1 Last Battery Question.... I promise

[mike4947]

To throw in a monkey wrench we've done several Saturday bull sessions and practical testing (it helps to have an electrical contractor in the extended camping family that uses his work truck to tow with, so we have all the toys to play with) and you will rarely see 14.4 volts in a vehicle system at least not at the battery. At that voltage you "boil" the electrolyte and it would slowly drain the maintenance free batteries normally found in vehicles. Practical and observed voltage was 13.7 volts.
And voltage does not stay constant throughout the circuit formed from the TV alternator to the trailer battery or other draw. We normally see at a minimum of a 1/2 volt at best and have seen as much as 2 volts on a circuit where they morons never clean the contacts.
Amperage does taper off (but not voltage) after the alternator has recharged the TV battery back at the trailer end of the circuit.
 
Remember TV "starting batteries" are quite different from deep cycle batteries. The starting batteries are designed with thin plates and specific addative to the lead to discharge high amounts of amperage and quickly recharge using high amounts of amperage. After that the TV battery is simply along for the ride and the alternator supply the vehicle needs.
Deep cycle batteries are designed with thicker plates and different addatives in the lead for more slower draws and corresponding slower recharges AND need to be charged at higher voltages than starting batteries to prevent sulfation and to get 100% charged in a reasonable time frame. And why deep cycle batteries have open caps so you can refill the cells due to losing water from the higher voltage and evaporation caused by it "moving" the electrolyte around.
 
And as to the ground wire/path not affecting the resistance, It does. Testing showed it's not exactly double the hot length but close enough to figure what you'll actually see back at the trailer.

[AustinBoston]

Enough of this; it's Memorial Day Weekend for me.   :U

Austin

[wavery]

To throw in a monkey wrench we've done several Saturday bull sessions and practical testing (it helps to have an electrical contractor in the extended camping family that uses his work truck to tow with, so we have all the toys to play with) and you will rarely see 14.4 volts in a vehicle system at least not at the battery. At that voltage you "boil" the electrolyte and it would slowly drain the maintenance free batteries normally found in vehicles. Practical and observed voltage was 13.7 volts.
And voltage does not stay constant throughout the circuit formed from the TV alternator to the trailer battery or other draw. We normally see at a minimum of a 1/2 volt at best and have seen as much as 2 volts on a circuit where they morons never clean the contacts.
Amperage does taper off (but not voltage) after the alternator has recharged the TV battery back at the trailer end of the circuit.
 
Remember TV "starting batteries" are quite different from deep cycle batteries. The starting batteries are designed with thin plates and specific addative to the lead to discharge high amounts of amperage and quickly recharge using high amounts of amperage. After that the TV battery is simply along for the ride and the alternator supply the vehicle needs.
Deep cycle batteries are designed with thicker plates and different addatives in the lead for more slower draws and corresponding slower recharges AND need to be charged at higher voltages than starting batteries to prevent sulfation and to get 100% charged in a reasonable time frame. And why deep cycle batteries have open caps so you can refill the cells due to losing water from the higher voltage and evaporation caused by it "moving" the electrolyte around.
 
And as to the ground wire/path not affecting the resistance, It does. Testing showed it's not exactly double the hot length but close enough to figure what you'll actually see back at the trailer.

Actually, the trick set-up would be to have an inverter in the TV, wired directly to the battery and run a 110v AC line back to a 12A battery charger on the trailer. You would have to shut off the inverter while the engine isn't running though. . You would certainly get to to CG with a full battery and cold fridge. You could even run the fridge off of 110v.

[mach8274]

Actually, the trick set-up would be to have an inverter in the TV, wired directly to the battery and run a 110v AC line back to a 12A battery charger on the trailer. You would have to shut off the inverter while the engine isn't running though. . You would certainly get to to CG with a full battery and cold fridge. You could even run the fridge off of 110v.

I actually have an invertor in my truck. It is powered by the trailer battery while towing and have the cables running in through the bottom of my tail gate. The invertor powers a dorm size fridge full off BEER so that it is cold when I get to the CG. This system works rather well. I will be posting more pictures on my webshots page after our Father's Day campout so you can see it then.