Are lithium batteries worth the cost?

Dodgemahal wrote:
... the lithium battery will absorb a lot of amps if you offer it up ...

Technically, voltage is pushed at the battery, and based on how many volts successfully reach the battery, the battery decides how many amps it wants to pull (at that voltage).

As hinted at above, Victron's burning-up alternator video is misleading in that it doesn't model in voltage drop, not to mention their pully gearing did not reflect what is typically installed in a truck, and they were running the alternator much slower than a truck at idle.

Lead-acid batteries typically want ~12.6VDC before they start pulling any current. Battery University says 12.6VDC +/- 0.3VDC.

LiFePO4 batteries typically want ~13.6VDC before they start pulling any current.

Factoring in voltage drop...

At ~13.6VDC from my 45A-capable Progressive Dynamics converter/charger with very short 4AWG wiring, my 100Ah x 2 BattleBorns at 50% SOC choose to pull ~4A total. At 13.6VDC, their thirst for current is minimal.

Assuming ~50 feet (one way) of 10AWG wire between your truck alternator thru the 7-pin to the battery, and an alternator putting out 14.4VDC, by definition you can only put a ~8 amp load on the wire before the voltage drops to 13.6VDC, which put another way means you can hook any number of LiFePO4s to such a 7-pin setup and you won't exceed ~8 amps of pull. No wires fry, no alternator burns out, etc.

Here is a link to the voltage drop calculation.

Assuming ~35 feet (one way) of 4AWG thru say Anderson connectors, a 46 amp load will drop the voltage to 13.6VDC, hence you won't exceed 46A of pull no matter how many LiFePO4 you hook up and how massive your alternator is.

Here is the updated calculation.

All that said to counter the myth that LiFePO4s always burn up wires and alternators if direct wired (unless the wires are really big and short!), DC-to-DC converters do so many valuable things, including countering voltage drop.

--tg