6v versus 12v

[Beau388]

Originally Posted by Chateau29Z

Whatever you do with the batteries DON'T WIRE THEM IN PARALLEL!!!!
Parallel wiring sets them up for a current loop which will allow the weakest cell to discharge the strong ones. Series wiring doesn't have this feature and while one cell may be weaker than others it can't be part of a current loop unless you are using the equipment in the RV. Then the equipment is part of the current loop.

In all lead batteries, the maximum supplied voltage per cell is 2.15 volt @ 70 F degrees. The minimum charging voltage for individual cells is 2.23 volts @70 degrees. Weak vs strong cells deals with amperage delivery and not with voltage, so how a a weak cell requiring 2.23 volts to charge, discharge a cell supplying 2.15 volts? Now if an individual cell is shorted, it will discharge all good cells in the circuit (parallel or series).

[ducksface]

If what anyone here says counter to what is fact, let's take it to another level to disprove their stance.

If two 6v batteries were better, why isn't six 2v batteries even better than two 6v and why aren't you running them or supporting their use?

Sometimes things need taken to cartoonish levels to expose hanna-barbera types of thinking.


OH, wait...
We're now back to as beau has said Again because some here refused to read it the first time:
Those are 2v(for easy math) CELLS put into 12v or 6v or 24v or 36v or 48v BATTERY.

BATTERY MEANS A NUMBER OF THE Same THINGS, GATHERED AS A GROUP TO ACT AS A WHOLE.

It does not mean a magical concoction of 2x6=12 but 3x6=19.

[Chance]

Actually, 2-Volt batteries make a lot of sense under the right conditions. There’s a reason they are manufactured, even though not normally used in RVs.

If the desired amount of energy storage is rather high, as in very high, and one doesn’t want to have to handle huge batteries weighing 100 pounds or more, then why not.

Of course, that applies only to 12-Volt electrical systems, “AND” if we limit the installation to no more than 2 parallel strings which is recommended by many experts.

With 12V batteries the “recommended” maximum is therefore 2 in parallel, and with 6V batteries a total of 4 (parallel and series), but with 2-Volt batteries, each string is made up of 6 batteries, with a total of 12 batteries possible (while not exceeding 2 strings). For a very high capacity system, having 6 or 12 batteries allows each battery to be lighter. And if flooded, less cells to check water on.

Before lithium became more common, I looked at 2-Volt batteries as the best way to run my air conditioner through the night using AGM batteries. Even if I could break it up into 6 or 12 smaller batteries, total weight was still higher than I was willing to accept. Instead, I purchased a generator and somewhat regret not experimenting with batteries.

[16ACE27]

Originally Posted by ducksface

If what anyone here says counter to what is fact, let's take it to another level to disprove their stance.

If two 6v batteries were better, why isn't six 2v batteries even better than two 6v and why aren't you running them or supporting their use?

Sometimes things need taken to cartoonish levels to expose hanna-barbera types of thinking.


OH, wait...
We're now back to as beau has said Again because some here refused to read it the first time:
Those are 2v(for easy math) CELLS put into 12v or 6v or 24v or 36v or 48v BATTERY.

BATTERY MEANS A NUMBER OF THE Same THINGS, GATHERED AS A GROUP TO ACT AS A WHOLE.

It does not mean a magical concoction of 2x6=12 but 3x6=19.

Actually, submarines use 2 volt batteries as their emergency power source. Each "cell" is a self-contained battery, but the entire battery consists of 128 of these cells wired in series. BTW each cell is bigger than a BIG man.

[taylorbob1]

Originally Posted by Chance

Actually, 2-Volt batteries make a lot of sense under the right conditions. There’s a reason they are manufactured, even though not normally used in RVs.

If the desired amount of energy storage is rather high, as in very high, and one doesn’t want to have to handle huge batteries weighing 100 pounds or more, then why not.

Of course, that applies only to 12-Volt electrical systems, “AND” if we limit the installation to no more than 2 parallel strings which is recommended by many experts.

With 12V batteries the “recommended” maximum is therefore 2 in parallel, and with 6V batteries a total of 4 (parallel and series), but with 2-Volt batteries, each string is made up of 6 batteries, with a total of 12 batteries possible (while not exceeding 2 strings). For a very high capacity system, having 6 or 12 batteries allows each battery to be lighter. And if flooded, less cells to check water on.

Before lithium became more common, I looked at 2-Volt batteries as the best way to run my air conditioner through the night using AGM batteries. Even if I could break it up into 6 or 12 smaller batteries, total weight was still higher than I was willing to accept. Instead, I purchased a generator and somewhat regret not experimenting with batteries.

In American compounds in Cabo San Lucas-Mexico, along the beautiful blue waters of the Sea of Cortez, off the grid, where there is no electricity...many Gringos use a large bank of 2-Volt Trojans with their solar array and 4-10,000 watt inverters.
Very common place in the higher-end homes.

