Five weeks into my summer travels has given me sufficient experience with my lithium battery system to provide a couple of observations:
1) Having two watt hour meters - one for power in and another for power out has proven to be very beneficial. Iv'e found that tracking watt hours in/out is more informative than amp hours. For example - 10 amps at 1 volt = 10 watts and conversely 1 amp at 10 volts = 10 watts. In other words a measurement of amps means nothing without knowing the voltage. Granted - the voltage during charging/discharging only varies by about 1 volt - nevertheless this does skew an amp hour only reading over time.
2) The icharger is highly configurable - which means one can adjust/adapt it to many circumstances - but this also implies a learning curve...
I'm currently in the Redwoods - where I have no solar gain - I really dislike firing up the generator in a campground - but here I only have two choices - start the engine and use the alternator or fire up the generator. In the past - living only with lead acid batteries - the charge current would start off fairly high - around 40 or 50 amps - but within 20 minutes or so it would drop off to 15 amps and gradually fall lower. With the icharger connected to the lithium battery the current draw from either generator or alternator is constant at about 36 amps. Note: I had previously - a few years ago - modified the wiring such that I can use the Mean Well convertors - air conditioner power supplies - to divert power to house batteries.
When I have had solar - whatever they were capable of outputting - the lithium batteries would gladly accept the full output. Whereas with lead acid - once the solar charge controller entered the absorption phase - the current would drop off to 1 or 2 amps regardless of how much was available. And that would go on for hours!
To try and summarize - one of the main advantages of lithium vs lead - as I see it - is that lithium batteries have a much higher acceptance rate than lead acid batteries. In other words - they charge up about twice as fast as lead acid. So whatever the charge source may be - you can leverage it's full output when charging a lithium battery!
The icharger - which is essentially a DC to DC converter - similar to a B2B charger - is an essential part of making the system perform well. It can load down the voltage output of an alternator or other charge source and force it to output more current. It can then step the voltage output up to provide sufficient 'push' for charging the battery to it's full potential. The icharger also monitors each individual cell and can balance the pack as needed and monitor the them to prevent over charging.
Iv'e taken some liberties with the proper terminology in an attempt to express the information in layman's terms.
The more technically savvy folks will no doubt question the quality of my technical writing.
Whereas the less savvy folks will no doubt still be scratching their heads wondering what the heck I'm talking about.
Ah well - such is life
John...