Voltaic Systems V25 6,400mAh USB Always On Battery Backup Power Bank for iPhone, iPad, Samsung Galaxy, Android, and HTC Devices (Gray)

If you are interested in something to carry around to recharge your cell phone or other portable, there are plenty of other power banks much cheaper than this that will do a great job. Skip this review and find one of those. My use case: make an Arduino-based toy that runs on batteries for portability, can be recharged with a standard USB charger, can be played with while recharging, and that restarts properly when the battery has been depleted and is then recharged. Power banks designed for cell phones don't work, because they come with a "feature" -- which is to shut off if the current drain has been low (thresholds vary) for a few minutes (times vary). The thinking here is that a diminished current demand means that the cell phone is fully charged. Unfortunately, microcontrollers are pretty efficient, and in my toy the Arduino drew about 70 mA. That's below the cutoff for standard power banks, so the toy would only stay "on" for a few minutes. I tried some other power banks that claimed to be "always on." Generally they needed a certain pattern of clicks on the on/off button to enter always on mode (which isn't possible when the pack is enclosed in a kid's toy) and, worse yet, once they're drained, recharging does *not* restart the output. The pack sits there waiting to be turned on again, by press of the unreachable button. I was about to give up when I finally found Voltaic. Their power banks meet all the requirements. "Always on" means there's always 5VDC at the output until it's exhausted, and the output recovers as soon as it's plugged in for a recharge -- which for an Arduino means it restarts its program, and all is well. Voltaic advertises that these are solar rechargeable, which I haven't tried. But that would be good for, say, a remote weather station. Compared to other power banks, this one costs the most per mAH, but as it ACTUALLY WORKS I'm happy to recommend it.

i've never been able to find a usb power bank that is always on and STAYS ON even after the device it's plugged into reaches full charge. because eventually your usb device starts dying again but most USB banks like this wont automatically kick back on and keep charging your device the BEST part of this is how it also functioms like an uninterruptable power supply for whatever you plus into it, protecting your USB from power outages. here's an example: I have a nice projection clock in the bedroom that ia powered by a USB wall plug. Everytime we received even the SLIGHTEST power hit on thw house (lightning, dropouts etc), the clock would reset to "12:00" and I had to set it again. ugh but with this nice little power bank (ans it really has a TON of mAh's for it's size, incredible), I can plug this power bank into wall power so it's always charging, THEN plug my USB clock radio into thia power bank, and now the clock radio is protected from power bumps and receives constant power. SO my clock radio now NEVER resets, even when we lose power for several minutes! this is unusual for portable power banks, most power banks stop sending power out their ports when you plug them in to charge them up. not this one, it can ALWAYS be used even when you're charging it up I had been looking for years for this. couldnt be happier with it. get this if you need a USB power bank that is always outputting power even while on charge itself, and one that's tiny with a lot of mAh's. kudos to the inventor. they should start marketing this as a "UPS for USB devices" because that's all I use it for and it works incredibly well and reliably for this!

If you're like me, and you have the Haslab Proton Pack, you most likely purchased a standard issue power bank to run a spliced USB cable from to use instead of those giant Duracell D batteries. THE BAD PART ABOUT THAT: 95% of them power down after 30sec if there's not enough of a power draw. This proved to be frustrating for me when I tried to turn on my proton pack after hooking up my Anker portable power bank after the initial test drive. I was like WHY IS IT POWERING OFF?! Enter the Voltaic Systems V25 power bank. This thing DOES NOT SHUT OFF. The V25, V50, and V75 models run standard Always On, regardless of power draw ranges. Certainly feels great being able to just have a decent power bank that not only stays on, it also feels like it has a relatively long charge life. Wish I knew this thing existed, I woulda gotten the V50 or V75. Excellent product!

I have an esp32 cam project that requires a battery always be on. This is perfect - never turns off - until it runs out of power. The good news is it will charge and discharge at the same time. So if you have a small solar panel connected it keeps your project running.

This is working great! I put motion lighting in a closet I converted to hold wine this stays powered all the time where almost every other power pack in the world does not. Lasts about a month before it needs charging in our use case. Great product. For good measure I mounted it in side of one of those lithium fireproof bags and Velcrod it to the wall.