2002 Q45 Alternator

[CHAD@FREEMANS]

Has anyone tried replacing the factory alternator with a high output one? I've been talking with Ohio Generator and they have nothing on record for my car. They want me to remove mine and ship it to them so maybe they can make me one. The down side of this is I can't have my car stuck on the lift at the local garage while I'm waiting god knows how long to get one made and shipped back. Thanks for any help.

[Q451990]

I haven't heard of one, but our 2002+ Q traffic is pretty light - in part because there weren't a ton of them sold, and probably also because they're just now getting to the age where we're seeing some issues that people are addressing.

Are you trying to power a lot of audio equipment?

Heath

[CHAD@FREEMANS]

Yes. I installed a Audison LRX5.1k and have had major issues since. The car runs like s*** when I'm jamming pretty hard. I've tried everything to try to get around doing an alternator, but had no luck. I've been doing car audio for a living since 1991 and have never ran into so many problems off of adding a amp. I'm doing some sick stuff, but it's fighting me the whole way.

[Q451990]

I suspect you might get to be our "beta tester" on this upgrade...

Heath

[CHAD@FREEMANS]

Should find out something this week. http://www.youtube.com/user/12voltchad? ... g-k5IH5Gh0

[CHAD@FREEMANS]

Replaced alternator with a 270 amp one. Replaced battery with a Kinetik HC1800. I still have the same problems. Nothing changed except I'm $1000 poorer.

[djwarner]

Remember the Q is an "electric" car in that it needs considerable amperage to run its own electronics. If voltage levels are not the problem, your amp may be throwing a lot of noise on to the 12v bus. This is certainly a possiblity with a class D amplifier.

As a next step, I would run a heavy duty ground from the amp to the chasis and add a one farad capacitor immediately ahead of the amp on the 12v power supply line.

The next issue may be RF noise from the amp interfering with the vehicle electronics.

[CHAD@FREEMANS]

Noise or vibrations was one of my first thoughts. That was ruled out when I installed a battery in the trunk only hooked to the amp and not to the cars electrical system in any way. I had no problems then. I've been doing car audio for a living since I was 18 and I'm now cough 37 and I have never ran into anything like this. Why did it have to be on my personal car

[djwarner]

If I get this straight, the car runs all right with the amp on a separate power system, but runs sh__y when the alternator charges the battery and the amp is on.

Do you have a one farad or better capacitor near the amp?

Just for the record, what is the rated power output of this amp?

[CHAD@FREEMANS]

Correct. The amp is rated at 60x2 170x2 and 750x1 at 4 ohm. It's a class A on channels 1 and 2 A/B on channels 3 and 4 and class D on the sub channel. I measured the sub channel at 2 ohm and it's making about 1200watts. It's a Audison LRX5.1k. I have also tried a JL Audio HD1200 with the same results.

[djwarner]

This means you may be peaking out at 200 amps. At 50% efficiency this means up to 400 amps at the supply. According to the owners manual you should be using AWG 0 or AWG 1 for both the power supply and ground.

If you have a superfard capacitor very near the amp and proper wire sizes, I would suspect the class D sub woofer throwing trash on the power line --- or ---- the voltage regulator sensing lead not accurately seeing the load way back in the rear of the car. Having two batteries separated by more than a few inches can often lead to problems.

I would try to dis-able the sub woofer first. Then, if the problem goes away, slowly build up the power until it reappears. This should give you some idea of how much the power system is capable of supplying.

[CHAD@FREEMANS]

Had Infiniti tech read the car while stereo was playing. The rear wheel speed sensors read 6mph and 4mph while the car is parked and the bass hits. This is not vibration related cause I pulled the subs out and placed them behind the car and still had the same results. Ideas?

[Bosworth Audio]

I have a company that makes them. Actually they make all the high output alternators for all my customers. Swing by the shop sometime and I'll show you them. we just put 9 350 amp alternators on a tahoe. If I'm not mistaken, the highest output you can get out of our stock casing is 290amps at 2000rpms. But I can double check tomorrow

[Bosworth Audio]

looks like i was too late on the reply.

[CHAD@FREEMANS]

I have a 270amp already on it.

[Skibane]

Had Infiniti tech read the car while stereo was playing. The rear wheel speed sensors read 6mph and 4mph while the car is parked and the bass hits. This is not vibration related cause I pulled the subs out and placed them behind the car and still had the same results. Ideas?

Sounds like your amp is swinging the electrical system voltage around enough to look like valid signals at the speed sensor outputs. Some of that voltage swing may also be on the ground side - If your amp is pulling huge current through the vehicle frame, it may be moving the ground potential around.

Suggestion: Use a separate battery for the amp, and connect it to the existing battery through relatively thin wire (6 gauge, maybe?). The resistance of this wire should help prevent your amp and new battery from moving the electrical system's voltage around much. Since the amp is only pulling a lot of current during momentary music peaks, the average current flowing through the wire should be enough to keep the new battery charged.

[CHAD@FREEMANS]

Got under the car and followed the VSS wire from the sensors up into the trunk. My power wire going into the amp was close to the wires. I moved it and the car quit reading VSS. Before anything on my Nav. screen that would turn off while the car was moving (maintenance, etc.) would turn off when the bass hit and the car was sitting still. That is now gone. However the car still jerks and shifts hard at higher volumes. At least I got one problem out of the way. I'll keep you posted.