Going From (2) 12V to (4) 6V Batteries

[98Dynasty]

Is this the proper wiring diagram for (4) 6V batteries? I am feeding a 2800 Watt PSW inverter with 4/0 DC cables. What size battery interconnect cables should I use?

[MisterT]

yes, the diagram is proper for parallel/series(the 4 in the middle)

this takes two 6v batteries and makes them a '12v battery',
and then the two '12v' units together double the amp hour capacity of each set, let's say from 100amphrs to 200. Now, since you effectively only run your batteries down to 50% during usage, you actually continue to have 12v at 100amp hours of usable battery storage.

these deep-cycle 6v batteries, wired together for 12v output, can provide a much 'deeper' usage of power over a long period of time, versus the 'normal' 12v 'starter type' batteries that are more designed for 'sudden' usage, such as starting a motor.

as for wire SIZES, this will be dependent on your 'lengths' ... do a quick search online and it will probably easily be found.

[Skip426]

The 4 , 6 volt battery " series/parallel is the one your after.

Because the battery bank also doubles for engine start up when using the boost ( emergency start ) switch , you want to at least match the size of cable from the chassis batteries to the starter, for all cables in the interconnect system
Inverter install instructions should have its own spec for inline fuse and cable size for the run from the batteries to the inverter.

[98Dynasty]

According to this chart I can use as little as 6 gauge cable for the jumpers that will be all less than 8 inches. Does not seem to be a very good idea. I was thinking 2/0. Is this overkill?

[twinboat]

Originally Posted by 98Dynasty

According to this chart I can use as little as 6 gauge cable for the jumpers that will be all less than 8 inches. Does not seem to be a very good idea. I was thinking 2/0. Is this overkill?

If your running 4-0 to the inverter, which sounds about right for a 2000 + watt inverter, it makes sense to use 2-0 for the interconnect.

A 2% voltage drop at 12 volts is almost 2 volts. Your inverter will shut down at any voltage below about 10.5 volts.

[Skip426]

Originally Posted by twinboat

If your running 4-0 to the inverter, which sounds about right for a 2000 + watt inverter, it makes sense to use 2-0 for the interconnect.

A 2% voltage drop at 12 volts is almost 2 volts. Your inverter will shut down at any voltage below about 10.5 volts.

Math check 2% of 12 = 0.24

[traveler999]

I don't think you can use a percentage for calculate voltage drop in a wire. It is a function of the current being drawn and the resistance of the wire. If for instance you have a 1200 watt Microwave, you would have to pull approx 100 amps @ 12volts to get the 1200 watts. At 100 amps using # 4 which has a resistance of .25 Ohms/1000 feet, a 10 ft run would drop 0.25 volts. (0.25/1000 Resistance per foot) X 100 amps X 10 feet = a voltage drop of 0.25 Volts.

[wa8yxm]

Bottom Center marked Series/Parallel

[lonfu]

2/0 only.... 6 volt batts are notorious for voltage drop, so you must use huge cables. Be sure to check the water level in them often because the tend to boil out much faster than 12v batts. 2nd, is be sure to clean the terminals once per year as they tend to oxidize. If you have the space go with 2 8D 12 volt batts instead. Most folks don't so the 6v's are the only choice. The 8D's are amp rated about the same but have more lead and no water problems like the 6v's. Oh, yeah, they cost a little more than 1/2 the 6v's.

[twinboat]

Originally Posted by lonfu

2/0 only.... 6 volt batts are notorious for voltage drop, so you must use huge cables. Be sure to check the water level in them often because the tend to boil out much faster than 12v batts. 2nd, is be sure to clean the terminals once per year as they tend to oxidize. If you have the space go with 2 8D 12 volt batts instead. Most folks don't so the 6v's are the only choice. The 8D's are amp rated about the same but have more lead and no water problems like the 6v's. Oh, yeah, they cost a little more than 1/2 the 6v's.

Since 2, 6 volt batteries in series, create a 6 cell, 12 volt battery and are charged by the same charging system as a 12 volt battery, there is no truth to them boiling out faster.

All flooded battery terminals can oxidize. 2 volt, 6 volt, 8 and 12 volt.

My pair of 6 volt flooded batteries are in a compartment since 2014. Added water twice and have yet to clean the terminals.

That is probably because I replaced the 1999 converter with a smart, 4 stage charger.

Most 8 D batteries are not true deep cycle, but a hybrid battery used for commercial applications. That why you don't see them in golf cars.

[vito.a]

Originally Posted by lonfu

2/0 only.... 6 volt batts are notorious for voltage drop, so you must use huge cables. Be sure to check the water level in them often because the tend to boil out much faster than 12v batts. 2nd, is be sure to clean the terminals once per year as they tend to oxidize. If you have the space go with 2 8D 12 volt batts instead. Most folks don't so the 6v's are the only choice. The 8D's are amp rated about the same but have more lead and no water problems like the 6v's. Oh, yeah, they cost a little more than 1/2 the 6v's.

I strongly disagree. Our Windsor came with two 8D 12-volt house batteries and they would last about 2 years. After some research, I changed it to four 6-volt golf cart batteries. The golf cart batteries lasted a min of 5 years and the last set of Trojan T-105's are going on 10 years now.
Our Executive also came with four 8D house batteries and they didn't even last 2 years. I changed it to eight Trojan T-105's and all was well. I usually gage how good the batteries are based on how long I can run the residential refrigerator on the inverter and batteries. The Trojan T-105 batteries will go at least a day or 2 longer than the 8D batteries.

[smallies]

Can be so kind as to tell me the length of wire needed between Trojan 105's, trying to save pennies.

[vito.a]

Originally Posted by smallies

Can be so kind as to tell me the length of wire needed between Trojan 105's, trying to save pennies.

This is a "That Depends" answer. You need to measure your battery box and then work out the best way to fit four GC2 golf cart batteries so the + and - on two adjacent batteries is as close as possible. The jumpers will go from positive on one battery to negative the other battery on each of the two 6v pairs.
Another factor is how long your main house battery cables are and where they will reach on the battery pack.
After all that, usually a jumper from 10-20" long is about right.

[smallies]

Since we're guessing here mine's 8 inches and 13 inches.