Toshiba Portégé 300CT → Portégé 7020CT Battery Swap

After receiving a used laptop with a dead battery pack, I decided to swap in the 18650 cells from a working pack.

This turned out to be a bit of a waste of time when the swapped cells died a few months later, but I did it anyways.

(Now that I think about it in 2023, the battery management system board was probably broken.)

Two battery packs, one is open revealing 6 blue 18650 lithium ion cells, and a Swiss army knife open to the screwdriver / bottle opener setting, sitting atop a blue bedspread with a regularly repeating white circle pattern A screenshot of Windows Explorer on Windows XP copying files from a laptop A picture of a Toshiba Portégé 300CT laptop running Windows 98, with a picture of a sunflower as the desktop background Two laptops, both powered on and running Windows, sitting on carpet Two laptop batteries, unopened, sitting next to an electronics toolkit containing a soldering iron, screwdrivers, wirecutters, and a spool of solder A close up of two laptop batteries, Toshiba Li-Ion battery pack model numbers PA2505U and PA2441U Two laptop batteries, with part of the casing removed. Each pack has six 18650 cells, one pack has green cells, one pack has blue cells. The two laptop batteries, disassembled, with the battery management system circuit boards removed from the battery cells. A close up of the blue battery cells and battery management circuit board A close up of the blue battery cells A close up of the Portégé 7020CT laptop running with the repaired battery pack

Timeline

December 19, 2002

Received my used Portege 7020 laptop from a company on eBay.

December 20, 2002

Battery turned out to be DOA.

December 21, 2002

I had a spare normal battery pack from my old Portege 300CT. After taking a few physical measurements, and comparing the case dimensions side by side, I figured that the actual lithium cells inside were probably about the same size. Electrically, they were both 10.8V ~2400-2500mAh packs.

So I cracked open the cases and took a look. They were identical cells with different connector/recharger electronics. Being the curious tinkerer I was, I decided that it would be pretty sweet to switch the cells and see what happened. The major snag that I foresaw was a difference in the connectors. Between the old Portege 300 and the 7020, the size of the connector shrank and moved off center. Being the lazy engineer that most of us are when faced with a lab situation, I chose the fewest solder points to detach on both packs and attacked the problem.

It took me about 5.5 hours to desolder both control electronic sets, run jumper cables, and reattach the jumper cables to the new cells, all the while maintaining the right order of connections. Basically, so long as the right voltages were connected to the right terminals on the new PCB, it would function identically.

The addition of the extra 2-3mm of 22 gauge insulated wire put even more space constraints on the internals of the battery pack. But I managed to fit everything back together roughly as it had come out. I squeezed the case back together, and plugged the battery pack in. The laptop was actually switched on when I had the opportunity to test my handiwork. When the yellow charging light flickered on, I knew that everything was a-ok. No overheating, no problems beyond a Power Management mis-read. I made sure to fully discharge and recharge the pack, which took care of that issue.

April 9, 2003

Caveat: The battery pack I installed in place of the dead cells only lasts 25 minutes. There are a few potential explanations. First, the 7020CT is much more feature rich system, with a faster processor, larger screen, and a hard drive that uses twice the power (1A @5V instead of 500mA @5V). So does that mean it should run half as long? Maybe. The old laptop screen was 10.4", the new one is 13.3", 63% larger, if not more.

Since the cells themselves are identical in voltage and amp-hours, there is some consistency to the idea that with all other components' consumption raised by ~50%, the battery life would be cut back. Indeed, my 300CT would usually get about an hour and a half on the standard battery pack. Which means that the extended-life pack for the 7020CT is probably only good for about 50-90 minutes.

After several months of using this laptop on a daily basis, I have to report that I am completely satisfied with it. It's fast, efficient, and miles away from the old one (except for batt. life).

May 16, 2003

Update: When all of the power-saving features of the laptop are turned on, e.g. scaling down the processor speed, turning down the backlight brightness, etc. I can squeeze about 45 minutes worth of use out of a fully charged battery.

November 2003

Well, the battery-swapped pack finally died. The cells refused to hold a charge, so the laptop was reduced to being an expensive paperweight when not connected to the mains, and worse yet, would shut off during power dips.

Frustrated with this situation for a few months, I ordered a PA3002U-1BRL / PA2506UR long life battery pack off of eBay for about $40. For anyone looking for information on these battery packs, the PA3002 is supposedly for the Portege 7200 series, but it works fine in the 7020. The pack arrived a few days later and works like a charm, running four hours between charges. More importantly, I discovered a gem of a power-management utility that's available for free from Toshiba!

A screenshot of the Version information for the TOSHIBA Power Saver V5.10.02, Copyright 1998-2001 TOSHIBA Corporation. All rights reserved.

Check this out: It's called Toshiba Power Saver, and it takes over all of the power management functions using the Portege's ACPI functionality.

All of the features work as you would want them to and as a utility it is a model of good User Interface design.

For instance:

A mouse-over on the light bulb looks like this. A screenshot of the battery life remaining in the pack: 74% or 2 hours and 33 minutes
Left mouse-click does this. A screenshot of what happens when you left click the tray icon: Long Life, Normal, High Power
Right mouse-click does this. A screenshot of what happens when you right click the tray icon: Adjust Toshiba Power Saver Properties

A double-click opens up a list of power-saving profiles that you can select on the fly.

Three pre-configured profiles exist, each with variations on screen brightness, processor speed, time to suspend and hibernate, and time to hard drive spindown.

A screenshot of the Power Save Modes available using the TOSHIBA Power Saver Properties A grid of options for Process speed, Monitor brightness, Turn off monitor, Turn off hard disks, System standby, and System hibernate, which can be customized depending on whether you have 100%, 75%, 50%, or 25% of the battery left. A photo of the box the new replacement battery pack came in when I finally got rid of the swapped pack.

Overall, it's pretty sweet, it works flawlessly, and lets you really extend the runtime of the battery.

The laptop's Standby mechanism is fairly impressive as well, I've left the laptop in Standby mode for over eight hours with only a 20-25% drain on the battery over that time, and the system resumes in an instant.

Last updated ➡️ 1 April 2023 (mobile friendly + image alt text)