I was on the Louisiana forum and read a thread started by theygotaeat
he asked the question "I have a set of heated seats from a wrecked vehicle I'm thinking about fabbing up a mount and putting them in my boat any thoughts opinions or has anyone done this before?" I though this was an very interesting question because, we all have this type of question about adding equipment to our boats and the effects that would have on the boat's battery's. I would like to share with you what i share with theygotaeat . I hope this is helpful to someone on this forum.

First you have to check the resistance of the heating element in the seat. Then using ohms law you can calculate the Current(I) drawn if the seat is powered by 12Volts. Once you know the current then you can go on to calculate the power, for example if the resistance(R) of the seat is 100 ohms and is powered by a 12 volts battery then the current would be Current I = (V/R ) = 12/100 = 0.12 Amps or 120 milli Amps.The power drawn would be Power P = (Current^Current*Resistance) = 0.12*0.12*100 = 1.44 Watts. Now lets look at how this would affect your battery on your boat, if you have a 120 Ampere an Hour (AH) using the example above it would take (120/0.12 )= 1000 hours to drain your battery, If you fish 8 hours per day your battery would last for (1000/8) = 125 days providing that the seat is the only device connected to the battery. NOTE:This example is only based
on a seat heating element resistance of 100 ohms @12VDC, If the resistance is less the current drawn will increase along with the power drawn and that would definitely affect your battery drain time.You must check the resistance of the heating element then do the calculation.

Lifrank.