Post-update battery weirdness

[diabloNL]

Originally Posted by HarryT

Hang on a minute. By your own figures, you could go a month without having to recharge. That hardly counts are "barely can keep a charge", does it?

If you've not reset your battery meter, eg by plugging in the wall charger briefly, as described here, how can you trust what the meter is showing you?

Nightwing means that after the update the Reader can't hold its charge.


To be honest, my reader has shown this behavior already before the update. I thought I had a bad battery but now everyone has the same strange problems.

[HarryT]

But Nightwing has said that, after the update, he's lost about 2 bars of power in two weeks - ie a recharge would be required after about a month. I am happy to accept that perhaps the update has increased the "switched off" power consumption somewhat, but to me, having to recharge once a month hardly counts as the Reader being "barely able to hold a charge". Obviously different people have different standards for judging these things .

[diabloNL]

Originally Posted by HarryT

But Nightwing has said that, after the update, he's lost about 2 bars of power in two weeks - ie a recharge would be required after about a month. I am happy to accept that perhaps the update has increased the "switched off" power consumption somewhat, but to me, having to recharge once a month hardly counts as the Reader being "barely able to hold a charge". Obviously different people have different standards for judging these things .

He lost two bars with only flipping nine pages in two weeks. So something is sucking the energy from the battery.

[Aprilbeginnings]

But is the battery really low or is the bar reader perhaps faulty and just doesn't know what the hell it's doing?

[HarryT]

Originally Posted by diabloNL

He lost two bars with only flipping nine pages in two weeks. So something is sucking the energy from the battery.

Of course it is - the operating system. Turning the Reader "off" doesn't actually turn it off; it just blanks the screen and disables most of the buttons. The operating system is still running, doing things like updating the clock, waiting to see if you've pressed the power button, and so on. It's like putting a notebook computer into "Standby" mode. It still needs battery power, although a lot less than when it's turned on.

[KlondikeGeoff]

I might as well add some strangeness to this thread. After the update, the first two times I charged, had to go through the plug in, charge, turn on, unplug, replug, and then the bar worked OK.

Last night it was down to one bar, so plugged it in overnight. This morning, turned it on, and it had all four bars. Unplugged and it still had them.

What did I do to fix it????

[NatCh]

Huh. I dunno, but if you figure it out, please let the rest of us know!

[diabloNL]

Originally Posted by HarryT

Of course it is - the operating system. Turning the Reader "off" doesn't actually turn it off; it just blanks the screen and disables most of the buttons. The operating system is still running, doing things like updating the clock, waiting to see if you've pressed the power button, and so on. It's like putting a notebook computer into "Standby" mode. It still needs battery power, although a lot less than when it's turned on.

I know that Harry. But still....let's calculate something:

Battery: 1150mAh /2 (2 bars down)= 575mAh. If the Reader last 7500 pages or let's be on the save side. We make it 3750. So 3750/2= 1875 pages for 2 bars.

575/1875=0.31mA per page. He flipped in two weeks 9 pages=9*0.31mA=2.79mA. 575-2.79mA=572.21mA. Let's be really save and take 50mAh off just for 2 times startup etc.That will give you 522.21mA left.

Are you still with me?

So 2 weeks is 336 hours. 336/522.21= 0.64mA per hour. According to the data sheets the CPU uses 35uA in standby. So 0.64mA is 18 times more then what it should be. I smell a firmware upgrade.

But seriously, I'm still planning to measure the standby current and the rest of the conditions like on, flip page, SD card etc.

[NatCh]

That's an impressive analysis, DiabloNL.

I think you and HarryT are both right, actually, because you seem to be explaining different points. You, that the "resting" battery drain is rather high, and he that a month between charges is ample.

For myself, I'd agree with both of you.

From my perspective, the length of time it does last tends to cancel out the self-draining aspect, but that's just me.

[diabloNL]

I was not trying to be right, just informative. I don't read a lot so that may explain why my battery goes down so "fast". If you guys can reach +2000 pages or even more on one charge and I can only reach +600 then maybe it's due to the fact I take maybe a month to read those 600 pages (or more)

So for me the self draining aspect is rather important.

