Author Topic: 6V battery configeration  (Read 1441 times)

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salty

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6V battery configeration
« on: May 12, 2016, 09:11:36 AM »
After 8 yrs of service I am replacing my 4 Trojan T105s with 8  T105s.  for a 12V system.  Two options I have come up with (there may be more) are 2 parallel banks of 4 in series or 4 parallel banks of 2 in series. They seem to need the same number on jumper cables.  Any reasons to use one configeration over the other? Other options ?

SparWeb

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Re: 6V battery configeration
« Reply #1 on: May 12, 2016, 12:22:38 PM »
Putting four T105's in series will get you a 24V "string".
Are you going up to a 24V system, or are you going to stay with a 12V system and set up 4 parallel strings of batteries?
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mab

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Re: 6V battery configeration
« Reply #2 on: May 12, 2016, 04:00:28 PM »
I think Salty means put 4 in parallel then series to make 12v, or 2 in series * 4 to make 12v.

personally I'd go for the 2nd option, but I don't think it makes a huge difference. Possibly it's a bit easier to diagnose if you suspect a dodgy cell somewhere - but that might be just the way my mind works.

Xan

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Re: 6V battery configeration
« Reply #3 on: August 31, 2016, 04:30:43 AM »
The usual way most people do it is to make up the system voltage with batteries in series first and then parallel each series set until the bank is complete. i.e. in your case the second option you have described. [series/parallel]

However, there is an advantage in making two parallel sets and then putting those in series to make up your system voltage. When done this way the batteries seem to balance better. They do this mainly due to the fact that all batteries will always be at the same voltage in each parallel set, I suspect. I have done this with a 24 volt bank (made from placing two paralleled sets of 12 volt batteries in series) and it works great. I don't see any reason why it wouldn't benefit six volt batteries in the same way. Bear in mind it takes slightly more interconnects to do it like this, but only a couple more. [parallel/series]

There is a third way which tries to gain the advantages of both methods. The H bridge (yeah, similar to what's inside an inverter). You wire your batteries in series/parallel, just like the typical way. But then you join the mid points of each series pair together. Imagine if this was done with just four batteries, it would look like an "H". If done with six, eight or more it starts to resemble a "ladder".  The whole point of this is to keep the basic layout like the series/parallel option but obtain the balancing advantage of the parallel/series option.

I have tried all three ways with my 24 volt bank & personally I prefer the parallel series method. The H bridge arrangement worked pretty well, but it is all to easy for "lazy" batteries to hide within the pack and harder to rat them out!

If you do happen to embark on a parallel/series scheme, it would probably work out best to put two older batteries and two newer batteries in each parallel set.

As it happens the last time I was really active on this forum was when I was deciding about all of this with my 24 volt bank! lol