Recharging AA & AAA Batteries Via Solar Power

Recharging AA & AAA batteries with solar powerThis is the first in a series of “solution” articles based on the need to recharge devices via solar power. I hope you find these articles of value when solving prepping needs that you might have. I hope that you find this article informative enough that you don’t get sucked into overpriced retail solution packages that sound and look pretty but are hardly the best choice…or even a good choice.

So, let’s get started by defining the need…

“The ability to recharge four AA batteries at a time using solar power.”

Seems simple enough, yes? Well, on the surface it sounds simple but as you well know there is always more to a problem/solution than what first appears. Let’s talk about a couple of those issues:

  1. What kind of AA batteries are involved, Ni-CD and/or Ni-MH?
  2. What is the mAh (milli-amp hour) rating of the batteries?
  3. Are they high quality batteries such as Tenergy?
  4. How many hours of sun will be available each hour of the day for charging purposes?
  5. Will this be a man-portable field operation or fix-location operation?

Lets take the solution options in order…

Batteries –

Please never use rechargeable batteries other than Tenergy, Eneloop, or Duracell. Any other brands pretty much suck. Generally speaking use the highest rated mAh battery you can find and afford. The higher the mAh rating the longer the battery will last; technically speaking mAh rating implies the “capacity” of the battery which infers the length of “run time” of a battery.

It is my personal experience that I have seen little to no difference in battery performance whether NiCD or NiMH batteries. But, you must know what type of battery you are using to ensure that the charger you choose is designed to charge that type of battery.

I personally use Tenergy AA & AAA batteries for my emergency preparedness requirements.

Type of Batteries –

NiCD batteries are Nickel-Cadmium. Cadmium is used in the battery and it is a toxic heavy metal. Please tenergy-nicd-batteries-aa-001dispose of them properly if you use this kind of  battery. The benefit of this type of battery is it won’t self-discharge as fast as a NiMH battery. NiCD batteries can also handle a higher charge rate than a NiMH battery. If your device requires a heavy or high load of amperage then the NiCD is the right choice. Most people will use a device such as a camera, flashlight, or weapons optical…a NiCD battery is probably not your best choice for those devices. Depending on your two-way radio, this type of battery may be the right choice.

NiMH batteries are Nickel-Metal Hydride. NiMH batteries will self-discharge faster than a NiCD battery. They tenergy-niMh-batteries-aa-001will also take a higher charge rate than a NiCD battery. Yes, that means they will charge faster. MiMH will not handle a high amperage load as well as a NiCD battery. A NiMH battery is more suited for long duration usage where there isn’t a high amp load required. Such usage would be something similar to a camera, flashlight, or weapons optical.

The reason why it is important to know the difference is to ensure you are using the right battery for your device to get the best performance. Another significant reason to know which battery you are using is the battery charger. A few older generation battery chargers can’t sense the difference between a NiMH or NiCD battery. And since they can’t sense the difference they won’t properly charge the battery. An example of an older generation battery charger that isn’t suited for NiCD batteries is a Goalzero Guide 10 charger…it can’t properly charge NiCD batteries.

Battery “Memory” –

Do rechargeable batteries have “memory” which affects their performance and ability to be recharged? Technically neither the NiCD or NiMH rechargeable batteries have “memory” issues. However, both types of batteries are affected by the “voltage depletion effect”. Simplifying the whole memory thing is this, both battery types benefit from being fully discharged occasionally, then fully charged immediately afterwards. You want a battery charger that can discharge the battery then immediately fully charge the battery. Battery chargers like the Goalzero Guide 10 or Sunjack unit do not have the ability to perform the battery “discharge” and then immediately fully recharge the battery.

Warning/Note: The Goalzero Guide 10 doesn’t have the ability to properly charge NiCD batteries. The company recommends that the charger not be used for NiCD batteries. The Guide 10 unit can not sense a NiCD battery if it is inserted into the unit. Battery damage may occur should you attempt to charge a NiCD battery in a Goalzero Guide 10 charger.

