This is why your battery drops 10-15% in the first 20 minutes.

[meyerweb#CB]

If you're really losing 15% in half an hour, you need to find out what is using that power. Load up System Panel, and see what apps are actually running and using resources. With knowledge comes power. Without knowledge, you're just pissing in the dark.

Saturday, I ran around running errands, getting a haircut, etc., for 3 hours in the morning. And I inadvertantly left wifi on while I was out, so I was probably using power searching for wifi signals that didn't exist. In addition to wifi, I had on the 3G radio with "always on data", the GPS radio, Bluetooth, and I have push email on both GMail and and Exchange Server account, as well as hourly updates on weather bug. Note that I wasn't using the GPS, I just had the radio on.

At the end of that 3 hours, I had more than 80% battery left. If you're losing 15% in 30 minutes, you have one of more apps that are constantly churning or using the radios. Until you figure out what those are, you'll never get it fixed.

 

[jobryan26]

I just think it's retarded how my battery last a lot longer when I don't have a SD card in.

More than likely you have a bad file on your card. If you have SystemPanel installed check to see if your system file "android.process.media" has high cpu usage.

 

[meyerweb#CB]

An SD card is flash ROM. It uses no power except when being read from or written to. So it would appear apollooff320 has an app running that's doing a lot of IO to the card.

 

[rfs830]

I wonder if this may be why when i have the phone on my car charger that its chargers very slow. I dont know if it may just be my charger but i think i may need to get another charger to test this out.

 

[ejc1214]

I noticed that if I use a non Evo car charger, my Evo does not charge as fast. Even the home charger is same way.

I wonder if this may be why when i have the phone on my car charger that its chargers very slow. I dont know if it may just be my charger but i think i may need to get another charger to test this out.

 

[androidvirgin]

I noticed that if I use a non Evo car charger, my Evo does not charge as fast. Even the home charger is same way.

I wonder if this may be why when i have the phone on my car charger that its chargers very slow. I dont know if it may just be my charger but i think i may need to get another charger to test this out.

Your OEM wall charger is 1A output (1000mA). Many car chargers are only 500mA. The lower the amp output from your charger, the slower your EVO will charge.

Note, if you are using GPS Navigation, your lower output car charger may not even keep up with the power drain from your battery.

 

[rfs830]

ah that may be why then. I may need to pick up the sprint oem charger that I used on my pre for 10 bucks then over and the precentral site. I still use my palm oem home charger to charge my evo though and it works great.

 

[trmoney24]

UPDATED 6-18-10​

So to help prove my theory, I've plugged my Evo into a Kill A Watt, and charged it to 100%. For those who don't know what a Kill A Watt is, it's a device you plug into your wall, and then plug your electronics into it, and it will tell you exactly how much electricity they're drawing. Coupled with the Battery Indicator app, I took readings on how much electricity my Evo was drawing as it charged.

I started charging at 78%, and it was drawing 0.08 amps until it reached 90%. At 90%, it began drawing less and less, until around 50%, at which point it was drawing only 0.04 amps. It stayed steady at 0.04 amps until it reached 100%. Soon after Battery Indicator was reporting a 100% charge, the Kill A Watt also reported a draw of 0.00. Meaning the Evo was not drawing any electricity whatsoever, indicating that it was in fact running off its battery. Even when I turned the screen on, maxed out the brightness, and ran Linpack, the Kill A Watt reported no electrical draw.

I kept my Evo plugged in for 15 more minutes, all while Battery Indicator reported a 100% charge, however, the Kill A Watt remained at a dead 0.00 draw. This doesn't necessarily mean that the Evo doesn't trickle charge, but it does mean it runs off its battery once it reaches a 100% charge. I have a feeling once the battery drops to a certain percentage (although still displaying a 100% charge), it will draw electricity until it reaches 100% again.

Still a bit more testing to do. Will be back with results.

this is very intersting, i always thought it was the battery not reporting the right information to the phone.
JESSE, have you tried using Kill A Watt with a non htc charger to see if the same thing is happening? Could it be possible the the phone is not asking for power once the battery is charged up? just trying to see if using an old BB charger or something would make a difference.

 

[nyc_rock]

This problem exists with the incredible and now the Evo. Maybe the guys at android central could do some research on our behalf. Boy Genius reported about the non deleting Internet screen shots issue and HTC made an official statement within 48 hours.

Can we get some love?

 

[MLN1963]

Note, if you are using GPS Navigation, your lower output car charger may not even keep up with the power drain from your battery.

I found this out already. I couldn't believe my phone was losing battery charge while plugged in during travels. My car charger puts out 500 milli amps. I didn't know the Sprint one put out 1000. Oh well, I don't plan on buying another charger.

