Does anyone know whether, in an '06 HiHy, the 12V battery will be maintained or depleted in "Ready" state, parked in "P", with a steady, say, 50 Amp draw on the battery (powering an external inverter connected directly to battery w/ heavy wiring).

Is the 12V connected to the traction battery through a DC voltage converter, or is it only charged by the ICE's MG1?

And will the ICE automatically start to recharge the 12V in "Ready" mode when a low voltage setpoint is reached?

If it all happened through the huge capacity of the traction battery, with the ICE maintaining it periodically, that would be a perfect solution to our recurring threat of power outages - last one three weeks ago was 4 days, another storm here now.

Pete

 

The Hybrid inverter system has a DC-DC converter section that converts the hybrid battery 288 volts DC to 12 volts DC to charge the 12 volt Auxiliary battery. The DC-DC converter's job is to keep the 12 volt battery always charged when the ignition is on.

Thus, the 12 volt battery is charged directly by the inverter and the inverter uses the 288 VDC hybrid battery as one of its power sources. If the hybrid battery charge level becomes low while in ready mode in park (not neutral) the engine will automatically start and stop to use MG1 to maintain the hybrid battery charge level.

There is a 120 amp fuse between the battery and the inverter so this is an absolute max limit to the charging capacity of the Dc-Dc converter. I don't know the continuous rating of the DC-DC converter though 50 amps would appear to be conservative considering the load with all accessories, lights, seat heaters, blower fans, and rear window defogger all powered simultaneously.

 

This has been done successfully by several Prius owners (basically the same inverter 12v charging system). See:

http://hiwaay.net/~bzwilson/prius/priups.html

or for a more robust approach (directly uses the Traction Battery):

http://www.priups.com/

JeffD

 

Thanks, Don and Jeff, for the great information and links - the HiHY seems the perfect solution for standby power with the traction battery feeding the little 12V one. Just need to get a larger inverter now - 1-1.5 KW to give a little headroom in motor starting. It will be interesting to see how often the ICE cycles at a 75 amp or so 12V load (900W).

If my calculations ar correct, the traction battery capacity is 1872 watt-hrs (288V x 6.5amp-hrs per series-connected cell). I would expect the ICE to cycle at 50% capacity or so, recharging to 80% possibly, above which charging usually becomes less efficient. Maybe every 30-40 minutes?

My 700W inverter was not able to start the refrigerator motor or heating system blower earlier this month. I ran it from the Volvo's battery with an added external deep cycle 100 amp-hr battery, and ended up only running a few interior compact fluoro lights for possibly a 100W total. Still had to run the Volvo every hour or so to keep above 12V.

Pete

 

Pete,

You need to adjust your calculations for the efficiency of your inverter (~80-90%) so it may cycle more often than you predict. When you plan your implementation, be sure to fuse the inverter input at 100 amps or less. The charging circuit fuse (120 amps) can be expensive to replace.

JeffD

 

Good points. Any recommendations for easily finding a 100 amp in-line fuse assembly - Home Depot, auto stores likely to have one?

Pete

 

Pete,

Contact Bob Wilson (one of the earlier linked UPS projects, he is very active on several Prius discussion groups) for any needed advice as he is the one that has personal experience with this approach.

JeffD

 

Try a boating store.

 

Pete,

Bob Wilson suggests (in a current Yahoo Prius_Technical_Stuff group thread) that an 80 amp circuit breaker can be obtained at Recreational Vehicle supply locations.

JeffD

 

Thanks Jeff, and Mark, for your suggestions. My old brain had let go of the fact that about 10 years ago I had installed a 75 amp/12V circuit breaker with an electric windlass (replacing the manual version), on the catamaran were living aboard for several years.

Pete