Right charger for solar?

Batteries and Chargers Chargers
1

I have ordered one of the Blitzwolf foldable solar panels for around $17 on special at the moment.

Now that I am thinking about it, and reading a couple of reviews of chargers, I am wondering which charger would be ok for use with this. Since solar will come and go, it will need to be one that will not shut off and wait for a button push or a battery reinsertion before continuing with the charge.
So here are the candidates I have

Lii 500 — no USB input
Lii 402 — won’t restart?
2x Lii 100
2x Lii S1
1x Xtar PB2 — tested - does restart, very good charging
1x Soshine E3 (4 bay Tomo rebadge?) - tested - does restart, less efficient and only 1A draw.
1x Nitecore F1 — ok for solar?

Wow, it’s embarrassing when I realise how many of these things I have bought. I could charge 19 cells at once with the above, more if I count the other rechargeable things I have that are not dedicated chargers.

Now I know the Xtar and the 402 won’t restart, from reviews I have read, and the 500 doesn’t have a USB input, but I think the F1 is fine. Which others are ok for solar, and what else should I be concerned about or testing before I can be satisfied I am pairing the right charger with the solar?

Perhaps the F1 could be used as a buffer (UPS function), its output feeding the PB2 to prevent it from shutting off?
What about the Lii 100’s, could I do the same with them, maybe using them to feed the S1’s and thus charging 4 cells at once with a nice LED readout of voltage at the end, so I can see progress?

Any thoughts on the most practical setup? Ideally I want to be charging an 18650 powerbank, not just a cell, so the Soshine or Xtar are what I am really aiming at.

Another thought, what about a USB hub? Could I use a power bank that supports pass through charging as a buffer, to feed a USB hub, then attach any number of devices to the hub for charging without risk of it shutting off (I’m thinking charged cell in the buffer to take up the slack)

2

The xstar vc2 will probably work if you have a week power supply it drops the mah down and will pick back up if it increases. Such as a battery finishing. But as the current flucatuates it adjust the charge on the go only down side it’s a slow charger 500mah I never bought the master version which does 1 amp and nihm. But it’s one of my own chargers that will bring back a true dead 18650 and not say error

3

The Lii-100 and Lii-S1 also don’t restart after a brownout. No good for solar.

4

I have the nitecore F2 and UM20 and both work great with my Anker 21 watt panel

5

So I’m down to the E3 and the F1, now if one of them can be used as a UPS, I can make the others work through it. Preferably the E3 since it has both 4 cells and a 2A output, but I think it charges itself first, then the attached device, I will have to check.

6

Ok just tried it from my laptop USB. Both the E3 and the F1 seem to work as a UPS. I can have laptop-F1-E3-phone or laptop-E3-F1-phone and both the two chargers and the phone will charge.

Disconnecting the laptop in either setup makes only the first device stop charging, the second bank and the phone continue to charge.

Disconnecting the first bank from the second bank in either case, the phone continue to charge without pause.

Reconnecting as per either case above, and it reverts to charging without a problem.

Xtar seems to work as well, but with a pause. It will continue charging the phone when disconnected from charge, but when reconnected to power it drops the phone charging for a second or so, so it is not a true UPS, but it does seem to work with interrupted power, which it is not supposed to do?

My Mistake, when disconnected the XTAR output stops completely, but on reconnection to power it resumes passing power through, and it only passes power through very slowly, like 100mA, maybe that changes when it is full.

Looks like I have a couple of good options here. I am especially pleased with the Xtar because it will balance cells, charging the more empty one first, and it is small and has a high input & output.

The Soshine is also a good option because I can get 4 cells charging, and it will accept button tops and tell me what is going on with all 4.

The F1 is also good, because it will tell me voltage, and accept other sized cells.

Maybe my best combo is the Soshine and an S1, because then I can charge all sizes and chemistries, and also get a voltage readout of any cell.

7

The 2bay Miller ML202 charger/powerbank works as an UPS but I don’t find it to be that efficient. I never really tested it with a usb doctor or anything, it’s just how I perceive it.
test/review

8

I have thought the same question and bought 1) Xiaomi Powerbank Pro and 2) Tomo charger for 18650 and 26650 - both options support simultaneous charging and discharging. Now I realized never tested how they work in real life, I will test both in the weekend and will report back

9

Im curious about that unit also, but have no solar experience.

Can someone help me learn how well it would work for these 3 scenarios:

1. my iPhone 8 has an 1800mAh battery
I wonder how long it would take to charge it up?

