If I build some LiFePO4 battery packs, would anyone buy them?

[rickst29]

This is only a preliminary query, and definitely not yet a "Part For Sale".

I see that I can buy parts for a "270/280 Ah battery, using EVE or LIFSHEN cells, along with decent 250A (continous power limit, peak is higher) BMS into a Group-31 box for roughly $820 each. This INCLUDES the low-temperature auto-sensing heater parts for plugged in campgrounds. The temperature display of the heating controller is built into the top cover, along with the coulomb-counter Meter and a small on/off "master switch" for enabling the heater circuit in Boondocking. (These three components could also be mounted separately, using relatively small cables.) During installation, it is possible to disable Solar Panel power when the battery temperature is too cold.

In a configuration where a separate "Charging" Wire can be pulled from the Power Converter, the Power Converter line can be connected directly as a "power input" for the heater circuit (which auto-switches to become the battery charging line, whenever the battery pack is warmed up to at least 45 degrees Fahrenheit).

But complications arise when a single wire is shared for both "charging" and output delivery to the TM +12v power distribution board. I recommend against using this configuration, because manual switching is required in Boondock situations, and wintertime battery maintenance becomes complicated. At a "plugged in" campground, you may simply turn on the "heat from the battery" switch and leave it set for the entire stay. When the heater needs to warm the battery, it draws power from the battery, and the battery draws power from the Converter. And when heat isn't needed, the warmer circuit is switched back to the battery itself (with zero power consumption and zero voltage). The battery stays warm all night.

Boondocking with the heater running through the whole night (from the battery) wastes energy. You turn the "master switch" of the heater OFF for the evening and night, making the thermostat ineffective. Then, if you want to charge with a Generator you must warm up the battery first (by turning the "master switch" back on and warming the battery), BEFORE connecting the generator.

Solar Charging (when boondocking) can be switched off automatically in low tmeperatures, so that the Charge Controller does not charge the battery before it is warm enough to accept the charge current. But in the morning, you must again turn on the "self-heating" switch for the battery to warm itself. When the Battery temperature has reached 45 degrees, Solar "PV power" is re-enabled.

Keep in mind that you probably need to spend another $220 on upgrading your old Converter. I will put most of the "cold weather heater"parts and wiring inside the box. Built into the Group 31 box cover two are the two switches and the heater controller's temp display, and the Coulomb-Counter Monitor Display. There is also a large heatsink for the BMS, on one long side of the box. The "Coulomb Counter meter, switches, and meter can be or left as a pair of terminated wire ends if you want to put the switch and temp display outside the battery box, on an interior storage compartment wall). Plus shipping, plus about $100 for my build-and-verify work.

At roughly $900 plus tax and shipping, they'd be expensive. But you would end up with 3x the capacity of a BattleBorn $1050 heated battery kit. (To match my box, you'd need to spend $3150 with BattleBorn, and you'd have to wrap the heater cables yourself, and you'd end up with 3 Group-24 battery boxes to wire together - instead of just one smaller one.)

Would anyone be SERIOUSLY interested in getting one of those from me? I know that it's way more battery than most TM Owners need. (It's possibly capable of running the Air Conditioner through a HUGE Inverter, for 1-3 hours). But I
'm not interested in building any battery pack smaller than 270Ah, or any simple battery pack which excludes my "auto-heating for charging" feature.