Without a shunt you are chasing your tail with voltage. LiFePo4 need a shunt for coulomb counting for the SOC of the batteries, I find it hard to believe that BB didn't say this but it is mentioned in their battery monitor section but use Victron stuff. Magnum has the ME- BMK. So you are saying that there is no shunt that is communicating/ interacting with the charger/ inverter? I believe this is your problem and not getting the full functionality of the charging/ inverting system.
After charging the lfp batteries they will always drop in voltage to their resting voltage if you have no loads on them but an rv will always have some sort of 12v loads. You have something that is drawing 12v draining the battery even slighly. Co detector, fridge, fans for fridge, maybe landing gear but something is drawing power and that is what needs to be found.
Edit... wiring batteries especially 8 of them, something to read and think about. BB batteries have a lot of small cyclinder cells making up 1 100ah battery now multiple by 8.
http://www.smartgauge.co.uk/batt_con.html
ok.....let me try to ask this in a way that I can be sure I get it all.
first, are you saying that without a shunt, the batteries are not even charging properly or that I am simply being deprived of a better way to measure capacity?
next, i certainly do have a few things drawing on the electrical system, albeit these days, while always hooked up to shore power. are you saying that such as, say, a large residential fridge (or an airxcel AC...that the fridge being the only things drawing any appreciable power under most circumstances),
even with shore power, is drawing enough power to make an immediate difference such that they will lower a fully charged battery bank within 20 minutes to a voltage level which BB's own charts show to be a heavily depleted battery?
I do have big foot struts, so to say, but once down they are off.........and other than small LCD tvs and lights, I have no clue what else would be drawing enough power, especially on shore power, that I would lose...at least based on voltages which BB says represent a huge drop in capacity...........such large amounts every single time...with the system automatically going back into another charge cycle each time. do you have any thoughts about that?
also, just to be sure, as you mentione 8 batteries. I HAVE 8 batteries, but it is only material in terms of having tried two separate groups of 4 while I sort this out. are you saying what you are, thinking I have all 8 hooked up at one time?
I have previously had, as mentioned, 2 sets of batteries....both AGMs.....one a no name Chinese set of 4 (6 volts wired serially) and the second set, Lifelines...great batteries but for a variety of reasons, I decided to move to BBs..........neither set of AGMs produced this "oddity" with voltate dropping precipitiously. why would that happen "now"....all my equipment is the same.....same fridge, same ACs and so on......and not for 7 years prior? this literally happened the minute I "dropped" these in.
I am getting a lot of input from a lot of people and I am grateful for it, but my head is spinning from some of it and I need to be better understand all this. if you would be so kind as to answer the above in as granular a fashion as you can, I would much appreciate it.
many thanks1