Battery bank update:
The standard Flagship LT (and new flagship HT hard sided) camper builds include one Battle Born 100ah battery. In my previous two campers, I did all or part of the house battery and solar wiring setups/installs (battery, solar panel, solar controller, battery monitor, etc.). I do like Lithium Iron Phosphate (LiFePo4) batteries and have experience with three different brands, including Battle Born and all have performed well.
In the original Flagship LT pop-top builds, Battle Born 100Ah batteries were the only choice. One could optionally add up to three additional Battle Born 100Ah batteries for a total of four batteries (400Ah). Two Battle Born batteries can fit in the electronics cabinet. Previously, if a 400Ah house battery bank was optioned, the drivers side under-bench storage would house two additional Battle Born 100ah batteries with conductors passing through the basement.
Coinciding with the the introduction of the Flagship HT but also available on the Flagship LT, STC is now using Victron Lithium 12.8v 200Ah Smart batteries for battery bank options of 400Ah or more. 200Ah Victron batteries are only slightly larger than the Battle Born 100Ah. This allows for two 200Ah Victron to fit within the electronics cabinet rather than utilizing the driver's side under-bench storage location. That location is still available, however, so there is now an 800Ah battery option that consists of two 200Ah Victron batteries located in the electronics cabinet and two 200Ah batteries in the under-bench location.
Below shows a Flagship LT driver's side under-bench storage being utilized for Battle Born batteries back when a 400Ah battery bank used four Battle Born 100Ah batteries. When batteries are added to this compartment (middle image below), a carpeted cover panel, with supporting tabs, separates the batteries from the upper storage compartment. That panel becomes the floor of the now-shallower storage compartment (right image below).
This is the same driver's side compartment when third and fourth batteries are not specced. The full-depth storage space goes all the way down to the "basement".
Victron batteries can fit more cells, in a given battery case size, because most Battery Management System (BMS) functions are performed outside of the battery case using external Victron components. Most other brands of lithium batteries have an internal BMS, and often also include internal Blue Tooth connectivity/monitoring and internal heat pad. Victron batteries have a few internal sensors/components and cell monitoring/communication cables that must be connected to one of five available model external BMS. The BMS, in turn, connects and communicates with Battery Protect disconnects (one on charge side and one on load side) to disconnect current from charge sources and disconnect current to a load. Battery heating pads are also external.
Victron makes five main BMS that are compatible.
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For house battery banks from 100Ah to 200Ah, STC will continue to utilize one or two Battle Born 100Ah batteries.
For house battery banks from 400Ah to 800Ah, STC will utilize two to four Victron Lithium 12.8v 200Ah Smart batteries, one Victron smallBMS and two Battery Protect BP-100 (one on charge side and one on load side.
With the extra external components and wiring needed when using the Victron batteries, it makes sense for STC to continue to utilize the somewhat simpler solution of Battle Born batteries for a battery bank size of 100Ah - 200Ah. Once battery bank size grows to 400Ah, the extra components and wiring are worth it since 400Ah can fit right in the electronics cabinet or up to 800Ah if also utilizing the under-bench storage for battery storage.
I really like the concept of separating components from the cells/battery case. If a BMS or Battery Protect goes bad, you replace it without replacing the entire battery cells/case. Similarly, if cells go bad, you replace the battery cells/case but without the waste/expense of discarding the built in BMS, heat pad, bluetooth, etc. like you do with some sealed LiFePO4 batteries. Granted, there are brands with battery serviceable battery cases that you can open and replace internal BMS, sensors or cells, which is great (and I've done on some brand batteries I've owned over the years).
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Victron Lithium 12.8v 200Ah Smart battery:
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Victron smallBMS:
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Two Battery Protect BP-100:
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Two Victron Lithium 12.8v 200Ah Smart batteries. 400Ah now fits in the electronics cabinet, leaving the driver's under-bench space available for storage or for another 400Ah of Victron batteries. External size heating pads are visible in this image.
Tipping forward the front panel in the electronics cabinet allows access to the Solar Controller, DC charger, smallBMS, Battery Protects, Busbars, shunt, etc.
All wiring is neat and tidy, even with the extra external Victron components. The main panels and components are wired with the panel on a wiring jig for consistency. Note that wiring loops accommodate the front panel leaning forward.
The two Battery Protects are mounted up high with one tasked to disconnect the charge side (cell overvoltage situation, cell temp too cold or hot for charging, etc.) and the other to disconnect the load side (cell voltage falls below set voltage, cell temp too high or too low for current draw, etc.).
The Victron shunt tracks inbound and outbound current to give a battery bank State of Charge (SOC).
The Victron smallBMS uses the information from the battery communication cables and makes decisions regarding when to trigger either one or both of the two Battery Protects.