Charge from external battery?

[sralmas]

I participated in a Webcast with Sony and Palm a few weeks back discussing the UX40/UX50, the video recorder, and the car audio kit. I thought that I remembered the Sony rep saying that, if you have the external battery charged, then you can use it to charge the UX battery, just as you would a plug in charger.

Is this correct?

If so, how long does it take to charge the UX from, let's say, the 50% discharge mark?

Will if FULLY charge an almost totally discharged UX?

and finally, if the external battery is fully charged, how long will it hold a reasonable amount of that charge if not used? In other words, I'd like to charge it from time to time and keep it in my briefcase for emergencies or for weekend trips away from the charging cradle. Will this work?

Thanks

Scott

[CliePet]

> ...external battery charged, then you can use it to charge the UX battery, just as you would a plug in charger.
> Is this correct?

It doesn't appear to.
When attached to the AC adapter/charger, the orange light goes on to see the internal battery is charging.

When attached to the spare battery alone, it gets the power from External, but the orange LED is not on, and there doesn't appear to be any change in the internal battery [ie. once you take off the spare battery it just resumes where it was, at least based on my limited testing]

I assume it will stop drawing power from the spare battery when it gets discharged too low, and go back to the internal battery.

----
Commentary:
Discharging one battery to charge another is an inefficient process. You would get total less battery time doing so. I'm glad they don't do it they way the Sony rep suggests (at least not automatically)
External batttery devices that act like a normal power supply are still an option of course.

[sralmas]

Originally posted by CliePet
>Commentary:
Discharging one battery to charge another is an inefficient process. You would get total less battery time doing so. I'm glad they don't do it they way the Sony rep suggests (at least not automatically)
External batttery devices that act like a normal power supply are still an option of course.

However, it would mean that you wouldn't have to keep the external battery attached to the PDA whenever you were using it. Instead, you could use the PDA through the day and "charge" it during down time (like in your hotel room at night or in your briefcase during a lunch break from meetings) I would like to use it as a traveling/emergency charger solution without having to (i) have it attached all of the time and (ii) worry about bringing a charger cradle with me on extended trips.

Anyone else tried placing a drained UX in the external battery with the UX power off and see if it charges the PDO?

[KBurton]

On the cradle, only the outside 2 of the 4 power pins are used. Pictures of the external battery look like it has all 4 pins, but perhaps only the inner 2 are used.

If any of you folks with an external battery also have curiousity and a voltmeter, I'd be interested in knowing which 2 of the pins the battery puts its voltage on.

I've been thinking about making a duplicate of the cradle and building my own battery extender. I did that on my PocketPC and Zaurus and they worked quite well. Of course, they had standard DC power sockets :-(

Just had a thought, and it doesn't look like I'd need to duplicate the whole cradle. A thin bar could just run across the front (of the underside) between the two front cradle latches. The cradle latch pins spring front-to-back, but I checked with a dental probe, and there's clearance inside so pins sprung side-to-side would hold the bar in place just as well. Wonder how thin I could build it, assuming the batteries themselves would be connected by wire rather than attached...

Keith Burton

[revschulz]

I don't have an external battery, but others have posted (see, for example, the thread entitled "external battery question") that the external battery does indeed recharge the internal battery.

[hausman]

Kburton,

I've been thinking exactly the same thing. A long time ago I did the same with the Zaurus, as you did, and I'd like to do something similar with the UX. Only problem is, don't have the UX yet...but I did see one at Best Buy last week.

My idea(s) were similar to yours - building something straight that fits the two holes in line with the contacts on the bottom. Or, as I often do, possibly a more invasive approach involving removing the bottom of the case (if possible) and poking around in there a little. Obviously not recommended for people who don't do this with a lot of stuff...then again that external battery, while expensive, does have a nice form factor to it that you can't get with a AA battery box.

[CliePet]

re: scoping/measuring the pins
Scoping the pins when the battery is not connected won't work. Sony uses smart battery technology that sends communication signals to control the battery (including not turning on the power to the pins until needed - to avoid shorts).

Measuring with the battery connected to the circuit is tricky because of the small connectors.

BTW: Charging a battery requires a voltage higher than the voltage of the battery.

re: other threads saying that the external battery does actually recharge the battery.
Please read the thread again. Far from conclusive IMHO.
BTW: you can see the battery voltage meter go up just by letting the batteries cool off.

----
I see some slow battery averaging when both internal and external batteries are connected together. Took about an hour for internal battery to go from 50% to 70% (with the external battery starting at 100%). My guess is it is just voltage averaging.

If you place two identical rechargable batteries in parallel, one more charged than another, it will slowly average out with the stronger battery charging the weaker one. I don't think Sony can exploit this as an advertised feature, because the dis-charging/charging will vary a lot depending on the exact battery cells involved.

I'll have to check a longer test, but my guess is the "charging" capability will be limited to the average (ie. even if you leave it connected for a very long time, the internal battery will never exceed the voltage of the external battery)

[CliePet]

Followup:
Well I checked the instructions (yes the battery does come with instructions ;-) and it is a semi-advertised feature.

If the internal battery is fully discharged, you can slap on the extended battery - but it won't work immediately.
Wait a little while, and then it will!
(good to know)

Also, it will turn off the external battery if it is too low (an advantage of "smart lithium" batteries) so a weak external battery won't "bring down the average".

[nlax]

I have the external battery. After attaching it to the unit when the built-in battery is low, if you wait a whiloe, the built-in battery gets recharged. So, to answer the question, yes, this allows you to essentially carry around a bunch of "recharges" for your built in battery if you want.

[nlax]

CliePet ... interesting point about battery averaging (sorry, should have read it earlier). It makes sense with what I've found (ie, slapping on the 100% charged external when it's down to around 10-15%, then a while later the built-in is at ~90% or so).

The external battery contains more energy than the built-in one, so I suspect it will hold it's voltage longer, swinging the "average" in it's favor.

[golalmo]

The external battery charge the internal battery, only when the device is in use.

Here are my times (full brightness, music in background, WiFi always on, using netfront):

Internal battery last for 3 hours.
External battery last for 6 hours. In that time, internal battery was charged to 100%.
One again, internal battery last for 3 hours.

Well, this half bulky device gave me a 12 hours with full battery usage.

[Eddy]

:eek: total of 12 hours usage?

[KBurton]

12 hours with Wifi active?

Okay I just went to Sonystyle and used my 25% registration promotion code toward an external battery. Looks like plenty of you got there ahead of me, since the estimated ship date is now Nov 4.

Golan, thank you very much for doing that test and publishing your results.

Keith Burton

[golalmo]

Yep, almost continusly usage with maybe 2-3 pauses.
The external battery rocks. For a convantional users, charge won't be needed for a week or two.