Battery life!

[zoran]

> What is your question?

what to buy, or course.
I read a thread and found no answer about 5V and 1A, more or less etc...
what works for most of you/us, gonna work for me too.
best regards.

[pholy]

Item 3 is not a charger, so that's out.

If you travel overseas, the international version would be useful. Other than that, as long as they have over-voltage protection, you're good to go. You do get what you pay for, but sometimes it's just a well-known name... The Kobo, which can draw up to 750ma, will charge faster with a 1000ma charger than with a 500ma charger or a computer.

[corona]

The Vivanco thingie is the only dedicated charger, and the only one that I could see that specifies a max. current -- 1A. Assuming that's honest.

Although I agree about the name-brand part to some extent. The one is from Logitech; that's pretty established. Even though it's a hub, it's going to provide power for charging.

I think I'd get the Vivanco one, and the internationalism is nice too.

This is all assuming that it's even available current/voltage regulation that's causing the charging issues.

[Stinger]

Originally Posted by Ghoda

Bottom line - if you've got the time a trickle charge at low amperage is always better than a quick charge at higher amperage.

Solicitous is correct in the sense that a circuit will only draw the amount of current it is needs, at a given voltage. However, Ghoda is correct that low-current charging is better for the battery in every way, except perhaps charge time (At lower current, we'll get to 90% faster. At higher current, we'll reach 100% faster).

Generally speaking, batteries live longer if treated in a gentle manner. High charge voltages, excessive charge rate and extreme load conditions will have a negative effect and shorten the battery life.

Not only does a lithium-ion battery live longer with a slower charge rate; moderate discharge rates also help. Figure 5 shows the cycle life as a function of charge and discharge rates. Observe the improved laboratory performance on a charge and discharge rate of 1C compared to 2 and 3C.

I also found a couple other points that seem to agree with Ghoda:

• The time at which the battery stays at 4.20/cell (100% charge) should be as short as possible. Prolonged high voltage promotes corrosion, especially at elevated temperatures. Spinel is less sensitive to high voltage.
• The charge current of Li-ion should be moderate (0.5C for cobalt-based lithium-ion). The lower charge current reduces the time in which the cell resides at 4.20V. A 0.5C charge only adds marginally to the charge time over 1C because the topping charge will be shorter. A high current charge tends to push the voltage into voltage limit prematurely.
• Increasing the charge current does not shorten the charge time by much. Although the voltage peak is reached quicker with higher charge current, the topping charge will take longer.

I really don't know what the 200mA difference in current between a USB 2.0 port (500mA) and the Kobo max (700mA) actually quantifies into, and I'm not much in the mood to to pull out my Engineering textbooks to find a bunch of equations right now. If someone really wants to know, I might look into it later.

[TallMomof2]

Originally Posted by StealthyScribe

Are you just using your computer to charge it or are you using a wall charger now? I sure wish I knew what I was doing wrong...are you powering the unit down at all or just leaving it on?

I use a powered USB port on my PC (they're all powered on mine). Sometimes I power it down, sometimes I don't.

[Stinger]

I was looking at the Kobo eReader website for a quote for a different thread and came across something that made me chuckle, thought I'd share:

so in the tech specs section, they have the nice quote we've discussed here plenty, "Battery charge of up to 2 Weeks: Or 8000 page-turns in 'Book Years'"

and below it is this:

"The Kobo eReader's long battery charge lets you read your eBooks, not your power gauge."

lol, I'm sure when they wrote that they weren't aware how true that second part was

[blkninja1961]

Originally Posted by Orochi

There are so many variables that can effect battery length. I think the real problem is the way in which battery length was presented.

Battery charge of up to 2 Weeks: Or 8000 page-turns in 'Book Years'

What the hell is that supposed to mean anyways!?

Most other electronic devices are stated in terms of "hours of use." Cell phones usually give battery length in terms of "standby time" and "talk time." MP3 Players/Ipods usually give battery length in terms of "music play back time" and "video play back time." I have even seen the Kindle state battery length in terms of "reading time."

While these terms can also be somewhat hazy, they do give the user, a better idea of what to expect from the device. While I am not dissapointed with the Kobo in terms of battery length, I would have liked to see it stated in "reading time," rather than page turns which really isn't that realistic when all other factors are considered.

As I understand e-ink, it only used energy when refreshing or drawing the page. With a paperback book, light reading, I can go approx 100 pages an hour or more. In order to state battery life in "reading time" they would have to establish a baseline number of pages an hour.

My question is "What are book years?"

