USB-powered charger: Practical to power via solar?

I'm trying to put together a little emergency kit, and power is one of the more important items. I'm not a hobbyist; I have dozens of AA and AAA eneloops, but that's it. Thanks to this forum, I've discovered that the "free" chargers that came with the eneloops aren't the best, so I was thinking of purchasing the new Panasonic BQ-CC87:

It seemed like a great idea to be able to power this charger via USB from a BigBlue solar charger:

But then I came across HKJ's charger reviews. Admittedly, much of what is in the reviews goes way over my head. But I did come to realize that of those usb-powered chargers he's tested for use with solar panels, most of them do not seem to be good candidates for that usage model. Since he hasn't tested the BQ-CC87 (and probably won't, given the limited interest in such a non-hobbyist charger), I can only guess as to whether or not it might tolerate being powered by a BigBlue. And my guess would be, probably not.

Somewhere I've read a suggestion to use a power bank to power a usb battery charger. But that leaves me with additional questions: How big would it need to be (at least 20,000 mAh, I'd think)? And can it be successfully charged via a BigBlue?

If anyone has any help or guidance, I'd really appreciate hearing it!



These are based on my limited observations, I have tried the Blitzwolf BW-L3 solar charger, which is also reviewed by dodge_911 (he occasionally posts here in BLF forum) here:

Look at HKJ's list of USB chargers, some of the more recent ones have been checked against "solar power" compatiblity, although the older ones were not (re)tested with regards to solar compatiblity since most likely HKJ doesn't have the unit anymore (or it may already have been dismantled...):

In my limited experience, many USB-powered chargers seem to like a USB power source where the voltage can maintain 5.0v and do not drop in voltage that much under load. So that may be a consideration when looking for power banks (some powerbanks that claim 5v/2Amps may be able to output 2Amps, but their USB output voltage drops to like 4.80v or so, which some USB-powered chargers treat as "insuffiicent" power and will slow down the charging rate -- based on my limited observations of a few chargers...

I have the bq-cc87.

You can ask me any question about it

Not anymore, sadly. RIP dodge_911.

I just bought this last night (via Amazon), so hopefully I made the right choice! I don't suppose you've ever tried charging it via solar panels? I don't really have any questions about it, other than is there anything I should know that isn't obvious from reading the specs? It certainly sounds better than the 4 older Sanyo and Panasonic dumb chargers I've been using that came "free" with my Eneloops. I had no idea until now that using those was not the best way to go.

As d_t_a experienced, it seems better to not use solar to power most USB-powered chargers, so I decided to go the power bank route. I'm just waiting for a higher quality 10-20k mAh power bank to go on sale, and I'll snag that. I haven't read anywhere that power banks shouldn't be recharged via solar, but have come across several instances where it's been successful. So, here's hoping .... I purchased the solar panels last night when I bought the bq-cc87: Looks very similar to the Blitzwolf BW-L3, by the way.

Sorry to learn about dodge_911. I hadn't come across his work until now, but it seems like he did high quality reviews. Not that that matters; it'd be sad anyway, he seemed too young.

I have not tried to charge via solar power…

It is good, but it is very picky with old batteries with high internal resistance

It has 3 color leds.

When charging old eneloop xx (that I have since 2013) it refuses to charge because of the internal resistance. No other eneloop charger that I have do this behaviour.

With relatively new batteries…. No issues

Oh, that's not good. Since almost all of my Eneloops are older (Sanyo Gen 1 & 2), that sounds like a problem for me. I don't have a way of testing internal resistance -- but sounds like this charger may provide it (indirectly)!

I'll of course try it out when it comes, but sounds like I might have to return it.

I'd been considering buying a 4-bay usb-powered charger that could charge Eneloops as well as test internal resistance, but after looking through HKJ's reviews, there wasn't one that looked particularly appealing.

Well, darn. But thank you for the warning. If you hadn't written that and I experienced the same problem, I'd probably worry I was doing something wrong (even though it's hard to imagine doing something wrong with a charger this simple).

Or maybe the problem is that my 8x units of eneloop XX are very bad.(I dont think so)…

I havent recharged them not even 20 times since 2013 and this charger refuse to charge them due to high internal resistance and no other eneloop genuine charger refuse them?? Weird.

