I have three of these units. I use one for my Leaf, one for a Chevy diesel truck with two large 12V batteries (in parallel), and one for motorcycles. The charge rate of 0.75 amps will get the job done eventually, but if your battery is very low, it takes a while. Also, when you charge a battery while it's installed in a vehicle, a portion of the charge current ends up powering the vehicle electronics instead of charging the battery. For example, if your leaf is drawing 0.25 amps, then there is only 0.50 amps going into the battery. That makes it take even longer. A fully discharged battery could spend days in the bulk charge phase.
The charge phases and LED states are:
Solid Red = Bulk Charge
Blinking Green = Balancing Charge (?)
Solid Green = Charge completed, float charge
But what does this actually mean? I was curious about what the charge profile looks like, so I gathered some data. What you see below is the charge profile and LED states when I charged a 51R battery outside of the vehicle after it had been discharged by a 30 amp load for 1 minute. This means approximately 1/2 amp-hour of charge would be required.
First is the bulk charge phase: In this phase, the output voltage is adjusted to keep the output current at 0.75 amps. As you can see, this phase lasts as long as necessary to bring the battery up to about 14.4 volts. Next comes the odd-looking blinking green phase. This always seems to last 15 minutes, no matter what. I'm not sure what algorithm is used to set the voltage (or current) during this phase. When that's finished, the solid green float charge phase starts. In this phase, the output remains at 13.1 volts indefinitely.
In case you are not familiar with lead acid batteries, do not worry about these voltages being much higher than 12V. This is expected, and perfectly fine for the battery and vehicle electronics.
So, if your battery is stuck in the solid red phase and it's below 14.4 volts, that probably just means it's slowly charging. If the voltage doesn't go up measurably in a few hours, something may be wrong.
2013 Pearl White SV, bought used in 2017 with only 5100 miles. Vancouver, WA.