2. I have an 18650 battery, rated for 2600mAh that can be recharged by USB
I wonder how long it would take to charge One battery?

3. I have a 16340 battery, rated for 650mAh that can be charged by USB.
I wonder how long it would take to charge One battery?

thanks for the education

10

I reckon don’t expect more than 1 amp out of it even though it is rated for 2, so 2 hours for the phone, 3 for the 18650, and you should restrict the current to the 16340 to make it take 2 to 3 hours for safety and longevity, rule of thumb is don’t charge a lithium faster than 1/3 of its capacity per hour.

11

In my experience, the combination that I have found to be the most successful for my needs is to leave a power bank hooked up to the solar charger and then use the power bank to charge up whatever needs some power. Some electronics may not reset or may take some time to reset (when there is a lull in the solar input, i.e. clouds) and thus you can lose sun time. I have found my Anker power banks to pick up charging right away after any interruption in the sun

12

thanks
I did a quick test, using my charger/powerbank

I learned that my iPhone charges at 0.64 amps, so Im guessing that would take 3 hours

my 16340 charges at 0.27 amps, and Im guessing that would take about 3 hours also

So, if I go camping and bring my 2 18650 cells in my power bank, I should have enough power to recharge my phone, and my 16340…

meanwhile, If I buy the Blitzwolf solar, I could charge my phone directly, or also the 16340 cell. And those would take about 3 hours each.

Am I understanding the numbers correctly?

13

I’ve got both a 12vdc solar setup and a 5vdc USB folder, so I have some experience.

Let’s face it, you’re not going to leave your $800 iPhone out in the sun while it’s recharging, no matter how long/short it’s going to take.

The key to solar panels for blackout (SHTF) circumstances is to have mother batteries that you charge up during the day and then use those to power up your personal devices during the night.

It the case of the 30w+30w rigid panels, they’re charging up a 12v 22Ah Chrome SLA/AGM battery under the bench and the Sunkingdom 14w folder is charging up a Ruinovo 5v USB power bank (4x18650 Sanyo UR-FM 2600mAh). I can then take those up into my condo and charge stuff up until I’m blue in the face.

If you’re out camping, or hiking and bringing along an extra power bank, or lead acid battery is problematic, then you have to bite the bullet and do the best you can.

Nobody discharges cells/batteries down to zero, unless they’ve made a mistake, but here we go:

1800mAh battery at 0, will take 1.8 hours at 1A input, less any charging inefficiencies (10-20%), or .9 hours at 2A, or 3.6 hours at 500mA.

Questions 2 and 3 are basically the same drill.

Throwing out charging inefficiencies for a moment, you need to know the true current output from any solar panel, under load, to make an educated guess. These things are woefully over-hyped and misleading. Even chargers.

So things depend on your situation. For home emergency ‘loss of power’ situations, getting a 12Ah-30Ah SLA/AGM battery which stays topped off via a Battery Tender Jr. during normal times, is the way to go. If you don’t want to get into 12vdc charging/solar, get a good power bank that lets you replace the cells inside and keep that topped off and then use your 5vdc folding USB panels to charge that up during the day.

There’s a 12Ah PowerSonic 12v (like you might see in a home UPS) being run through my Morningstar SS-10L digital charge controller (for 12vdc solar) powering my Maha C9000 and charging up 4 Energizer 2300mAh AAs at 1A each.

There is the 60w 12v system charging up the same 12Ah mother battery AND charging up some li-ions in my Xtar WP2 II, which like the Maha above, runs off of 12vdc, so perfect for the car and solar with the right adapters.

Chris

14

thanks, that is starting to make sense,

It sounds like the Blitzwolf might be able to fill up one 2600mAh 18650, one 1800mAh iPhone, and one 700mAh 16340, all in <3 hours of sun. Am I understanding correctly?

twitchy finger

15

Well, you’re in California somewhere and you get pretty many solar hours per day. I’m in Miami and I get, according to the solar hour charts for America that I’ve seen, roughly 3-5 solar hours much of the time.

Say you get 5 good solar hours from 10:30 am to 3:30 pm, per day.

Let’s say that your BlitzWolf panel can reliably put out a constant 1.5A at 5v, (7.5W) per hour, for a total of 37.5Wh for those 5 hours you have. Let’s say that all three of those examples above are one third full, so you would need 2600*67, 1800*67 and 700*67%, so 1742mAh + 1206mAh + 469mAh for 3417mAh in replacement energy. At 1.5A per hour, you’re looking at just about 2.5 hours, but probably closer to 3 hours, taking into account panel/charger inefficiencies and slower termination points on various chargers/charging modules.

