1 volt too many

I've tried running my 5v modem from a 9v battery with a voltage regulator and it didn't work.

I tested the modem directly on the 9v battery, it lit-up, then I think it blew coz there is no more lights at all - oops!

Now, with modem no.2 I've connected it to a 6v latern battery and it works!

QUESTION - Will the 1 extra volt shorten the life of the modem?
If it lasts 1 year instead of 5, thats OK. But if it's gonna last only 2 weeks, that could be a problem.

ronvegas said:

I've tried running my 5v modem from a 9v battery with a voltage regulator and it didn't work.

I tested the modem directly on the 9v battery, it lit-up, then I think it blew coz there is no more lights at all - oops!

Now, with modem no.2 I've connected it to a 6v latern battery and it works!

QUESTION - Will the 1 extra volt shorten the life of the modem?
If it lasts 1 year instead of 5, thats OK. But if it's gonna last only 2 weeks, that could be a problem.

Click to expand...

Well it's never a good idea to exceed a device's rated voltage, but I suspect it will be OK if it hasn't died already. You could just wire a simple diode (1N4001) in series with the positive power wire and that would drop the voltage to around 5.3 or so.

Lefty

Double posting!

Refer to "Voltage regulator or diode"

Either zip it or just rename it to .zip and tell people to change the extension back to what it should be.

3v0 said:

Either zip it or just rename it to .zip and tell people to change the extension back to what it should be.

Click to expand...

The quote above refers to posts I have deleted because of errors in those posts!



Based on a five year life at 5 v, the modem will last 6 weeks at 6 v. See spreadsheet cut-and-paste below:

at 5 volts
121.6 <Enter temp-rise-above-amb values here until the ratio line below shows a ratio of the life at 5v/9v = 5 yrs/1 second (assuming it blew out in 1 second @ 9v)
12.16 = A (dividing temp by 10)
0.000218512 =1/(2^A) because service life halves for each 10 C rise above ambient

at 9 volts
393.984 =calculated rise above ambient = 121.6*[(9/5)^2]
39.3984 = A
1.38007E-12 =1/(2^A)

ratio line 158334455.9 ratio of 5v life to 9v life
5 yrs = 157680000 seconds
close enough

now
at 6 volts
175.104 =calc'd rise above ambient = 121.6*[(6/5)^2]
17.5104 = A
5.35605E-06 =1/(2^A)

40.79724991 =calc'd ratio of 5 to 6
0.024511456 =calc'd ratio of 6 to 5

so at 6 v the modem will last
1.470687366 =calc'd months = .02 * 60 months