Boost voltage

[Claudio L.]

(06-08-2015 09:55 PM)Claudio L. Wrote:  Later, I will measure the voltage (with no load, as the calculator can't function) on these batteries and report back. This will be the reference voltage for "fully depleted" batteries.
Stay tuned.

The NiMH batteries read 1.18 V without load, all four show a surprising 4.68 V on my (dubious quality) multimeter.
I put the batteries back and the calculator is functioning, so it looks like they bounced back after the reset loop. But with the critical warning on, under load I'm getting 4.21V (slow mode). I started calculations, and voltage dropped to 4.10V. It stayed there for 10 seconds, while the machine kept doing calculations in a tight loop. After that, started descending slowly (around 0.1V per second) and it went downhill from there all the way to 3.5V and started resetting.

So it seems 4.10V is still not as safe as my previous measurements would suggest (this probably is an older set of batteries, with many recharge cycles on them). I'll have to revise my numbers.