appliance clock running slow

[rtwang]

My 5100 time runs slow and keep falling behind, although it updates OK when it checks NTP server.

If there a backup battery which I need to replace?

[AndyRH]

The battery is used when the system is off. A slow (or fast) clock is because the clocks in PCs are cheaply made, sometimes they do not keep good time. It is not uncommon for a PC clock to be off by seconds each day.
If it is an issue decrease the time between time checks.

[rtwang]

Thank you.

Seems to be losing 1-2 sec per hour.