12v or 6v ?

[jaga]

One more comment,
Two 12v 100ah batteries will weigh roughly the same as two 6v 200ah batteries, and you'd have the same capacity (when the 6v are wired in series to give 12v): 200ah at 12v. Cost can be similar as well. The 6v golf cart batteries are awfully appealing and will likely be my next batteries, but not always the best solution.

[dakno]

Hello..I'm really enjoying my DC 101, when I wrote of 1 batt for engine, 2 batts for house, I WAS THINKING IN TERMS OF 12V, so if there r advantages in going the 6v route I would b doubling # of batts to 6 total. Two for engine, four for the house.

[TexSail]

I would go with the twelves but do you have to do all one or the other? Two sixes in series might work for the house bank plus one twelve volt for a starter.

[jaga]

I agree with TexSail - get on good 12v starting battery for the engine, then either 2 or 4 6v batteries wired to give 12v for your house. I have the latter on Jaga. Whether you get 2 or 4 depends on how much capacity you need. Remember, you don't need 4 6v batteries to have the same capacity as 2 12v batteries. Amp hours are not additive when you wire 6v batteries in series.

[David M]

You don't want a 6 volt system for a couple major reasons. Hardly anything is made that runs on 6 volts compared to 12 volts.

The second reason is that your wires will need to be twice the ampacity in order to carry the same amount of power (watts).

Amps and power are not the same thing. It gets confusing when current is equated to power. The potential difference in volts times current in amps is equal to power in watts.

Power in Watts = Volts x Amps

[GordMay]

Originally Posted by BluesTraveler

http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel
Connecting Batteries in Series or Parallel
Here's an explanation of how to accomplish your task of getting the right combination of 12 volts out of multiple 6 volts batteries.
Happy sparking
Steve

Steve’s link shows an undesirable (but workable) method of paralleling 2 batteries to get increased capacity.

Here’s the preferred Parallel connection.
Note that Positive & Negative connections (either charging input or load output) are to/from different batteries:

[Chief Engineer]

I'm Puzzled.......If those were 6 volt batteris wouldn't the left give you 12 and the right give you 6?

[GordMay]

Originally Posted by Chief Engineer

I'm Puzzled.......If those were 6 volt batteris wouldn't the left give you 12 and the right give you 6?

So you should be - you're absolutely right!
I've corrected my wording to reflect this.
Paralleling 2 batteries doubles capacity.
Series connecting 2 batteries double voltage.

[Tellie]

Keeping in mind series or paralleled wiring, if they are 200amp 6V batteries as first stated in the original post, you'd get 400 amps at 6V or 200 amps at 12V. Remembering you only get to calculate half of those final amps for usage.

[muchmsw]

I've been following this thread with some interest, because replacing my 4D 12 volt battery in my boat is a one of my winter projects.

The boat is a 1998 Beneteau Oceanis 352 with Bene's standard two battery system; 1 12-volt starting battery in the engine compartment and a large house battery in a compartment under the aft berth. In addition to the 50 amp engine alternator, we have a 20 amp shore-power battery charger installed. Both the house and the starting battery have cut-off switches, and IIRC, there's a third switch to isolate both at once.

Attached is a diagram that I found on the web that shows what I'm considering using to replace the house battery. I was thinking about buying 4 6-volt batteries and wiring them to create the equivalent of 2-12 volt batteries. If I understand correctly, this is what most folks do when going with the 6-volt systems.

What is the best way to recharge the 4x6-volt system, then? Do people just treat such a system just like a big 12 volt battery, or are there special considerations? Does anyone have a diagram of how to properly hook up a chargers to a 4x6-volt bank?

Thanks for your help,
Steve

[Trekka]

I have four 6v batteries, divided into two pairs each wired in series as 12v's then those series pairs wired in parallel to make one big bank. I have a separate 12v starting battery.

I'm doing away with the 1-2-All switch. The 12v will just go to the starter. I'm using a Blue Seas 8080 switch panel. House bank is just house, starter is just starter and each has it's own on/off switch - although there is also a switch to put all in parallel in an emergency.

Output of 100A alternator (regulated by Xantrax 3 stage) goes to the house bank, and an echo charger feeds the starter battery up to 15amps from there.

[w42]

Originally Posted by Trekka

I have four 6v batteries, divided into two pairs each wired in series as 12v's then those series pairs wired in parallel to make one big bank. I have a separate 12v starting battery.

Output of 100A alternator (regulated by Xantrax 3 stage) goes to the house bank, and an echo charger feeds the starter battery up to 15amps from there.

We have a nearly identical setup. We used 6v golf carts because they fit the old space nicely. The paralell connection between the 6v can be critical. We found one of the 6v did not discharge as consistently as the other which affected the "appearance" of the whole bank to the charging system. Adding the paralell connection helped.

As others have said, they all should be same type, brand, chemistry and when replaced, ALL should be replaced at the same time.