Battery Life compromise.

[Binky]

Blinky and ekianjo seem to be completely lost in fairy land.... and WB seems to have super nano batteries which don't exist yet

Explain...

The idea I'm getting is that a P2 is likely to use much less power when not doing much (screen black, radios off, processor idle, etc), and much more power with CPU going flat-out, screen all white on full brightness, all radios in use.

It will use less power to achieve equivalent performance to the P1.

Is that wrong?

 

[ShleeDragon]

That is kind of the point too... Yes, clock for clock - We should reach the Super Pandora 2.0 1Ghz performance on a single A15 core running lightly.

The usage will drop if we are hammering the A15.... could we advertise 10 hours of usage when running the current standard of PNDs and 5hours of PND-NG releases?

Regardless, I'm going to assume the new A15 SOC consumption peaks at about 4 to 8 watts with GPU? I'm thinking a good screen is 400mW? Wifi/bluetooth on top of that.

Dragon will need to figure this stuff out

edit: Id assume we would try to fit the bigger battery with hopefully better tech? (people are asking for the same battery, but I think that's silly)

 

[EvilDragon]

This indeed can not be calculated, it surely depends on the usage case.

Using the same emulators, the A15 should need less power indeed.

However, with the power the A15 has, CRT simulation, etc. is possible. That might use more power than before.

So does it use more power or not? Depends on whether you want CRT simulation or not.

For websurfing:

FireFox will run a lot faster and need more power. However, the same website renders way quicker too, so the power usage might be the same (peaking more when rendering the site, but as the peak is not as long as before, it doesn't matter).


DOSBox will need more power when emulating a Pentium fullspeed.

However, that wasn't even possible with the current Pandora.

When doing the same emulation, it will probably use less power.

As ARM cores are extremely flexible when it comes to power usage, it really isn't possible giving out battery times.

It varies a lot.

Someone who only plays MegaDrive games without any CRT filter will have a LOT more battery time than someone playing complex 3D games stuff like Doom 3.

 

[_wb_]

Note that on the current Pandora, the screen (mostly its backlight) is the biggest power consumer, even though it's a rather power-efficient screen. The CPU is idle most of the time (especially if it's going to be a much faster one), but a screen is not, it's always on during use.

For the P2 we all want an even bigger screen, and screen power consumption scales about linearly with the screen area I guess. If we would go from 4.3" to 5.5", that means a 63% increase in area. Add to that the fact that a higher resolution also requires more power, it could very well mean a doubling of the power consumption for the screen. This is a major reason for me to use an AMOLED screen, since in the average case (not too much white), it saves about enough power compared to LCD to compensate for the larger screen area. (The other main reasons why I would like AMOLED are response time (no ghosting!) and contrast)

We may want to redesign the color schemes of some of our software and stuff if the screen is AMOLED, e.g. PNDManager and these boards are very white, so that would be bad for power consumption. The black theme of System Info and the default skin of minimenu are good examples of very power-friendly interfaces on AMOLED.

 

[Exophase]

A CortexA15 dualcore under full load can suck the current Pandora battery dry in under two hours.

I need to remind you again that that ~8W for Exynos 5250 included the GPU at full load. The CPU cores themselves used more like 3-4W under full load.

 

[Klumpen]

a screen is not, it's always on during use.

Is there an audioplayer, that has the pause/play-function on a shoulderbutton?

If there is, the Pandora would indeed be the perfect mp3-player (besides all the other functions)

and you would not have to use the screen too often for this function.

 

[Grench]

How much heat can they dissipate when poorly ventilated?

The current pandora gets warm quite easily if working hard while in a case or pocket - won't overheating be a problem with newer/more powerful SOCs?

Here's a thought...

Use two small batteries - a pair of the ones from a Galaxy S3 for example.  Have them insert from the sides.

On the back cover, between the batteries, have a copper, brass or aluminum heat sink fins exposed to the air.  It wouldn't have to be very wide - and would be recessed a bit.  Just a passive radiator really.  On the 'inside' side of the block, have a thin not quite foil copper plate the size of the motherboard that presses gently against the hot features - and is cut around the tall ones.  This would allow the heat to transfer from the components to the dissipation area on the back.  It would be between the batteries - between the hand holds, etc...

That kind of system  should be able to dissipate heat from the components and the back side of the batteries to the air.

I'm not talking about a giant copper monoblock CPU heat sink here.  This entire thing could weigh an ounce in aluminum or 3 in copper. 0.2mm thick for the transfer skin and maybe 5mm for the fin section.  It would all need to be cast or cut as a single piece, but that's relatively straight forward.

Heck, you could start with a long thin piece of copper and bend/fold the center of it a couple dozen times to make small fins in the middle so it looks in profile something like:  

Case back

___________          ___________

battery_____|_|_|_|_|_____battery

Motherboard

Keyboard

 

[Grench]

Make that aluminum - thinking about it, Cu would turn green pretty quick.

