new line on the 12v

That is only true for the High Voltage battery not the 12v.

 

Good questions. If I understand your question:

The VDC Battery Minder – the new model - is current limited to 1.33 amps and voltage limited to 14.4 vdc. Once float charge level is reached, the current is limited to a range of 5-200 mA and the voltage is limited to 13.4 vdc. These are quite safe values and allow the unit to be used indefinitely on a battery

Once float charge level is reached, the unit will switch to a desulfation mode to break up any sulfates on the plates. The desulfation works by sending a pulse into the battery of 1 amp at 3.26 MHz. I was concerned this pulse might trigger the car alarm, but after almost 4 years everything is fine

VDC has the manual for download. According to VDC, a badly discharged battery should be recharged first with a conventional battery charger. A mildly discharged battery can take up to 72 hours to reach float charge level using the Battery Minder. VDC also has an approximate voltage vs SOC (State Of Charge):

VDC, SOC
12.7, 100%
12.5, 75%
12.3, 50%
12.1, 25%
11.8 0%

If the battery voltage is 11 vdc or lower, the Battery Minder is designed not to work at all. This is a safety feature

I disagree about the dealer comment. That may be true in warm climates, but in bitter cold climates a Prius delivered with a partially discharged 12 vdc battery will have problems. The voltage-limited charge works fine in warm climates, but in bitter cold temps it can fall short of recharging a battery, especially if severely discharged

I think a lot of dealers have an incentive to skip parts of the PDI. I sent you the pdf and I’m sure you’ll agree it is quite picky and time consuming. If the dealer can skip the time consuming parts, just wash the car and hand you the fob, the PDI charge on the invoice is money in his pocket

I’m sure a lot of Prius owners have noticed after picking up their car following a dealer service, the traction battery SOC is lower, sometimes even purple. The lot boy who washed/vacuumed the car probably had it in Ready the entire time. Unless he put the car into Accessory so all the load was on the auxiliary battery, with no charge

Given the short commute you have, I think it best to use a Battery Minder whenever the car is parked. Saves the hassle of a dead Prius and early – pricey – 12 vdc replacement

 

I think once the VDC has been in use for awhile, the 12 vdc battery performance will be restored and it will recharge much quicker, plus not be as sensitive to bitter cold temps

Just do what I do and plug in the Prius whenever it will sit for more than 4-6 hours. Absolutely leave the Battery Minder plugged in overnight

When I had the condo, I always backed into my assigned space in the underground parking. That way if I forgot to unplug the connector when driving away, it would harmlessly unplug itself. With the house, I also back into the garage for the same reason

In practise, when I use my Prius for a short trip to get groceries in bitter cold temps, upon return from the store I plug in the harness once I get the bags out of the hatch. Usually within 10-20 mins the green LED is blinking, indicating a float charge has been reached and the unit is actively desulfating the battery