Aura HD Aura battery life using glow light

FJames · 06-25-2013, 11:02 AM

I see a test report posted on ReaderRocket that the Aura supposedly has a much shorter battery life than the Glo when using the glow light. They claim Aura 28 hr. versus Glo 55 hr. (source: "real world tests").

This one says Aura 30 hr. versus Glo 70 hr., but no source is given, so they are probably copying and combining the Glo spec with some other source about the Aura (maybe just rounding up the ReaderRocket number).

Kobo's spec for battery life for the Glo says "Over 1 month" and "Up to 70 hours of continuous usage with ComfortLight on". For the Aura it says "Up to 2 months" and nothing about the light.

In theory the battery on the Aura is supposed to have 2x more capacity, right? And one of the reasons for that was to support a longer life with the light on, right? I find it hard to believe that it takes a lot more LED power to light a 6.8" screen than it does to light a 6" screen, so what's up with these numbers? Is it just one test improperly conducted? Has anyone actually tested the battery life of the Aura with the light on? At what level setting? (no level specified for any of these specs or test reports)

My personal sense so far is that the Aura does last longer than the Touch with the light off most of the time, but it does drain noticeably quicker if the light is used a lot. But faster than the Glo?

TechniSol · 06-25-2013, 05:00 PM

I did a test a while back with my Glo and got around 46.5 hours of reading time with the light on the lowest setting, or possibly one setting higher, if I recall correctly. This was on the version of firmware before percentages were displayed, 2.4? or 2.5?... The posts I made were in the thread concerning higher battery drain on the Glo in sleep mode to present a baseline for what one might expect with a Glo not suffering the higher power drain during sleep mode issue. The eventual conclusion seemed to be that some people having the problem were having an issue with something touching the screen, or at least interrupting the IR above it, before the unit finished going into sleep mode. My theory was that the neonode hardware was then not shutting down due to being in the middle of sensing a "touch" event.

It might also have to do with an outside factor, like if one assumed the Aura was more likely to be purchased by people requiring larger type fonts one might also make the correlation that they might crank the brightness up higher to get more contrast or somesuch... I'm not suggesting that is the case, just spitballing.

Area-wise the Aura has a larger screen, but not double I don't think, haven't done the math. It's probably safe to assume it takes a slightly higher LED output and higher current consumption to make it appear to be lit at the same brightness level as a Glo if the light has to travel further through the same light guide/diffuser material from top to bottom at a slightly longer distance... Could also be more stuff going on in the firmware running on an Aura, though I would suspect the latest firmwares for the Glo & Aura might be about the same in terms of internal branching, of course the screen driver might be a bit different since with the greater resolution it does have to push more pixels. The greater number of pixels might lower battery life a bit as well, but with the bigger battery you'd think it would still kick the Glo's butt.

FJames · 06-25-2013, 05:41 PM

The math is simple: the total light output required to deliver the same screen brightness is strictly a function of the relative screen area. The Aura/Glow screen area ratio is 1.28:1 (Aura has about 28% more screen area). The both use LEDs which should be of similar efficiency, and the number of them doesn't really matter compared to the total light output. So the Aura with about 2x the battery capacity should last more than 50% longer at the same brightness.

Of course since the comparison tests don't seem to include any actual light measurements, and the percent scales are not necessarily equal, we can only assume that they adjusted the light to some personal standard of comfort. That might have been quite different between the Glo and Aura tested at different times.

robko · 06-25-2013, 08:24 PM

I have to admit that this is more anecdotal than hard numbers, but with the same usage patterns (I always leave light on, download 2 newspapers per day) I get more life out of a charge with Aura vs Glo.

FJames · 06-26-2013, 11:32 AM

I find it hard to estimate because I frequently forget to turn the glow light off before shutting down after reading at night, and then I don't realize that it's on for a couple of days while reading in bright daylight.

ewphoenix123 · 06-26-2013, 02:01 PM

Yeah... not buying their numbers.
I usual reload my aura every 1-2 weeks when I add new books and I read at least 2-3 hours a day. Make that 3+ hours as I usually don't turn it off when i put it down, and the auto turn off is set to 30mins. The light is always on.

I never went below 70% charge so far in a week stretch.

