4.10 Applying the DC Bias Voltage
4-48 ZM2376
• If an error message "DC Bias unbalance" is displayed
Remove the battery immediately and check the polarity and electromotive
force.
This message is displayed instead of the measured value when the auto balance
failed. When the measurement failed, check the polarity and electromotive force
of the battery. When leaving the actual electromotive force and the DC bias
voltage differ significantly, a large current may continue flowing to deteriorate
ZM2376 and the battery.
As with the battery, a charged EDLC (Electric double layer capacitor) with big capacity can be
measured.
When the internal registance is significantly high, the auto DC balance may not work properly. In this
case, disable the auto DC balance function and adjust the DC bias voltage manually.
When many batteries are measured with a higher measurement speed, disable the auto DC balance
function and match the DC bias voltage and electromotive force as exactly as possible. If an exact
match is difficult, take the following actions.
Increase the measurement signal level.
This increases the margin to the unbalanced voltage.
However, the available max electromotive force (= DC bias voltage) is restricted.
Make the output impedance 25Ω or more.
This can decrease the charge-discharging current compared to 6Ω.
Note that the variation may become large when measuring low impedance.
Fix to a measurement range for a larger current.
However, the measurement accuracy becomes lower.
Enables the auto DC cancel function.
It makes low impedance easier to measure.
Although the measurement becomes slow, it can save time for the auto DC balance.
For a battery whose electromotive force exceeds 5V, measure it in the same way as “ Figure 4-9
Example of external voltage bias circuit”. Usually, DC blocking capacitors C1 and C2 are charged
from the battery, external voltage source is not needed. If you do not want to take off the load current
from the battery or you want to save charge-/discharging time, charge C1 and C2 to the electromotive
force of the battery by an external voltage source in advance. You can reduce the load of the battery
by removing the external voltage source or increasing the resistance value R1 for
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