I don't see any significant differences in the two approaches from a battery management point of view, given a good low power design for either approach it seems to be 6 of one, half dozen of the other.
In terms of actual pros and cons for the two system approaches, here are some thoughts off the top of my head...
There are clearly some pros and cons to the two system architectures used by ARV and Roadtrek.
In terms of the parasitic loss of usable energy by the battery management system there is no technical reason that either architecture cannot have a negligible loss of energy from powering the battery management system. The pros and cons of the two basic architectures are not related to the usable power from the lithium cells, both can have essentially equivalent usable power from equivalent lithium cells. The design of the battery management system in the Roadtrek Ecotrek 200 AH module could be modified to reduce the power loss to a negligible level where it is not an issue.
The ARV design is a pretty standard design for an RV lithium battery bank these days, the ARV implementation can be noted for: selection of quality components, robust installation under the van, integration of the battery system status and control into the coach wide display and control system, and the addition of battery heaters to the battery bank. .
The Roadtrek Ecotrek 200 AH module approach is similar in some ways to the drop-in lithium battery designs from Stark and others, the Roadtrek implementation can be noted for: the addition of an auxiliary AGM battery wired in parallel with the Ecotrek modules, the addition of battery heaters inside the drop-in modules, splitting the connections on the module into charge and load terminals with the connection to the battery cells on both terminals likely controlled by relays, and a connector on each module to interface to control switches for each module and possibly an interface to a central controller.
In terms of pros and cons, some that have been noted include:
A pro for the ARV approach of building integrated battery banks with a single battery management system for each AH capacity option is that the size and weight of the battery system are minimized for each AH option.
Only cons that I recall being mentioned for the ARV system design are the lack of a built in facility to bring a cold soaked inactive battery bank up to temperature (may not be a feature needed by a majority of buyers) and the fact that a failure of any of the battery cells will shut down the entire battery bank (this may be a rare enough failure that it can be dismissed as a con).
I don't recall any statements from Roadtrek discussing the reasons for their choice of architecture but I can imagine that the modular approach gives them more flexibility by building and stocking a single modular component that can be produced in volume and configured for the wide variety of vans models they produce. Repairs would seem to be facilitated by the easy swapping of modules vs the work needed to repair an integrated battery bank. The con to this is that there is a weight and size penalty by using multiple modules with internal battery management vs an integrated battery bank with a single battery management system. The fact that the modules are mounted under the van does reduce the size penalty somewhat vs a case where the modules would be located inside the van where space is at a premium.
Pros that have been mentioned for the Roadtrek approach include: the capability to bring cold soaked inactive batteries up to operating temperature using power from the underhood generator and the ability to take a failed module offline and continue operating with the remaining modules online.
The cons mentioned for the Roadtrek system have been extensive here on the forum but I am not going to mention those that are due to the unnecessarily large power loss of the battery management functions (these are fixable). The aux AGM battery is considered by many to be a kludge to resolve a design flaw but it does allow the system to power the battery heaters from the underhood generator so other than the weight and size penalty of the extra battery I am not inclined to list any other cons associated with the AGM battery but I accept that this may be a minority opinion. A major con of the current Roadtrek system is the lack of any useful system status information, the most glaring issue being no information on the state of charge of the batteries. The two control switches associated with each Ecotrek module get very unwieldy as the battery bank grows up to the case where there are 8 pairs of switches for the 1600 amp hour option. I would hope that the reintroduction of the Coach Connect option is taken as an opportunity to get rid of the physical switches and integrate all display and control features (including system status info) into a touch screen display.
That's enough for my thoughts on this for the moment, I expect others will add their thoughts to expand on this attempt to summarize the pros and cons of the two systems...
Hybrid Mode