I found that if i put the phone to sleep it would charge, not discharge while using navigation. It will still give commands and I can bring it to life if I need to see something.

BTW, I like the Google Navigation system much better than Sprint Navigation. The only thing missing on GN that I miss is a speedometer.

 

[rfs830]

Same here. If you all need a good deal on the sprint charger get it here

http://forums.precentral.net/market...-oem-sprint-palm-pre-car-charger-10-a-16.html

its only 10 bucks and I picked up a few from the seller and so has just about anyone that has a pre on that site.

 

[xorbe]

I found this out already. I couldn't believe my phone was losing battery charge while plugged in during travels. My car charger puts out 500 milli amps. I didn't know the Sprint one put out 1000. Oh well, I don't plan on buying another charger.

I measured the stock plug-in 1000mA HTC wall charger @ 500mA (on the DC line, the red wire inside the USB cable) ... so the car charger is probably even less if it's "rated" 500mA.

 

[Cliffs71]

I can confirm that the phone seems to be pulling power from the battery when its been fully charged but left connected to the charger. When I let the phone charge overnight and unplug it in the morning, it seems to go from 100% to 94 or 93% within the first ten minutes or so. If I charge it to 100% and pull the cord right when the LED turns green, it'll show 100% power sometimes for 90 minutes (tonight I was getting a 100% battery reading for 1 hour 40 minutes). HTC definitely needs to see if they can tweak the firmware so the phone continues to pull power from the charge rather than the battery once charging is complete (or at least give the option in the settings menu).

 

[biscodude]

I haven't read this entire thread, but the OP is absolutely 100% correct. I noticed the same thing, so now I just charge my batteries on a wall charger and swap my batteries out. It takes a good bit of time now to get to 90%, like well over an hour with light usage where before it would hit 90% in 10 minutes or less. Thanks for posting this op!

 

[SPL15]

If this is correct, then it's just another engineering flaw on HTC's part. Lithium Ion Batts need a topping off charge at around 4.2 Volts for a duration of time to reach full charge. CHEAP charging systems (OR charging systems designed by half ass EE's who don't know their science) will reach the 4.2 volts & then shut off leaving the battery partially charged. EVERY rechargeable battery I've designed charging systems for need a topping off "trickle" charge at the rated charge voltage to reach maximum charge. If you charge a battery only until the rated voltage is reached, you only charge to approximately 80% of full capacity.

A PROPERLY designed charging system will use the IUU charging profile. Constant current within the safe charing current up until the charging voltage is reached, then the charger maintains this constant maximum temperature dependant charging voltage for a duration of time until current consumption drops to a defined level according to the battery design, then it will maintain a lesser voltage to not over charge the battery but maintain the full charge indefinitely until disconnected. If the OP is correct, the EVO is only doing the first step where it has a constant current charge until the charge voltage of ~4.2 volts is reached & then shuts off... This is POOR ENGINEERING

EDIT: & Rereading the OP's post. The charging system in the HTC seams to be flawed hardware wise so sorry no software fix for the POOR HTC ENGINEERING. If the Killowatt meter has no change in current consumption with & without phone use then the charger ONLY directly connects to the battery charging circuit and does not directly supply power to the device electronics. For UL approval, this is ONLY needed if the charger Amp rating is LESS than the maximum current draw of the device. UL mandates that if you have a battery operated device with a wall charger then the charger needs to be isolated from powering the device's electronic operation if the device can draw more amperage than the charger is rated to supply (which makes sense for safety). Now the Wall charger is rated at 1 amp, I doubt the device draws one amp. BUT most USB connections are only rated at 500ma so HTC would need to build the charging circuit around this limitation because it will charge from a USB connection. I could see the evo drawing 500ma in certain circumstances.

But in any case, this does not excuse the fact HTC designed a half ass charging circuit that only charges to around 80% of maximum capacity. When the OP noticed the current dropping off towards the end of the evo charge cycle, this is EXACTLY what is supposed to happen when the charge voltage reaches the maximum BUT the charging circuit SHOULD switch to a constant 4.15 or so charging voltage for at least an hour until the battery draws about 45 ma of current (1500mah battery), then it should switch off. HTC decided this was too hard & expensive to do on a premium top of the line phone so they once again made a shortcut hoping the American public was too stupid to notice. They made a cheap charging circuit that charges to 80% to eliminate the cost & potential battery explosions of overcharging & damaging the lithium battery. Old cell phones used a constant current type charger that would continue to charge & over charge the battery if left on overnight thus killing battery life & potentially exploding lithium ion batteries. Either way they cheaped out again when they could have made the phone absolute greatness.