[Solicitous]

Originally Posted by Stinger

I was looking at the Kobo eReader website for a quote for a different thread and came across something that made me chuckle, thought I'd share:

so in the tech specs section, they have the nice quote we've discussed here plenty, "Battery charge of up to 2 Weeks: Or 8000 page-turns in 'Book Years'"

and below it is this:


lol, I'm sure when they wrote that they weren't aware how true that second part was

The second part is true, you don't read your power gauge, it doesnt update apparently lol

[terifili]

Well, I wrote to Kobo about my 1000 page clicks battery life and they suggested they would send me an envelope so I can return it to them so they can "try and fix it or replace it". I am leery about doing this, considering it appears all are getting about the same battery life.... has anybody heard about anybody getting anything more than 1000 clicks or so? If not, I don't want to go through the hassle of giving away my beloved Kobo for nothing...

[Ghoda]

Originally Posted by terifili

Well, I wrote to Kobo about my 1000 page clicks battery life and they suggested they would send me an envelope so I can return it to them so they can "try and fix it or replace it". I am leery about doing this, considering it appears all are getting about the same battery life.... has anybody heard about anybody getting anything more than 100 clicks or so? If not, I don't want to go through the hassle of giving away my beloved Kobo for nothing...

My usage is well above 100 page turns, let me see - just read Shutter Island, 25 chapters averaging 30 pages per - around 750 pages. I would read 3 chapters a night so that's about 8 power cycles in there as well plus required navigation. Also I have an SD card so there's some more juice being used in the mix. Loaded some PDF bike trail maps for camping on the weekend. Lots of flipping and zooming there (and head scratching too but that's not the Kobo's fault). Let my friends fool around with it.

Right now my battery is still at about 25%.

All in all I'd say I am satisfied that the charge has lasted this long.

[terifili]

Originally Posted by Ghoda

My usage is well above 100 page turns, let me see - just read Shutter Island, 25 chapters averaging 30 pages per - around 750 pages. I would read 3 chapters a night so that's about 8 power cycles in there as well plus required navigation. Also I have an SD card so there's some more juice being used in the mix. Loaded some PDF bike trail maps for camping on the weekend. Lots of flipping and zooming there (and head scratching too but that's not the Kobo's fault). Let my friends fool around with it.

Right now my battery is still at about 25%.

All in all I'd say I am satisfied that the charge has lasted this long.

sorry, I meant 1000 not 100...

[artificial]

Originally Posted by terifili

has anybody heard about anybody getting anything more than 1000 clicks or so?

On my first charge (3 hours charging) I estimate about 1200-1500 page turns, plus of course a lot of loading books and PDFs, navigating menus, testing things out.

It was less than I expected, but not unacceptable. My charge lasted six days.

For my second charge I left it overnight. I have been counting the page turns, and all actions I am performing (navigating menus, loading content), so that I will have an accurate figure to share (and for my own benefit).

In your case, before returning the battery I would do a full charge, and try to use the kobo under ideal conditions (no menus, no loading new content, no constant plugging and unplugging, no switching books all the time), and try counting/estimating the page turns. See what figure you get.

If you're game you could even try doing the page turns consecutively (i.e. don't read, just flip really fast). That will give you the best use of battery life, and you'll know for sure how many turns your unit can achieve on a single charge.

[SeptemberWasp]

Just to chime in my experience to the pile...

Day 1 purchased white kobo. I've charged it once plus syncing since purchase. (I did not initially charge the device upon purchase, although for all the playing around with it day 1 and 2 it might as well have been)

I'm at about 25% battery life and I'm likely at 800-1200 pages and I have not turned the device off once in over 2 weeks.

[artificial]

Here's an update on my battery life.

Second charge: Charged overnight. I counted the page turns, and got 950 turns.

In addition I estimate I performed the following battery-draining functions: transferred 12 books to the device, loaded ~12 books, powered on/off ~5 times, and consumed ~25 refreshes browsing the library and the menu.

In total I used the unit no more than 15 hours.

I have to say, ~1000 page turns is quite disappointing, as is the combined reading time. I would probably get almost as much game time from my Nintendo DS, which powers an LCD constantly, whereas the Kobo Reader's battery is unused 95% of the time.

I'm not going to write my battery off as faulty (yet), since it seems that ~1000 page turns is fairly standard for the Kobo Reader, but I would love to know: is anyone getting anywhere near the hyped 8000 page turns? Even 2000 or 3000 would be good, but frankly 1000 seems shabby.

For my current charge I'm reading quite a lengthy book (768 'real' pages, about 1500 turns), and I don't plan to power on/off, browse menus, or switch between books. The only drain on the battery will be page turns, so it will be interesting to see if I can finish the book before the battery dies.

[Bismar]

My first two charges have gotten me about 800 for the first and 1200 for the second.

Still short of the 8000, but i'm hoping it improves after more charges.

On that note, both times i ran out of charge within a book.

The first time the book became content locked and had to be re uploaded. The second time, the book lost its bookmark but otherwise could be read fine.

Have to say, if the firmware doesn't deliver or if the battery life does not approach its rated capacity, i'm returning this and getting an Astak Reader.