Karel details plans for Power Mangement - Page 5

Shaggy · 10-24-2008, 10:22 AM

Quote:

Originally Posted by wallcraft

There really isn't anything like the DR1000S out there now, but that would be even more true if iRex put a 2x capacity battery in the device. Many laptop/tablet vendors are now offering 2x larger batteries as options. Laptops are so power hungry that this gives a major hit in weight and device thickness. In the case of the DR1000S is would be a minor hit in these areas for a major advance in per charge life.

An interesting point that I saw mentioned elsewhere is that since the DR1000 is recharged via USB now, rather than from a power adapter, it can only charge with 500mA. Perhaps the decision to only put a single battery in the DR1000 is because the time it would take to charge a 2X battery via a USB connection would be really long.

I wonder if the decision to have half the battery capacity of the iLiad was a tradeoff for making it rechargable via USB, and they were hoping to make up the difference with the future power management functionality?

Gogolo · 10-24-2008, 11:38 AM

Quote:

I wonder if the decision to have half the battery capacity of the iLiad was a tradeoff for making it rechargable via USB, and they were hoping to make up the difference with the future power management functionality?

I think you hit the nail on the head.

Gogolo

bob_ninja · 10-24-2008, 12:17 PM

These comparisons are far too simplistic. It should be noted that even when considering a single device, such as a standard PC computer, power usage can vary a great deal between different software applications. Right now I am typing a message in a browser, so CPU, disk, etc. most components are not busy, hardly doing anything at all. Right now my LCD screen uses the most power. When I start a new build or any other CPU intensive processing then suddenly CPU could be drawing more than the screen. When you play an action game then between your CPU, GPU and disk they will draw far more power than LCD display!!!!

That means having a lower power display may sometimes provide a much longer runtime (when display uses most power) and other times may not (when other components use more power).

Now we come back to eReader vs mobile phones (tables and UMPCs are still limited to perhaps 5 hours, so not much better than regular laptops). You are comparing DR rendering PDF documents against a mobile phone rendering plain text. In general mobile phones run simple small apps, nothing even close compared to the complexity of rendering PDFs. In fact, you should understand that PDF rendering is far from trivial. Therefore, DR CPU is using far more power on average while rendering PDF docs compared to mobile phones doing very simple rendering of icons and simple text. DR is doing far more work. So clearly when DR is tasked with heavy duty computations such as PDF rendering then despite a low power screen it still needs power for CPU.

The point is, compare runtime between DR and mobile phones doing the same work, rendering PDF docs!!!! Then let's see how their runtimes compare.

Even comparing DR and Cybook is not fair. Cybook crashes for any non-trivial PDF. So it has a smaller CPU using less power, *BUT* cannot handle compex context and is much slower rendering content than DR.

I think DR is getting too much flak for this battery issue. I think iRex for the most part made all the right choices. DR needs a more powerful CPU to handle more complex PDF content, despite using more power. It is unfortunate they slipped on battery and power mgmt. Either power mgmt is mandatory and in V1 or they offer options for battery (2x builtin, 1 options, whatever) They clearly understimated this area.

But hey, most manufacturers make the exact same mistake. Most laptops have small batteries. They cannot handle the load and end up lasting only couple of years, then capacity degrades rapidly.

ppxnouse · 10-24-2008, 12:20 PM

I read the "USB only delivers 500mAh and so a larger battery would take too long to charge" excuse for the weak 1300mAh battery a few times now. I think it is pretty lame. And I hope for iRex that it was not their way of thinking when they opted for the 1300mAh.

To charge a larger battery that far that it can deliver the run time to the DR that it gets with the current 1300mAh battery would take exactly the same time. Sure it would take longer to have it charged 100%, but you can also see charging the device on the PCs USB port as optional since USB cables and ports are everywhere. When you are at home and you want to prepare the device for a long absence from power sources, you can still use a charger with 1,5 A or more on the DR.

I for once use a 3000mAh battery on my phone which charges via an USB plug and "it takes to long to have it 100% charged" never was an issue.

ghostwheel · 10-31-2008, 01:53 AM

Quote:

Originally Posted by bob_ninja

Even comparing DR and Cybook is not fair. Cybook crashes for any non-trivial PDF. So it has a smaller CPU using less power, *BUT* cannot handle compex context and is much slower rendering content than DR.
.

Sorry, I'm going a bit

....
When a CPU is more or less powerful, it just means it can do tasks faster or slower. Once a CPU reaches a certain level of complexity in computation, it can do any computation - that is what is called a Universal Turing Machine

. Once it reaches that it is only a matter of time and memory. All CPUs we encounter have that complexity. The cybook crashing on complex pdfs just means buggy software, or maybe buggy hardware

.

bob_ninja · 10-31-2008, 10:00 AM

Let us say that all the software bugs are resolved and Cybook software can handle full PDF feature set. However, say a certain page takes 20 seconds to render on Cybook. Most would compare an eReader to a printed PDF or using PDF on PCs. Thus clearly you would consider Cybook's PDF handling to be deficient even if it didn't crash.

