TBammer
Nov 29, 2015Explorer
12V vs 6V
Recently bought our first travel trailer, and it has been quite the education, including understanding the dual electrical system. One thing I am thinking about doing is adding a 2d battery. I have ...
ktmrfs wrote:
If you dry camp a lot, then a pair of 6V has an advantage of more AH ...
... and the ability to withstand hundreds of discharges to less than 50% of capacity. Something 12V aren't real good at.
Also, if you intend to run a very heavy load (>100A) like inverters etc. for > a few minutes at at time, and do it fairly often then 12V offer an advantage in that they have lower internal resistance and are much better at high current draw situations.
SoundGuy wrote:
I would be interested in seeing supporting documentation to both these claims as my primary interest in upgrading to dual batteries from my current single G27, aside from the fact it's now 8 yrs old, is that I am now running a 1K inverter for those times we don't have on-site shore power available.
ktmrfs wrote:
looking at the Trojan website, cycle life if a pair of GC2's discharged to 30%SOC is around 500 cycles IIRC. So in terms of useable AH 6V has an advantage in cycle life and capacity over most 12V. Most 12V even the trojan's, cycle life degrades rapidly beyond 50%DOD. So a 250AH 12V has around 125 "useable AH" per cycle with reasonable life. While a 250AH 6V bank has 180-200 useable AH per cycle for the same or higher cycle life.
And how many of us will ever do enough camping to get to 500 cycles? Golf carts, yes, campers, not many of us.
As for high current discharge, myself and several others have gone through that with 6V. A pair of 6V will handle a 800- 1000W load down to about 80%SOC before dropping below the trip voltage on most inverters. Get's very frustrating when the bank needs to be almost fully charged to run the microwave for a few minutes. A single 12V will do better than that. for 1000W load, 4GC is a better choice. They will run 1000W inverter down to around 60%SOC. But a single or pair of 12V will do that as well will ease. and Four 12V will handle that with lots of margin.
Which battery (6V or 12V) best works for you really depends on what your needs are and how you intend to use them.