Here are some thoughts on the new iPad based on discussions with my colleagues and advisors.

How did Apple fit in a 1.7x larger battery in the new iPad?

The new iPad’s battery capacity is 42.5Whr, a 1.7x increase compared to 25Whr of the iPad 2. Battery capacity is basically area x battery thickness, so either the area or the thickness has to increase to fit in a 1.7x larger battery. Tablet thickness increased only 0.6mm, from 8.8mm to 9.4mm. For now, let’s assume the battery area is the same and the 0.6mm increase in tablet thickness all came from the battery. Battery thickness in the iPad 2 was 2.5mm, giving the new iPad a 3.1mm thick battery, resulting in a 1.24x increase in battery capacity, far smaller than 1.7x. This means that the battery thickness might have increased by more than 0.6mm. Maybe the new iPad uses a thinner glass for the display, leaving more room to increase battery thickness. If the battery area is the same, battery thickness in the new iPad would be 2.5mm x 1.7 = 4.25mm, meaning that Apple somehow shaved off over 1mm in thickness from other components such as the display, glass, aluminum body etc.

Another possibility is that battery area increased. However, the following teardown photo of the iPad 2 from iFixit shows that there is really not much room to increase the battery area.

The black part is the battery and the top part covered by aluminum shields is the PCB that contains all the chips (processors, DRAM, Flash memory etc). The battery already occupies the majority of the area compared to the small PCB. White space on the top right corner is left for the 3G module that contains chips for 3G communication (the iPad 2 in the picture is a WiFi version, hence no 3G module). Since the PCB and battery are placed side-by-side, the PCB area has to get smaller to increase battery area. However, the image below, a zoom-in on the PCB with the shields taken off, shows that the PCB is already pretty tight on space.

You can see that there is not much space to shave off in the PCB. The white space next to the orange square (NAND flash chip) is left for another NAND flash chip for the 32GB version (image shows a 16GB version). It seems it would have been very difficult to increase battery area and thickness, but Apple somehow pulled it off. Hopefully iFixit will soon release teardown images of the new iPad that reveals how Apple could fit in a 1.7x larger battery.

Battery life is the same despite a 1.7x larger battery

According to tech specs on the Apple website, both the new iPad and iPad 2 have up to 10 hours of battery life in WiFi mode. This means that the new iPad consumes 1.7x more power than iPad 2. Where is this additional power consumption coming from? It’s not coming from 4G since the battery life is for WiFi mode. Maybe it is coming from the higher resolution display. Assuming 1.7x more power is entirely coming from additional display power and that display power was ~50% of the total power consumption of the iPad 2, display power would have to be 2.4x larger in the new iPad. Does this make sense? Display power consists of backlight power and TFT switching power. Assuming backlight power does not change based on the display resolution, the power difference is from the TFT switching power that increases proportionally with display resolution. Basically, backlight power stays the same, but TFT switching power increases by 4x in the new iPad. A 2.4x increase in display power is possible if the TFT switching power was ~50% of the total display power in the iPad 2. Another possibility is that the processor power increased due to bigger graphics in the A5X compared to A5.

New package for A5X

The A5X processor in the new iPad seems to use a metal-ish material for the package compared to the A5 chip in the iPad 2. Maybe Apple changed the package material for better thermal conductivity because of higher power consumption in the A5X processor.

No iPad 3

Seems Apple is no longer putting numbers in iPad models. It’s now just a “new iPad” or “iPad 2012”, just like how Apple calls their macbook and iMac models. Maybe they are running out of new things to add to the iPad. Customers tend to expect a significant design overhaul when the model number changes, so Apple might be preparing for the time when there is no significant changes in consecutive iPad models. It could also be related to not wanting to sell prior models at a cheaper price.  Currently, Apple sells older models like the iPhone 3GS, iPhone 4, iPad 2 at a cheaper price. They don’t do this for the Macbook models. The previous models just disappear when new models are released. Maybe Apple wants to expand this to the iPhone and iPad lines.

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