Recommendation for Solar Powered Battery Charger
Posted by TheDude50484@reddit | preppers | View on Reddit | 11 comments
Hey everyone, I'm looking for some recommendations for a solar powered battery charging bank. Something to charge, AAA, AA, Cr123 and D batteries. Do you have any recommendations?
Ryan_e3p@reddit
Something small and easy? Pick up a 5 or 6W panel that has USB out, and a USB-powered battery charger. Small, lightweight, can take camping.
These are very popular, especially in the Mesh community, where they are used for deployed and mobile nodes. I have close to a dozen myself, and used it to charge cell phones, flashlights, and other battery powered stuff while camping.
https://www.amazon.com/Soshine-Mini-Solar-Panel-Monocrystalline/dp/B099RSLNZ4
IGetNakedAtParties@reddit
1st point is that those listed (AA AAA D CR123) are battery sizes, the specific battery chemistry dictates if it can be recharged.
So let's assume you have NiMH rechargeable cells in the above sizes and want to charge them from solar, IMO the best option is to use USB based chargers and solar panels as they are universal and the 5V power is easily stepped down by a simple charger. I've seen NiMH chargers which take 4 AA/AAA cells and charges them together from USB but it can also work as a powerbank, taking power from 4 AA/AAA cells (either chemistry) and delivering USB output to charge your phone etc, thus giving you plenty of resilience. A typical AA NiMH holds 2000mAh @ 1.2V so 2.4Wh of energy, 4 of these together is 9.6Wh and will comfortably recharge in 2 hours, so about 5W of power is needed.
The CR123 could be lithium ion rechargeable, which needs a different charger as the voltage is different. This is a very small capacity cell, so power is very low.
I would like to make the case for upgrading from NiMH chemistry to lithium ion for all your devices, they have double the energy density and don't self discharge like NiMH. A single 18650 cell has the same energy as 4 NiMH AAs and the higher voltage drives lights with higher output. You also have much more options for chargers and devices with 18650 cells, and they are readily available and can be scavenged from many devices like laptops and PDQ machines.
In any event you're looking at about 5W of solar, but due to efficiency I would recommend you look at 10W panels which have 2 USB outputs. This way you can charge 2 devices at once and make the most of the sunlight, I find charging something which is almost full (trickle charging) and something almost flat (fast charging) together is most effective. 10W solar is not an unreasonable size, needing about 1 square foot of solar cells, these are available as efficient but fragile monocristaline cells of flexible thin film, and can be foldable.
Any product which combines a battery and a solar panel in one item is trash and must be avoided, for reasons of resilience, thermal, scale, cost, etc.
Paranormal_Lemon@reddit
I'd say go even bigger. Winter, overcast, clouds, angle to sun not good - you get a fraction of the power. I have a "10w" panel and the most I can get out of it is USB 5V 500mA. I'd say go for 20-40w folding panel that has multiple panels.
IGetNakedAtParties@reddit
Well OP didn't mention anything useful, like climate, nor how much energy is needed per day, just that they wanted to charge some batteries. 10W will charge some batteries.
Name and shame your 10W panel, that's shocking output (pun not intended and does not apply)
Paranormal_Lemon@reddit
Similar to this. Big enough to be 10w or fairly close, but the cells and/or the USB converter are not efficient. If you are using something like a charger it might not work unless the full required power is provided, something like a phone will charge with a wider range. The 10w panel will still put 50-100ma into my phone in overcast conditions.
IGetNakedAtParties@reddit
That's only about 3W of solar at that size! It even says 1000mA in the listing which is only 5W in ideal conditions so this fits with your experience. A genuine 10W panel must have at least 1 sq ft of solar cells and two usb outputs. Unfortunately unscrupulous Chinese product descriptions abound, like the 10,000,000mAh powerbank the size of a Mars bar, or the 1,000,000 lumen flashlight which doesn't vaporise the user.
Paranormal_Lemon@reddit
I will take a 1M lumen light that DOES vaporize the user, any links?
IGetNakedAtParties@reddit
This guy's 1,600,000 lumens, and the case is plastic so it's sure to vaporise something. https://a.aliexpress.com/_EJa26JQ
This brightness requires 20kW of power, about the same as a small town. Very impressive.
smsff2@reddit
Most specifications on AliExpress are fake.
IGetNakedAtParties@reddit
I didn't think /s was needed, but apparently it was.
YYCADM21@reddit
If you're looking for something very small, save your money; those gadgets with a 4X6in solar panel on top don't work.
You need to have enough solar panel to actually give you 15W or more of output. getting a 10X12in panel with theoretically charge a couple of batteries as a trickle charger, but if you want to actually charge them from dead flat to full in a few hours, you need at least 100W in solar panel, and a charge controller to balance the cells and properly charge them. You can get portable panels in 100W output, they are 24-30in X 48-52in.
Small panels are virtually useless for any meaningful charging. You're better off getting a small solar generator, a 100W panel to charge it, then charge the cells with a conventional plug in charger to the solar generator