CR1632 Lithium Coin Battery voltage question

Discussion in 'General Electronics Chat' started by Tonyr1084, Apr 14, 2016.

  1. Tonyr1084

    Thread Starter Active Member

    Sep 24, 2015
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    I have a CR1632 battery for the remote keyless entry into my car. In fact, I have two remotes. My wife has one and I have the other. Only one is working reliably and I don't want to pull that one apart just to take a voltage reading.

    The battery is a "3V" battery. On my workbench it tests out at 2.93 volts (unloaded). I have no idea if that's a good voltage or not. And I would like to know a good way to test it for its capacity (or state of charge). I once had an 80 volt battery that was claimed to be dead by a college professor. It read 80 volts, so I thought it must still be useful. In fact, it was still useful. It was able to power a red LED WITHOUT USING A RESISTOR. 80 volts? Sure. SOC? Well, I learned it was a dead battery in deed. Capable of being used as a christmas light tester via the LED. So I have much to learn about batteries (apparently).

    How can I test it properly?

    Yes, I know they're cheap. But I NEED to know. If for no other reason, I just need to know for the sake of knowledge.

    Thanks guys and girls (though I don't think I've seen any girls here yet - at least not that I'm aware of).
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
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    In general, batteries should be tested with a load. Energizer uses 15K in their datasheet.
     
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  3. Tonyr1084

    Thread Starter Active Member

    Sep 24, 2015
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    Thanks. I found the Energizer data sheet (DS) for this battery, though the one I have is Rayovac. Still, using the characteristics listed on the Energizer DS using 400Ω (actually used a 470Ω) the voltage drops below 2 volts (1.7v using the 2 second pulse test).

    OK, thanks. I'm convinced that the reason why the keyless won't work is because the battery is dun plain nacard!

    Still, if anyone has any battery testing recommendations I'd love to hear them.

    Thanks again.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Once you get a fresh one, I'd check it by the same test. I agree that a drop to 1.7V is suspicious but in my opinion it's not an absolute smoking gun.
     
  5. Roderick Young

    Member

    Feb 22, 2015
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    Probably not supposed to do this, but if I suspect a battery is dead, I try it on the 10A scale of my multimeter. The AA size of a NiMH will give me 5-8 amps if it's good, less if marginal, and nil if dead. Smaller coin cells have built-in current limiting, so I might use the 200 mA scale, and consider anything over a few mA to be good. 2032 cells do not have a limit - I don't know about 1632.

    My first test is on the voltage setting of course, as you did. Anything below 3.0 volts for a lithium battery I would presume to be bad, then follow up with the current test.
     
  6. Tonyr1084

    Thread Starter Active Member

    Sep 24, 2015
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    New battery tested at 3.3v unloaded, 3.0 loaded. Load = 470Ω. (6.4 mA)

    Rod; I agree, probably shouldn't try dead shorting. I would guess (I said "Guess") that if a AA battery is rated for 2 amps then I'd calculate the load at its nominal voltage and use that. Still, I wouldn't know what that was telling me, other than a load should be 0.75Ω. Testing at that low resistance is NEARLY a short, but just what would I read? I haven't a clue.

    A double A battery on a 470Ω load tested at 1.56 volts. Unloaded it was 1.6. That doesn't tell me very much. Guess I still have lots to learn about batteries.

    But thanks for the input.

    [edit]
    Incidentally, dead shorting a AA battery produced 750 mA. That's a new battery right out of the box.
     
    Last edited: Apr 14, 2016
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    You're comparing apples to oranges. A typical AA battery will have 10X the capacity of a CR1632, so the load test resistance should be correspondingly smaller. The end of life voltage for CR1632 is 2V, for an alkaline AA it's 0.8V. End of life voltage may not be relevant. What matters is the minimum voltage required for proper operation by the device being powered.
     
  8. #12

    Expert

    Nov 30, 2010
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    I test coin cells at 1 ma, which is a pretty big load compared to the microamps they generally deliver to the cmos memory in a computer.
    Anything else that will fit in my pocket, 10 ma.
    Car batteries? Turn the headlights on.
     
  9. wayneh

    Expert

    Sep 9, 2010
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    And did this fix the remote? (I'm guessing yes.)
     
  10. Tonyr1084

    Thread Starter Active Member

    Sep 24, 2015
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    Yes, it's fixed.

    Thanks.

    And at 1.7 volts (under load test) the doors would not open. I had to use the key to gain access. Then once inside the remote had enough juice for the vehicle to detect. One of those "Push to Start" cars. No ignition key (that I know of) (Wonder what I'd do if the battery completely failed)
     
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  11. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    If it is a Nissan, you put the whole key fob in the little slot to the left of the steering wheel. Other brands have similar features.

    upload_2016-4-14_14-55-1.png
     
  12. Tonyr1084

    Thread Starter Active Member

    Sep 24, 2015
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    Thanks Gopher.

    Found out - no slot for the fob; just step on the brake pedal and hold the fob to the start button. When the car ding's the car can be started. Without your input I wouldn't have searched out how to start the car with a totally dead fob.

    Toyota Venza. Other Toyotas are similar.
     
  13. hp1729

    Well-Known Member

    Nov 23, 2015
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    Re: AA battery
    What kind? Carbon-zinc, "heavy duty", alkaline?
     
  14. crutschow

    Expert

    Mar 14, 2008
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    My observations on single-cell alkalines are that the open circuit voltage is a reasonable indication of their state-of-charge:
    ≥1.5V --at or near full charge
    1.4V-1.5V -- around half charge
    1.2V-1.3V -- not much charge left but enough to run most clocks for several months
    ≤1.1V -- pretty well dead
     
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  15. Tonyr1084

    Thread Starter Active Member

    Sep 24, 2015
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    HEY! Anyone wanna come cut my grass? It stopped raining for a few hours. I wonder what kind of electronics Moses would have taken on his arc? Anyone wanna guess?
     
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