Battery Life - The Good The Bad and The Ugly

Well, I've had my Evo for a week now and I've made some interesting observations about how it seems to manage battery charging and external power. Please note that I've been reading the Evo forums for months while I've impatiently waited for my "full discount" upgrade eligibility, so I'm well aware of the "issues" that some of you have observed. Now that I can observe for myself, here's what I think is going on:

It seems that the Evo actually runs off of the battery even while it's connected to an external power source. This is a bit tough to explain, but what I mean is the external power only seems to charge the battery and it basically gets disconnected by the device once the battery is fully-charged. Then it isn't reconnected again until the battery charge level drops below a certain point (which seems to be somewhere between 85-90%). This scenario differs from more conventional systems where the external power continues to provide the energy required to operate the device after the battery is fully charged rather than simply shutting down and letting the battery operate the device.

Here's what led me to this conclusion:

Like others, I've experienced that rapid drop in remaining battery capacity shortly after I remove the device from the charger, but only if I leave the device on the charger for an extended period after the light switches from amber to green (like overnight). But I've never experienced this sudden drop if I begin using the phone shortly after the light goes green.

I've also noticed that the battery level will actually go down while the phone is connected to a charger. Like everyone (I imagine), I spent hours exploring the capabilities of my Evo on the first couple of nights I had it and I did most of that playing with the charger plugged in. And as I was playing, I noticed that the battery level would drop, the charging light would change from green to amber, the battery level would go up, the charging light would switch back to green, and this cycle would repeat itself every ~15-30 minutes or so depending on what I was doing with the phone.

My normal routine with all my past phones has been to put them on the charger before I retire for the night and then grab 'em in the morning before I leave the house. I never noticed any issues when doing that with my past phones, but doing so with my Evo has typically resulted in less than a full charge. About the only exceptions have occurred when I've retired real late and got up real early.

So I've modified my routine a little: Now when I get up, one of the first things I do is unplug my Evo and plug it right back in again. The light will almost always change from green to amber when I do this and if it doesn't I'll just go online and read the news for a few minutes to use a little battery. Once the light changes from green to amber it will typically charge for about 30 minutes before the light turns green again and the battery will be fully-charged at that point.

So in summary, what I believe is happening is the battery -is- being fully-charged when I plug the phone in at night, but once the charge cycle is complete the phone runs on the battery until it drops to that magic ~85-90% and the charging cycle begins again. And If I grab my phone while the battery is in that netherworld between 100% and the point when the charging cycle kicks back on, then I'm grabbing a phone which is no longer fully charged.

Why HTC chose to do things this way remains a mystery and I certainly hope that it's something that can/will be fixed with a firmware update.

I'll also add that the Evo definitely doesn't last as long on a full charge as my Hero did with like-and-kind use, but I expected that. That's the unavoidable consequence of a more powerful processor.

FWIW, my phone is hardware version 0003 and firmware number 3.29.651.5.

Pete

HTC chose to do it that way so the battery isn't constantly charging up to 100%, which I hear can effect the lifecycle.

That was an extremely long winded way to say what countless others have already told us about how the Evo charges. What was the fresh idea that was brought to the table?

bvbull200 said:

What was the fresh idea that was brought to the table?

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Hell, I wasn't trying to bring a fresh idea to the table. My only goal was to annoy you.

Pete

bvbull200 said:

That was an extremely long winded way to say what countless others have already told us about how the Evo charges. What was the fresh idea that was brought to the table?

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His personal opinion and experience in a daily growing community.

Even though it all has been stated, in more than one of the many threads on the subject, in the forums he has been reading over the past few months.

conor.in said:

HTC chose to do it that way so the battery isn't constantly charging up to 100%, which I hear can effect the lifecycle.

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It's true that LiPo cells will last longer if they're not stored fully-charged for extended periods but unnecessary charge-discharge cycles are at least as detrimental to their cycle life, even if they're only partial discharges.

And what's more important to the average user of a device with a user-replacable battery pack; the pack's overall lifetime or how long the device will operate before it needs to be recharged? Which do you think would have the most influence on a prospective buyer?

My guess is the issue we're discussing is the result on an engineering mistake by HTC because there really is no practical advantage to doing it that way. But there are consequences, as witnessed by this and the rest of the threads on the topic.

Pete

PGR said:

It's true that LiPo cells will last longer if they're not stored fully-charged for extended periods but unnecessary charge-discharge cycles are at least as detrimental to their cycle life, even if they're only partial discharges.

And what's more important to the average user of a device with a user-replacable battery pack; the pack's overall lifetime or how long the device will operate before it needs to be recharged? Which do you think would have the most influence on a prospective buyer?

My guess is the issue we're discussing is the result on an engineering mistake by HTC because there really is no practical advantage to doing it that way. But there are consequences, as witnessed by this and the rest of the threads on the topic.

Pete

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I can se where you're coming from, and that's probably all correct. I have no idea what really happens when devices are constantly charged from 99% to 100%, I'm just spitting back what I've read in most every thread about this topic. Of course, those threads also have your viewpoint well represented as well.

The Evo batteries are not LiPo, they are Lithium Ion.

Just switched from WebOS to the EVO. Fantastic phone, and the battery life is great as long as you're not pulling down background updates all the time.

I'm at 74% after unplugging my phone 11 hours ago, and that includes some light use with email, messaging, and app management.

EVO for the win!

Welcome aboard

I think anything is better than WebOS when it comes to battery. (Fellow Palm --> Android migrant here)

I see a lot of folks on Pre Central that bought an EVO then went back to the Palm. I do not know how that is even possible when I play with my Pre its like a toy in my hand. its "Cute"

I use Juice Defender and only loose 3% overnight. It is so much better than Pre.

