My dad Just purchased a Genius 1.
I put it on my near fully charged Ub12220 AGM 22 amp hour 13.1 LB battery, which was reading 13.07v several days since it was last charged.
Inside, room temperature is 74 degrees.
My clamp meter is attached over one Noco output black wire, reading Noco output amperage
I have a separate voltmeter/wattmeter attached to battery
I have a LED light, variable brightness/amp draw, upto 1.36 amps attached to the wattmeter, the wattmeter reading the draw of the LED.
I hooked everything up, set it to AGM mode, voltage quickly rose to 14.7v, green light came on, then Noco quit supplying current and battery voltage naturally fell, slowly.
I turned on the LED light, 1.36 amps and battery voltage fell to 12.56v. The Noco's green light stayed on It only supplies 0.2 amps, battery stayed at 12.56v.
I unplug Noco, turn off the LED light load, battery voltage returns to 12.82v quickly.
I plug in Noco again, and it starts outputting 1 amp exactly.
Once voltage hit 13.7v, it switched to 0.5 amps, green light came on, and battery voltage rose slower.
Once voltage reached 13.9v it switched to 0.2 amps and battery voltage rose slower
Once voltage reached 14.7v at 0.2 amps of current all amperage stopped, and battery voltage fell.
I turned LED light on again at precisely 1 amp of load
Voltage over a few minutes fell to 12.56. The Noco is providing 0.2 amps and voltage holding steady.
So it appears to me, on initial hook up, the NOco only supplies its 1 amp rating, until 13.7v is reached, then it switches to 0.5 amps and the led goes from flashing red to solid green.
Once 0.5 amps pushes voltage to 13.9v, it switches to 0.2 amps, until 14.7v is reached.
Once 14.7v is reached battery voltage is allowed to decay.
I did not see it turn back on, until battery voltage reached 12.56, and it only provided 0.2 amps.
Once I removed the LED light's 1 amp of load battery voltage began to rise, with 0.2 amps of current.
So this charger is not trying to maintain a constant float voltage. It is trying to get the battery to 'full', with 1 amp of current until 13.7v is reached, then 0.5 amps until 13.9 is reached, then 0.2 amps until 14.7v is reached, then it shuts off.
It turns back on, with 0.2 amps max, once voltage drops to 12.56v
These are my observations, so far.
I think for ~25$ it is certainly a good enough product, within reason, in certain usages. I'd prefer it turn back on at 12.8 vs 12.56v, and perhaps it would if I were to monitor it over a longer period. I was loading the battery to force its voltage lower
The 0.2 amps max, is not enough to offset leaving doors open with dome lights on.
All this was tested within the space of an hour. Results could be different with bigger batteries at different states of charge and observed over longer periods..
I do not think that this unit suffers from poor temperature compensation, I think the OP just measured battery voltage after it had reached 14.7v and shut off, and that is just where battery voltage had declined to at that point. This is why one should know the amperage flow at the voltage reading they take.
After typing all this, and having turned off the Light's load on the battery, 0.2 amps has raised battery voltage back upto 13.43.
I'll see if it plateaus and holds a fixed voltage or if it will seek/attain 14.7v, and shut off again.
This time....Once battery voltage dropped to 12.69 under a 0.2 amp load, the Noco kicked back on and is now providing 0.2 amps. Battery voltage rose to 12.85...so far, with the 0.2 amps of led lights still on.