bass911

I have a new alt and battery that came from AutoZone. The car runs fine and I can't feel or see any voltage dips. I hooked up a second small battery on the trunk to power an amplifier. The amp works fine and doesn't go into protect, but I have to turn the gains up too much to get any real power out of it. The most I've seen with the car running is 13.2 and 12.2 with the car off. Yesterday it was reading 12.02 with the car off and the same running. This problem is causing my amp to struggle to make rms power and is barely pushing the sub. I have yet to see it drop on the 10-11 volt range. I would like to see 14.1-13.8 while running and 12.6 at idle. I have some led foot well lights and they dim on a hard midbass or bass note, but the rest of the interior lights don't. The leds are hooked up to the amp battery as the amp. Even with everything unhooked the voltage is still too low.

My question is how do I raise the voltage? Is my new alt bad? I cannot see the alt or battery being bad, but $h!t happens! If I get an aftermarket voltage regulator will it raise the voltage? The car runs fine but it seems like the electrical doesn't like an extra battery or amp. Does anyone know what it could be?

deanshark

Did you get a bigger alternator? The cheap 100amp alt wont be enough for 2 batteries. With an amp and subs the stock size alt isn't enough. I think 180 amps is good but you should wait for an answer from someone else with more electrical knowledge then me.

bass911

Keep in mind that the voltage is still low with nothing hooked up. It is not a bigger alternator. I think it is duralast brand. I'm only running a Precision Power p900.5 amp and a small 600 watt rated agm battery. I don't even see the headlights dimming.

Yamae

The alternator for a Celsior / LS400 has a built in regulator inside and you cannot adjust the voltage at all.

bass911

http://www.ebay.com/itm/ALL-LEXUS-MO...e71843&vxp=mtr

http://www.ebay.com/itm/ALL-LEXUS-MO...e71843&vxp=mtr

http://www.ebay.com/itm/Lexus-Scion-Performance-F-Boost-Volt-Engine-Power-Chip-FREE-3-DAY-USA-SHIPPING-/251323712796?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1997%7CModel%3ALS400&hash=item3a840f851c&vxp=mtr

LScowboyLS

these things are scams - there is no magic power chip to give your LS400 more power, just snake oil

the programming on the LS400 has never been cracked, and until it is, no cheap magic power "chipping"

you can get a very modest gain from a piggyback system such as a MINES, but I sure wouldn't spend $1500 on something barely even noticeable

if you want a cheap performance gain, fix your failing ECU capacitors that have a known defect, not to mention are ~20 years old!

Yamae

I find there are many people who are wasting money and time not knowing the facts.

Yamae

Although the seller is using an expression "Performance F Boost Volt Engine Power Chip", it is just the name. I must say those who want to buy this is the ignorant people.

It is just a capacitor box. Using this will add some capacitance in parallel with the battery. But the ESRs of the actual capacitors used in the box are much bigger than that of the battery's. If it were far less than battery's, the rectified 3 phases AC would have less ripples.

You have to know that automobiles are designed to work well with some ripples. Only strict units like amplifiers and electronics circuits hate ripples but they have filters inside using both serial bigger impedances and parallel low impedances and they eliminate ripples. The ECU hates ripples and that is the reason why low ESR capacitors are needed in the ECU.

The unit is only effective when one or two rectifying diodes in the alternator are dead or the battery is deteriorated and have a too big ESR. Come to think of it, you never can crank the engine with that condition. So I would say the unit is not needed. All you need is a good alternator and a good battery. Don't waste the money buying scams. Sometimes they damage your precious car.

bass911

The alt I have isn't the best but it should still be able to handle the small amount of power I'm running. Getting a HO alt isn't going to help of the ecu is failing, which I don't think it is? I know the car is old but it only has 107,xxx miles on it. I'm not saying the voltage regulator works, but there are some YouTube vids that show an increase. The increase is probably too high and would damage the electrical system?

LScowboyLS

the ECU having issues will not normally cause the alternator to put out less current - the LS400 is, however, kind of on the edge current-wise, with a measly 80amps on your year i believe, so it doesn't really come with any reserve current for your aftermarket accessories

if you like putting aftermarket stuff on your car that uses power, just get a higher output alternator from a reputable manufacturer - problem solved!

the ECU caps tend to fail on your year model, and it is more of a time thing, and setting up for some of its life thing, than it is mileage - my '96 had only 112K and the leaking caps had almost completely ruined the ECU beyond the scope of any repair

bass911

The reason I feel like this alternator should be enough is because I had a first gen ls400 running some real power with 2 Fosgate amps and it was fine. It had a yellowtop battery and no second battery in the trunk. I don't want to spend $200 for ho alt just to replace a brand new alt. The current alt should be reading higher than what it is. I'm taking it to AutoZone tomorrow to have it tested, but I guarantee the batt and alt will test fine. My only other options is to get a stronger amp that does more power at 12 volts because it's not dropping down past 12 or get a weaker subwoofer.

LexGX

iTrader: (1)

OP: what is the amp that you're using? what size gauge wires are you using?

fixmiester

Don't blame the alternator until you are POSITIVE the battery is good. I jumped to conclusions a few years ago, blamed the alternator, took it out and had it tested at two places. It was fine. CRAP!! Turns out the cause of low voltage readings while running under load/no load was a flaky cell in the battery. Have THAT tested first.

bass911

ppi p900.5 with 4 gauge wire. I have a 4v line driver that has a 12db gain. I'll hook it up tonight because the Jvc kw-nt300 has super weak 2v outputs. I had a Jvc with 5v output and did a direct swap with a 2v Pioneer. The Pioneer was louder. It was a night and day difference, and I had to turn the gains down.

Yamae

Check the voltage of your alternator at the terminal B which is the biggest terminal with a rubber cap.
Rev the engine up to 2000rpm. If the voltage stays low like below 14.2V, your only choice would be to replace the alternator.