There are instruments that checks the battery impedance on the market
two versions one is made by hoki industries and sold by yuasa (the
cheepect one) Yuasa YP1 and the Midtronics celleron both info is on the
net. Both of these inject ac into the battery and check its impedance at
particular frequencys look at the midtronics web site the patents
(expired and current) are there.

However for a given load the dip voltage at the same time is directly
proportional to the capacity of the battery providid that you can
establish that the state of charge is similar and that they are at the
same temprature. You also have to establish that the surface charge is
overcome whilst taking measurement from battries just off charge.


Or there is the quick and dirty method
Apply a large load and check the dip voltage is greater than 1.6vpc
after 10 seconds (similar to garage testers for car battries)not very
accurate across a range of battries

Regardz Steve...

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Rod Phillips
Sent: 21 December 2002 13:06
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE:] Qualify Sealed Lead Acid batterys.


Hello to all,

I'm interested in qualifying SLA batteries of various ampere hour
ratings up to a maximum of 35AH.  Is there a formula or rule of thumb
relating test current, AH rating, time and voltage across the battery
under test?  Thanks in advance for your help.

                                         Rod

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