Volvo D11F Operator's Manual And Maintenance Instructions page 85

Maintenance and Service 81
The electrolyte level on maintenance free batteries cannot be checked.
Periodically, the condition and the state-of-charge of each battery should be
checked by a Volvo Truck dealer. Maintenance free batteries DO NOT require
any attention other than keeping them clean and firmly clamped in place in
their respective trays. Keep the cable connections clean and tight. Check the
battery state-of-charge indicators periodically to determine battery condition.
Check for worn cables at every major inspection. Replace worn cables. Check
battery terminals for cracks.
Battery Terminals
When disconnecting battery terminals, always disconnect the ground terminal
first. When reconnecting, always connect the ground terminal last.
Disconnecting battery cables may result in a loss of preset radio controls,
radio programming and require refreshing.
Lighting
Using incorrect bulbs or lamps may result in failures that could lead to a
fire or a vehicle accident caused by improper lighting.
Check all lights on the vehicle daily for proper function. Replace burned out
inserts and bulbs. Replace any broken or cracked side or rear reflectors.
Headlights should be checked for aim at least once per year.