HP30B retunrning to "default values"

[ElectroDuende]

(05-07-2015 01:34 PM)Katie Wasserman Wrote:  The low battery warning does not work in these machines and your 30b will resent when the battery voltage gets too low. This is unfortunately a very common occurrence with all the new HP ARM-based calculators. The power supply design is just horrible, they've put 2 CR2032 cells in parallel instead of using them blocking diodes so that one cell won't drain the other when it's exhausted or shorted,

I recommend that you buy a good supply of 2032 cells, they're under $0.25 on Amazon and elsewhere and change them often and carefully. "Carefully" because it's pretty easy to short the battery contacts when inserting a new cells and you'll reset the calculator.

Thank you Katie!

I knew (and suffered) about the battery indicator problems in the 15C LE, but didn't expect it will be the same in "non emulated models".

I didn't realize that they were wired in parallel... then an easy test can be done.

- Powered just by cell A: continuous resets, just trying to do self-tests or run little programs.
- Powered just by cell B: doesnt't seem to reset (just like when powered by the two of them... maybe some reset may happen "randomly").

Finally, I got a multimeter, Batt A: 2.3v under no load, Batt B: 2.8v under no load... clear now; I'll get a couple of them on my way home!