Battery life

If you're having problems with the hardware of a DM42, post about them here.
tbruylan
Posts: 6
Joined: Wed Aug 15, 2018 10:31 am

Re: Battery life

Post by tbruylan » Sun Sep 09, 2018 3:33 pm

rprosperi wrote:
Wed Sep 05, 2018 12:28 am
tbruylan wrote:
Tue Sep 04, 2018 5:43 pm
Hi, not sure if still relevant, but I have the same issue. Put in a fresh battery (tried Panasonic and Varta) and it drains in about 3 to 4 weeks. Is this the expected lifetime of a battery, or is something wrong? Calculator usage is also limited to a few minutes per day max.
A few is... how many?

And are those few minutes pressing buttons for manual calculations, or is it a few minutes of continuous program execution?

If only 3-4 minutes per day of manual entry and batteries die in 3-4 weeks, I'd look into it further.

Otoh, if this means 5-10 minutes daily of mostly continuous program execution, I'd say 3-4 weeks isn't bad at all.

More info will help to give better feedback.
Well, the calculator is sitting on my desk at home and I'm not yet making a lot of use of it. Usage basically means turning on the calculator daily to check the voltage (diagnostics menu) and turning it back off. I could literally see the voltage dropping every day. My battery just ran out a few days ago. It measures 2.01V (after removing it from the calculator), so it's empty.

Maybe important to specify: My device was still running DMCP 3.7 (I only noticed when the battery was already close to empty). Thus, I upgraded to DMCP 3.9a a few days before the battery finally ran out. Tomorrow, I will insert a brand new battery. But, I'm going to measure the calculator's current draw first (while at work in our lab with the proper equipment, as shown by @keithdalby). I hope the firmware upgrade to DMCP 3.9a fixed the issue :)

I will report about my findings :)

PS: Looking at the PCB, I see that R12 (one of the resistors next to the USB header) is not populated. Is this expected? If a resistor should be there, what value?

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akaTB
Posts: 214
Joined: Tue May 02, 2017 11:56 am

Re: Battery life

Post by akaTB » Sun Sep 09, 2018 8:29 pm

tbruylan wrote:
Sun Sep 09, 2018 3:33 pm
rprosperi wrote:
Wed Sep 05, 2018 12:28 am
tbruylan wrote:
Tue Sep 04, 2018 5:43 pm
Hi, not sure if still relevant, but I have the same issue. Put in a fresh battery (tried Panasonic and Varta) and it drains in about 3 to 4 weeks. Is this the expected lifetime of a battery, or is something wrong? Calculator usage is also limited to a few minutes per day max.
A few is... how many?

And are those few minutes pressing buttons for manual calculations, or is it a few minutes of continuous program execution?

If only 3-4 minutes per day of manual entry and batteries die in 3-4 weeks, I'd look into it further.

Otoh, if this means 5-10 minutes daily of mostly continuous program execution, I'd say 3-4 weeks isn't bad at all.

More info will help to give better feedback.
Well, the calculator is sitting on my desk at home and I'm not yet making a lot of use of it. Usage basically means turning on the calculator daily to check the voltage (diagnostics menu) and turning it back off. I could literally see the voltage dropping every day. My battery just ran out a few days ago. It measures 2.01V (after removing it from the calculator), so it's empty.

Maybe important to specify: My device was still running DMCP 3.7 (I only noticed when the battery was already close to empty). Thus, I upgraded to DMCP 3.9a a few days before the battery finally ran out. Tomorrow, I will insert a brand new battery. But, I'm going to measure the calculator's current draw first (while at work in our lab with the proper equipment, as shown by @keithdalby). I hope the firmware upgrade to DMCP 3.9a fixed the issue :)

I will report about my findings :)

PS: Looking at the PCB, I see that R12 (one of the resistors next to the USB header) is not populated. Is this expected? If a resistor should be there, what value?
For me this issue seems related to the upgrade to version 3.9a.bin
My beta unit started to deplete batteries in a couple of days; voltage indicator kept lowering while looking at it.
I had no issues after reflashing 3.8.bin both with 3.7.1 & 3.9.1 pgm.
Greetings,
    Massimo

-+×÷ ↔ left is right and right is wrong

tbruylan
Posts: 6
Joined: Wed Aug 15, 2018 10:31 am

Re: Battery life

Post by tbruylan » Mon Sep 10, 2018 10:05 am

I made some power measurement (see attached screenshots).

Connected the calculator to a 3.00V power supply with Imax set to 20mA, and in series a precision multimeter to measure the current in uA range. The calculator boots fine.

It runs DMCP 3.9a and PGM 3.9.1
dm42_about.jpg
dm42_about.jpg (89.84 KiB) Viewed 486 times
.

Current draws measured:
  • ON - 490uA
    dm42_on.jpg
    dm42_on.jpg (73.27 KiB) Viewed 486 times
  • OFF - 420uA
    dm42_off.jpg
    dm42_off.jpg (76.93 KiB) Viewed 486 times
  • With USB cable connected - 6uA (no screenshot)
So, calculating from a 230mAh CR2032, it theoretically drains in about 22 days, which is coherent with my practical experience.

I tested DMCP 3.8 with PGM 3.9.1 and without a PGM loaded, but the current measurements remained the same.

grsbanks
Posts: 712
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK

Re: Battery life

Post by grsbanks » Mon Sep 10, 2018 10:08 am

You should definitely update to DMCP 3.9a because that fixes an issue with powering the QSPI chip down.

Battery drain when powered down should be around 6uA, not 500uA.
Not SwissMicros staff, just an enthusiast.

tbruylan
Posts: 6
Joined: Wed Aug 15, 2018 10:31 am

Re: Battery life

Post by tbruylan » Mon Sep 10, 2018 10:14 am

Well, as stated in my post, it is running DMCP 3.9a and it is consuming 420uA in OFF state.

grsbanks
Posts: 712
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK

Re: Battery life

Post by grsbanks » Mon Sep 10, 2018 11:42 am

Sorry, I missed that.

I've passed the info on.
Not SwissMicros staff, just an enthusiast.

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akaTB
Posts: 214
Joined: Tue May 02, 2017 11:56 am

Re: Battery life

Post by akaTB » Mon Sep 10, 2018 12:26 pm

grsbanks wrote:
Mon Sep 10, 2018 11:42 am
Sorry, I missed that.

I've passed the info on.
And Michael already knows about my issues with 3.9a...
Greetings,
    Massimo

-+×÷ ↔ left is right and right is wrong

User avatar
ijabbott
Posts: 111
Joined: Fri Dec 15, 2017 1:34 pm
Location: Manchester, UK

Re: Battery life

Post by ijabbott » Mon Sep 10, 2018 6:40 pm

It sounds a bit like a leaky capacitor somewhere.

tbruylan
Posts: 6
Joined: Wed Aug 15, 2018 10:31 am

Re: Battery life

Post by tbruylan » Tue Sep 18, 2018 6:08 pm

So, I received a replacement (a brand new DM42). To verify, I measured the standby current of this new DM42, and it consumes a perfect low 3.4uA.
IMG_4943.jpg
IMG_4943.jpg (101.31 KiB) Viewed 328 times
SwissMicros is really taking a no-nonse approach as advertised. Their service is great, as are their products :) Thanks.

groenewe
Posts: 20
Joined: Sat Dec 02, 2017 10:49 am

Re: Battery life

Post by groenewe » Wed Oct 10, 2018 6:32 am

battery died without using the Dm42 in 13 days..... Aargghgggg!

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