Originally Posted by jakegw2
TaxWonk - thank you for this writeup, your system is very thorough.
Two items that I thought of when reading:
Your DC-DC charger might not be doing any limiting of current since 60A is probably more current than your alternator has to spare, after feeding the chassis load, much of the time when you are driving. Your alternator (probably a 160A unit?) may be running flat-out when you are charging. My 220A alternator supplies between 65A and 85A when driving, depending on what else is running (it supplies as much as 120A at startup for a few minutes). I do not use a DC-DC charger. I don't know if the Sterling device lets you set a max current, but if it does you might consider dropping it to 30-40A so that the alternator does not run at max load.
The charger will still raise the charge voltage slightly to accommodate the LiFEPo chemistry, which can be important if you seldom charge off of other sources (LiFEPo needs the higher voltage to balance the cells - not all the time, but periodically to protect the battery).
You have capacity to power the AC if you wish. Based on my experience with two Battleborn batteries and a slightly more powerful AC I estimate you could get 2.5 to 2.75 hours of AC off your setup. You may not need it, but in FL it is really nice to be able to go shopping or in to eat at a restaurant and come out to a comfortable vehicle. Also great for rest breaks without having to idle the van.
According to the RoadTrek owners manual I have a 150amp alternator. The charger does have a half power mode and I think if you want to really get into the coding you can set the max charge amperage. Interesting that you say to cut the charging amperage back to 30A. So far I have not seen it charge any higher than 30A according to my battery monitor. But you make a good point and I think I will set it to half power just to make everything last longer.
As for the AC, I had not originally intended to install a mciroaire soft start and I knew that the Mutliplus could not handle the starting amps so I wired it to not run the AC on battery. I thought it was a good feature for someone using my wife's van that did not understand the system. But now that I have the soft start I might go back to having the AC supply back in the main panel.