Planning on this setup as a 12V supply and backup:
Load connected to 12V 100Ah SLA Battery connected to a charger (Residential Gateway UPS).
Continuous load will be minimal (<0.5A), with an intermittent load that kicks on once daily at 12A for <5 minutes. This comes out to
Charger is a Residential Gateway Backup power supply. Limited data sheet info says it can output 36W max.
Based on my math there is plenty of charge current to keep the battery topped off in that average load < charger output. My concern is that when the higher load switches on, will the battery provide all the current it needs, or will the the load try to draw from the power supply, which may be inadequate?
I've found this, with a trickle charger instead of a UPS, and conflicting answers: Does lead battery + trickle charger = UPS?
My hunch is that it will mess up the charging circuit, but I have turned up nothing conclusive to back this.