 

[_wb_]

I don't think heat should be a big problem unless you want to do things like stress-testing the cpu and gpu while charging the battery with your P2 inside a closed bag. I suppose it should be possible to automatically lower the clockspeed / number of active cores if the temperature exceeds some threshold.

In practice there should be very few games or applications that manage to put a full load on all cpu and gpu cores at the same time. Nearly everything will be either cpu-limited or gpu-limited, and most threaded stuff tends to have one intensive thread that puts a high load on one cpu core, the other threads being used for less demanding tasks. On any handheld the amount of multi-tasking will always be relatively low (because of the small screen), so that's also not going to be a major thing to spread the load over all cpu cores. So basically the peak power consumption of the SoC will be rarely reached, and if it is reached, it will typically be in short bursts, with time in between to cool down.

 

[Binky]

Would an aluminium sheet pressed across the entire back of the PCB (without fins or external contact) be enough?

 

[Grench]

Would an aluminium sheet pressed across the entire back of the PCB (without fins or external contact) be enough?

That would redistribute heat within the case, but wedged between the batteries on one side and the MB on the other...  The objective is to get the heat out - or not to generate so much heat to begin with.

 

[C0smikD3bris]

Would an aluminium sheet pressed across the entire back of the PCB (without fins or external contact) be enough?

That is pretty much how the majority of netbooks employ a heatsink.

Not sure if the newer generations have changed anything but i know an asus eee pc 701, 900, 901, 1001HA use this method as i have taken them all apart.

Just a thermal pad wedged between the chip and the metal chassis behind the keyboard.

 

[monstercameron]

I wonder how feasible would it be to have the mainboard inside the top lid with a heat sink on the back? then there would be some kind of linkage down to the bottom half where a bigger battery and deeper keyboard could go...I guess it might be a little top heavy though...

 

[_wb_]

Not just a little. For ergonomic reasons you certainly want to concentrate most of the mass and volume in the base.

 

[klapse]

Case back

___________          ___________

battery_____|_|_|_|_|_____battery

Motherboard

Keyboard

Fins are  only useful for dissipating heat to the air. For conducting heat to the back plate, you would only need one somewhat thick piece of metal, like this:

___________________________

   b a t t e r y      ||      b a t t e r y

_____________||_____________

  ========Motherboard=======

                    Keyboard

EDIT:

And since metal conducts heat so well, you wouldn't need to have two batteries at all, just move the conductor to the side:

___________________________

||                b a t t e r y

||__________________________

  ========Motherboard=======

                    Keyboard

 

[Binky]

What about metal grips on the sides (carefully textured to be comfortable)?

 /|                keyboard               |\  
| |_______________motherboard_____________| |
|  _______________________________________  |
 \|                 battery               |/

 

[xiongxioi]

What about metal grips on the sides (carefully textured to be comfortable)?


/| keyboard |\
| |_______________motherboard_____________| |
| _______________________________________ |
\| battery |/

Isn't P2 modular based? Mr. Binky

It should be more like:

 /|                                  screen                               |\


| |_______________motherboard_____________| |


| _______________________________________ |


 \|                                 battery                                 |/

But, not, that would make the upper bit too heavy. It will not stand up, I think. The hinge on P1 is bad enough, this design would need 3 burly Italian plumbers to hold it in place.

I hope the 28 nm cortex-15 based chips will produce less heat under heavy load. 

 

[Grench]

Case back

___________          ___________

battery_____|_|_|_|_|_____battery

Motherboard

Keyboard

Fins are  only useful for dissipating heat to the air. For conducting heat to the back plate, you would only need one somewhat thick piece of metal, like this:

___________________________

   b a t t e r y      ||      b a t t e r y

_____________||_____________

  ========Motherboard=======

                    Keyboard

EDIT:

And since metal conducts heat so well, you wouldn't need to have two batteries at all, just move the conductor to the side:

___________________________

||                b a t t e r y

||__________________________

  ========Motherboard=======

                    Keyboard

Case back

___________          ___________

battery_____|_|_|_|_|_____battery

Motherboard

Keyboard

Fins are  only useful for dissipating heat to the air. For conducting heat to the back plate, you would only need one somewhat thick piece of metal, like this:

___________________________

   b a t t e r y      ||      b a t t e r y

_____________||_____________

  ========Motherboard=======

                    Keyboard

EDIT:

And since metal conducts heat so well, you wouldn't need to have two batteries at all, just move the conductor to the side:

___________________________

||                b a t t e r y

||__________________________

  ========Motherboard=======

                    Keyboard

My  plan wasn't to transmit heat to the back plate - but to have a gap in the back plate with exposed fins between two batteries - a trough full of fins so to speak.

 

[Binky]

Wouldn't that make it vulnerable to dirt and the like?

 

[_wb_]

I'd really like the P2 not to consume the amount of Watts needed to make it useful as a hand-warmer.