Hello all… Just got my first solar gen… the AC200L, mostly due to the 30a RV connection on the front panel and the integrated charger.
My RV is a 2021 Bullet 258RKS and uses a 30amp cord for shore power… the fridge runs on 12v only, all the lighting is LED, and right now the house battery is a 12v lead acid 100ah that charges while plugged in to the truck while towing or plugged in to shore power. My fuse panel does have a breaker to shut off the converter so if I plug in to the bluetti its not trying to charge the house battery…
We off grid camp a few times a year, so my plan is to plug directly in to the bluetti using the rv’s 30a shore power cable and keep it topped off with a portable 300w solar setup… but I’d like to be able to provide extra capacity using the house battery… and I’m thinking of changing the house battery to a 280ah LiFePO4…
Any thoughts on how to connect the house battery to the bluetti for extra capacity and recharging the house battery?
Should I only add the house battery when and if it’s needed?
Should I attach the solar input charge to the house battery and will that put power in to the bluetti as well as the house battery?
I am not completely new to solar as on my last RV I had a traditional 300 watts on the roof through a controller in to 2 house batteries that kept them topped off all the time, but I had no inverter to run the outlets in the RV… it was strictly for lighting and phone charging etc.
I appreciate any advice on how to best utilize the bluetti in conjunction with an additional battery for off grid use…
My 1st comment is use the KISS principle (Keep it Simple …)
I have a RV with 200Ah LFP, some fixed solar and additional portable solar. I use an AC180 primarily for its inverter to run the Microwave.
Solar is a subjective recharge source when off grid, very weather dependent. In the scenario you note, I would keep the 2 systems separate. i.e. With both the RV house battery and AC200L fully charged, use the 200L for a time to power the RV to around 40% SOC, then switch to the RV battery while you recharge the 200L. Then the opposite when the house battery needs a recharge. All you then need is to divert solar to where the charge is needed. I definitely recommend using LFP for the house battery.
If you use the 200L to charge the house battery, it needs to be charged first to do this, which has an efficiency loss, then charging the house from the 200L incurs a further efficiency loss. Charge it once, use it, then recharge is simple and the most efficient.
Forgot to note - I charge my house batteries off grid separate to the AC180 charging. (It does not have the capacity to run my RV 12V system)
My primary charging is solar, however I have other options. When several days of crap weather occurs, I can plug my 4x4 into the RV, which has a DC-DC charger and idle the vehicle for a while, which is not ideal.
I also carry a small 800W inverter petrol generator (Gas), which has enough capacity to run my RV 240VAC 500W battery charger. This is my last resort and for the last 3 years have used it 4 times.
The other thing to know is your average daily load in Ah. For me this is, in winter due to a diesel heater and 12V fridge, around 50Ah per day. Which means, my 200Ah of house LFP will last at least 3 days without any recharge.
More than one power option and charging option is always better than relying on one system. Cos, a failure out in the boonies can cut short your trip.
The above are my personal opinions, that said…
In my decades of working in engineering design, the one mantra was that for every design problem, there are multiple solutions, rarely wrong just different. The one selected can depend on need, time, cost or effort etc and that is personal, because we are all different.
