Originally Posted by orange4boy
Does the Prius have an alternator? If it does are you going to do the disable? Or does it use the synergy drive to generate power for the electrical system?
I understand there is a lead acid battery somewhere in there which has an unusually short life. Probably not getting fully charged by the only intermittently on engine.
Originally Posted by Daox
No alternator. The high voltage pack feeds a dc to dc converter to keep the 12v auxiliary battery charged. I hear they have problems here and there too. I'm looking up a bit more on that to see if I can't do something about it.
All of our Prius have the 12 V DC-to-DC converter and both our 1.5L 2003 and 1.8L 2010 models can provide about 1 kW to power an inverter:
Prius - UPS Project
BTW, this was one of my earliest mods and we have used it at least once each year since 2005. The longest was four days and six hours when tornadoes tore up the TVA transmission lines in North Alabama. We burned about 2 gallons per day; almost no carbon monoxide due to catalytic converter; so quiet we could hear the neighbor's generator a half a block away but our car could not be heard beyond the property line, and; ran an extension cord to neighbors for a small TV and cell phone charging.
I have a first version, sine-wave inverter in the 1.8L but I am planning to rework it. The problem is the 120 A, 12 V circuit breaker and the Anderson connectors waste too much energy, nearly 100 W.
I will go with an earlier design of a one foot, #4 gauge ground cable connected to the battery terminal and stored, safely loose in the battery compartment. The 12 V cable will be permanently connected to the inverter and with a stored, insulated wrench for the B+ nut. The inverter will only be connected when needed.
I am doing this because I could not find a sensible way to permanently install the inverter. The Anderson connectors were an attempt but they ran too hot at a 930 W, tested load. I'm out for a solid 1 kW and this 'emergency only' mode will reach my goal.
BTW, my sine-wave inverter is rated at 1.5/3.0 kW. This means sustained, 1.5 kW which means the 12 V battery will provide the surge energy, 10s of seconds, before the low voltage threshold trips. The 3.0 kW is good for about 300-400 msec and is really only useful for inrush loads . . . more about this later if there is any interest.