06-25-2013, 11:02 AM	#1
FJames Addict Posts: 320 Karma: 320941 Join Date: Jun 2011 Location: Canada Device: Kobo Touch & Aura	Aura battery life using glow light I see a test report posted on ReaderRocket that the Aura supposedly has a much shorter battery life than the Glo when using the glow light. They claim Aura 28 hr. versus Glo 55 hr. (source: "real world tests"). This one says Aura 30 hr. versus Glo 70 hr., but no source is given, so they are probably copying and combining the Glo spec with some other source about the Aura (maybe just rounding up the ReaderRocket number). Kobo's spec for battery life for the Glo says "Over 1 month" and "Up to 70 hours of continuous usage with ComfortLight on". For the Aura it says "Up to 2 months" and nothing about the light. In theory the battery on the Aura is supposed to have 2x more capacity, right? And one of the reasons for that was to support a longer life with the light on, right? I find it hard to believe that it takes a lot more LED power to light a 6.8" screen than it does to light a 6" screen, so what's up with these numbers? Is it just one test improperly conducted? Has anyone actually tested the battery life of the Aura with the light on? At what level setting? (no level specified for any of these specs or test reports) My personal sense so far is that the Aura does last longer than the Touch with the light off most of the time, but it does drain noticeably quicker if the light is used a lot. But faster than the Glo? Last edited by FJames; 06-25-2013 at 01:05 PM.

06-25-2013, 05:00 PM	#2
TechniSol GranPohbah-Fezzes r cool! Posts: 1,056 Karma: 3151024 Join Date: Jul 2010 Device: Nook STRs, Kobo Touch, Kobo Glo	I did a test a while back with my Glo and got around 46.5 hours of reading time with the light on the lowest setting, or possibly one setting higher, if I recall correctly. This was on the version of firmware before percentages were displayed, 2.4? or 2.5?... The posts I made were in the thread concerning higher battery drain on the Glo in sleep mode to present a baseline for what one might expect with a Glo not suffering the higher power drain during sleep mode issue. The eventual conclusion seemed to be that some people having the problem were having an issue with something touching the screen, or at least interrupting the IR above it, before the unit finished going into sleep mode. My theory was that the neonode hardware was then not shutting down due to being in the middle of sensing a "touch" event. It might also have to do with an outside factor, like if one assumed the Aura was more likely to be purchased by people requiring larger type fonts one might also make the correlation that they might crank the brightness up higher to get more contrast or somesuch... I'm not suggesting that is the case, just spitballing. Area-wise the Aura has a larger screen, but not double I don't think, haven't done the math. It's probably safe to assume it takes a slightly higher LED output and higher current consumption to make it appear to be lit at the same brightness level as a Glo if the light has to travel further through the same light guide/diffuser material from top to bottom at a slightly longer distance... Could also be more stuff going on in the firmware running on an Aura, though I would suspect the latest firmwares for the Glo & Aura might be about the same in terms of internal branching, of course the screen driver might be a bit different since with the greater resolution it does have to push more pixels. The greater number of pixels might lower battery life a bit as well, but with the bigger battery you'd think it would still kick the Glo's butt. Last edited by TechniSol; 06-25-2013 at 05:18 PM.

06-25-2013, 05:41 PM	#3
FJames Addict Posts: 320 Karma: 320941 Join Date: Jun 2011 Location: Canada Device: Kobo Touch & Aura	The math is simple: the total light output required to deliver the same screen brightness is strictly a function of the relative screen area. The Aura/Glow screen area ratio is 1.28:1 (Aura has about 28% more screen area). The both use LEDs which should be of similar efficiency, and the number of them doesn't really matter compared to the total light output. So the Aura with about 2x the battery capacity should last more than 50% longer at the same brightness. Of course since the comparison tests don't seem to include any actual light measurements, and the percent scales are not necessarily equal, we can only assume that they adjusted the light to some personal standard of comfort. That might have been quite different between the Glo and Aura tested at different times. Last edited by FJames; 06-25-2013 at 05:44 PM.

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06-25-2013, 08:24 PM	#4
robko Wizard Posts: 2,454 Karma: 5469320 Join Date: Jul 2010 Device: Kobo	I have to admit that this is more anecdotal than hard numbers, but with the same usage patterns (I always leave light on, download 2 newspapers per day) I get more life out of a charge with Aura vs Glo.

06-26-2013, 11:32 AM	#5
FJames Addict Posts: 320 Karma: 320941 Join Date: Jun 2011 Location: Canada Device: Kobo Touch & Aura	I find it hard to estimate because I frequently forget to turn the glow light off before shutting down after reading at night, and then I don't realize that it's on for a couple of days while reading in bright daylight.

06-26-2013, 02:01 PM	#6
ewphoenix123 Addict Posts: 201 Karma: 42238 Join Date: Oct 2012 Device: Kobo: Glo, Aura , Aura H2O, Aura ONE, Forma, Elipsa	Yeah... not buying their numbers. I usual reload my aura every 1-2 weeks when I add new books and I read at least 2-3 hours a day. Make that 3+ hours as I usually don't turn it off when i put it down, and the auto turn off is set to 30mins. The light is always on. I never went below 70% charge so far in a week stretch.