What is the make and model (And ampreage) of your converter
You have 300 amp hours of batteries. Let's say you use 80% (240 amp ours)
Well converters can be as low as around 20-25 amps or as high as 100.
To replace 240 amp ours will take at least 250 amp hours.. 25 amps that's 10 hours in theory.. but wait there's more.
As the battery charges the converter "Backs down" a bit so it might take 12 or more.. and if it's not a LI-charger (Still an LA charger (Lead acid) it may well never it 100% because it simply has not the push to do it.
3.4 volts resting. 3.65 charging times 4 cells = 13.6 volts resting and 14.6 charging.... Many converters are 13.6 Float(that's good) and some that's all they do and 14.2-14.5 Boost/Absorption (Not enough) to fully charge LiFePO4.
(Voltage source google)