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SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS
reply to Subaru

Re: Electronics that stop working when cold

said by Subaru:

has will not come on until it's warmed up above 20-26 F

Got the same problem with my body.

Here's Maxell's battery, not too much variation with temp.




As Tom said it's a good chance it's the LCD
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"Facts do not cease to exist because they are ignored." - Aldous Huxley


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

said by SparkChaser:

Here's Maxell's battery, not too much variation with temp.

That chart is at 0c

0c is not an issue.

My iphone's battery went from 100% to 0% sometime during the 6 hours I left it in my car at -20C


cowboyro
Premium
join:2000-10-11
Shelton, CT

said by alkizmo:

That chart is at 0c

Goes to -10C (14F).
I'll do a test just because I can and I'll post the results.


cowboyro
Premium
join:2000-10-11
Shelton, CT

Took a 2032 cell. From room temperature to -5F in the freezer and back to room temperature the voltage was between 3.33 and 3.34V (more precisely 3.332 and 3.342). There was an initial jump in voltage after putting the battery in the freezer that lasted about 10min, the the voltage decreased to 3.336-3.338V. After bringing it back to room temperature the voltage stabilized again to ~3.332V.
BORING....



Cho Baka
Premium,MVM
join:2000-11-23
there
kudos:2

That was an unloaded voltage?



cowboyro
Premium
join:2000-10-11
Shelton, CT

Yes, no load...


sergey3

join:2004-08-25

said by cowboyro:

Yes, no load...

Batteries produce electricity using a chemical reaction. When it is cold, the reaction slows down. This means that with no load the voltage will be mostly unchanged. But under load the battery will produce less power (fewer amps). I don't have enough experience to say how much less power to expect. But I have heard of cars in cold climates having an additional car battery because one battery might not be enough to start a car in very cold climates.

The same logic would say that adding an additional battery might be helpful. But realistically it might be easier to leave the electronic gauge at home and take it out for only a few minutes.


SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS
reply to alkizmo

said by alkizmo:

That chart is at 0c

The chart is from 60 to -10C @ 15K load LiMnO2 chemistry

I have a LiPo cell sending me temp data from the front of the house and it's -8C outside. I've had it in the freezer for over 24 hrs @ -16C and sending data.

I have no experience with iPhones.
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"Facts do not cease to exist because they are ignored." - Aldous Huxley


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to sergey3

said by sergey3:

But under load the battery will produce less power (fewer amps).

That without doubt. But then the power requirement of a pressure gauge isn't that big to start with...


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
Reviews:
·Frontier Communi..

said by cowboyro:

said by sergey3:

But under load the battery will produce less power (fewer amps).

That without doubt. But then the power requirement of a pressure gauge isn't that big to start with...

But that extra resistance may decrease the output voltage enough to cause the gauge to malfunction. I had a similar issue (and I did my own troubleshooting to find the culprit -- Subaru, that's a hint for you ) where the battery played an important role. See: »Highest voltage 2032 battery

Of course in my case the root cause was an improperly designed circuit that required 3+ volts to function properly instead of going down to 2.6 - 2.7V.
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Wacky Races 2012!


cowboyro
Premium
join:2000-10-11
Shelton, CT

said by aurgathor:

But that extra resistance may decrease the output voltage enough to cause the gauge to malfunction.

I'm still willing to bet on either LCD or the gauge refusing to work outside a temperature calibration range.
But I guess the voltage drop is something that I can easily test...

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to aurgathor

said by aurgathor:

Of course in my case the root cause was an improperly designed circuit that required 3+ volts to function properly instead of going down to 2.6 - 2.7V.

Typical "3V" CMOS chips are actually designed to accept VCC = 3.3V +/- 0.3V. So the lower end of acceptable VCC is actually 3V which may be higher than a partially discharged CR2032 battery.

Now, the current drawn by all CMOS chips increase with lower temperature, so VCC could go down even more than acceptable range.

Solution is a buck-boost DC-DC converter IC to supply stable 3.3V from a single CR2032 cell. But that of course will cost an extra buck or two.


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
Reviews:
·Frontier Communi..

said by lutful:

Typical "3V" CMOS chips are actually designed to accept VCC = 3.3V +/- 0.3V. So the lower end of acceptable VCC is actually 3V which may be higher than a partially discharged CR2032 battery.

So in this particular use, they should be using a custom CMOS circuit designed to work with 3.0V +/- 0.3V, which more closely matches the CR2032.

I guess I need to take apart my gauge to see what's in it.

Solution is a buck-boost DC-DC converter IC to supply stable 3.3V from a single CR2032 cell. But that of course will cost an extra buck or two.

And would also decrease efficiency.
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Wacky Races 2012!