So I really need to measure the standby current. I found some shrink tube so I can cut the ground wire of the battery and fix it after I measured it. I think I will do it tomorrow because I'm really getting anxious to know.

[BobVA]

Originally Posted by diabloNL

So I really need to measure the standby current. I found some shrink tube so I can cut the ground wire of the battery and fix it after I measured it.

Not sure what your parts situation is over there, but the connector looks pretty similar to that used on li-poly batteries in PDA's, MP3 players, etc. If you can get a dead gizmo you could scavenge the connector.

Then you could unplug the battery, plug in your connector and plug the wires from that into the connector on the battery (wiring your meter in one side).

....or you could just cut it

[diabloNL]

Originally Posted by BobVA

Not sure what your parts situation is over there, but the connector looks pretty similar to that used on li-poly batteries in PDA's, MP3 players, etc. If you can get a dead gizmo you could scavenge the connector.

Then you could unplug the battery, plug in your connector and plug the wires from that into the connector on the battery (wiring your meter in one side).

....or you could just cut it

Good tip! I will have a look at work today if I can find something lying around in one of the machines I reapair.

[diabloNL]

Well, I finished measuring and here are the numbers from the Dutch jury:

• Standby ("off"): 1.65mA
• Standby ("off") with SD card: 1.85mA
• Standby ("off") without SD card, with any button pressed except "Power": 1.8mA
• Boot-up: ~240mA (very fluctuating)
• On in idle mode: 2mA
• On in idle mode with SD card: 2.10mA
• Page Flip without SD Card: ~240mA (very fluctuating)

Conclusion: The difference between standby ("off") and "on" in idle is really small. The battery usage in standby ("off") is way too high and there is either something wrong with my Reader or with Sony's firmware/hardware.

I hope you guys find this info useful because my Reader's battery wires are now hanging together with tape, shrink tube and solder.

[BobVA]

Very interesting. Using 10% charge remaining as "low", that would give us about three weeks of "off" time. This tracking with anyone's experience?

I'm particularly interested in the SD/power-off figure. The card needs no power to maintain it's memory, so power should be shut off to it when the reader is off, which means there should not be a difference between the power off consumption with or without a card.

This might be a brand-specific card issue, since I've read that some don't respond to the "power off" command - so the Reader may be trying to power down the card but it isn't complying. Natch, could you try ten or twelve different brands? And memory sticks ?

Seriously, the only thing I could think to add to your measurements would be a "power off after one hour", just in case it's got a lower power mode it might drop into after some period of time. Probably unlikely, though.


It would have been nice to leave it on the shelf for a few months and not have the battery drop, but I guess that wasn't a design priority. For example, if they elected to keep time with the main microcontroller rather than a dedicated clock chip, that could keep hardware costs down, but raise standby power. (Just an example, I don't know if this is the case for this design.)

Depending on the issue it may very well be fixable via firmware, if Sony is convinced it's a problem, which they may not be.

Thanks for the info - definitely going in my "stuff" folder!

[NatCh]

Originally Posted by BobVA

Natch, could you try ten or twelve different brands? And memory sticks ?

Sure, except that I've only got 2 brands (SanDisk and ATP), I'm not real inclined to go out and buy 8 or 10 more, and DiabloNL's test equipment is a bit inconveniently located for me. (yes I know you were joking ).

Originally Posted by BobVA

... if they elected to keep time with the main microcontroller rather than a dedicated clock chip, that could keep hardware costs down, but raise standby power.

I'm pretty sure that is exactly what they elected to do, and I can only guess that it was for precisely that reason.

Originally Posted by BobVA

Depending on the issue it may very well be fixable via firmware, if Sony is convinced it's a problem, which they may not be.

I'm unhappily suspicious that they, indeed, do not consider it a problem. I can see what's probably their point, namely that a month of battery power is pretty durned good under pretty much any circumstances. On the other hand, it rather pains me to know that the capacity might be 3 or 4 months if it had been approached a bit differently.