1999 Volvo Penta "WT" Models Workshop Manual, Page 389Get this manual
Battery gas is explosive! While charging or discharging, remember Never yank cables off battery postsit's sure way to make lots of sparks.surrounded by battery gas
No Smoking No Flames No Sparks
Don't check battery condition by placing metal objects across postsYou're sure to make sparks and serious burns are possible
After ChargingShut off charger Remove charger plug from wall socket ThenTake charger cable off battery posts
Gasoline! Handle With Care