7 feet between 6 volt batteries in series?
Looking to upgrade to two 6 volts. Can't fit a double box in the area my single 12 volt is. Would it be ok to locate one on one side of the camper and one on the other with the batteries wired in seri...
Forum Discussion
Sure, bigger is better, but let's be reasonable. If we follow the "bigger is better" rule to the letter, we would all be using buss bars between our batteries.
The resistance of a #4 conductor is .2485 ohms PER 1000 FT.
The resistance of a 4/0 conductor is .049 ohms PER 1000 FT.
The OP would be adding approx 14 ft of conductor (one pos, one neg) between his batteries. This is compared to an approx 1 ft. connection between batteries if they are side by side. Therefore, the total resistance of the added #4 conductors would be .003479 ohms and the total resistance of the added 4/0 conductors would be .000686 ohms.
A Trojan T-105 battery can deliver 225 amps for short periods, but that's not the typical current demand in a camper. A more typical draw would be 20 amps for the load the OP has described. So, at 20 amps...
The voltage drop across the #4 at 20 amps would be .06958 volts, and the drop across the 4/0 would be .01372 volts.
The difference between the #4 and the 4/0 cables, at a 20 amp discharge rate, would be .05586 volts, not a significant amount.
This would be the value for discharge. The immediate voltage difference for charging would be much lower since it is at a much lower current.
Lets be practical with the conductor size. The additional cost and difficulty of installation for a 4/0 cable is not worth the return.
The resistance of a #4 conductor is .2485 ohms PER 1000 FT.
The resistance of a 4/0 conductor is .049 ohms PER 1000 FT.
The OP would be adding approx 14 ft of conductor (one pos, one neg) between his batteries. This is compared to an approx 1 ft. connection between batteries if they are side by side. Therefore, the total resistance of the added #4 conductors would be .003479 ohms and the total resistance of the added 4/0 conductors would be .000686 ohms.
A Trojan T-105 battery can deliver 225 amps for short periods, but that's not the typical current demand in a camper. A more typical draw would be 20 amps for the load the OP has described. So, at 20 amps...
The voltage drop across the #4 at 20 amps would be .06958 volts, and the drop across the 4/0 would be .01372 volts.
The difference between the #4 and the 4/0 cables, at a 20 amp discharge rate, would be .05586 volts, not a significant amount.
This would be the value for discharge. The immediate voltage difference for charging would be much lower since it is at a much lower current.
Lets be practical with the conductor size. The additional cost and difficulty of installation for a 4/0 cable is not worth the return.
