along the lines of an inverter charger

Would you care to share with us why you'd want such a setup?

Lead batteries have a limited cycle life as well. Especially "deep" cycles all the way down to 12v.

Assuming you want to run off battery and solar then charge batteries, trying to reduce electric charges?
Then solar must come into play, and be sufficient amount, and night rates electric charges preferably less than daytime charges
Remember take out 1kwHr and it takes 1.2kwHrs to recharge the batteries
Conversion losses come into play
With out solar it cost less to just use the utility power direct
Than to run down batteries then recharge them

IF you have the Solar to keep the batteries while running what ever
then only power being used is at night when the solar goes to sleep
and that is still cheaper than draining the batteries, then recharging them, the recharge power is cost more than the direct use power by a factor of approx 20 percent, unless you have say night rate that is over 20 percent less. and then you only brake even unless it is 30 percent or more less costly

My Victron battery monitor has the ability to signal a relay when the battery gets low, I would guess that the trimetric can as well.

smkettner wrote:
I would be looking at something similar to a generator automatic start system. These are programmed to start a generator if the voltage drops below the set point. Instead of starting the generator you would have it close a relay and let your converter charge the battery for a set amount of time.

Of course you could do this manually with a switch.

I did think of just doing it manually but would prefer reasonably autonomous. On the weekends i could watch it but i work 3rd so it wouldn't work during the week. Of course that would be the cheapest to test it out.

jayw900 wrote:
I was sitting here thinking, cause that's what i do, and have tried to do a search however it seems i'm not asking the right question.

Is there something that does the opposite of an inverter-charger? Instead of prioritizing shore power to battery, i'm looking for something that will choose battery over shore until the battery voltage goes below a user chosen set point.

For example, always running on battery(solar) until 12.0-12.1 volts when it switches over to shore power while batteries charge up to float(~13.2) then changes back to battery. All i need is a name or phrase and i can do the rest. The search i've done so far have only brought up "normal" inverter-chargers.

Get a Magnum Inverter, they were originally designed for residential alternative energy systems.

The inverter can be programmed to use DC as the primary power source until other conditions are met, then it will connect to grid or start a generator if so connected.

1> Battery voltage low set-point
2> Battery state of charge set-point (requires battery monitor kit), more accurate than voltage
3> Time of day / quiet hours window
4> Manual control, inverter will just shut down rather than connect to grid power / generator

There is a problem with grid tie
They depend on utility power being available
If there is no incoming utility power, the grid tie inverter shuts off
This is a required safety for grid tie, so there is no back feed on the utility line in case of a power failure and line men are Working on the power lines,
Grid tie chooses solar over utility as long as solar has enough power, batteries are not involved as nothing to do with battery cut off voltage
Maybe something could be kludged together and made to work,
But it doesn't come setup that way
Maybe check the solar and off grid website's see if they have some info on this
Perhaps a modified auto start generator control
Used to pull in a transfer switch instead of starting the generator
When the batteries get low

I would be looking at something similar to a generator automatic start system. These are programmed to start a generator if the voltage drops below the set point. Instead of starting the generator you would have it close a relay and let your converter charge the battery for a set amount of time.

Of course you could do this manually with a switch.

A grid tie system never even crossed my mind thank you for that.

Not exact, but a grid tie system does that- uses inverter first, supplementing with shore power. It's always hot though.