[Test-Equipment] "Conductance" battery checker

[Raymond LaRue]

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
>
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