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This is a quick update that AASaver has been upgraded to version 2.1. It inherits all the capabilities of version 2.0, including built-in 5V voltage booster, flashlight LEDs, breadboard power pin headers, USB port (for charging USB devices), LiPo charger (with adjustable charging current). On top of those, version 2.1 adds a 3.3V LDO and a switch you can use to choose between 5V or 3.3V output voltage. This has been the main requested feature that was missing on version 2.0. Using an LDO (instead of changing the feedback resistors) has the advantages that the voltage booster and USB port always output 5V, while the 3.3V output is only effective on the LEDs and the breadboard pin headers. Here are some pictures:



For those who are curious what AASaver is: it’s a multi-purpose voltage booster for AA/AAA batteries. I came up with this idea initially when I was cleaning up a box of ‘dead’ AA batteries one day, and was surprised that many of them actually have pretty good output voltage, like 1.2 to 1.3V. Many AA batteries rejected from gadgets (e.g. remote controls and smoke alarms) still have plenty of juice, but these gadgets don’t have built-in booster circuit to bump the voltage up, so a lot of batteries are wasted this way. I was learning voltage booster at that point and had the idea of designing a multi-purpose circuit for AA batteries, so that I can harvest the remaining energy in ‘dead’ batteries for a variety of things, like lighting up LEDs, powering breadboard circuits, charging LiPo batteries etc. That’s how AASaver was invented. It’s not restricted to used or ‘dead’ batteries — if you plug in a fresh pair of batteries, you can also use it to charge your phone or other USB gadgets. It’s a really neat, useful, and inexpensive tool that everyone should have a few of these!

Below is the original video I made for AASaver. Keep in mind that the current version has a lot more features than shown in the video, including USB charging, LiPo charging. You can even modify it to become a solar charger.

With this new version, I’ve also prepared a more detailed User Manual, with assembly and usage instructions. We have just fulfilled an order from Micro Center so in the near future you may even find AASaver in the Micro Center retail stores 🙂

6 Responses to “Announcing AASaver 2.1 — a versatile boost converter for AA/AAA batteries”

  1. Joe says:

    I think this is a very important invention, like the sparrow is small, but has all the right organs. Imagine all the batteries thrown out with life still in them.

    If we had a device like this it would be useful, we could use it to charge our phones, as a flashlight and to power other usb devices. I have some ideas for expansion of this.

    Why not be able to put 4 or more used batteries of different states of charge so that the power lasts even longer? Please contact me if interested in pursuing this project further.

    • ray says:

      The reason I didn’t want to go with more batteries is that because the battery conditions vary a lot, in the end some batteries will end up charing other batteries, reducing the overall efficiency. This is similar to laptop batteries: often the problem with one cell causes the entire battery to be unusable. So ideally you want to stay with a small number of cells.

      • Joe says:

        Ok, that makes sense, yet it would still be nice to have that option. I could envision two rows of batteries with an adjustable end on each side, just load them up and have the voltage regulator do it’s job and use the batteries until they’re used. Does it really hurt if another battery charges the other? They are after all, used batteries that were going to be thrown in the dumpster.

      • ray says:

        The effect of one battery charging another battery is that energy is wasted on heat due to the battery’s internal resistance (which is quite large on used batteries). Also, using more batteries would make the gadget more bulky. In any case, if you want to use more batteries, you can always solder a different battery holder to replace the current one.

  2. Joe says:

    Great! So if I did solder a different battery holder would the circuitry automatically regulate even if the voltage was higher than your original configuration? How many Volts max could be used with your circuit board?

    • ray says:

      Yes the circuit will automatically regulate the output voltage. However, keep in mind that since this is a boost regulator, the input voltage has to be less than the output voltage (5V), otherwise the output will exceed 5V. If you have multiple batteries, you can connect them in parallel to avoid increasing the voltage.

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