I have the mdu-001 which is USB too and zero problems when charging my eneloop XX…

I also have the kbc-e which is also USB and zero problems with the XX…

I have the bq-55 or 65 (I dont remember exact model, which is MAINS powered) but it was reviewed by HKJ and is a very good smart charger).Zero problems with this one too…

I have other chargers such as the xiaomi ZI-5 USB powered too… Zero problems with my eneloop xx.

Maybe my unit is a lemon… Or my XX are bad (with almost no use???). Who knows.

BUT! BUT! With other batteries, such as my old white eneloop from 2012… No problems at all.

Conclusion? …. I dont know…

Ah, thanks, samgalax. I didn't know you had some non-XX Eneloops. It's strange about the XXs, but I'm relieved to hear that the CC87 does charge your old white Eneloops. Hopefully it will work with mine, too.

I'm considering getting a non-usb-powered charger, specifically the Zanflare C4, as HKJ's tests seem to show it's quite accurate in measuring NiMH internal resistance (as well as good at charging NiMHs). Seems slightly silly to pay so much just to know which batteries might not be holding their own anymore, but curious minds want to know. Even if I can't use it for my emergency kit, it'll mean I have 2 good smart chargers to use, so I really can throw away all those dumb ones.

I don't have any XX Eneloops, so unless the CC87 refuses to charge some of my old white ones, I won't be able to give any useful info for your dilemma.

Oh, didn’t saw that news… I like his reviews. Have also communicated with him via private messaging here before. His reviews are a big influence to why I also got several different USB meters myself…


anyway to go back on topic…

This guy also tests a number of USB-powered battery chargers with solar panels:

I forgot to mention…

The bq-cc87 is not only picky when used as a battery charger. It is picky even when used as power bank…

When being used as a power bank, the internal resistance of the batteries also plays a big role.

The specifications declare that it gives 1A of output at USB. That is true… But partially…

1A output is only possible when batteries are fully charged and their internal resistance is low… In short…. New batteries.

With my old eneloop XX, I only get between 0.5 and 0.75 Amps at the usb output. If I try more amp draw… The unit switchs off…

When using white eneloop I get 1Amp with no problems…

But these tests should be done by HKJ or any other person with better knowledgements and professional equipment.

Only to let you know…

Thanks, d_t_a, that video is a great supplement to HKJ's solar testing of usb-powered chargers. (I noticed today it appears he removed the 'solar' column from his tested chargers worksheet; too bad. ) Definitely adds to this thread's original intent. However, I have decided that I feel better about the use of a power bank as an intermediary between the charger and the solar panel.

samgalax, I think most every battery charger that can double as a power bank had issues in the reviews I've read (there may have been a couple that worked acceptably). I hadn't read anything about how the bq-cc87 performed as a power bank, so that's good to know, if maybe a wee bit disappointing. It'd have been a nice-to-have, but not a big deal that it's basically missing.

Unrelated to the original topic, I didn't like what the negative reviews on Amazon said about the durability of the Zanflare C4, so I'm back to not getting another charger right now. I'll continue to read and learn, and hopefully come across one that seems right for me. I've seen some good threads here on chargers that test internal resistance, and it seems pretty tough to find something worth getting. Maybe that will change in the near future; I'll keep reading.

Thanks, guys, I do appreciate your help!

The “solar” column in HKJ’s charger table will only be present if you select the “USB power input” in “Select index”, which leads to this table:

Aha! I had that link cached in a browser tab for a few days, so had forgotten that I'd selected it. I later went to his list and selected 'All', and that's when I thought it had been removed.

Thanks again!

So HKJ has two “solar” icons — there’s “round yellow dot with radial lines” and plain unornamented round yellow dot.

I didn’t find any mention in a couple of charger reviews of what distinction that’s meant to convey, searching for the word “solar” in the reviews.

The yellow ‘sun’ dot by itself indicates the charger works well with solar charging. The other one is supposed to be a crossed out sun, indicating this charger doesn’t play well with solar. I had to read a few reviews of each icon type to make sure that’s what they really meant, but once you know, it’s intuitive.

There’s a crossed-out sun icon with a big dark black X over the sun.

I thought I saw two other icons — a round yellow dot, and a round yellow dot with radial lines coming from it.
But now I don’t see the former. Guess I wasn’t peering closely enough at the screen.

I see; sorry, I didn't mean to imply you were dense or anything. I didn't notice the radial lines coming from the yellow dots at first, either.

I only have two sun icons:
No sun, i.e. it do not work reliable with a 5V solar panel.