I am not familiar with the details, but I read here how Sony and DR seems to be doing some sort of combination of pre-processing and/or results caching to speed up display of complex pages. Could be wrong.

The point is simply that DR has both more powerful CPU and seems to have a more advanced rendering engine for PDFs. Clearly far more effort was invested by iRex into PDF handling for DR as compared to Cybook. Not that there is anything wrong with that. Cybook still works well and is a great value for the price.

Simply some comparisons don't make sense. That is all.

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10-24-2008, 12:17 PM	#63
bob_ninja Addict Posts: 208 Karma: 582 Join Date: Aug 2006 Device: Zire71	These comparisons are far too simplistic. It should be noted that even when considering a single device, such as a standard PC computer, power usage can vary a great deal between different software applications. Right now I am typing a message in a browser, so CPU, disk, etc. most components are not busy, hardly doing anything at all. Right now my LCD screen uses the most power. When I start a new build or any other CPU intensive processing then suddenly CPU could be drawing more than the screen. When you play an action game then between your CPU, GPU and disk they will draw far more power than LCD display!!!! That means having a lower power display may sometimes provide a much longer runtime (when display uses most power) and other times may not (when other components use more power). Now we come back to eReader vs mobile phones (tables and UMPCs are still limited to perhaps 5 hours, so not much better than regular laptops). You are comparing DR rendering PDF documents against a mobile phone rendering plain text. In general mobile phones run simple small apps, nothing even close compared to the complexity of rendering PDFs. In fact, you should understand that PDF rendering is far from trivial. Therefore, DR CPU is using far more power on average while rendering PDF docs compared to mobile phones doing very simple rendering of icons and simple text. DR is doing far more work. So clearly when DR is tasked with heavy duty computations such as PDF rendering then despite a low power screen it still needs power for CPU. The point is, compare runtime between DR and mobile phones doing the same work, rendering PDF docs!!!! Then let's see how their runtimes compare. Even comparing DR and Cybook is not fair. Cybook crashes for any non-trivial PDF. So it has a smaller CPU using less power, BUT cannot handle compex context and is much slower rendering content than DR. I think DR is getting too much flak for this battery issue. I think iRex for the most part made all the right choices. DR needs a more powerful CPU to handle more complex PDF content, despite using more power. It is unfortunate they slipped on battery and power mgmt. Either power mgmt is mandatory and in V1 or they offer options for battery (2x builtin, 1 options, whatever) They clearly understimated this area. But hey, most manufacturers make the exact same mistake. Most laptops have small batteries. They cannot handle the load and end up lasting only couple of years, then capacity degrades rapidly.

10-24-2008, 12:20 PM	#64
ppxnouse Connoisseur Posts: 60 Karma: 10 Join Date: Dec 2007 Location: Aachen Device: Gen3	I read the "USB only delivers 500mAh and so a larger battery would take too long to charge" excuse for the weak 1300mAh battery a few times now. I think it is pretty lame. And I hope for iRex that it was not their way of thinking when they opted for the 1300mAh. To charge a larger battery that far that it can deliver the run time to the DR that it gets with the current 1300mAh battery would take exactly the same time. Sure it would take longer to have it charged 100%, but you can also see charging the device on the PCs USB port as optional since USB cables and ports are everywhere. When you are at home and you want to prepare the device for a long absence from power sources, you can still use a charger with 1,5 A or more on the DR. I for once use a 3000mAh battery on my phone which charges via an USB plug and "it takes to long to have it 100% charged" never was an issue.

10-31-2008, 10:00 AM	#66
bob_ninja Addict Posts: 208 Karma: 582 Join Date: Aug 2006 Device: Zire71	Let us say that all the software bugs are resolved and Cybook software can handle full PDF feature set. However, say a certain page takes 20 seconds to render on Cybook. Most would compare an eReader to a printed PDF or using PDF on PCs. Thus clearly you would consider Cybook's PDF handling to be deficient even if it didn't crash. I am not familiar with the details, but I read here how Sony and DR seems to be doing some sort of combination of pre-processing and/or results caching to speed up display of complex pages. Could be wrong. The point is simply that DR has both more powerful CPU and seems to have a more advanced rendering engine for PDFs. Clearly far more effort was invested by iRex into PDF handling for DR as compared to Cybook. Not that there is anything wrong with that. Cybook still works well and is a great value for the price. Simply some comparisons don't make sense. That is all.

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