Battery use while off

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pica
Posts: 63
Joined: Fri Mar 30, 2018 11:36 am
Location: Eswatini

Battery use while off

Post by pica »

I got my DM42 over 3 years ago, May 2018, and it has used very little power. I changed the battery earlier this year. Suddenly, over the last few days, consumption WHILE OFF suddenly increased. The voltage is around 2.98v while in use. However, when powered on after being off for a couple of hours, the startup voltage drops, depending how long it's been off. This morning the screen failed, locked up completely, and would not respond to the reset button at the back. Until I took out the battery, which recovered I guess. It restarted when the battery was replaced. After turn on, the voltage quite quickly recovers.
I have cleared the calc state and downgraded the firmware, to no avail. No problem when left on the USB.
Anyone with a similar experience?
HP50G HP35s Free42 DM42.
Testing WP43S, C43.
reavy
Posts: 95
Joined: Tue Feb 06, 2018 9:08 pm
Location: Phoenix, AZ

Re: Battery use while off

Post by reavy »

I haven’t had this experience, but I have had wildly inconsistent performance between individual CR2032 batteries, even batteries from the same manufacturer and same retail package. Could this be due to the new battery you put in?
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pica
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Location: Eswatini

Re: Battery use while off

Post by pica »

I will try a different battery make. But it does not explain why the voltage recovers after switching on.
HP50G HP35s Free42 DM42.
Testing WP43S, C43.
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pica
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Location: Eswatini

Re: Battery use while off

Post by pica »

Interestingly, when I opened the calculator, I found that the actual battery voltage stays very close to 3 V. The on screen voltage indicator is what changes.
If I do an operation that uses power, like reading or writing to the flash memory, the actual battery voltage dips only momentarily. The on screen indicator registers this drop immediately, but holds the lower reading for about 30s before returning to the normal voltage.
It would nice to know what the on screen indicator actually measures, and how this relates to the on/off state of the calculator.

My problem was eventually solved by loading an older state file. I have not been able to work out what the difference was.
HP50G HP35s Free42 DM42.
Testing WP43S, C43.
Peet
Posts: 159
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Location: Germany

Re: Battery use while off

Post by Peet »

After seeing this behavior for the first time (DMCP-3.22 / DM42-3.20 not state-file loaded), I'm not sure whether it's new or has always been. Normally the voltage shows 2.97 or 2.98V, if I switch the DM42 off and on again, then it usually shows about 0.02V less: off/on - 2.95, off/on - 2.92, off/on - 2.91, off/on - 2.88 (droppet it until 2.70 and loss of one battery-bar) ... but it shows the same behaviour when enter SETUP und EXIT. After a while it shows e.g. 2.96V again.
My programmable calculators - former: CBM PR100, HP41CV, HP28S, HP11C - current: HP48G(+), HP35S, DM41X, DM42
Thomas_ER
Posts: 112
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Re: Battery use while off

Post by Thomas_ER »

Peet wrote:
Fri Sep 03, 2021 1:19 pm
After seeing this behavior for the first time (DMCP-3.22 / DM42-3.20 not state-file loaded), I'm not sure whether it's new or has always been. Normally the voltage shows 2.97 or 2.98V, if I switch the DM42 off and on again, then it usually shows about 0.02V less: off/on - 2.95, off/on - 2.92, off/on - 2.91, off/on - 2.88 (droppet it until 2.70 and loss of one battery-bar) ... but it shows the same behaviour when enter SETUP und EXIT. After a while it shows e.g. 2.96V again.
Now i did the same steps you described, and yes, this behavior is new for me.
Each action reduces the displayed battery voltage.
To me it seems, the return to the higher value occurs, when the calculator time changes the minutes.

SwissMicros should have a look on this behavior, maybe related to DMCP.3.22.
[ HP48/49/50/42S/WP34/HP Prime/ DM42 (#00185+00318) ]
ljubo
Posts: 44
Joined: Sat Jun 20, 2020 1:46 pm

Re: Battery use while off

Post by ljubo »

Thomas_ER wrote:
Fri Sep 03, 2021 3:08 pm
and yes, this behavior is new for me.
Have you explicitly tried also with an older firmware version? (and the voltage is not dropping during that rapid on/off sequence?)
HP-15C, DM15L, HP-35S, DM42
Thomas_ER
Posts: 112
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Re: Battery use while off

Post by Thomas_ER »

ljubo wrote:
Fri Sep 03, 2021 11:18 pm
Thomas_ER wrote:
Fri Sep 03, 2021 3:08 pm
and yes, this behavior is new for me.
Have you explicitly tried also with an older firmware version? (and the voltage is not dropping during that rapid on/off sequence?)
This behavior I have never seen before.
It's not only during on/off sequence, as Peet mentioned in viewtopic.php?p=21537#p21537
And it is so remarkable, that it is easy visible. Please try yourself.
Also the "Reset" at every minute-change also is somehow surprising and irritating.
Did you do also this observations?
[ HP48/49/50/42S/WP34/HP Prime/ DM42 (#00185+00318) ]
ljubo
Posts: 44
Joined: Sat Jun 20, 2020 1:46 pm

Re: Battery use while off

Post by ljubo »

Thomas_ER wrote:
Sat Sep 04, 2021 12:30 pm
This behavior I have never seen before.
It's not only during on/off sequence, as Peet mentioned in viewtopic.php?p=21537#p21537
And it is so remarkable, that it is easy visible. Please try yourself.
Also the "Reset" at every minute-change also is somehow surprising and irritating.
Did you do also this observations?
My assumption is:
  • Turning calculator on and off is probably quite energy intensive and leads to some voltage drop - whole screen update, writing some persistent data (?)
  • Status line is updated once per minute (probably also to save energy)
If this is correct the same or similar behaviour should be observed also with an old firmware during rapid on/off sequence.
HP-15C, DM15L, HP-35S, DM42
Thomas_ER
Posts: 112
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Location: Germany

Re: Battery use while off

Post by Thomas_ER »

Please add your values (with old/new firmware), so we should have more specific observations.
Peet started this, only SwissMicros can answer this questions.
Then SwissMicros (Michael, David) should investigate.
[ HP48/49/50/42S/WP34/HP Prime/ DM42 (#00185+00318) ]
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