DM 41L Battery life

Discussion of hardware issues related to the DM1x/DM41. Please ensure that you specifiy whether the issue is related to a credit card size unit or a "Voyager" unit (DM1xL/DM41L).
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Universalbinary
Posts: 15
Joined: Tue Apr 25, 2017 12:38 pm
Location: Germany

DM 41L Battery life

Post by Universalbinary » Mon Sep 18, 2017 10:02 am

Hello,

i've got my DM 41L end of October 2016
After some testing and working with the calculator (approx. 5 hours "ON") i stopped using it end of May 2017 (because i got the beta version of DM 42 :D ).
Last time i had a look on the battery level was in may 2017. It shows 2,93 V
Now, 4 months later (without any operation with the calculator), the battery level shows 1,973 V an the "BT" (Battery?) appears in the display.

What is with the "extended battery Life" ("a single CR 2031 will last for many years...")?

Thanks in advance for any hint.
Markus

(DM 41L #00441)
DM42: SN 00069
(DM 41L, HP 15c, HP 12c, HP 48G, HP 50g, HP 35s, HP Prime)

Michael
Site Admin
Posts: 227
Joined: Wed Apr 05, 2017 9:31 pm

Re: DM 41L Battery life

Post by Michael » Mon Sep 18, 2017 10:31 am

That is rather unusual. I wonder how that happened.

grsbanks
Posts: 704
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK

Re: DM 41L Battery life

Post by grsbanks » Mon Sep 18, 2017 12:31 pm

A recurring alarm that turns the unit on periodically, maybe?
Not SwissMicros staff, just an enthusiast.

Universalbinary
Posts: 15
Joined: Tue Apr 25, 2017 12:38 pm
Location: Germany

Re: DM 41L Battery life

Post by Universalbinary » Mon Sep 18, 2017 2:25 pm

Thank you for your fast response.

a few minutes ago, i tried to save and restore a small Programm via putting the DM 41 in mode "Serial console" ("C" + "ON")
On the Display, the words "SERIAL CONSOLE" appearing for a short time, before fading away.

After disconnecting the calculator from my Notebook, i pressed the Buttons "E" + "ON" for Information.
Instead of the battery voltage the letters "RTC" appearing on the display...

Maybe i should replace the "old" battery now and going to wait for some months to see what will happen...?

Best regards
Markus
DM42: SN 00069
(DM 41L, HP 15c, HP 12c, HP 48G, HP 50g, HP 35s, HP Prime)

sadsilence
Posts: 14
Joined: Thu Jun 15, 2017 5:50 am
Location: Germany

Re: DM 41L Battery life

Post by sadsilence » Mon Sep 18, 2017 7:06 pm

Hello Markus,

I have same problem with one DM41 (without "L", but internal electronics is most probably same, as there is no seperate "L" firmware). It's (measured) standby current in switch off state is at normal CR2032 voltage of 3V more than 100 times higher as given in datasheet somewhere on SwissMicros' homepage. Around 150 uA dropping down to 19uA at 2V (with CR2032 nearly done). It should be only 1.2uA. With former values even a brand new high quality CR2032 is finished within 1000 hours = around 6 weeks. In all other areas this DM41 works perfectly and working currents are between 200 uA in on state without key pressing or display change and 13.5 mA when an endless program doing constant display change is running @ 48 MHz processor speed or 4 mA when same program is running @ 12 MHz processor speed.

As Michael states, that is unusual and I can confirm as my second DM41 indeed has a standby current of clearly less than 10uA.

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