28142 Rev 15 TROUBLESHOOTING
Gentherm Global Power Technologies Page 71
The power unit normally requires no maintenance. If after maintaining and adjusting all other
systems the TEG does not produce expected power, consider examining the power unit. Use
the procedures below to help determine if the power unit could be damaged.
Check the Internal Resistance
Follow these steps to check the power unit’s internal resistance:
Start the TEG.
Move the jumper clip to the SETUP position, between terminals 2 and 3 of TB-1.
Connect a voltmeter between terminals 2 (+) and 4 (-).
NOTE:
Alternative resistor values are acceptable so long as the resistance is close to
1 Ω and accuracy class better than ± 1%.
Wait for the TEG to reach nominal operating temperature, providing a stable voltage
measurement on the voltmeter. Allow 1 hour if the TEG was just started from cold.
Measure V
set
and record the voltage seen on the voltmeter.
While observing the voltmeter display, remove the jumper clip (creating an open
circuit condition) and note the momentary voltage. On a digital multimeter this will
be the first number displayed after removing the clip, usually within 2 seconds of
removing the clip. Record the number as the momentary open circuit voltage (V
oc
). If
this was not recorded quickly enough replace the jumper clip and repeat above steps.
NOTE:
When the jumper clip is suddenly removed the measured voltage leaps up to
a value, known as the momentary open circuit voltage (V
oc
). Measured voltage
continues to climb gradually after this.
WARNING!
Do not allow V
oc
to exceed 29 V,
could be permanently damaged.
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