Higher Wattage??

<div class='quotetop'>QUOTE(TheParadox @ Jun 5 2006, 12:25 PM) [snapback]266003[/snapback]</div>

1) There is no alternator. All 12 volt accessories run off the HV inverter, which converts the HV battery's voltage to +12 volts.
2) The 12 volt system does not start the car, the HV does that. However, I believe several people have posted recently that they did successfully upgrade their battery to a higher capacity one.
3) The HV Inverter's output capability is a little limited, but doesn't seem to be a factor if all you want to do is upgrade the sound system, which only draws higher amperage in peaks, not RMS.

 

The OEM 12 volt battery is about 28 amp-hours and Toyota offers an alternative with about 38. It is somewhat expensive and requires a different hold-down. I am not aware of anything larger than that which also has a vent tube. If you do not feel constrained by the lack of vent tube, there are many larger batteries which will fit the space.

The DC/DC converter is fused at 100 amps, and if you are going to approach that, add a smaller sacrificial fuse for your audio eqpt. You don't want to kill the Prius main fuse.

Even with the headlights and HVAC fan off there is something like a 200 watt load on the 12 volt system, which may cut into what you can do with Big Audio. For thumping bass, you may need a few Farads of capacitors.

A heavy, power hungry audio upgrade will cut mpg by a few. Not more than 5 I'd guess

 

<div class='quotetop'>QUOTE(TheParadox @ Jun 5 2006, 03:52 PM) [snapback]266134[/snapback]</div>

Yes. Or, it also means you can drain 1Amp for 28 hours.

<div class='quotetop'>QUOTE(TheParadox @ Jun 5 2006, 03:52 PM) [snapback]266134[/snapback]</div>

When a battery is being charged, it produces gas, that's what the vent tube is for.


<div class='quotetop'>QUOTE(TheParadox @ Jun 5 2006, 03:52 PM) [snapback]266134[/snapback]</div>

Yes.

 

"This battery, it has a vent tube, what for? where does it vent (Hydrogen?) and where, if i replace it do i need to make some fancy tubing to a new battery?"

Yes it is to blow off hydrogen gas under extraordinary circumstances. Probably won't ever happen, but I cannot say it will never happen to you. If you buy a different battery without the vent tube, it cannot realistically be added.

"The DC/DC Convert... converts traction battery power to 12 volt aux power?"

yes.

"100 amps for the main fuse, so does that mean i only have a max wattage of <1000? or like <800 with headlights HVAC, ect."

I suggest you plan your Prius audio upgrades for 600 watts or less average power consumption. You can handle the peaks with capacitors; see a "competition" audio installer for more details. The most important thing is to protect (by additional fusing) your DC/DC converter and its fuse. If that fuse opens, You Stop. Starting again will cost some real money.

If your audio upgrade plans require more than 600 watts average, fitting it all into the Prius operating system will require some clever work. I am asking for a little "cushion" here, because I am having a hard time with the idea that 600 average watts won't do it for you. How about adding some sound dampening to the body panels? That would reduce the external noise and add some "headroom". Prius people to this; check the archives.

I do not mean to dissuade you from tapping into the 12 volt system. I have, with an added 110 vac inverter. I use it a lot. But you can be sure that it is conservatively fused, so as not to kill my car.