[Test-Equipment] "Conductance" battery checker

[rbethman]

When you obtain a "cell", i.e., AA, AAA, C, or D, you have a "specified" 
voltage and maH charge.

Conductance is the *ability* to allow the flow of current at specified 
voltage.  Therefore, you "must" know the internal resistance to 
determine this.

Determination of the *remaining* charge, requires test "under load".

These are entirely *DIFFERENT* measurements, and provide different 
*characteristics* of THE cell under test.

Bob - N0DGN

On 3/16/2011 12:44 PM, J. Forster wrote:
> The "reference" could be either charge or internal resistance. I'm
> inclined to think the latter. Conductance is the inverse of Resistance.
>
> Think of it as like the ESR of a capacitor.
>
> -John
>
> ============
>
>
>> Bob,
>> Thanks for the response.
>>
>> You may be right, but the information on the Midtronics Power Secure 6/12
>> seems to indicate a "percentage" of charge remaining.
>>
>> I had one here from the local Interstate Batteries office last week.  It
>> displayed xx% of "reference".  The "reference" (therefore I assume full
>> charge), is developed by testing several good batteries first.
>>
>> How they obtain and interpolate that is one of the major questions I have.
>> Ray
>>
>>
>>
>> -----Original Message-----
>> From: rbethman [mailto:rbethman at comcast.net]
>> Sent: Wednesday, March 16, 2011 12:25 PM
>> To: Discussion of Electronic Test Equipment
>> Cc: Raymond LaRue; jfor at quik.com
>> Subject: Re: [Test-Equipment] "Conductance" battery checker
>>
>> "Normally" battery conductance is a measurement of the battery's internal
>> resistance.  NOT the remaining charge.
>>
>> Bob - N0DGN
>>
>> On 3/16/2011 12:06 PM, Raymond LaRue wrote:
>>> I believe the amount of "charge" left in the battery, is what is
>>> measured.
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: test-equipment-bounces at mailman.qth.net
>>> [mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of J.
>>> Forster
>>> Sent: Wednesday, March 16, 2011 11:52 AM
>>> To: Discussion of Electronic Test Equipment
>>> Subject: Re: [Test-Equipment] "Conductance" battery checker
>>>
>>> Do you mean they measure:
>>>
>>> The amount of charge left in a battery (A-H)?
>>> or
>>> The internal resistance of a battery?
>>>
>>> -John
>>>
>>>
>>>
>>>> Looking for information on designing and building a battery
>>>> "conductance" tester.  In an extended web search, I see a couple
>>>> companies that sell small 6 and 12 volt conductance testers.
>>>>
>>>> They apparently inject a small AC voltage into a battery on or off
>>>> line, in a non-intrusive way.  Calibration data is developed by
>>>> profiles from testing good batteries.  The resultant voltage and
>>>> current phase differentials are processed and utilized to give an
>>>> indication of remaining battery capacity.
>>>>
>>>> The commercial testers available are not very expensive, but those
>>>> found on line give little detail about how they operate and they
>>>> appear not to quite meet my needs, as I would like to try this
>>>> technique by composite testing of a series of SLA batteries.
>>>>
>>>> I am prone to try building one if helpful info were available.
>>>>
>>>> Does anyone have any experience with such, or have design info for
>>>> building a battery conductance tester?
>>>>
>>>> Thank you for your attention.
>>>> 73,
>>>> Ray, W4BYG
>>>> Cleveland, TN
>>>>
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>> |               AM Amateur Radio Operator    NØDGN                 |
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>> | Bob Bethman                \\\|///     " The absence of a danger |
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>
>

-- 
+------------------------------------------------------------------+
|               AM Amateur Radio Operator    NØDGN                 |
+------------------------------------------------------------------+
|               http://home.comcast.net/~rbethman/                 |
+------------------------------------------------------------------+
| Bob Bethman                \\\|///     " The absence of a danger |
|                           \\ ~ ~ //      signal does *NOT* mean  |
| rbethman at comcast.net      (/ @ @ /)      that everything is OK " |
+----------------------o00o---°(_)°---o00o-------------------------+