V50

Expensive, but perfect for my project that uses a Solar panel to keep battery charge while continuously providing power to small esp32-c6 controller that is controlling & powering a small water pump. Be aware that you need at Solar panel of minimum of 6V, 5W to charge this powerbank when you are also powering a separate device. if you just need to charge the powerbank then 5V solar panel will work.

We needed a power pack for the lights in our tent. It had to be always on even when the lights weren't working. This power bank works great. Is compact, hold enough charge for more than we need. Very simple to use, just plug in your device and its on! Easy to charge, great quality. Very happy with it.

Excellent item. Long lasting and reliable. Exactly what we needed in a rechargeable, always on device.

So I have one of the original Voltaic solar backpacks from wayyyy back in the day (if you feel like digging you can find that review here on Amazon) - and the backpack / panels are still going strong. The rechargeable battery that came with the backpack no longer holds a charge, though. So I did a little research for what came next. I noticed that Voltaic no longer offers the exact same type of battery that came with my backpack, so I evaluated the replacement options they had available. The V44 seems to offer the best bang for the buck, in terms of milliamp hours / price - though I took a long hard look at the V72, I'll admit. So far I've been using it for about two weeks, and I love it. I use it to charge my cell phone - and I get about a week's worth of charges, at which point the battery is down to about 50% capacity. Based on every thing I've read, lithium batteries seem to work the same way the deep cycle marine batteries do - they work best when you bring them down to roughly 1/2 capacity, then charge them back up to full. So far, that's what I've been doing, and it's been working great. I love this battery because I don't have to worry about charge controllers, amps, volts, - I just plug it into my (admittedly old) backpack, and let it charge. I don't have to worry about overcharging or anything of the sort. So it doesn't necessarily offer the power storage capacity of a marine deep cycle battery, but it offers a whole bunch of electronic logic and convenience that takes the guesswork out of solar charging. Well worth it.

The always on feature is wonderful for charging things that don't take much current, like my FitBit watch. All the other power banks shut off at low charge rates. But the capacity is a bit small: would not fully charge my iPad, for example. If you need the always on feature for low charge rate devices, then this would be great, but for larger items, get something else.

If you are looking for an “always on” portable power source this is it. Other reviews touch on its purpose in solar or other scenarios. I purchased because I was looking for a portable power supply that didn’t require me to press “on” and merely drawing power by connecting a device would enable charging. This device does that. However, since it will always send a trickle of power if you don’t pair this battery with a solar panel or other continuous charge source it will discharge over the course of a week. This isn’t a design flaw. But if you are just trying to charge a phone it’s probably not the best power bank. That said, this tech is truly impressive. Pass thru charging. The ability to continuously trickle charge. The use of lithium ion instead of lithium polymer. This is engineered for a very specific purpose and I don’t think any other company is solving this. This takes IoT to new levels.

I own a V20 and a V50. These packs are fantastic for my radio-related applications because they are 1) always on and 2) have overcharge protection. I use them to power unattended low power radio beacons (WSPR if you are interested). First, the "always on" feature is very important because the low power draw of the (0.2 watt) transmitters isn't enough to keep other Li-Ion battery banks operating (they turn themselves off). Second, the overcharge protection is great because I can semi-permanently hook the V20 / V50 up to a 20 watt solar panel (with a 5v buck transformer with USB output). One of my beacons has been operating (off-grid, of course) for 6 months now without any human intervention. For my sort of application - low power devices that are solar charged - the V20 / V50 saves me having to purchase a charge controller and lifepo battery. Using the V20/V50 is both cheaper and less bulky (and easier to fit and wire up in a weatherproof box).

I have a motion detector light in the hallway and since there is a lot of traffic I have to charge about every day. Regular power banks turn off when the light goes off and doesn’t turn on until you press the button to turn on as you know. With this it is constantly charging and I haven’t had to charge the battery for over a week so far and very little charge is depleted in the power bank. It is expensive so make sure you need this type of power bank. There appears no competition so that’s why it is expensive. All my other power banks are useless in this application. I intend to buy another one for sure.

On all the time required for 50kg clock which is mounted 2.5M on wall. No requirement for scaffolding to change AA battery