battery on both provide 24 volts....... this will burn your starter motor, and the 80amp fuseible link holds that amp and current back from your harness, until it melts.
There are two basic ways to wire multiple batteries together, in "Parallel" or in "Series".
Wiring two batteries which have the same output voltage in "Parallel", the output voltage of the combination stays the same but the amp/hour capacity of the combination is equal to the sum of their individual amp/hour capacities.
Wiring: Battery 1 Positive to Battery 2 Positive and Battery 1 Negative to Battery 2 Negative is Parallel wiring, retaining the voltage rating of either one of the batteries.
It is not a good idea to wire two batteries which have different voltage ratings in parallel because the one with the higher voltage will immediately send current to the other one with the lower voltage to try to make their voltages both the same. The very high current which will flow between the two batteries is likely to make the batteries get very hot. IF THEY ARE CAR BATTERIES THEY COULD EXPLODE!
Wiring two batteries which have the same output voltage in "Series" makes their combined output voltage equal to the sum of their individual voltages but the amp/hour capacity of the combination will be no greater than the amp/hour capacity of the smallest battery of the two.
Wiring: Bat 1 Positive to Load, and Bat 1 Negative to Bat 2 Positive, then Bat 2 Negative to the other side of the Load is Series wiring and the total voltage of the combined batteries is the sum of both individual voltage ratings.
So, assuming you want to get 24 volts out of two similar batteries, you could wire two 12 volt batteries in series.
NEVER OPERATE A 12 VOLT ELECTRICAL SYSTEM as in CARS or most BOATS with 24 VOLTS. YOU WILL BURN UP YOUR COMPONENTS AND SOME WIRING.
Common Flashlights are simple examples of series wiring. Flashlight batteries are usually 1.5 volts whether they are AAA, AA, C or D size. So flashlights with with 1 battery are operating at 1.5 volts, 2 batteries are 3 volts, 3 batteries are 4.5 volts, etc.
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