DM42: Lower shut off voltage (CR2032)

General discussion about calculators, Swiss Micros or otherwise
mcc
Posts: 136
Joined: Fri Jun 23, 2017 3:10 am

DM42: Lower shut off voltage (CR2032)

Post by mcc » Sun Jan 07, 2018 4:31 am

Hi,

I have a "funny CR2032" in my DM42: As I turned on the DM42 the first time, it was at 2.88V. In the meanwhile it had reached 2.94V.
Currently it is at 2.92V. Is this a "self-recharging" coin cell ? :) ;) :)... only joking.

At what voltage level the DM42 wants a new CR2032?

Cheers!
Meino
DM 42 - SN: 00373, Firmware v.:3.5

User avatar
Walter
Posts: 700
Joined: Tue May 02, 2017 9:13 am
Location: Close to FRA, Germany

Re: DM42: Lower shut off voltage (CR2032)

Post by Walter » Sun Jan 07, 2018 6:38 am

mcc wrote:
Sun Jan 07, 2018 4:31 am
As I turned on the DM42 the first time, it was at 2.88V. In the meanwhile it had reached 2.94V.
Currently it is at 2.92V.
That phenomenon was known for the beta units. It's reduced for production calculators. Personally, I doubt the precision of 10mV makes sense - it generates extra questions only. YMMV
DM42 SN: 00041 --- Follower of Platon.

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

mcc
Posts: 136
Joined: Fri Jun 23, 2017 3:10 am

Re: DM42: Lower shut off voltage (CR2032)

Post by mcc » Sun Jan 07, 2018 7:32 am

Hi Walter,

thanks for your reply. :)
I dont care about the exact voltage...I see this more as a "tendency meter". Battery voltages -- especially when
it comes to batteries with a huge surface area compared to their volume -- are depending of the current temperature
of the environment. And Lithium cells are even more prone to it.

But back to my initial question:
At what voltage the DM42 says: "A new battery, please...Sir/Lady!"
What is the shut off voltage?

Cheers
Meino
DM 42 - SN: 00373, Firmware v.:3.5

grsbanks
Posts: 628
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK

Re: DM42: Lower shut off voltage (CR2032)

Post by grsbanks » Sun Jan 07, 2018 9:54 am

All batteries exhibit this phenomenon to varying degrees. When you stop drawing power from them they "relax" and their voltage rises again.

The DM42 refuses to operate below 2V if memory serves.
Not SwissMicros staff, just an enthusiast.

mcc
Posts: 136
Joined: Fri Jun 23, 2017 3:10 am

Re: DM42: Lower shut off voltage (CR2032)

Post by mcc » Sun Jan 07, 2018 12:06 pm

Hi grsbanks,

thanks for the information! :)

Cheers!
Meino
DM 42 - SN: 00373, Firmware v.:3.5

User avatar
Walter
Posts: 700
Joined: Tue May 02, 2017 9:13 am
Location: Close to FRA, Germany

Re: DM42: Lower shut off voltage (CR2032)

Post by Walter » Sun Jan 07, 2018 3:09 pm

grsbanks wrote:
Sun Jan 07, 2018 9:54 am
The DM42 refuses to operate below 2V if memory serves.
Is there anything like a low-battery warning before?
DM42 SN: 00041 --- Follower of Platon.

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

grsbanks
Posts: 628
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK

Re: DM42: Lower shut off voltage (CR2032)

Post by grsbanks » Sun Jan 07, 2018 6:56 pm

Walter wrote:
Sun Jan 07, 2018 3:09 pm
Is there anything like a low-battery warning before?
I'm told there's a specific battery icon between it showing as empty and when the DM42 stops working but I have yet to see it. The battery even in my beta DM42 isn't that flat yet.
Not SwissMicros staff, just an enthusiast.

Thomas Okken
Posts: 438
Joined: Tue May 02, 2017 3:48 pm
Contact:

Re: DM42: Lower shut off voltage (CR2032)

Post by Thomas Okken » Sun Jan 07, 2018 7:41 pm

grsbanks wrote:
Sun Jan 07, 2018 6:56 pm
Walter wrote:
Sun Jan 07, 2018 3:09 pm
Is there anything like a low-battery warning before?
I'm told there's a specific battery icon between it showing as empty and when the DM42 stops working but I have yet to see it. The battery even in my beta DM42 isn't that flat yet.
Obvious next question: when the battery icon changes to this almost-empty state, does the HP-42S-style low battery annunciator turn on as well? Enquiring minds want to know. :D

grsbanks
Posts: 628
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK

Re: DM42: Lower shut off voltage (CR2032)

Post by grsbanks » Sun Jan 07, 2018 9:09 pm

Thomas Okken wrote:
Sun Jan 07, 2018 7:41 pm
Obvious next question: when the battery icon changes to this almost-empty state, does the HP-42S-style low battery annunciator turn on as well? Enquiring minds want to know. :D
I'm pretty sure the answer to that is "no" because the DM42 has a battery indicator whereas the HP-42S doesn't!

Removing that annunciator also allowed us to pack the others closer together and make room for the user flag 00-10 annunciators.
Not SwissMicros staff, just an enthusiast.

User avatar
Walter
Posts: 700
Joined: Tue May 02, 2017 9:13 am
Location: Close to FRA, Germany

Re: DM42: Lower shut off voltage (CR2032)

Post by Walter » Sun Jan 07, 2018 10:37 pm

grsbanks wrote:
Sun Jan 07, 2018 6:56 pm
Walter wrote:
Sun Jan 07, 2018 3:09 pm
Is there anything like a low-battery warning before?
I'm told there's a specific battery icon between it showing as empty and when the DM42 stops working but I have yet to see it. The battery even in my beta DM42 isn't that flat yet.
Obvious next questions: at which voltage the battery icon changes to this almost-empty state? How much calculating time will be left? Enquiring minds want to know (thanks, Thomas!). :D
DM42 SN: 00041 --- Follower of Platon.

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

Post Reply