Battery issues?

[GrouchoM]

I got my jetbook about 2 weeks ago and the bateries were
almost new. Right now I'm getting the message to replace battery only after reading 2 books. One was 109 page and the oterh 700, I'm not sure this matters but total reading time was around 10 to 15 hours. Is this normal?

[jblitereader]

Here is the thing. When you press the button at the bottom to "turn off", you're not actually turning it off. You're just puting it to sleep. While it's sleeping, it's still draining your battery.

In other words, if you're just letting it sleep, eventually it will run out of battery regardless of if you actually do any reading or not.

Before you decide to write a really bad review blasting ectaco for building such a defective product that drains battery while it sleeps, please consider the fact that this happens with EVERY electronic device, including the $300 or so kindle and the $500 or so ipad.

Everything drains battery when it sleeps. If you're going to let it sit for long periods of time, consider taking out the battery or pressing the reset button to turn it off.

[Ken Maltby]

You might want to check out the test results I've been getting:

https://www.mobileread.com/forums/showthread.php?t=74936

The primary/non-rechargable batteries that came with the JetBook
should do better than what you described even with two weeks of
standby time.

Luck;
Ken

[Seabound]

Originally Posted by Ken Maltby

You might want to check out the test results I've been getting:

https://www.mobileread.com/forums/showthread.php?t=74936

The primary/non-rechargable batteries that came with the JetBook
should do better than what you described even with two weeks of
standby time.

Luck;
Ken

Ken, thank you for doing those tests. One thing I'm wondering about is that your test results seem to show that the low battery warning comes up not long after the battery indicator drops to two bars. Does this mean that there is still plenty of reading time left even after the low battery warning comes up, or will the JBL not let you read after the warning comes up?

I just got my JBL this weekend, so I don't know the answer to that question. However, I'm quite pleased with the battery life I'm seeing. I've used my JBL for about 12 hours--reading, poking around menus, removing and inserting SD cards, testing how long eBooks load, doing hard resets--and the battery indicator is still at three bars. I'm using rechargeable Rayovac Platinum batteries (NiMH, 1.2V, 2100 mAh).

[GhostHawk]

After doing a lot of reading on these forums and others I found out (much to my dismay) that I had not been treating my Jetbook right.

When the low battery warning pops up, just plug it in.

All too often I would keep reading, cussing the stupid battery warning that kept popping up. After 6 months I could see a marked decrease in how many hours of use I could get out of it. Instead of 20 hours it was probably closer to 14- 16 on a regular basis.

Eventually I bought a Jetbook Lite, so I could just switch battery's and keep reading.

From what I've read the battery does not seem to suffer from partial charges, so if in doubt, plug it in every other night. Then you'll always have 2 days worth of good reading time.

Or, get a Jetbook Lite, and a couple of good sets of rechargeable battery's.

Choice is yours.

[GhostHawk]

In my case with the JBL and the NiZn 1.6v Rechargeable batterys I actually get the change battery window before the bars drop.

Try reading after that and 2 min later I get the "Jetbook is shutting down".

Originally Posted by Seabound

Ken, thank you for doing those tests. One thing I'm wondering about is that your test results seem to show that the low battery warning comes up not long after the battery indicator drops to two bars. Does this mean that there is still plenty of reading time left even after the low battery warning comes up, or will the JBL not let you read after the warning comes up?

I just got my JBL this weekend, so I don't know the answer to that question. However, I'm quite pleased with the battery life I'm seeing. I've used my JBL for about 12 hours--reading, poking around menus, removing and inserting SD cards, testing how long eBooks load, doing hard resets--and the battery indicator is still at three bars. I'm using rechargeable Rayovac Platinum batteries (NiMH, 1.2V, 2100 mAh).

[Ken Maltby]

If I can engage in a little speculation, without adding too much to what is a confusing
situation, regarding the battery performance/JBL power management response.

First it looks like the JBL, at least with the 0.15 firmware, puts up the low battery
warning when the battery pack drops to 4v. I have no data on the hysteresis that
is being employed by the JBL's power management logic. It may be that the warning
is triggered as soon as the battery voltage dips to 4v.

I have noticed that batteries in general and these rechargeables as well, can recover
some of their charge level, when they are removed from a load. (It may be that the
chemical reaction involved can catch up, once the battery is not being drained and a
little charge get built up. Total speculation.) This shouldn't amount to a whole lot of
additional reading time though. One of the good things about the JBL is that you can
easily replace the batteries, so there is little reason to worry about getting every last
bit of juice out of the batteries.

It also seems that the sets of batteries under test are doing better with use. It looks
to me like you can easily expect 20+ hours of use from the commonly available rechargeable batteries. During that period there is plenty of time for recharging and
thereby having a recharged set ready to go, the moment the 20+ hours are up for the set in use.

Luck;
Ken

[Seabound]

Originally Posted by GhostHawk

In my case with the JBL and the NiZn 1.6v Rechargeable batterys I actually get the change battery window before the bars drop.

Try reading after that and 2 min later I get the "Jetbook is shutting down".

It seems to me, then, that the JBL battery indicator is a bit misleading, or at least poorly designed, in that it does not translate to amount of reading time left, as is the case for my other reading devices. It appears from what I've been reading that for the JBL "your time's up" is at around the 2-bar mark.

[aagstn]

I have been getting very satisfactory reading times out of Eneloops, but when it hits two bars it is definitely time to change batteries. I usually finish the chapter I'm on and change them out. Once I have two bars it seems I am minutes away from a shutdown with Eneloops.

[DoctorOhh]

Originally Posted by Seabound

It seems to me, then, that the JBL battery indicator is a bit misleading, or at least poorly designed, in that it does not translate to amount of reading time left, as is the case for my other reading devices.

Not misleading or poorly designed, the battery indicator is tuned to normal non rechargeable batteries.

Without going into detail suffice it to say normal alkaline batteries are very different beasts then rechargeable batteries and the power indicator reacts differently to the two types of batteries.

Originally Posted by Seabound

It appears from what I've been reading that for the JBL "your time's up" is at around the 2-bar mark.

For rechargeable batteries the 2-bar mark is par for the course. If you must see 1-bar buy regular alkaline batteries.

[GhostHawk]

"Not misleading or poorly designed, the battery indicator is tuned to normal non rechargeable batteries. Without going into detail suffice it to say normal alkaline batteries are very different beasts then rechargeable batteries and the power indicator reacts differently to the two types of batteries."

Quoted for truth!

Very well said, karma headed your way.