[Chance]

Yes, Trojan and Lifeline make them, as do other manufacturers.

I was looking at needing about 500 pounds of batteries, so 2 X 12V would be 250 pounds each (rule that out immediately), 4 X 6V around 125 pounds each, still a bit difficult to install below floor and not a common size, or 6 X 2V around 85 pounds each, which seemed workable.

When I started called around, finding 2-Volt batteries wasn’t as easy or as inexpensive as 6-Volt batteries (either flooded or AGM), which drove me to evaluate 8 X 6-Volt in series just like a golf cart for a 48-Volt system.

Choices for pure sine 48V inverter/charger in size range I wanted weren’t great a few years ago, and charging 48V battery bank from alternator wasn’t going to be easy either. It was too much work and expense for a camper that was close to being worn out, so I opted for a portable inverter generator as a temporary solution. Plus I can use it for other needs like hurricanes. Batteries would have been more of a challenge, yet a lot of fun to play with.

[The_Breeze]

Originally Posted by Chance

cut...

Of course, that applies only to 12-Volt electrical systems, “AND” if we limit the installation to no more than 2 parallel strings which is recommended by many experts.

cut...

Can you go into that statement a little more. What is two 'strings'? I was going to wire 4 in parallel. Are you suggesting two in parallel, joined at the junction block or jump battery to battery and just one to the junction block?

[Chance]

Originally Posted by The_Breeze

Can you go into that statement a little more. What is two 'strings'? I was going to wire 4 in parallel. Are you suggesting two in parallel, joined at the junction block or jump battery to battery and just one to the junction block?

Whatever you wire in series makes up a string. Therefore, if you use 12V batteries, you can’t wire 2 in series because you’d have 24V, etc. You are therefore limited to 1 X 12V battery being a string.

Likewise, 2 X 6V batteries wired in series makes up a string. And 6 X 2V batteries wired in series also makes up a 12-Volt string.

In a Golf Cart they typically wire 8 X 6-Volt batteries to make a single 48V string.

In doing research, I found most battery “experts” recommend not exceeding 2 strings in parallel. So while it’s possible to wire 4 X 12V batteries all in parallel, it’s not ideal. For example, if one battery goes bad, how would you even know?

One string is simplest, but doesn’t provide redundancy. Two strings is a middle ground. Three or more gets complicated, etc. Anything can work, it’s just about best practices.

[The_Breeze]

Originally Posted by Chance

Whatever you wire in series makes up a string. Therefore, if you use 12V batteries, you can’t wire 2 in series because you’d have 24V, etc. You are therefore limited to 1 X 12V battery being a string.

Likewise, 2 X 6V batteries wired in series makes up a string. And 6 X 2V batteries wired in series also makes up a 12-Volt string.

In a Golf Cart they typically wire 8 X 6-Volt batteries to make a single 48V string.

In doing research, I found most battery “experts” recommend not exceeding 2 strings in parallel. So while it’s possible to wire 4 X 12V batteries all in parallel, it’s not ideal. For example, if one battery goes bad, how would you even know?

One string is simplest, but doesn’t provide redundancy. Two strings is a middle ground. Three or more gets complicated, etc. Anything can work, it’s just about best practices.

So like diagram 'A' or 'B'? Hoping it's 'A'. It just looks better/simpler and/or would it be better to sire the two in series to make two strings of 24V, which I can then feed into a step-down to 12v?

[Beau388]

Originally Posted by Chance

{snip} In a Golf Cart they typically wire 8 X 6-Volt batteries to make a single 48V string.

I think you will find most 48 volt golf carts do not have the space for 8 group GC-2 batteries, but instead use 6 GC-8 batteries
(8 volt) GC-2 and GC-8 are about the same size and weight, but GC-2 has about 225 amp-hrs while a GC-8 has about 165 amp-hours. Now days only the cheapest golf carts use flooded or VRLA batteries. The 54 or 72 volt lithium batteries seem to be the best sellers at least in the E-Z GO brand (Textron). I live in a retirement village where the primary transportation is a golf cart. In fact, we have our own golf cart sales and service person. It is amazing how much technology a E-Z GO Freedom golf cart contains. <https://ezgo.txtsv.com/sites/default/files/_attachments/resource/con-0819_72voltfreedom_ss_82546-g6_0.pdf>

[ducksface]

Those twelve 6v batteries I have are from a 1992 and a 1993 ez-go.
The best ranch vehicles I ever had.
Quiet, torque forever, they were rated at 800lbs and 1000lbs carry capacity, and did.

The 8v battery thing weirded me out the first time I read about them.
That I couldn't easily make 12v from those batteries is one of the major reasons we don't have newer golf carts now instead of the gator and sportsman.