Inverter and optima install question

I suggest you have a look at the 12v battery and the amount of room available. A size 51 Optima will fit but a "standard size" one will not. There isn't a lot of room in the rear fender well.

Remove hatch floor.
Remove right side battery compartment cover (behind right rear wheel in hatch).
You can use a tape measure to guesstimate how much room you have. Note that there is a ridge down there that the battery must miss if it is to sit all the way down.

The Prius charging system should be able to handle about 40A. That's about 500 W. It can certainly recharge the larger battery, though it will take some time. So you could -draw- your 1800 W from the battery only, but only for a short period of time before it gets too discharged.

Looks to me like 1800W is just too much for a Prius. You need a vehicle with a 120A alternator.

 

The Prius charging system can handle 74A (~1020 watts) without breaking too much of a sweat. Check out the Prius UPS Project. The author has some good detail on his install. It looks like he's only using the stock 12V battery, as well. Throw a few Optimas in there, and you've got your extended run-time.

 

^^^

I do not know. It just says there's a 120 amp fuse, but I don't see where it charges at 120amps. It does mention in one of the diagrams, that the HV battery charges the Aux battery at ~100amps.

I'm referencing the part of the document that talks about the current draw from the heater about 3/4 the way down.

 

The first thing with any large inverter added to the Prius12 volt system is protecting the car. Bob Wilson (linked above) feels that the added inverter’s own fuse does this, but for mine (2001 Prius) I added a 60 amp ANL fuse. That size will actually pass 100 amps for quite a while before it melts.

Lacking any such protection, the Prius main 120 amp fuse could open. This immobilizes the car and is a nontrivial replacement job. Not what you want at the wrong end of a long dirt road.

The 1000 watt (or so) capability is there when the Prius is in ‘ready’. As suggested above, you would need much more battery capacity to carry such loads with the car off.

 

This has some good information on installing a yellowtop in the Prius:

Prius Optima Aux

 

I just sent off an order for the Elearnaid optima and install
kit, in fact -- while my OEM battery is still functional, it's
a bit below 12V when supplying IG-ON mode and being the original
'04 MY unit I figure maybe it's time to replace it proactively.
It'll be interesting making sure my Anderson connector can still
interface to the new connection hardware.
.
Otherwise, darell's page pretty much has this swap/upgrade covered..
.
_H*

 

Up to the 1 KW limit as demonstrated by Bob W. A small voltage sag at high current load would be anticipated.

The car's computers and inverter coolant pump are always on in 'ready' AFAIK these are the only loads to the 12 v system you cannot shut off (ntil the radiator fans decide to spin). I don't knw that this 'base load' has bene quantified.

 

Read the posted readings more carefully. Notice how the voltage starts to drop. The Prius 12V system runs at 13.8V when the car is "on". If it starts to drop you have "overloaded" the charger circuit. Probably no damage will result, but as I stated above, it's capable of supplying about 40 Amps, which I consider with NO voltage loss. If you start drawing 70-100 Amps your voltage will drop below 12V and your inverter will suffer accordingly.

It just isn't designed for a 1000 or more watt draw!

 

In the Prius UPS link I posted, you can see that 74A drops the voltage a bit (13.75V from 13.94), but not what I would call, "stressing the system". 1000 watts is not a problem for the Prius to handle in READY mode. Depending on the loads that will be run, it's not going to be a constant draw. Based on these numbers, I would say it's safe up to 1000 watts. Beyond that, the voltage starts dropping heavily to maintain the current.

 

you could always just add any extra battery you want in the trunk with an isolator. that way once the battery dies, your main car battery is fine. another option is just swap it with the optima yellow top, and also add on battery brain. my old car a beretta said this certain yellow top model would fit. i had to take out the battery tray, cut one side off, and beat in part of the wheel well to give enough room so that it would fit right. so if you measure or estimate what will actually fit, this may be an option to give you a lil more size as long as the new battery is and will be secure.

 

It'll be fine. You probably don't even need the car in READY mode, if it's only going to take 4 min. When my AUX battery was minty, I had no problems blasting tunes for 30+ minutes or watchin' an hour worth of TV shows. I'm gonna have to look into that Optima Yellow Top kit, since I seem to like to deep cycle

 

Here is an interesting read from an old-timer. Designs of using the Prius up to 3kW.

PriUPS-getting electricity FROM your hybrid vehicle

 

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