Lastly, how many batteries are you going to be needing to charge? Our example is four.

Hours of Sun Available –

The sun generates rays that reach the earth. Harvesting those rays and converting them into electricity is the key. solarpower-100The fewer number of hours the sun is available, the higher the harvesting capacity the solar panel system needs to have. If you have 12 hours of sun per day that is efficiently reaching your solar panels that is great. But, if you only have 6 hours, then you need at least twice the harvesting capacity in your panels.

But, before you worry about that you have to know that total power needed to properly charge a single AA battery. This is only for “rough calculation” purposes, there is an entire science behind the scenes that we won’t go into. So generally speaking figure 1 – 3 hours of sun per battery at 7watts. We have to charge four batteries. If we are going to charge them all at once we need a 4-slot charger connected to a 28w solar panel system working for 2 – 3 hours. That is all under ideal/optimum conditions. There are many factors that can reduce the efficiency of the charging rate. An option would be a 14w system charging for 4 – 6 hours of sunshine time, potenitally up to 8 hours if charging NiMH batteries. A 7w system would need 8 – 12 hours minimum, maybe much more. Remember, perfect conditions rarely exist.

However, you may also only have partially discharged batteries that only need partial charging. But, occasionally you may want to “condition” your batteries to extend their life and improve their charge delivery efficiency. So you have to allow for the discharge process, then charging them fully back to maximum. Some folks would call this, “clearing the memory.”

I don’t recommend any solar charging panels less than 14w. Anything less than 14w doesn’t allow for anything PortableSolarHarvestingSuningdom-600other than ideal conditions. I like the Sunkingdom solar panel system, a 19w system. The unit can handle two battery chargers at once if needed. The unit’s built in SmartTechnology (IQ) can vary the power delivered to the USB ports to maximize the battery charger efficiency.

As a basis of comparison: The Sunkingdom solar panel unit is nearly three times more wattage than the Goalzero Nomad 7 unit. And the Sunkingdom’s full price is 33% less expensive than the Goalzero unit. And last I looked Amazon had the Sunkingdom on sale making it half the price of the Goalzero unit. More than twice as powerful at half the price…a no brainer.

I will hold off on a “fixed-loaction” option for a day or two. For now you have some great options for portable solar power units and AA & AAA battery chargers.

Summary –

Solar Panel Unit Comparison Chart –

Portable Solar panel unit comparison chartBattery Charger Unit Comparison Chart –

batterycharger5vdc-comaprison-chartWhat to buy & use?

Battery Charger –

If you are only using NiMH batteries then the Sunjack unit is a great choice. If you are going to use, or potentially use NiMH & NiCD batteries then go with the PortaPow unit. The PortaPow unit also gives you the discharge/recharge clearing capability (memory affect). If you are going to go with a NiMH or a Lion battery (a.k.a. Li-Ion, LIB, Lithium-Ion) then you need the XTAR unit.

Note: The Goalzero battery charger (Guide 10) is a 1st generation battery charger that is not capable of properly charging NiCD batteries and has no auto-shutdown capability. That, coupled with a poor warranty and extremely high price I would not buy the Goalzero Guide 10 battery charger. The Sunjack is a more advanced battery charger at 1/3 the price of a Goalzero.

Solar Power Panel Unit –

I really like the Aukey BP-P4 21watt unit. It has a power sensing/sharing 2-USB port delivery system allowing you Portable Solar Harvesting Aukey 21Wto run two battery charger units at the same time. It has the highest “efficiency” rating on its panels and protects its controller unit really well. On top of everything else it has the best warranty of all the units tested.

Note: The Goalzero Nomad 7 unit is an “old technology” unit. It has only 1/3 the wattage rating of the Aukey unit while costing 40% more. The warranty on the Goalzero unit is also only 6months vs. 2 years on the Aukey unit.