& Also high amerage chargers will reach the charging voltage quicker, but they will also leave the battery less charged in the HTC EVO's case. The ramp up to 4.2 volts will be quicker, but the duration of the "Bulk" full voltage time would need to be greater to reach full charge & the EVO does not give the bulk charge. In the case of the stock charger rated at 1 amp, the battery charge will be around (70%). Also a slower lower amperager charger will charge the battery to fuller capacity (80%)

The reason you guys are seeing such a rapid fall off of charge when disconnecting a charger is because one the reason the OP stated that the charger no longer charges after reaching 100% charge voltage, but also because the battery is NOT FULLY CHARGED TO BEGIN WITH & THEN IS BEING DISCHARGED WHEN THE CHARGER DISCONNECTS. BLAME HTC FOR THIS BLATANT FLAW.

 

[xorbe]

But in any case, this does not excuse the fact HTC designed a half ass charging circuit that only charges to around 80% of maximum capacity.

My phone was on all night and plugged into the charger. It was at 4.203v (100%) when I checked the voltage this morning, as I grabbed it to leave to work.

My hacked USB cable was rejected by the EVO for measuring current post-charge. (It works during the charge and then is rejected when the charge is complete, not sure.) I will agree that under HEAVY load while plugged into the charger, that the battery appears to drain. But not under light load. Are you guys running LinPack all night or something?! I will try a higher quality cable and only splice the red wire next time.

Old cell phones used a constant current type charger that would continue to charge & over charge the battery if left on overnight thus killing battery life & potentially exploding lithium ion batteries.

Pure BS. Lithiums WILL vent, puff, and catch fire if over-charged.

-

 

[SPL15]

My phone was on all night and plugged into the charger. It was at 4.203v (100%) when I checked the voltage this morning, as I grabbed it to leave to work.

My hacked USB cable was rejected by the EVO for measuring current post-charge. (It works during the charge and then is rejected when the charge is complete, not sure.) I will agree that under HEAVY load while plugged into the charger, that the battery appears to drain. But not under light load. Are you guys running LinPack all night or something?! I will try a higher quality cable and only splice the red wire next time.



Pure BS. Lithiums WILL vent, puff, and catch fire if over-charged.

-

So what you are saying is that the evo will constant charge @ 4.2 volts for several hours if not used heavily? This would also be BAD & OVERCHARGE the battery. A Proper Lith-ion charger will Charge at the highest safe current until 4.2 volts is reached then maintain 4.2 volts until a certain current draw is reached, then shut off & turn back on when the voltage reaches around 3.9 to 4.0 volts from self discharge.

The quality of the cable? What do you mean by this? A cable is a cable, the phone doesnt know that you are using nice quality cable as long as the voltages are A-OK which shouldnt be an issue because of the low current draw. Could you elaborate cause it could give clues on how the evo is sensing full charge & operation of the charging circuit.

& to the last thing, NOT pure BS in any way shape or form. Lithium Ion Batteries ALL have protection circuits built into the battery pack. This is the 3rd terminal of the lithium battery pack in cell phone batteries. It is slightly dumb where it only protects from OVERVOLTAGE above appoximately 4.3 volts & also tells the external charging circuit if it gets too hot. You can EASILY overcharge a Lithium Ion battery & it will NOT vent, puff, or catch fire because the protection circuitry protects this from happening by preventing the OVERVOLTAGE & HEAT that can cause these situation. However, it WILL NOT whatsoever prevent OVERCHARGING because 4.2 volts for 25 hours straight will not over heat the battery or set off the overvoltage, but it WILL overcharge the battery thus killing battery life.

 

[xorbe]

So what you are saying is that the evo will constant charge @ 4.2 volts for several hours if not used heavily? This would also be BAD & OVERCHARGE the battery.

Well, with a properly functioning lithium battery -- if the supply is 4.2v, once the battery is 4.2v, current will cease. The supply voltage must exceed the battery voltage to charge. ie, even though the charger voltage is maintained at 4.2v, no charging is actually happening. It will not kill the battery's life.

However for safety reasons, this is not how chargers are be designed (think old lithium batteries that don't peak at 4.2 very well). The chargers are designed to stop after a certain small mA/time-out is reached. The charger should be powering the phone at that point, with the battery idle. (I should mention that if the EVO is charged and on the charger, and you pull the battery, it goes off!)

I have a stack of lithium batteries without any protection circuits. They are available at any R/C store or via mail order.

Yes, over-charging a lithium is technically when 4.5 volts is exceeded generally. By over-charging I mean non-stop trickle charge (where more is trickling in than is trickling out, clearly.)

The quality of the cable? What do you mean by this? A cable is a cable, the phone doesnt know that you are using nice quality cable as long as the voltages are A-OK which shouldnt be an issue because of the low current draw. Could you elaborate cause it could give clues on how the evo is sensing full charge & operation of the charging circuit.

