DM1x battery voltage

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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Joined: Wed Jan 30, 2019 10:07 pm

DM1x battery voltage

Post by michel_b » Wed Jan 30, 2019 10:24 pm

Hello there,

I'm the new happy owner of a DM-15 since yesterday.

When I use the key combination E-[ON], it displays its firmware revision and battery voltage.

When running at 48 MHz, mine displays 2,740 V, and at 12 MHz : 2,828 V.

I'm a bit surprised both with the battery level (new, supposedly 3V CR0232) and with the difference clearly related to the CPU speed.

But I'm telling myself that the battery voltage reading makes sense only when one knows at which voltage the battery should be considered “low”... So this is my question : on this device, at which level should I consider that the battery will need a replacement ?


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Re: DM1x battery voltage

Post by Michael » Wed Jan 30, 2019 10:44 pm

The battery voltage drops under load.
The more load, the more the voltage drops.
The higher the CPU frequency is, the higher the load, the lower the voltage.
But the voltage rises again after taking the load off.
A low battery icon is displayed somewhere around 2.2V.
The LCD starts fading at about 2V.
The LCD controller operates down to 1.8V and the CPU even lower, 1.65V IIRC

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Re: DM1x battery voltage

Post by grsbanks » Thu Jan 31, 2019 6:53 am

Not only the clock frequency but also pressing a key causes load on the battery, so by viewing the battery voltage you are also causing that voltage to drop "artificially."
There are only 10 kinds of people in the world: those who understand binary and those who do not.

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Re: DM1x battery voltage

Post by michel_b » Thu Jan 31, 2019 7:52 am

Thanks for the clear and comprehensive replies :)

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