Bottom line & Ultimate Combo –

Hook up the Aukey BP-P4 solar panel unit to two PortPow battery chargers and you are good to go! Yeah, charging up to 8 AA or AAA batteries at a time, keeping those batteries properly conditioned, and not spending a bundle of money doing it.

Aukey 21W Dual USB Solar Charger








Note #1: I never stop testing. If I find a better solar unit or a better battery charger unit for charging AA & AA batteries I will get that info posted.

Note #2: If you purchase either the Aukey or PortaPow items by clicking on the Amazon icon above I will make a small commission on the sale. Any and all the money I make through any potential commission will go right back into testing emergency preparedness equipment for reviews that are posted on this website.



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5 thoughts on “Recharging AA & AAA Batteries Via Solar Power

  1. I’m sure that I am not alone in saying thank you for this article. One of my tech concerns has been how to keep AA/AAA batteries going when not connected to the grid. I discounted the wildly touted Goal Zero long ago for several reasons. The practical reasons, well, you have laid them out neatly in your article, and companion Comparison Chart.
    All but the X-Tar have been on my radar for some time, but reading so many pros & cons really clouds the thought process. Anyway, I jumped for the X-Tar and two PortaPows. The reason I held off so long on the one is because of the issue of over-heating which I read about in more than one review. Yes, when I plugged in the PortaPow unit the batteries became quite hot. Too hot to touch for even a short time. My solution was really simple. Open the door (the black front of the unit) so that the batteries are exposed and heat can escape. Seemed to help . . . warm, but not cooking. After charging a pair of Duracell’s which I have been using for months in a flashlight; the light they put out is noticeably brighter than when I was using either a dumb Energizer or Duracell wall unit.
    By the way, your shop now button came in handy, however my order got really fouled-up so I have no idea if you got credit for this item, but I’ll be getting more down the road.
    Again, thanks for the time you put into your website.


  2. The last time we talked here, I mentioned Vinsic for Solar Panels, but as you are dealing with the storage side of the equation, I hope that you’ll give a look at the Vinsic 20000mah
    One reviewer who seems to have done his due diligence says it contains 93% of stated capacity,
    Thanks again for all the work you are putting into your
    blog entries.

    Liked by 1 person

    • Hey NG, Yup! The Vinsic is on the menu. The “solution” article was simply for folks wanting to recharge AA & AAA batteries from a solar panel. Kind of a simple down & dirty solution. For the last couple of months I’ve been working on a series of articles for solar harvesting and different options to recharge batteries. The Vinsic is part of that series. The solar panel (harvesting) articles are already out there (). Look for the charge/recharge articles to start showing up in less than a couple of weeks. Thanks for being a loyal visitor and contributor! AH


  3. What about the newer LiFePO4 batteries? My review of batteries suggest these might be a viable option and in some ways advantageous over other rechargeables. In reviewing your ingenious power box project I also wondered if a LiFePO4 battery might really work well in place of an AGM or deep cell. The weight savings is significant and the life expectancy is really attractive. They are also biodegradable thus avoiding the discard concerns inherent with NiCD and others. Admittedly, I do not have a lot of experience with these things yet. I do know they have some recharging quirks – requiring a charger that either senses or can be “switched” to specifically accommodate the LiFePO4 chemistry.

    I have been using a NOCO X-Grid solar panel set-up which I think does a pretty good job and was pretty fairly priced. However, I’ve never tested the actual output. It was not one of your test items but I wondered if you had any experience with it?

    Liked by 1 person

    • Hey Steve, thanks for the info and suggestion. I have looked at the LiFePO4 batteries. What I found was while they have a real potential they are still out of the mainstream for AA & AAA batteries. The first thing is they are 3.2vDC vs. 1.2 – 1.5vDC for mainstream AA & AAA batteries. Next, they take a special charger to handle their 3.2vDC. There is also a bit of an issue with standardized sizing matching AA batteries. So for now I am thinking it is best for most people to stay in the mainstream till LiFePO4 batteries mature a little more. AH


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