The other day i found myself with an empty battery on my yard man, in fact two empty batteries both of the batteries on my yard man where discharged because someone (me) forgot to turn off the headlights when i had it in the shop. the next day i went to the gas station with my friend to fill up our tractors and it again my batteries werent able to start my engine, if my friend wasnt with me this incident would have sucked, at least we werent in the woods and we had jumper cables. after that i got thinking and i found a way to add an emergancy/backup battery.
i wanted a way to add another battery that would be kept fully charged and isolated from the main batteries but that could be used in conjonction with the other ones to start the engine if the main batteries crapped out. i
the solution is simple i only need two components:
a battery disconect switch
and a diode.
sorry for the horrible looking schematic
any diode that can handle 3 amps and 100 volts or more should be fine.
diode part number that would work:
1n540X ( X being any number fomr 1 to 8 ) <-- this is the stock diode briggs uses on most flatheads