I'm a Navy Sailor stationed in Italy with a 2018 SV, which doesn't exist in Europe, so it's VERY CHALLENGING to get this diagnosed. I bought the car and got it couple weeks ago shipped from America, everything seemed fine at first, so I don't know if getting amplifiers and high wattage speaker and subwoofer upgrades the Italians installed on the stock battery is the reason for this. I'm pushing 3000+ watt RMS.

On two occasions, I have driven and come to a stop, and then I press on the pedal, and the car just inches along slowly. I can't remember if it even revved, but I don't believe so.

As I'm holding down the pedal, the car just rockets forward after a 5-6 second delay like a spaceship.

The only common denominator that I can remember is that both times this happened, i had been booming the new Hertz speakers and subwoofers at a deafening level for like an hour on city roads. And both times, i freaked out, causing me to turn down the music and after a minute of the issue continuing on and off, everything went back to normal.

 

It's entirely possible you're running too much power for the current electrical system (thank you captain obvious). I know there's a grey area in most discussions, but typically once you cross a line with power input demand you're taxing the electrical system, period. It only has so much reserve power over the normal engine operation before it's just too much. Capacitors may not do it, upgraded alternator is normally the best way to go. In the old days guys would had multiple batteries in the trunk. All a bit overkill this day and age, the high output alternator is a good place to be. Also note, that with all this going on, your battery may not be getting a regular charge thus the lifespan of that battery will be diminishing.

Good luck finding an aftermarket high amp alternator for this car though. My guess is it hasn't been made yet.

 

The company that installed the system suggested adding a second battery. Is this the way to go since finding a high powered alternator is difficult for this vehicle?

 

As with everything, it's all subjective to the variables. You mentioned RMS output, but never mentioned the hardware or the input power required. That's really more important when evaluating options. If you're gonna crank it like this all the time, then yeah you gotta do something about it. But if you only experience problems after a full hour of pounding, then what I would suggest is that #1, don't pound it at idle for extended periods, and in-between turn things down for 5-10 minutes while cruzing so you're getting the battery back up to charge. Also, pounding for that length of time, even high quality woofers are going to heat up, they may be more prone to fail if you are constantly playing them loud. Car audio is much different then say DJ/PA systems audio. Those systems are designed for prolonged abuse, as much as 100 straight hours of peak recommended RMS...but car audio, not really that durable most of the time.

But I guess the short answer is yes, an additional battery with the proper wiring and any other considerations is likely your best option. I'd have them run some tests without the second battery at peek RMS, then externally add a second battery, be sure everything is back up to full charge, then test it again, with the adequate meters on the terminals to see if there's an actual improvement with the extra batter. Proof of concept before investing in the install so to speak.

 

That being said, even with the second battery, you may still have some limitations as to how long you can pound at full volume. Point being, the extra battery may help but it may not completely achieve unreasonable expectations of how long you can run at full volume. The extra weight of at least 50-70 pounds for the battery and wiring in addition to all the other equipment you have added, you could possibly exceed the cargo capacity of the car, all to get 1.5 hours of hard hitting instead of 1.0...

 

For the door speakers, my Hertz HP 802 needs 100 Amps at max musical power (1800W) which I not near as I run 1000 watts RMS to the door speakers.

The amp for the subs Hertz HP 3001D uses 150 amps at Max musical power which is 3600 watts. I run 2400 RMS.

The amp for the 300 watt RMS tweeter system is Hertz ML Power 4 and needs 50 amps at max theoretical power.

So theoretically 300 amps required for the speakers.

 

You are pulling out more power than the alternator can keep up with. You need at least a 150 amp alternator or more as well as the 2nd battery for reserve. Any good alternator can be adapted if it fits in the tight quarters. Check the Infinity Q 80 alternators for a start.

Try this vendor for good advice.

https://www.powerbastards.com/

 

Thanks for the pro tip. If I wanted to save money, would I be fine with just getting the battery since I can find that very easily in Italy? I hope I don't have to fork out cash for both after breaking bank on a sound system . Which upgrade would you do first, and why?

In addition, what do our stock alternators crank out and why do recommend a Q80 alternator?

Thanks again!!

EDIT: Do you recommend this product? It's 125A at idle (less than the 150 you said) and then 250 at 1,200 rpm.

 

I think you need the more powerful Alternator then you do the second battery. I'd devote my funds to get that option in place before adding the battery. As stated, you may still need a second bat, but just having an extra battery with a load like that, there's no way that alternator is going to keep up with that demand from the stereo and still be able to charge both batteries. So my recommendation would be get the alternator upgrade, and see if that by itself solves this initial problem.

 

I'm on board with Madmax's advice. While I don't know for sure, I think the Q80 alternator might be more powerful, yet still fit. You'll need to do some research to be sure but at least you have a starting point. So the stereo installer has no wisdom on this? Seems like they would be 1st to squalk about this power loss possibility

 

He says the alternator is unnecessary and that he installs 20 speakers on tiny little Euro hatchbacks with weak alternators and all that's ever necessary is adding more batteries.

I'm still gonna follow your advice and get the alternator.

 

Have you performed the big 3 upgrade? That many watts is too much for the stock battery system.

 

No i haven't. Reading up on it now.

 

Coming from someone who also has a high powered audio system in their maxima sr (6000W+ RMS) you will either need to upgrade your alt (there are a few people that do HOA for our vehicle) or I would recommend bypassing the stock battery and placing a lithium battery in the rear. I took the later route and have 0 issues. My voltage does not drop below 13.5 after bumping full tilt for over a hour or so on city roads. I will more than likely upgrade my stock alt soon as well though so that I don't drop below 14v.

 

6000w RMS...I love loud music, and I love car audio upgrades, but even I gotta say...why so much power?

 

I am pushing 4x custom built Digital Design 10's. My build is for competition as I compete in SPL car audio competitions. Smaller box = more power needed to get loud, bigger box = less power needed to get loud. I am right around 150dbs with my current setup. Hoping to get a bit louder after alt upgrades.

 

I guess for a competition it's worth it. But damn...it's not like you're driving it on the track so you can test your own merit, it's just who can build the loudest proudest sound system that stands still in a parking lot. Which I get it, but I personally couldn't justify the expense.