In my coach the second AC unit can run off the inverter. I only do this when I have the big engine running and it is a little to warm for just the dash air but no hot enough where I need to run more then 1 roof air. Alternator in coach is 340 amps and feel the roof AC unit is using around 120 amps 12V power while running.
I know my time is coming when I am going to need to replace the 6 house batteries I have and figured I would have this figured out now so when the time comes I can react.
In reading the threads about Battle Born batteries the talk is you will need a DC to DC charger so you do not burn up your alternator. The problem I see is the DC chargers are not big enough to let through enough amps to cover what the roof AC unit use.
This morning I saw were someone is using the Life Blue batteries. I had never heard of them so went to their website. First I notice was they were cheaper then Battle Born. They have a 60 month - 120 Month warranty where Battle Born has just a 10 Year warranty. Their web site says that the batteries BMS will handle the charging where you do not need a special DC charger. If this is the case then my problem of running the roof AC unit while going down the road would be getting it's power from the Alternator and not discharging the coach batteries and it would also have power to be able to charge the house batteries if need be.
I know nothing about these batteries and setup so what am I missing. Are the LifeBlue's the way for me to go?
Another one you might check is Lithium Pros in Indiana,24 month free replacement 10 year pro rated,we charge them from the alternator.
At least with the Victron Orions, you can run multiple units side by side. I have two @ 30amps each and intend to supplement the other ~80amps for the roof air with solar.
I have two Lithionics GTX315s (NOT the way to go if you want to save money btw) and my choke point for the roof AC is actually my Victron 3000 inverter. Soon a MicroAir Easy Start will solve that problem.
You need to check and see if your system would take the 340 amps from the alternator. Voltage is one thing amps are another.
This is one example of where which battery to select is less important than a complete design that accommodates your needs on the demand and the supply side sources.
You can charge most LiFePO4 batteries up to their rated capacity for a short while. In your case maybe 800 ah total capacity would have no problem with maxing out a big alternator. If you want the maximum life cycle count you should be charging at about 20% of capacity using a lithium friendly charge profile. BB sells an alternator charger interface that probably works like the LiFeBlue BMS does ... on for a while and then off, repeat. Smart B2B chargers are available up to 60 amps and some can be run in parallel. Sterling makes a 120 amp B2B as well but there was a software issue a year go, not sure if it has been resolved.
If you combine some solar with a sufficient B2B component you can have enough to maintain the batteries and run one AC.
LiFePO4 batteries are amazing but they are not really a simple drop in replacement. It takes a bit of design work to optimize for what you want to do.
If you are paying someone else to do this for you then saving a few hundred bucks per 100 ah is likely not going to make much difference. Doing it yourself save the most money, so do it in the best way possible.