GR-8018U Dead Reckoning Calibration Not Retained After Long Power-Off Period
A customer reported that after completing Dead Reckoning calibration on the GR-8018U, the calibration appears to be retained only for a short time.
If the receiver is unplugged briefly, Dead Reckoning resumes normally after reconnecting. However, if the receiver is disconnected for around 12 hours or longer, it may perform a cold restart and the Dead Reckoning calibration may be lost. After GNSS fix is restored, the heading and position may not be stable until the calibration is performed again.
The customer asked whether there is a procedure to permanently save the Dead Reckoning calibration, or whether this is the intended operating behavior.
The GR-8018U uses an internal rechargeable backup battery to help retain certain data while the device is powered off. According to the MS621 Li-ion battery data sheet used for the GR-8018, the battery voltage can reach up to approximately 3V when fully charged.
Based on testing from Navisys, the backup battery voltage gradually decreases after the device is disconnected from power:
|
Period After Full Charge |
Battery Voltage |
|---|---|
|
0 hours |
3.0V |
|
48 hours |
2.529V |
|
73 hours |
2.4V |
|
104 hours |
2.2V |
|
119 hours |
1.63V |
If the backup battery is not sufficiently charged, or if the device is left disconnected for a longer period, the receiver may not retain the previous Dead Reckoning calibration data and may require recalibration.
Before use, please make sure the GR-8018U has been fully powered and the internal backup battery is sufficiently charged. If the device has been unplugged for an extended period, it may be necessary to allow it to operate again and repeat the Dead Reckoning calibration.
In short, this behavior is related to the backup battery and power retention. There is no separate manual “save calibration” procedure provided. Keeping the internal backup battery fully charged helps the receiver retain data for a longer period while disconnected.
how long do you recommend powering the GR-8018 to fully charge the internal backup battery?
The answer is overnight charging.