I think that I have the math mostly correct, lol. You can buy a USB voltage/current meter like the one posted above and get an idea of what your panels/power banks are outputting into the meter, for a general idea of what you’re actually pumping into X, Y or Z device. They’re not too much money.

12vdc systems will obviously output more power, but USB panels are easier to employ.

As we say on the gun board—“get both”.

Chris

16

thanks for the education
I have that Xtar also. like you said, its 12v, so I guess buying a USB to Cig lighter cord, plugged into the Blitzwolf USB output wont work because the Blitzwolf is 5v.

otoh, the Blitzwolf would work to charge USB enabled lights or cells directly:

much appreciate the info, seems the 15w Blitzwolf is good to charge a couple 18650 per day, and thats enough to run a couple flashlights through the night… thanks for my first intro to the practical realities of solar…

here btw is the deal Zulumoose mentioned
code 6897bf
link https://www.banggood.com/BlitzWolf-15W-2A-Foldable-Portable-Dual-USB-SunPower-Solar-Cell-Panel-Charger-with-Power3S-p-1044843.html?p=Z8200610213334201704&utm_campaign=fin17&utm_content=chendongling

17

Hi Jon,

Yeah, I don’t think that going 5v USB solar to a 12vdc adapter is the way to go, due to boosting the voltage to 12v and all of the associated loses inherent in that process.

12vdc solar panels are cheap and if you’re awash in 12vdc chargers, like I am, just buy a rigid panel for those and an inexpensive digital charge controller, like the SunForce 7A jobbie, if you’re running anything over 20W, which is the point that you kind of need a DCC.

https://www.ebay.com/itm/Sunforce-7-Amp-Charge-Controller-New-Free-Shipping/251837611515?epid=22019334761&hash=item3aa2b0fdfb:g:DYgAAOSwZjJU3Tz0

Otherwise, solar chargers are like aquariums, in that one should buy the biggest solar panel that they can afford. Bigger is better and better is faster, meaning less time in the sun.

BlitzWolf makes bigger chargers and I’ve been tracking them on Ebay for two years, but haven’t pulled the trigger. If money isn’t a concern, just buy the Anker 21W PowerPort and call it a day. You’ll pay more than the smaller panels, but that will pay dividends down the road.

Here I was after IRMA last September, charging up my power bank with my Sunkingdom 14W jobbie:

It was hot as Hades out there and being in a condo, I didn’t want to leave that crap out there, but I had the chair/umbrella and that made the 3 hours tolerable, lol!

Mother batteries/power banks are your friends.

Chris

18

+1 on 12V solar panel and charger. Because most 12V chargers are “dumb”, they just work as a CC/CV converter with preset volt/amp output, and being buck converters they can take much lower than 12V. This way you can also reduce one conversion step by skipping 5V.

There are only a handful of USB solar chargers on the market that has true automatic restart function, and they are certainly not MPPT so you have to consider huge additional losses besides the panel misleading rating.

I had an idea for solar charging li-ion cells long time ago, and it was directly wiring 4S LiFePo4 cells with the panel (with diode to prevent self discharge) to act as buffer for whatever 12V device I needed. It might not be the most efficient but the easiest for uninterrupted charging.

19

If I am understanding this right, you are implying that you can buy a 12v (or less) bare solar panel, and wire it to a 12V input battery charger, because that kind of charger, designed to drop available voltage to Lithium range, will accept a voltage input range that could be as wide as 4.2V to maybe 17V to deal with possible car voltage spikes? If that works, then the same could be done with a car cigarette lighter USB converter to charge a USB device?

Sounds a bit dodgy to me, 12V solar panels without a charge regulator can output up to around 21V open circuit, so unless the panel is quite small and can only put out negligible current above 15V it seems a bit risky for the charger?

Or am I misunderstanding?

20

Yes, I get your points. 12vdc solar > 5vdc solar. The problem comes from one’s intended usage. You’re out hiking some mountain and you’re not lugging some 12v solar panel, even a smaller one. If you’re worried about power at home and you want to charge up a few things, the power banks, or mother batteries are the way to go in my opinion. Even the 12v AGM/SLA mother batteries are preferable, IMO.

If one just wants to fiddle with this stuff, than a USB 5v solar panel is easiest.

If you’re in cloudy weather, than you’re screwed any way you slice it. If you have constant sun, than there aren’t too many problems.

Again, USB power banks and mother batteries are the way to go, IME.

Chris