The plug end of the cable is messed up. I ordered a dozen cables. One of them gave me issues -- so I hacked that one up to use for measuring current and then the cable totally quit working. The end is visibly a bit messed up compared to the other cables.

Yeah, I'd like to try again, and I was just talking to a co-worker about ideas of how to sneak between the battery and the 4 pins (easily) on the phone for measuring there too. I'd like to know the answer for sure too!

 

[SPL15]

Well, with a properly functioning lithium battery -- if the supply is 4.2v, once the battery is 4.2v, current will cease. The supply voltage must exceed the battery voltage to charge. ie, even though the charger voltage is maintained at 4.2v, no charging is actually happening. It will not kill the battery's life.

However for safety reasons, this is not how chargers are be designed (think old lithium batteries that don't peak at 4.2 very well). The chargers are designed to stop after a certain small mA/time-out is reached. The charger should be powering the phone at that point, with the battery idle. (I should mention that if the EVO is charged and on the charger, and you pull the battery, it goes off!)

I have a stack of lithium batteries without any protection circuits. They are available at any R/C store or via mail order.

Yes, over-charging a lithium is technically when 4.5 volts is exceeded generally. By over-charging I mean non-stop trickle charge (where more is trickling in than is trickling out, clearly.)



The plug end of the cable is messed up. I ordered a dozen cables. One of them gave me issues -- so I hacked that one up to use for measuring current and then the cable totally quit working. The end is visibly a bit messed up compared to the other cables.

Yeah, I'd like to try again, and I was just talking to a co-worker about ideas of how to sneak between the battery and the 4 pins (easily) on the phone for measuring there too. I'd like to know the answer for sure too!

No. With a PROPERLY working charger on a 3.6 Volt Lithium Ion Pack, Charge Voltage will Reach 4.2 Volts AND MAINTAIN this voltage until current reaches approximately 5% of the Amp Hour rating of the battery pack AND THEN it will shutoff AND turn back on when terminal voltage reaches around 4 volts. You are still forcing energy into the battery pack if there is a current draw from the charger REGARDLESS of standing battery terminal voltage with ANY & ALL battery types. 4.2 Volts indefinitely WILL kill a Lithium Ion Battery's capacity due to the formation of dendrites that will increase the internal leakage, BUT it will not cause the battery to explode or set off the protection circuit inside the battery pack from voltage. If too many dendrites form, it will cause the thermal protection to kick in from internal leakage causing heat & the battery will not be chargeable at all due to the locking nature of this protection. It will simply self discharge & the battery will be isolated from the terminals. With Lithium Ion, the more time it spends at 4.2 volts, the shorter it's charge/recharge life will be due these dendrites forming. 4.3 volts is the critical voltage for lithium ion where bad things will happen and is where the protection circuit kicks in, 4.5 volts you are asking for uncontrolled heat from forming short circuits between the two electrodes. Lithium ion chargers need to be regulated within 0.05 volts of 4.2v or you'll start seeing a high amount of failures in the field.

The Evo has a high device current draw which makes it so that in order for the phone to be powered by the charger the charger would need to have a higher amperage capability than the phone could ever draw in worst case scenario mandated by UL regulations. The stock wall charger is rated at 1 amp, but HTC would need to account that USB can only supply 500ma according to IEEE specs. So HTC made a charging circuit that DOES NOT supply the phone with direct charger power to ensure that the power draw can't . The power connection to the Evo is buffered by the battery charging circuit, the phone is directly powered by the battery & the charger can only supply power to the battery & cannot be allowed to supply current higher than what the lowest amperage typical common use charger would be (which would be 500ma from a USB port). I havent measured it, but I would say that the Evo has the capability to pull over 500ma of current during worst case scenaro which is why the HTC wont be powered by a charger.

In the past for work, I've made PCB's that have the same terminal outlay as a battery to insert into the battery slot to make contact with the terminals. This way you can have external access to the terminal & have the battery outside the phone. Make a PCB is simple, I think even radio shack would sell the stuff needed to do this.

 

[eagle63]

I'm seeing the same thing as the OP. I haven't seen it drop 15 or 20%, but I have seen it drop up to 10% in the first few minutes of removing it from the charger. (after an overnight charge) When I take if off the charger right after the light turns green, then there's no problem.

@xorbe
I read this whole thread, but I'm not sure I understood (maybe I missed?) your analysis. So you're stating that when following the OP's procedure (fully charged battery left connected to the HTC charger) and then you "apply load" to the device by using it, the current is coming from the charger rather than the battery? In other words, you're NOT seeing what he (and a lot of the rest of us) is seeing?