Chargie Phone Battery Saver

I got a Chargie device for my phone. I’m sorry but I can’t recommend it.

The promise is “Chargie is an app+hardware phone charge limiting solution that makes your battery last for much longer than if you had charged it regularly to 100% all night, every night.” It limits charging by unplugging the USB cord when your phone is charged enough.

Here’s the review I emailed to the developer and posted on Google Play. I’m sad that after a month, there’s been no response.  

Two Stars out of Five: I got my Chargie April 2, 2020 for my Pixel 2. This review is on Jun 3. It’s a good idea, the app is well written and the device works (with a few tiny glitches) but I’m concerned that it won’t save my battery. Now instead of staying at 100% in the overnight, my battery goes between 80 and 85% charge several times per night. If it’s the act of discharging that is bad for a battery, then Chargie won’t solve the battery-wear problem. :-( I want it to work but I uninstalled it. Maybe it would help if it automatically turned on Battery Saving mode while on the Chargie device.


  1. Tyler says:

    Your battery is discharging energy constantly, (even if you were to remove the battery it would still slowly lose charge) but charging your phone in the 60-90% range is more efficient then a full charge to 100%, (the lower you set the maximum charge the better within the 60-90% range, anything below 60% and the scale starts to tip back towards inefficiency) so it makes sense for the charge to fluctuate if the app’s trying to keep your battery close to 80%.

  2. Lee says:

    Tyler, I assume that batteries lose capacity by being used (ie. turning chemical reactions into electric potential and back again). So then the best way to maintain the capacity of a battery is to hold it at one particular voltage. If I could plug my battery directly in to a 3.6 volt DC power supply, that would do the trick; my phone would draw electrons from the power supply and not the battery. But the battery in my phone is “hidden” behind the power system. When I used the Chargie, my battery bounced between 60 and 70% charge several times in an evening. That’s not good. It is conceivable that less wear on a battery happens between 70% and 60% than between 90% and 80% but NO wear happens between 100% and 100% when I plug it in at night. I’d be happy to be wrong about this, heck, I bought 2 Chargies hoping it would help, but, absent some good research, it seems like it won’t help the problem. :-(

  3. Chris says:

    Lee, I understand where you’re coming from but in my opinion you are mistaken. I have used Dell’s Battery Command Center for years and set it up to maintain a charge between 55 and 85 percent. The result is that my battery capacity decreases very slowly. I have done the same thing with Battery Charge Limit (on a routed Android phone) and my wife time some application that bros at her when her phone gets up to 80 percent. Her phone is three years old and mine is two, and they both have almost all of their original capacity. It’s been a night and day difference for us. In fact, my wife’s battery is still rated at over 90 percent. Then I unrooted my phone and just started charging to 100 like everyone else and my battery’s capacity fell like a brick. It’s about 2/3 what it was before. That’ why I’m here, going to find a good solution that doesn’t require root.

    TL;DR – don’t jump to conclusions based on what you _think_ will happen. It seems odd that you would but this product, observe it doing exactly what it says it will do, and then declare that it’s no good on hypothetical grounds. I can tell you that this works using software, or by just being disciplined about it like my wife. Try it. If I’m wrong, you will just have one in a long line of phones you own over time with a battery that degraded just like all the others did, as I swear that bouncing between two percentages has not hurt my laptop or phone batteries.

    Wow, that’s a long TL;DR, sorry. But I love telling people how well this works with software. I’m just trying to find out if chargie will do it as well. And it might surprise you to know that your review tells me that chargie does exactly what I want: it cycles my phone battery between two percentages. Thanks. :)

  4. Lee says:

    Chris, thanks for the comment. Since you’ve now tried both methods (Battery Charge Limit with rooting and Chargie) you might want to answer this question for yourself and the world: How many charge cycles does your phone experience using the two different methods?

