Looking to install new amplifier and was told "DO NOT exceed a 30A current draw or 350W RMS"

That's a first. I'm not an EE, but I can't think of anyway it could cause any damage unless installed incorrectly. You would run that risk with any aftermarket install. There are plenty of examples of Prius with upgraded audio from mild to wild. I also have a PDX-V9 that I just acquired. It isn't installed yet but I don't forsee issues.

Who was the retailer? Do they have evidence to back up their claim? The problem you will find is that among the uniformed. To many, the Prius is made of this mystical technology that defies the laws of mechanics and physics. Therefore they create idiotic replies like this.

 

If the gear really draws 350 watts, that is about 29 amps and IS a lot of extra load.
It also is a LOT of strain on your eardrums.
If it is good gear and true RMS, about 50 watts per channel is plenty for the inside of a car.

Will it damage your "electronics" ?
I don't know; it is a gamble.

 

Yes, but i don't know that "damage" is the correct word. He's probably right though about not exceeding 30A, the DC-DC converter is only spec'd for so much amperage. There's no alternator on the prius, the MG1 and MG2 are used as generators to charge the HV(high voltage) battery, which then uses the DC-DC converter to step down the voltage and charge the 12V battery located just forward of the rear right tail light. The prius already has headlights, tailights, stereo and computers to power through the step down converter, and 30A is probably the headroom left once you turn everything else on. Generally, when designing electronics, you want to give yourself some headroom to stay under the thermal envelope and not destroy your components. But the manufacturer of a part specs out their products to their own testing, so it should be ok to use up to the limit.

Personally, i would buy some high sensitivity speakers with smaller magnets to get the most from a 50x4 headunit. Make sure the headunit is CES2006 rated to get an accurate standard of wattage. Speaker sensitivity is crucial when designing an audio system around a known power source and one must select the right speakers to adequately match the power source(headunit). You can get decent sound if you do it right. Or you can get low, muffled sound if you just go out and buy the highest wattage speakers you can find. Audio doesn't work that way, and you musn't play into the marketing numbers. It's like camera's and megapixels, it gets me every time when some unknowing consumer thinks more megapixels=better pictures. "It's a higher number, must be better right??".

 

For the geeks on this board. This is what the inside of a prius ICU(Inverter-Converter-Unit) looks like. The DC-DC step down converter(200->12v) is on the same circuit board as the high voltage inverter which steps up the 200V battery to 500V for the electric three phase motors.

Special Issue: Inside the Toyota Prius: Part 5 - Inverter/converter is Prius' power broker | EE Times


This is why you shouldn't go overboard with a big amp. The current has to come from this module.

 

The only real way to know is to set everything up the way you want it. Install the amp, speakers etc.. Then set the sound levels and gain exactly where you want them. Set the volume for the highest you would ever reasonably listen to it.

Then attach an amp clamp over the power wire of the amp, and read the actual amperage and see where you're at.(something like this )

Honestly, i don't know what the max current of the DC-DC converter is either, we're just going off of cfield's word for it, but it does sound reasonable. I also have a 2008 impreza which only had a 95amp alternator stock. I had a 400Wrms class D amp to power a 10" sub and even that would dim the lights heavily if i turned the gain up more than 1/4 way. I had to upgrade to an aftermarket 150amp alternator to give me enough juice and headroom for the amp.

