How to wire battery bank for 24V with 6 12V batteries and Vanner?

[belfert]

I am looking to buy six 12 volt batteries for a 24 volt house battery bank.  I also have a Vanner Equalizer to center tap the battery bank for 12 volt.  The ideal battery bank would probably be three strings of two batteries in parallel.  I can't see this working for the Vanner.

Do I have to parallel three batteries each to make two large 12 volt batteries and then place those in series to work with the Vanner?  Is there a better way?

[Stan]

The Vanner doesn't care which way you do it. The cleanest way is two rows of three jumpered at one end and taking 24 volts of the the other two ends

[belfert]

I don't quite understand how it would work with three parallel strings.  Would I also have to connect all three strings in the middle for a center tap to get 12 volts?  I might have to draw something up in Paint or something to show what I am thinking.

[Stan]

This would be easy if I could just draw a picture and put it on the board. To make it simpler, just think of using three batteries.
If you take two of the batteries and connect a positive to a negative, you can use the remaining two terminals for 24 volts.
When you connect a Vanner to the common jumper for 12 volts and the other two terminals for 24 volts, the Vanner will draw current from the 24 volt battery to keep the batteries in balance when you draw current at 12 volts.

If you now connect an additional battery with the positive to the common point and the negative to ground, you have increased the maximum current draw possible at 12 volts and the Vanner will continue to draw from the single 24 volt battery to keep everything in balance.

If you have a 60 amp Vanner, that means that yu can draw up to 60 amps of 12 volts and the Vanner will maintain balance. However, there is nothing stopping you from drawing 100 amps at 12 volts but in that situation the 12 volt battery voltage will be dropping and will not be in balance until you reduce the draw below 60 amps and allow the Vanner to bring it back to balance.

Does this explain it?

[Sean]

Brian,

To keep the cycles on all your batteries equal, you need to do three batteries in parallel, then series that with the other three batteries in parallel.  You can't do three series pairs in parallel and still get (1) the full benefit of the equalizer and (2) equal use of all batteries.

-Sean
http://ourodyssey.blogspot.com

[Len Silva]

Does this help?

[H3Jim]

And remember that you can also just use the Vanner as a voltage splitter, or just buy a voltage splitter (much cheaper) and use that.  I bought my Vanner before I had figured out all my runs and usage.  I have it hooked up to 24 volts only, and do not have it center tapped at all.  I use it to run all my 12 volt loads.  Probably better for the batteries anyway to not use 12 volts from a center tap.

Since I bought all my batteries at the same time, they are all identical, I don't use any power from the middle of the string, I don't really have a reason to try to make sure they are equalized.  I use only 24 volts, I charge only 24 volts so the bottom battery in each string does not recieve any different treatment than the top battery in each string. I have 6, 12 volt batteries, in series paralell. 3 pairs of two.

The Vanner will work fine as a splitter, its just sort of a waste of $ since you paid for a capability thats not being used.  Although I'm not sure we really need that capabillity.

Although I tried to make all my DC loads 24 volt, below is a list of my 12 volt usage


control circuit for my roof airs
fanatastic fans
some 12 volt lighting
power for all my lighting circuit latching relays
power for the indicator LEDs for lighting circuits
charger outlets for accessory 12v
power for signal amplifier for TV antenna
Electric toilet
control circuit for my tank sensors (can tell almost to the nearest gallon how full they are)
Zirgo fan for my generator radiator - now this draws a lot, probably 15 to 20 amps, more on start.

This system has worked well so far for the 2 or 3 years its been in use.

[belfert]

And remember that you can also just use the Vanner as a voltage splitter, or just buy a voltage splitter (much cheaper) and use that.  I bought my Vanner before I had figured out all my runs and usage.  I have it hooked up to 24 volts only, and do not have it center tapped at all.  I use it to run all my 12 volt loads.  Probably better for the batteries anyway to not use 12 volts from a center tap.

What exactly is a voltage splitter?  Is this the same as a voltage converter?  I have a small 24 volt to 12 volt converter under my dash to provide switched 12 volts to my digital gauges and my backup camera.  I already have a Vanner Equalizer that is 60 or 80 amp.

I do plan to have six matched batteries.

[Stan]

I answered Brian's first two questions in my first post. I answered his second question in my second post. If he asks what is the best way or which way will make the batteries last longer that requires a different answer.

It is not necessary to point out that my answer is wrong, because you want to answer a different question.

[Sean]

It is not necessary to point out that my answer is wrong, because you want to answer a different question.

Stan,

I just went back though the whole thread and I don't see where anyone said you were wrong.

Since I don't know who you've aimed this comment at, I'll say for myself that my own answer was intended to impart additional information to Brian about keeping his entire bank in balance.  None of that was intended to contravene anything you wrote.

-Sean

[H3Jim]

Stan,
If it was my answer that seemed to suggest you were wrong, my sincere apologies.  It was merely intended to provide more information and possibly some grist for additional analysis and information. 


So, I'll ask it, what do you think is the best way? and what way will make the batteries last longer?  and of course, why?

Thanks,

Jim

[Don4107]

Vanner has online manuals at:

http://vanner.com/vp/manuals.htm

Shows various layouts.

Don 4107