HP Forum Archive 16

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Spice Battery, Chapter 3 Message #1 Posted by Dan Stein on 23 Nov 2006, 2:06 p.m. Thanks again for for the suggestions and comments. I bought a multimeter and now can report more information that may lead to a solution for the quick draining battery in my 37E. When leaving the battery to charge overnight, I receive a respectable 2.6V reading. After removing the AC adapter and turning the calculator on the low battery indicator turns on after three minutes. A few of the LEDs start to dim or flicker at five minutes (isn't this dramatic?). By seven minutes the display is dead. I then check the voltage of the battery and it registers 1.7V. The 37E funtions perfectly on the AC adapter. Other potential information that may be helpful in the diagnosis is the voltage at the cord is 11V and the power at the battery terminals is ~7.2V. This may be unrelated, but I do sense that there is some play in the off/on switch. Your thoughts and suggestions will be greatly appreciated. Dan

Re: Spice Battery, Chapter 3 Message #2 Posted by Charles on 23 Nov 2006, 4:23 p.m., in response to message #1 by Dan Stein Dan, I have had a similar problem when using poorer quality rechargeables on a 67. The problem disappeared when I put in better ones. It seems that not all are the same. There was a discussion on this perhaps 18 months ago. The low battery indicator also shows up on my 33E but doesn't stop the calculator running so I just ignore it.

Re: Spice Battery, Chapter 3 Message #3 Posted by David Smith on 24 Nov 2006, 11:37 a.m., in response to message #1 by Dan Stein Most likely your battery pack is bad. Just charged should be around 2.9V. Try and charge it out of the machine. Also try running the machine on 2 alkaline cells AA (strapped tpgether at the end). Another problem could be bad contacts to the battery or charger or cord. It may only be charging for a few seconds while you wiggle things around. Finally you could have a bad charge circuit (not likely since you measure voltage at the terminals).

Re: Spice Battery, Chapter 3 Message #4 Posted by Palmer O. Hanson, Jr. on 24 Nov 2006, 8:35 p.m., in response to message #1 by Dan Stein Quote: "When leaving the battery to charge overnight, I receive a respectable 2.6V reading. After removing the AC adapter and turning the calculator on the low battery indicator turns on after three minutes. A few of the LEDs start to dim or flicker at five minutes (isn't this dramatic?). By seven minutes the display is dead. I then check the voltage of the battery and it registers 1.7V." This sounds like you might have one cell with an internal short. What are the individual cell voltages when the output is 1.7V? If you have an internal short the battery will lose voltage relatively quickly when it is off the charger but not in the calculator. If you have an internal short a shock of the battery pack may help.

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