My only beef with the Genasun is that the charging voltages aren’t adjustable and they have no charge termination, they stay at the absorption voltage all day. I would be pleased to be proved wrong on this.
They make "standard versions that have fixed settings that they have chosen.
They also make a version that you can ask them to program in the settings that you want and they will embed them into the charger for you. There is a modest charge for this ( built into the price of the unit ) and they cannot be changed in the field.
I have used both types and there is in fact charge termination and stages, but for instance with the 4 x 100 amp-hr batteries wired in series battery packs that I usually use, they can accept moderate current for a long time, especially AGMs.
For LiFe batteries, they often go through balancing internally, so it is hard to tell sometimes if it the power going in is being used for charging or balancing cells.
There is also the reality that a battery pack almost always has at least some power being drawn from it to run something, at least in mobile use. The simple model of an isolated battery being charged all by itself with nothing else happening is not my reality.
One of the challenges with solar charge controllers in general, is that they trigger on the battery voltage dropping to a pre-set level, so it is possible for the batteries to be partially discharged, in the middle of the afternoon with plenty of sun, but nothing happens because the voltage has not dropped low enough to trigger.
I really pushed them to make this set point more like a hair trigger, as soon as some power was drawn from the pack at all - it would trigger a charge cycle. ( at least for the ones that I buy with my custom settings. )
I am not sure what they are using right now for their standard set point.
Every night, the solar charging stops and the battery voltage / SOC will drop anyway, if nothing else just powering the battery monitor, so I don't view it as a big deal.
My simple setup that runs my off grid shop most definitely goes into a standby voltage. That rolling wire rack has ~ 150 watts facing up and another ~ 300 watts mounted vertically. All of that is going through one genasun to charge the 48 volt pack. At the same time, I am running 120 vac tools off the inverter, as well as fans, etc, so it is getting a work out most of the time. That is about 5 pm / 17:00 hrs locally in the photo.
I have multiple customers using both Lifeline AGMs and battle born battery based packs working this way in the field for years.
Are your observations similar to this or different ?