[New PSP Tear-down] Exploring the Battery Module [Epilogue]
Nikkei Electronics Disassembly Squad revealed the insides of the PSP-1000 and PSP-2000. We finished most of the analyses. Both the LCD modules and wireless modules were taken apart into members. We probably disassembled every single part ...
When our disassembly craze began to wane, one of the engineers said, as if a devil whispered to us, "Shall we open that battery module?"
Wasted space in module?
One of the characteristics of the PSP's battery module intrigued us: a shallowly curved surface of the exterior package. If a rectangular battery cell is inside, it means that there is some wasted space.
Along the curved surface of the PSP's chassis, the left side of the battery module is thinner than the other sides. The battery modules of the old model "PSP-1000" (bottom) and new model "PSP-2000" (top) have current capacities of 1800 mAh and 1200 mAh, respectively.
"Maybe safety circuits to prevent excess current are stored in this space. Anyway, let's open it," one of the engineers said. And he reached out for a tool.
The clamp really looks tough.
Caution: It is very dangerous to take apart battery modules. Never do it without help from an expert.
"Exterior packages of most battery modules split up when this tool put pressure on them." He attached the battery module to the clamp with a practiced hand and began to turn the handle. Soon, with a snap, the exterior package cracked. And we began to pry it apart, and the next moment ...
White smoke floated. Did we open a pressure valve that lets out battery electrolyte? Suddenly, the atmosphere became tense. Fortunately, there was no sign of danger, such as heat generation, in the battery module. So, while monitoring the temperature, we began to analyze it.
Dismantled battery module of the PSP-1000.
"Oh, I see. We guessed it right. The curved part is empty." Probably, the exterior package of the battery module is curved not to make a space between the exterior package of the PSP and battery module. Safety circuits are stored beside the battery module.
The new model makes use of the space
We started to open the battery module of the PSP-2000. "Hmm ... the clamp doesn't work on this." The clamp, which easily opened the battery module of the PSP-1000, did not work on the new battery module. We had no choice but to use tools such as a slotted screwdriver.
Caution: Again, never do it without help from an expert.
The security circuits of the battery module is mounted on the battery cell. Also, there is a black resin plate between the security circuits and the battery cell.
Dismantled battery module of the PSP-2000.
We found that some improvements were made to the battery module of the PSP-2000. First, security circuits are formed on a single-sided board, not on a double-sided board as in the case of the PSP-1000, and are placed in the space made by the curved surface of the battery module's exterior package.
This design change contributes to the miniaturization of the battery module. In fact, the current capacity of the PSP-2000's battery module is 1200 mAh, two thirds of that of the PSP-1000's battery module.
In addition, the strength of the battery module is increased by inserting a resin plate between the security circuits and the battery cell. The clamp did not work probably because this resin plate absorbed the pressure.
These measures increased the weight of the battery module, but, probably, the security of the battery module was prioritized.