Quote:
Originally Posted by jcwilde1
I would love to put a LFP battery in there, but don't really want to change out the on board charge controller. From what I had read it may still work it just wouldn't ever charge them fully, but then again the solar would do that potentially. Thoughts on that?
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Many "Lithium Compatible" RV power converters implement a constant voltage charge of 14.6 volts, that's too much. Although lead-acid batteries should be kept as close to 100% full as possible, for the highest possible prportion of time, LFP batteries do not like being stored at 100% SOC. It degrades lifespan.
Changing out the power converter main board is not difficult, it is only costly. A "Converter" which can be re-set to do WHAT you want, WHEN you want it, is optimal - so a Progressive Dynamics converter with the controlling "charge wizard" pendant is the way to go. My own converter, a sightly modified PD, has that pendant. For long-term storage, including the entire winter, I let it settle into a low voltage "storage mode". Then, when I open the TM and pack for a trip, I push the button to force "boost mode" (which is only 14.4 volts, not 14.6). BMS in the battery packs stops charging at around 14.2 volts.
Interior LFP storage (under the couch) helps to prevent the issue of charging in extreme cold weather, the batteries cannot be charged below freezing (and really shouldn't be charged until at least a few degrees higher than that). But other TM owners have them elsewhere, and are pretty happy with their results.
The batteries cost a lot more than the converter replacement, but they last forever. With a "decent" converter, the 10-AWG wire between the load center/power converter will need to be replaced, because LFP batteries can be charged fast (with lots of current, too much for that small wire). My Converter can and does deliver nearly 60A into my batteries.
My most difficult "issue" in upgrading to LFP battery packs under the front couch was replacing that wire. From the batteries under the couch, I ran about 16 feet of liquid-tite conduit underneath the floor and into the curb-side frame (at the large torsion bar hole, exiting at one of the rear torsion bar holes. The liquid-tite is then clamped to the floor, crossing the underside and rising through a sealed hole (with a clamp above) behind the load center. It contains a single cable, AWG-6, THHN/THWN-2 .
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