 

Here's a guy with a PDX-V9 installed. Good installation tips also. Maybe ask him: Amplifier Installation Issues - A First Hand Perspective | PriusChat

Here's some other good threads I found that you might want to read/scan through:

Last Build of 2012 3GEN Prius - Mosconi, Illusion Audio, Audible Physics - Car Audio | DiyMobileAudio.com | Car Stereo Forum

2011 Toyota Prius by JT Audio & Accessories - Car Audio | DiyMobileAudio.com | Car Stereo Forum

2013 Prius SQ Build - feat. review of two new products - Arc, AM, Morel - Car Audio | DiyMobileAudio.com | Car Stereo Forum


Total Sound Makeover - Sound Deadening, Speakers, Processor, Amp, and Subwoofer | PriusChat

Sub woofer Install for dummies, no upgraded audio. | PriusChat

Complete Stereo Overhaul | PriusChat

Complete stereo overhaul with Navi and custom subwoofer enclosure | PriusChat

Factory speakers upgrade project (Hertz HSK163 & Audison Voce AV X6.5) | PriusChat

Is there a place to buy a cubby subwoofer/enclosure? | PriusChat

Squawker Mounting Hole Dimension | PriusChat

2010 Prius Fiberglass Subwoofer Enclosure-Left cubby hole | PriusChat

Warning regarding Metra Surround (buy the Scosche) | PriusChat

Custom Stereo Install - JL Audio and DLS - Sub in Cubby Hole | PriusChat

Sub Enclosure Left Cubby Build Pics | PriusChat

 

Doubt it. I have a JL Audio XD700/5 (which is spec'd at 700W) plus several processors and my car is just fine. (except for the smoke I saw coming out of the inverter the other day.. )

In all seriousness, amplifiers don't continually draw what they are specc'ed to draw. You'd be lucky if it draws 100 watts in one burst, especially if you listen to regular music. It's also a Class D amp so it's more efficient. If it was a class A/B then *maybe* I'll be concerned. But unless you listen to test tones at full volume all day, I don't think this is really a concern.

If you're worried, put a 20A AGU fuse on your main +12. See how long til that blows. I'm willing to bet it will be just fine.

Remember that most of the current draw comes from the 12v battery. All the inverter does is top that off.

 

Wow lots of cool builds there, perhaps the prius DC-DC converter can handle more current. But there is another issue. Anyone know the stock battery wire size? That'll be your limiting factor as well. What guage wire does the amp take??

A new junkyard salvage ICU is about $300 if you do happen to burn it out down the road. About what i pay for an upgraded alternator anyways.

Since you already own the amp, just remember what gain you normally keep it at and connect it to the prius battery. Everything loose, just floating around the trunk. Connect some speakers and measure the current with the amp clamp i linked above. See how much extra current you use. If it's not alot, you should be fine, i would install a nice size cap as well to reduce any peak current surges through the ICU.

 

Alpine recommends a 4 gauge wire to the amp. The stock battery cables won't matter as you connect directly to the battery via a fused connection and possibly a terminal block if you need to split out power.

 

Not really.
If you apply a large load for more than a minute or so, then BOTH battery and inverter must be able to keep up. The little battery doesn't have THAT much capacity.

 

That's not how things work. If you are marginally on the line, you could possibly use your battery as a buffer similar to a cap. But when talking about electricity if the current draw averages over time more than the cable can transfer, you will have problems.

If i took a normal gas car, and wired a 10 guage cable to the front battery/alternator and the other end to a battery in my trunk. Then the amp with 4ga cable to the battery in the trunk. That 10 guage cable will burn up. Because the battery will charge when your amp is on it's low points, and then expend energy when it hits. Anyway you look at it, you'll have to average the current over time and spec out the main source wire to that average current. I've installed plenty of systems and i can tell you the only real remedy is to install a larger source(new higher amperage alternator) with larger wiring. Or you can live with flashing headlights and burned out alternators.

But really the 4ga wiring is most likely because of the 100wx4 + 500wx1. If you're only using the 400w side, you'll probably be fine. If you are using all 900w to their full potential(gain up, with bass boost etc..), you might run into issues.

 

That amplifier is not a large load.

 

If he's only using the 100wx4 side, then it's probably not considered a "large load" depending on how you look at it. But if he decides to utilize the 500Wx1 mono sub channel, that's what i would consider a heavy load for a prius. Anything that requires 4ga wire is heavy duty for a factory system on any car. You need to run separate wiring to the alternator even if your battery is in the back, and possibly upgrade your alternator depending on how much headroom was there from the manufacturer.

