And still it keeps on going

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grsbanks
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And still it keeps on going

Post by grsbanks »

Maybe I should think about replacing the battery in my beta unit some time soon :)

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Walter
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Re: And still it keeps on going

Post by Walter »

I assumed there would be a voltage limit with the calculator refusing to work below. Where is it?
DM42 SN: 00041 Beta
WP 43S running on this device

HP-35, HP-45, ..., HP-35S, WP 34S, WP 31S, DM16L
keithdalby
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Re: And still it keeps on going

Post by keithdalby »

Interesting font ;)
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H2X
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Re: And still it keeps on going

Post by H2X »

Walter wrote:
Tue Apr 10, 2018 2:53 pm
I assumed there would be a voltage limit with the calculator refusing to work below. Where is it?
Maybe it's in lemming mode?

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DM42 #40 running C43 | DM41X #50 | various HP models
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toml_12953
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Re: And still it keeps on going

Post by toml_12953 »

H2X wrote:
Tue Apr 10, 2018 3:31 pm
Walter wrote:
Tue Apr 10, 2018 2:53 pm
I assumed there would be a voltage limit with the calculator refusing to work below. Where is it?
Maybe it's in lemming mode?
Yeah, but the alternate route isn't as fast! :o
Tom L

If I buy someone a drink to congratulate them, is it a Mazel Tov cocktail?

DM10L SN: 059/100
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DM41X SN: 00506 (Shipping)
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DM42 SN: 00221 (Shipping)
Zaphod
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Re: And still it keeps on going

Post by Zaphod »

Walter wrote:
Tue Apr 10, 2018 2:53 pm
I assumed there would be a voltage limit with the calculator refusing to work below. Where is it?
Processor data sheet says lower supply limit is 1.71v , although the Vbat monitoring is done internally via a divide by 3 network , so I wouldn’t like to rely on it being too accurate ....

Anyone actually physically measured battery voltage and then checked what the system reports ?
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stefanoaz
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Re: And still it keeps on going

Post by stefanoaz »

As the battery voltage goes down in stand-by mode, the battery internal resistance increases. That means that, under load, such as running a program, the battery voltage will sag more. Since the calculator battery meter has a filtered response time, it will not report the total depth of the sag during current surges.

Bottom line - by the time the battery reaches something like 2V at standby, you have consumed more than 90% of the battery's energy. I wouldn't take it to any kind of - for instance - college entrance exam, before replacing the cell.

Looking at the datasheet, the battery resistance increases 6x by the time the open cell voltage drops to 2V (bottom right graph on the datasheet):

http://data.energizer.com/pdfs/cr2032.pdf
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grsbanks
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Re: And still it keeps on going

Post by grsbanks »

You're preaching to the choir :)

I was deliberately running the battery down to see how the machine behaved with such a low power supply.
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Russel
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Re: And still it keeps on going

Post by Russel »

grsbanks wrote:
Sun May 06, 2018 9:17 am
[...]I was deliberately running the battery down to see how the machine behaved with such a low power supply.
Is 1.90 volts the lowest you have seen? Have you replaced the battery yet? You know what they say about the curiosity and the cat...
rprosperi
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Re: And still it keeps on going

Post by rprosperi »

Russel wrote:
Sun May 06, 2018 8:49 pm
Is 1.90 volts the lowest you have seen? Have you replaced the battery yet? You know what they say about the curiosity and the cat...
So, you're looking to be killed? :?
--bob p

DM42: β00071 & 00282, DM41X: β00071 & 00656, DM10L: 071/100
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