Friday, June 26, 2015

Power Tool Battery Failure Analysis

My first YouTube video is about a power tool battery pack that I rebuilt about a year ago.  It failed recently, melting the case a bit, and damaging several of the cells inside.  In the video I discuss what went wrong and a couple possibilities on fixing the issue in other battery packs I rebuilt with new cells.

About a year ago I rebuilt several power tool battery packs with new Sub-C NiCd cells I bought online.  For the last year they have worked great.  My Dad has used several on a regular basis and he said they have better capacity than the original cells and a year later they are still going strong.

Except for one that quit rather suddenly a while back.  It was working normally, and he put the cordless drill down and not long after smelled something burning.  He ran around and checked a bunch of stuff and found that the battery pack on the cordless drill was very hot.  The cells had overheated, melted the case a bit, and then failed.  

I opened the pack up to find that four of the cells in the pack were damaged.  They measured zero volts, and one was burned on the ends.  Inspecting the cells showed that the thin heat shrink covering on the cells that were damaged had split.  But that was just a symptom of the cells overheating, not the cause.  I found a spot on two cells that had rubbed together, causing four cells to short circuit through the case of a fifth cell.

Watch the video to see the damage and my discussion of how possibly to prevent the issue from occurring again.

Wednesday, June 24, 2015

Software Creates Ownership of Hardware?

For my first post I thought I'd share something I wrote about a month ago on my Facebook page:

Remember the thing a while ago about John Deere saying that farmers don't own their tractors because the computer software that runs the tractor's control systems is copyrighted by John Deere? Now General Motors is making the same claim about their cars.

So here's my take: It has been a long standing thing that when you buy computer software, such as Windows or Photoshop, that you don't actually buy it, you just buy a long term license to use it. This allows the manufacturer to retain rights that allow them to prevent you from misusing the software, such as stealing parts of the code for other uses, or making modifications to the software.

I have no problem with that aspect of this situation. GM, and John Deere, can claim copyright and ownership of their software even when it is in your tractor or your car. They can tell you that you are not allowed to modify the software. This is in their best interest. If you reprogram your tractor's engine control unit to somehow put out a bunch of extra horsepower you are running the tractor outside their design limits. I also don't really have a problem if they were to tell you that if they have found that you have modified their software that your warranty is instantly null and void, since you are now pushing things beyond the limits they designed it for.

But I don't see how John Deere or GM can claim ownership of the tractors or cars that contain their software.

Back to the computer analogy. Even though Microsoft retains rights to Windows and Adobe retains right to Photoshop when they are installed on my computer, that does not mean they own my computer. I own the computer, and I have every right to remove Windows at my whim and install Linux, or remove Photoshop and install some other photo editing software.

The same should apply to John Deere and GM. We own the cars. We own the tractors. We may not be allowed to modify their software, but if we could obtain replacement software, we should be able to install that and keep ownership and use of the tractor or the car, and do whatever we want. GM doesn't own a car, and John Deere doesn't own a tractor, just because it contains their software, any more than Microsoft owns my laptop because it contains Windows.

Some people believe that GM is doing this to push out independent auto repair businesses and auto parts stores. If a garage can't get the scan tools and such to work on a car you'd have to take it back to the dealer. I don't believe that retaining ownership of the software gives GM this right either.

Back to the computer analogy. Microsoft still "owns" the Windows OS on my laptop. That doesn't prevent many other software companies from writing programs that can look into the Windows OS and see what it is doing, such as task manager programs, software that monitors disk or memory usage, or programs that fix issues in Windows to increase performance.

So independent auto repair shops still have the right to plug in a scan tool to monitor the performance of your engine or any other system in the car. GM retaining copyright on the software doesn't prevent this. The independent shop still has the right to change any parameters that the scan tool allows them to tune, just as I can change settings in Windows to tune how my computer works.

These concepts have been legally established long ago in the world of software licensing, and they apply the same to cars and tractors as to my computer.