If someone truly wanted to know the max output of the prius ICU DC-DC converter. It would be an easy test. Just make sure all your lights and systems on the prius are on, then hook up a bunch of steady state 12V lamps, like offroad lights or something. Or hook up a 12v inverter and hook up a bunch of shop lamps. Then just measure the current and voltage as you add more lamps. When the voltage starts to drop from 14v, then you know where the limit is. I would then back it off 10-20% below that max amperage and spec out an amp who's rms wattage falls under that.

Or since you already own the amp, just hook it up and see if the voltage drops when you have your volumes and gains set to your max. Run it for a while and make sure the wire feeding the battery from the ICU isn't hot.

 

4 gauge is a bit on the big side, but not overkill for a 350w rms amp. You really should beef up your ground wire. If you look at my amp build (so far), I used a 6 gauge ground wire. You definitely should be using a reasonably efficient amp. It should be about 80% efficient at full load. If the amp maker doesn't specify efficiency, you should stay away from them. You should be looking for a switching topology amp (generally known as class d or class t). If the amp is class a or class a/b, it will be inefficient. You should also use reasonably efficient speakers. All things being equal, larger magnets mean more efficient. An above poster suggested efficient speakers with small magnets; but that makes no sense. 350w is a lot of power. Unless you really like pipe organ music, I suspect it is more power than you will really need. My personal build will use a jbl ms-8 (8*20w) and a blaupinkt switching amp rated at 75w*2 (78% efficient). the blaupunkt will be powering two 12" subwoofers.

My woofers are 91db efficient. You should be buying reasonably efficient speakers, as it is cheaper than big amplifiers. You should also be using reasonably large speaker wires. I am using 16 gauge for my main speakers and 14 gauge for my woofers.

 

You won't hurt anything with that equipment if installed correctly. I've been running a JL HD900/5 since the car was 2+ months old, so that 3 years 4 months, and no problem what so ever.

frodoz Stereo Upgrade | PriusChat

 

I wasn't referring to magnet size in that context, i was trying to be as simple as possible, sorry for the confusion. Larger magnets may be more sensitive relative to the input, but notice the word relative. The problem with larger magnets is usually larger power handling requirements. So while it may be more efficient with the power it does get, the power requirements are higher overall due to a larger voice coil. My point was to buy lower power handling requirement speakers, with more sensitivity to get the most from a low wattage head unit.

Also, i wouldn't recommend using a smaller guage ground wire as general good practice. While true you can get away with a smaller ground wire due to the short length compared to the 12v wire you run to an alternator. It's generally not good practice to do so. I don't see any reason to either since it's so short and relatively inexpensive, why bother?

All things considered, you can take the advice of people on here and just wire it up. But i would check for any voltage drop on the hardest hitting of all of your music. It should stay rock steady at 14v. If not, then i would back it down.

 

Larger magnets have nothing to do with larger power handling requirements. Some speakers can accept more power before overloading. This is a higher power handling ability, not a higher power handling requirement. The OEM prius speakers have tiny magnets. I haven;t measured the efficiency, but I presume they aren't very efficient. My OEM camry speaker magnets are roughly 4 or 5 times bigger.

I agree you should use a relatively large ground wire. That is why I used a 6 gauge wire for ground, and two 8 gauge wires for my power amps. If I was using 4 gauge for my amp, I would use something heavier for my ground wire. Also, if you read my write up on power for amps, you will see a lot about fuses. The standard cylindrical glass fuses are ok, but their holders range from marginal to dreadful. The blade type fuse holders generally are much better. I personally use the maxi blade fuses which go up to 100 amps. Also the way the wire is attached to the fuse holder is critical. I bought a ratcheting crimp tool. I have seen some 4 gauge wire used for high power amps with ring terminals that I could pull apart with my hand. Not good at all.