    With Chargie, I was seeing about 5 cycles per night going from 80% to 85% and back again. So the battery got 25% of a cycle. when you use Battery Charge Limit, does the charge hold at exactly one percentage of charge? That might give a good idea as to whether Chargie would work. But the best way to test out whether Chargie saves batteries is to run it for a few years. I just didn’t have a patience to do it. And it don’t have a “control” for the experiment so my multi-year-long study wouldn’t be terribly valid. Good luck to you and have fun!

  5. Sergiy Markutsya says:

    To better understand the charging process in smartphones (laptops work the same way) we need to accept the following facts:
    1. Smartphone always drains energy (unless you remove a battery from it), so it is constantly discharging.
    2. When you connect your smartphone to a power source, power from the outlet goes to the battery and charges it. Smartphone uses energy from the battery. There is no way smartphone can bypass the battery to get a power directly from the outlet.

    Based on statements 1 and 2 we may draw the following conclusions: 1. The level of charge you set up for a battery doesn’t prevent or limit discharging/charging cycles that happen in your smartphone. 2. By lowering the level of charge to 80% we are significantly reducing physical and chemical stress within a battery during discharging/charging cycles. Thus, significantly increasing the “life” of a battery.

  6. Lee says:

    I’m sorry but I disagree with your “facts”. Though neither of us know exactly how our phones are wired, which is unfortunate.

    I can’t speak to the phone in my pocket because I don’t have a schematic for it. But in general, if a device and its battery are held at a certain voltage by a power supply and the device draws some power, that power will come from the thing that is at the highest voltage, namely the power supply. I assume that phones have internal circuitry that try to hold the battery at 3.7 volts (max charge for a lithium-ion battery). If you could tell that circuitry to hold the battery at a lower voltage, you’d be rockin’. I hear there are Android apps that require rooting that actually have this function. But Chargie doesn’t have access to that subsystem. I’ve owned laptops and phones that had the ability to stay at a lower state of charge than full.

    I’d love to be wrong about Chargie’s core failing but your argument doesn’t sound convincing to me.

  7. Henry says:

    I see a different problem entirely than what has been discussed. You reported that while using Chargie, you saw your battery bounce from 80% to 85% and back 5 times during the night. That indicates that while idle for around 8 hours, your phone consumed 25% of its capacity. Android has supported a deep sleep mode for years now, and that should put you in the 1-2% range for overnight discharge.

    On one hand, it sounds like Chargie is doing what it is supposed to be doing. It is charging the phone to 85% then turning off. But what is causing it to repeatedly drop from 85% to 80%? That’s the important question. I’ve ordered three of the devices just now. One for Android Auto, one for nighttime charging, and one for a phone I keep plugged in 100% of the time to use as a server of sorts. I’ll keep an eye on it and make sure that the phone isn’t quickly draining when using Chargie.

  8. Josh says:

    I’m trying to figure this battery stuff out as well. One thing that is mentioned lots of other places but not here is that staying at 100% charge (even if at that point the power goes directly to the device and not through the battery) does more damage to the battery (or ages it more) than some cycles in the 60-80% range. Henry, have your observations yielded any results?

  9. Lee says:

    I’m not going to keep my chargies. I’ve got 2 “Founder Edition” Chargies. Would anyone like to buy them from me for $40, free shipping in the US.
    [update 9-14-21: I had no actual takers and threw them away]

  10. Pete says:

    Do you still have your Chargies for sale and do you take Paypal?

  11. Lee says:

    Pete, yes and yes. I’ll email you.

  12. Ron says:

    Lee, did you end up selling the Chargies? If not, I’m interested.

  13. tom says:

    Lee, I can see where your intuition leads you to the above conclusion, but note that for lithium rechargeable batteries (both what’s known generally as Li-ion, and Li-poly, the latter being your cell phone battery; there are numerous specific chemistries) the intuition is unfortunately very wrong.

