The Citizen caliber B877 is a solar powered (Eco Drive) quartz watch movement found in the Promaster Nighthawk family of watches.
Some of the topics covered in this caliber listing:
Citizen claims that the accuracy of the B877 is within +/- 15 seconds per month when the watch is in normal operating temperatures of +5C to +35C (41F to 95F).
The B877 holds a power reserve of up to 6 months on a full charge when the capacitor/battery is storing energy correctly.
B877 Charging Time
The fastest way to fully charge your B877 powered watch is to expose the dial side of the watch to a bright and sunny day for about 9 hours. When doing this, be careful that the sunlight is not too hot or else it can damage the dial. You can try to place your watch on a windowsill which gets full sunlight, in an air conditioned room. Periodically check to make sure the dial is ok and that the watch is not getting too warm.
If you attempt the same as above but on a cloudy day, it can take up to 33 hours. Fully charging under a fluorescent lamp can take 105 hours, and regular interior lighting takes as much as 640 hours (almost 27 days of continuous exposure to the light). The Citizen B877 cannot be overcharged.
Low Battery Indicator
The B877 features a built-in Insufficient Charge Warning Function. When the watch does not have sufficient energy to operate correctly, the seconds hand will jump in a two-second interval for about 3 days. When your watch starts skipping like this, refer to the charging information above to get it back to full charge. If you feel that you have done the appropriate steps to fully charge your watch but the seconds hand is still skipping/jumping, then perhaps your capacitor/battery cell needs replaced.