3 together to try increase the solar power). The Coleman Exponent Flex 5 that Amazon tells me I bought in 2005 was similar to the folding panels of today. But these were quite woeful in comparison with newer panels today. I still have them in a storage box somewhere.
Fast forward to now, and I've got various Goal Zero panels from around 2012 to 2014 (the Second Gen Nomad 7W, 3rd Gen Nomad 7W, 1st Gen Nomad 13W), the Instapark Mercury 10 solar panel (my favourite panel for a while ), and a few of the newer higher efficiency panels - a Blitzwolf 20W tri-fold panel, a Sunkingdom 6.5W panel, the Sunwalk 6.5W panel, and some various cheap 6W panels I picked up for testing.
I use my panels on long distance hikes so weight is probably more an issue for me than for bike touring.
My current panels weigh:
- Goal Zero Nomad 7W 430g
- Goal Zero Nomad 13w 750g
- Instapark Mercury 10W 500g
- Blitzwolf 20W high efficiency panel 550g
- Sunkingdom 6.5W high efficiency panel 250g
- Sunwalk 6.5W high efficiency panel 125g
The Blitzwolf works really well (and I have also tested an Anker 21W similar panel last year). I would take it if I was hiking in a group.
But for solo hikes, I am preferring the stripped down Sunwalk 6.5W panel as it is my lightest, but still performs well. I did a 100km hike in November and a 250km hike in January and I took the Sunwalk 6.5W panel and did not baby it. It sat in a dry bag in the external pouch of my backpack when not used, and strapped to the pack when being used. It functioned well.
Back in 2013 I took both the GZ Nomad 7W and the Instapark Mercury 10W to Nepal for a month. They could charge a 1000mAh camera battery from flat to full in around 2.5 hours (strapped to a backpack). At the time, I also took two 5000mAh powerbanks. These could not charge at high current (limited to the original USB spec 0.5A), and would take around 2 days to charge to full with the GZ and Mercury panels.
Now there are higher efficiency panels, and these panels have controllers that can output higher current, and newer powerbanks can charge at higher current as well. With my hiking use of the Sunwalk panel I found it performed quite well in non-ideal sunlight, and would restart charging when exposed to sunlight which some of my other panels would not do.
I had it attached to my pack and while walking and did not always have it facing the sun, nor at an ideal angle and occasionally under tree cover. Despite this, it managed to charge up my fully flat 10000mAh Xiaomi battery bank almost halfway in around 5-6 hours walking. It would charge quicker in more ideal conditions.