    There are two conditions that are at work:

    A typical lithium rechargeable, left at 100% charge, at room.temp (worse if hot), will loose (*permanently*) roughly 20% of its total capacity. Eg a 1000mah battery simply left full for 12 mo now has only 800mah capacity – no way to recover this a LA old nicad days.

    And ‘cycles’ are critical but NOT simple calc you are using – depth of discharge is the most important factor. Light discharge cycles like you’re seeing simply don’t “add” to a full cycle, they are much less wear.

    Zero affiliation to chargie.

  14. Lee says:

    It would be great if you could point us to some research showing about the loss of capacity at 100% charge vs 50% charge. I couldn’t find any research that claimed it. And I’d think the owners of the Chargie would be touting that research! I read a lot of articles saying “everybody knows….” but no one that actually tested it.

    >And ‘cycles’ are critical but NOT simple calc you are using – depth of discharge is the most important
    >factor. Light discharge cycles like you’re seeing simply don’t “add” to a full cycle, they are much less

    Yes, but how much less wear? I looked at depth of discharge charts and came up with an estimate of “yeah, maybe I’ll get a little more life out of my battery… or maybe not. It’s hard to tell.”

    Starting here: (via)

    Look at the chart
    If you discharge 20%, you get 9,000 cycles.
    If you discharge 80%, you get 900 cycles.
    That sounds like an amazing wonderful difference but look closer…
    0.20 * 9,000 = 1,800
    0.80 * 900 = 720

    1800/720 = 2.5

    So, you can store 2.5 times as much power if you treat your battery very gently. That’s never letting the battery use more than 20% of its capacity. That’s nice, but the Chargie doesn’t hold the battery at a particular voltage, it turns on and off within a range. So the battery is going through charge and discharge cycles all night. How much more power is going through it in total? I saw it charging and discharging several times in a night. Is it using less than 2.5 times as much power? If it is, then Chargie is still saving my battery! But if it isn’t, then… ugh. I just want the darn thing to work. All this math and guestimating is too much trouble. If isn’t making a solid claim with charts and testimonials, I’m liable to believe it’s not saving my battery.

  15. tom says:

    Lee –

    Your reply above does raise valid questions, being more specific about the exact discharge/cycle behavior.

    Unfortunately, as you do point out, answering this really does require more data, both on the absolute number of cycles and the actual definition of that cycle. I believe the chart you display references “cycle” as “charge to 100%**, discharge to “. Eg, if you cycle between 80% and 90% – that is likely *not* the same definition of “cycle”.

    I am personally considering Chargie for the “autonomous” mode – so my use case isn’t affected by the “overnight partial cycling” you are asking about – i intend to plug in my (phone, garmin, watch, etc) for an hour, and simply have it prevented from ever reaching 100% charge. Currently, i plug in my, say, watch, take a shower, then forget; returning 2 hours later to a 100% battery. Completely inconsequential now and again – but if repeated twice a week for a year, now we’re talking substantial (and unnecessary) degradation of capacity.

    If you want a reasonably good answer about repeated ~70%-80%-70%-80%… cycles, you might try posting this in the context of Tesla on one of the many enthusiast forums; this exact problem would occur: should I charge daily after my ~30 mile round trip commute (~10% of the total pack capacity discharged)? Or should i just wait until i get to (20%, 30%) and charge up to 80%? The answer there should be apples-to-apples.

  16. Allyn says:

    Bouncing between 80-85% a few times overnight is going to be far gentler on the battery than charging to and remaining at 100% every night. The act of increasing battery SOC from 90-100% swings voltage from ~3.8V to 4.1-4.2V, which causes more wear than a few 5% swings consuming 0.1 of a cycle. If the bistable action is still a concern, then use a charger with a lower rating (5W), which will result in slower charging / less time at 80-85% / fewer swings once it’s in that region.

  17. Lee says:

    Allyn, if you could find some proof of this, I’d be more interested in using a Chargie. Best regards

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