La Crosse Technology RS-900 Instruction Manual page 20

By pressing the MODE key within 8 seconds after inserting the rechargeable batteries, the Test
mode can be selected. (The mode key shall first be pressed and held for 1 second to activate
the mode change. The subsequent pressing of the mode key will enable to toggle between the
"Charge", "Discharge", "Test" and "Refresh" mode.)
Note:
After selecting the Test mode, user may select different charging current in the Test
mode by pressing the CURRENT key, within 8 seconds after the batteries are inserted.
The afterward-discharging current will be half of the selected charging current (see Table
3).
52
The Charging
current in (mA)
Test mode