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Therefore you need to use a special device
(device set) for measured discharge with the character-
istics not worse then following: discharge current stabil-
ization (error < 3 %) or discharge current registration
(error < 1 %, sampling rate < 1 minute); automatic cut
off with cut off voltage 10.5 V; automatic discharge time
registration (error < 1 %).
To get the most accurate result keep the battery
under room temperature for time needed for temperat-
ure equalizing.
Charge battery in full and keep it under float
charge at least for 24 hours. Disconnect battery from
the charger and from any loads. After 20-30 minutes (or
later) connect Qulon-12ns (adjusted for work with K=1)
to the battery (see section 3.2). Write down the estim-
ated capacity E
0
.
Connect the battery to your device for measured
discharge. Set the discharge current to receive dis-
charge time about 15-20 hours and cut-off voltage 10.5
V. Switch discharge on. After battery is cut off write
down the discharge time and calculate battery capacity
using one of two formulas:
a) for device set with stabilized current:
E
m
= I * T ,
(1)
where: E
m
– measured capacity, A*h; I – sta-
bilized discharge current, amperes; T – discharge
time, hours.
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b) for device set with current registration:
E
m
=
∫
0
T
I
t
dt
,
(2)
where: E
m
– measured capacity, A*h; I(t) – cur-
rent, changing in time, amperes; t – time; T – full dis-
charge time, hours.
Calculate calibration coefficient for your battery
according to formula:
К = E
m
/E
0
Coefficient error could be reduced if you make
measured discharge for several batteries of the same
type and take the average coefficient for the group of
batteries.
8.3. Method of average
The method of average is used if making meas-
ured discharge is impossible or inconvenient. This
method is based on the assumption, that batteries to be
tested are part of some group (for example, intended for
connection in the battery system or already connected
in the battery system) and on the average have known
capacity (in the elementary case - nominal capacity).
This method is recommended for use with the new or
poorly worn out batteries.
Connect Qulon-12ns (with K=1) to each battery
of the group and write down the estimated capacity.
Calculate the average estimated capacity for the group
E
av,
then calculate calibration coefficient for your battery