HP 15c Collector's Edition save/restore does not work

[Johnh]

hi fade0ff

Sounds frustrating! I'm no expert (unlike many others here), but I got mine going starting with updating the fw which I see is already in place in yours.

I'm using Voyagersave on my two Win10 machines. Is there anything that I described in my posts above on this thread (post #7 and #8) that might give a clue for using it with your Win10 computer? Or Geoff's at post #15?. I tried to describe how it went in my case and if wasn't quite as the instructions had led me to expect.

[fade0ff]

Shortly after posting here, I found that the issue is really caused by low battery voltage. While I just bought the HP15C CE, both batteries where at ~2.7V. Obviously enough to work in principle but not enough for a reliable USB mode. I replaced the batteries and now the HP15C CE is detected at once in USB mode.

Of course, this raises some questions regarding the HW design.
Is the calculator drawing so much current in OFF mode that it depleted the batteries after just a year? From what I can tell, this is not the case for an original HP16C at least. Then again, the HP 35s also drains batteries quickly in OFF mode.
Also, the low battery indicator doesn't seem to work at all and there is not even a brown-out detection to reset the device, instead it just freezes.
These kind of design flaws are not exactly what you would expect from a HP calculator.

[JAK08]

I havent had to replace my CE batteries quite yet, but there is a whole thread here discussing the battery quality they provided.

I plan to get some soon though as it seems there have been some quirks with the ones it shipped with.

[AnnoyedOne]

(Yesterday 05:34 PM)JAK08 Wrote:  ...there is a whole thread here discussing the battery quality they provided.

https://www.hpmuseum.org/forum/thread-22763.html

A1

[Johnh]

I also had battery issues at the time I was updating firmware and getting Voyagersave running. This was after a full year of actual use. On mine only one battery was connecting.

Now that I can keep fully backed up as I add more programs, I'm letting it run and using it daily until it eventually gets to the next battery issue. Maybe it will run out of power, or maybe Voyager save won't connect? All seems good so far, Keyboard issues are gone and it runs well. I'm about 3 months into a new set of fresh high-quality batteries. Since I'm currently fully backed-up, and there's some free time, I think I'll test again to check the Voyagersave operation and see how the voltages are looking.

It's all a lot less stressful than worrying about my Hp35s, which has more power issues and no way to restore.

[DA74254]

(Yesterday 10:13 AM)fade0ff Wrote:  Then again, the HP 35s also drains batteries quickly in OFF mode.

That, I find, is a bit hit-and-miss.
When I bought my 35S back in 2008 in Singapore, it chewed through batteries like an American car guzzling petrol. After 3 or 4 battery changes and resets, this somehow stopped. My 35S is currently used/tested on and off very 2-3 months and I have not replaced the batteries in about 3 years.

[ajay_m]

I can confirm on my CE device that with batteries removed, a DVM reads 0 ohms between the two negative terminals and 0 ohms between the two positive terminals, so if this is not the case on any unit, there is a wiring fault.

[Johnh]

(Yesterday 08:25 PM)ajay_m Wrote:  I can confirm on my CE device that with batteries removed, a DVM reads 0 ohms between the two negative terminals and 0 ohms between the two positive terminals, so if this is not the case on any unit, there is a wiring fault.

Thanks, that's good info. Mine had no negative to negative continuity. I fixed it with my own work-around wire in the battery area rather than return it or hack it open. Your post also confirms that no blocking diodes are included, which is totally fine, but I had wondered about that while diagnosing.

[Johnh]

(Yesterday 06:27 PM)Johnh Wrote:  Now that I can keep fully backed up as I add more programs, I'm letting it run and using it daily until it eventually gets to the next battery issue. Maybe it will run out of power, or maybe Voyager save won't connect? All seems good so far, Keyboard issues are gone and it runs well. I'm about 3 months into a new set of fresh high-quality batteries. Since I'm currently fully backed-up, and there's some free time, I think I'll test again to check the Voyagersave operation and see how the voltages are looking.

...So I did the checks, after 3 months of daily intermittent use, 5 days a week. Batteries were draining evenly, currently at 3.03V each. My added wire to fix the connection between the negative terminals has a small bare patch, so I can measure battery voltage from there to the top exposed positive faces, without removing a battery.

And I did another Save file which connected and saved fine. I imported it into Pierre's (awesomely useful) Excel file to save and check my listing's.

BTW I've got a small but eclectic program collection for the '15c now. I'm a structural engineer with an outside interest in electronics. So I have a program for structural section properties of box sections I sections and circular sections, one to assess reactances vs frequencies of capacitors and inductors, and a Celsius to Fahrenheit converter for helping with some US-based fire temperature calcs.