Battery Maintenance - Colorado time systems Ultimate Pace Clock User Manual

Colorado Time Systems recommends that you recharge the

Battery Maintenance

internal batteries in the portable UPC-LR or UPC-LED model
displays after each use. To recharge the batteries simply turn
the display OFF and plug in the display to a 115v outlet using
the AC power cable.
Recharge the batteries overnight to obtain the optimal charge.
Do not leave the portable displays plugged in for more than
eight consecutive days.
Reference 4-5