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Frequently Asked Questions
Got a Question?
Battery Discharge Indicators I
Electromechanical I
DC Contactors I
Timing & Counting I Motor Controllers
I just installed a new battery gage. The gage indicates “full
battery”, but I know that this battery has been in use for several
hours, and the battery capacity is much lower than “full”. Why does the
gage show Full?
A new gage installed for the first time will read “Full” (the final step
of our Quality Control procedure is to reset the gage to full). As
vehicle use begins, the energy from the battery is used, and the gage
will move quickly through its steps to “catch up” with the true battery
capacity. The process of the gage dropping from full to empty will take
at least ½ hour on a loaded battery. |
How does the instrument measure the discharge of the battery?
The instrument measures the Voltage under Load below a ‘reference”. As
the vehicle is operated, the load on the battery causes the voltage to
drop below this reference level. The gage will accumulate the time the
voltage is below the reference. When the voltage is below the reference
for a sufficient period of time, the gage will reset its timer, lower
it’s reference, and indicate a lower state-of-charge. This process is
repeated until the gage reaches “empty”. If the load is removed from the
battery, the voltage will rise above the reference, the timer will stop,
and the gage will continue to indicate the current state-of-charge. This
technique of voltage-time integration to calculate the battery
state-of-charge is far more accurate than using a simple voltmeter. |
Why is it important that the wire from “Battery Plus” connects to
the first positive vehicle connection (before all switches and fuses),
and the “Battery Minus” wire connects to the first negative vehicle
connection ?
Every wire has a resistance, which will produce an additional voltage
drop when there is a load on the battery. The intent is for the
instrument to measure the drop in voltage (under load) of the battery.
If there is an additional resistance (extra wire, keyswitch ,etc) that
causes an additional drop in voltage, the instrument will behave as if
the battery voltage is dropping lower than it really is, and the gage
will show “empty” before the battery is “empty” Voltage under load
measured at the battery, should be within 1% of the voltage at the
instrument terminals B+ and B-". Example: a load on a 24 volt battery
causes a voltage reading of 22.6 volts when measured at the Battery
Terminals. The same load, when measured at the B+ and B- terminals of
the instrument, is 22.2 volts. (a .4 volt difference. .4 divided by 22.6
= approx. 2 %. This is not an acceptable installation. |
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