[Test-Equipment] "Conductance" battery checker

[rbethman]

That being the case, you will have to determine the cost benefit ratio 
with regard to the purchase of the instrument.

My use of Gel Cells, (SLA), in my UPSs is limited in scope.  Therefore, 
once again, I use load testing to determine capacity, or remaining charge.

I tend to be inherently "frugal" when stocking my test equipment.

My UPS use is to ONLY automatically shutdown my desktop PC in the event 
of power loss.

Bob - N0DGN

On 3/16/2011 3:42 PM, Raymond LaRue wrote:
> My application is for SLA batteries, specifically 12 V 7.2 Amp,
> typically used in UPS apps at less than 3KVA.
> Ray, W4BYG
>
> -----Original Message-----
> From: test-equipment-bounces at mailman.qth.net
> [mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of rbethman
> Sent: Wednesday, March 16, 2011 3:13 PM
> To: Discussion of Electronic Test Equipment
> Cc: Grant, Ken
> Subject: Re: [Test-Equipment] "Conductance" battery checker
>
> This paper refers specifically to "lead acid" batteries.
>
> !) I do NOT know if this is the type of batteries or cells being
> discussed.
>
> 2) My specific usage referred to NiCads, and their testing for
> capacity.  I test them from initial purchase, and keep records to
> understand their *state* after use to determine whether or NOT to take
> them out of use.
>
> I do NOT know the TYPE of battery being considered for "conductance"
> testing.
>
> This *could* be apples vs. oranges.
>
> Bob - N0DGN
>
> On 3/16/2011 2:50 PM, Grant, Ken wrote:
>> Hi guys,
>>
>> Have a read of this paper:
>>
> http://www.lordconsulting.com/images/stories/TechnicalPapers/Battery-Man
> agem
>> ent.pdf . It describes evaluating a battery's condition by measuring
> its
>> internal impedance and comparing it to the value of a fresh battery.
> There
>> are several inexpensive testers available that use this principal.
>>
>>    Usually, you measure Zint by applying a constant alternating current
>> (around 1 KHz) to the battery and measuring the resultant AC voltage
> drop.
>> Zint is then E / I. Conductance (if you wish to think in a less
> intuitive
>> way), is then 1 / Zint.
>>
>>    Pay special attention to graph #3. It shows that when Zint is about
> 150% of
>> its initial value, the battery is at 80% capacity and 'heading south'
> real
>> quick.
>>
>> Ken, VE3FIT