14 hours and at 70% still... extrapolate and that gives me about 45+ hours. ;-)

Yeah, WebOS is not bad, and it excels in the way it handles multi-tasking, but the platform isn't open enough yet (something like Tasker or Voice Search definitely cannot be done at this time) and I'm very integrated with Google services, so Android is a natural thing for me. Give me the card multi-tasking and Synergy on Android, that'd be perfect!

Shawnz said:

The Evo batteries are not LiPo, they are Lithium Ion.

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Nope, lithium polymer. Any time you have lithium batteries in non-standard cell (think AA shape, but larger) shapes, they're lithium polymer. In fact, read the label on your EVO battery and it says lithium ion polymer.

Shawnz said:

The Evo batteries are not LiPo, they are Lithium Ion.

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Well you're right and you're wrong. The proper name for the battery technology used in the Evo and virtually every modern cell phone is lithium-ion polymer because the electrolyte is contained in a solid polymer rather than a gel.

The first clue is the form-factor of the cells. The layers in a true lithium-ion cell needs to be tightly compressed so they are typically rolled into a cylinder and housed in a hard cylindrical shell. The layers in a lithium-ion polymer cell do not need to be compressed and the most common form factor is a flat package. In addition, the nominal voltage of a true lithium-ion cell is 3.6V while the nominal voltage of lithium-ion polymer cell is 3.7V.

So the fact that our cell phone batteries are flat rather than cylindrical and have a 3.7V rather than a 3.6V nominal voltage indicate that they are lithium-ion polymer (LiPo or Li-Poly) cells.

I understand the confusion, though, because "lithium-ion" has become a generic "family" name for an entire class of battery technologies including Lithium-Ion Polymer. But in actuality, the original Lithium-Ion cells with their gel electrolyte have pretty much been obsoleted by Lithium-Ion Polymer cells.

Pete

HeyRobi said:

I see a lot of folks on Pre Central that bought an EVO then went back to the Palm.

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I bought one of the original Pres and carried it for 26 days before I returned it and got my Hero. I actually liked how it worked a lot, but I couldn't live with the cheap plastic toy-like feel of it. I also had a gut feeling that Palm was going to fail and I didn't want to get stuck with an orphaned phone.

While I've never had any second thoughts about picking the Hero over the Pre, I've always wished that the Android OS had a few of the features that WebOS has.

Pete

PGR said:

While I've never had any second thoughts about picking the Hero over the Pre, I've always wished that the Android OS had a few of the features that WebOS has.Pete

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On the flipside, I've spent the past year with WebOS wishing it had some Android features.

I have the same problem until:
- install APNdroid aplication and disabel EDGE/GPRS and check only MMS
- disable Use My Location (save in data transfer mode and batery life)
- disable automatic network-provided values in data&time settings
- disable background data transfer (this value use android OS for all updates on system, date and instaled programs)
- uncheck automatic brightness

With this I can now use my phone app. 2-3 days.

Sorry If I make some mistake because english is not my first language.

I'm not sure I understand this obsession with battery life on this phone. Is it really that hard to gain access to a car charger or ac adapter? In the rare occasion that I need to be somewhere all day without access to either of those then I carry a rechargeable battery pack that I can plug in USB. That gives me three or four charging cycles without a problem. Frankly I don't see the point in turning off all the features that make this phone great just to save a few hours of battery life. I say use the phone has it's made be used and stop worrying about battery life.

Make sure you have logged out of Google Talk and turned off the automatic sign in.

If you have LED Flashlight installed, you should also uninstall it as 2.2 Froyo comes with a Flashlight program.

Venkman said:

New finding: I was taking a nap and all of a sudden it restarted on me. Before I went to sleep uptime was 21 hours and awake time was 3 hours. However, after the restart, my uptime = awake time again. Nothing is running that shouldn't be and I didn't install any new apps other than the ones I described in my previous post; all of which still allowed me to have the uptime to awake time ratio I mentioned above.

Still had about 30% battery after the sound of the restart woke me up.

***I've restarted the phone several times but still get 100% awake time. Battery drains like crazy now.

Spare parts analysis
(partial awake, other usage): Android system running nearly the entire time
(network usage): a program called "0" has been using the network 100% of the time.... absolutely NO idea what that is... when I click it for more details in spare parts, the following notification pops up: The application Settings (process com.android.settings) has stopped unexpectedly. please try again"

Furthermore, after leaving the phone by itself for a few hours... Uptime = awake time and phone idle = cell standby; autocyncing has been turned off.

Something after restarting the phone is causing problems =\

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My battery get me through the day just fine. Can't complain about it.

Glad to hear that dude!

jalan94 said:

I'm not sure I understand this obsession with battery life on this phone. Is it really that hard to gain access to a car charger or ac adapter? In the rare occasion that I need to be somewhere all day without access to either of those then I carry a rechargeable battery pack that I can plug in USB. That gives me three or four charging cycles without a problem. Frankly I don't see the point in turning off all the features that make this phone great just to save a few hours of battery life. I say use the phone has it's made be used and stop worrying about battery life.

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For most of us I'm sure that isn't a big deal but I'm sure there are people that work in places they can't get to a charger, or don't have the time to be away from the phone while it charges. I have a laptop in my work truck and when I'm at my desk at work I have the laptop and a desktop so all I need is a usb cord. It's still nice when the phone makes it through the day on it's own though...

i use the external charger with the 3500 batt and i get about 18hrs with ahout 10-12 text streaming music throught bluetooth for 4hr and moderate phone use.

With moderate usage I can get anyway from 16 to 18 hours out of my battery which is more than enough. But days like today where I am on my phone constantly streaming, browsing, playing games that use data, you better believe I have my charger at my work desk *problem solved*.