sometime?Alty not charging at Iddle?

[Xprime4 10+ year member]

i found this so weird. I started noticing this just after i got my whole big 3 done.

Sometime, maybe 1/5 of the time i take my car and make short shopping ride around... when i stop at stoplight, is see 12.8v on my voltmeter. Most of the time it's running 14.4v (cold) to 13.8v(hot), stop (iddle).

Then other times, when the motor is at iddle, without the sound being loud enough to draw signifiant amperage, is just stay there at 12.8v. As soon as i push slightly the gaz pedal (not big rpm there... just over 800) the voltage goes back to 13.8v within few second

what's up there? i only noticed this after the big 3. Batteries are full i'm pretty sure of this. stock alty 90amp on elantra gt

Click to read more...

 

[lostdaytomorrow 10+ year member]

Could be the ECM regulating voltage like **** Honda's do.

 

[x1le 10+ year member]

Most alternators output more when driving and less at an idle. That's why if you've ever been to a bass comp, you'll hear some of the cars revving their engines slightly...

 

[dman4486 5,000+ posts]

Could be the ECM regulating voltage like **** Honda's do.

I removed the wire going to the ECU as my system was double regulated....it is great now

 

[Xprime4 10+ year member]

Most alternators output more when driving and less at an idle. That's why if you've ever been to a bass comp, you'll hear some of the cars revving their engines slightly...

yeah but i mean it does charge at all... even if i stay few mins at iddle...

ecm plug? how do i check

 

[clouduz 10+ year member]

lol wow i need to read everything first

 

[clouduz 10+ year member]

except mine will slow drop to the low 13's before i revv it to bring it back to 14.

 

[eggster 10+ year member]

What kind of batteries do you have and what's the weather like where you're at? Sometimes when you add a second battery, if it's in the trunk and the weather is cold, this may cause excess load on your alternator. This can also happen if your batteries are not matched, one may be losing charge quicker than the other, then your alt has to work overtime to get it charged up.

Also, this may be normal, you may not have noticed it in the past because of the fact that the Big 3 wasn't done so you may not have been getting accurate readings..

Check this out.

I decided to run a Fosgate T30001BD on a pair of JL12W7s.. I came across the Fosgate amp on Craigslist, picked it up for $300 BNIB. Some poor idiot bought it "WITHOUT HIS WIFES PERMISSION" (that shit cracks me up, grow a pair, anyway, his loss, my gain)

Until then, I was just running 4 Gage from the main battery to the Optima in the trunk, Mmats D3500.1 for subs.. Mind you, I had just installed the JLs about a month before, didn't have much time to do anything, just slapped it all in there rush job.

For music it was fine, the bass hit pretty hard but I knew there was much more in it.

When I came across the Fosgate, I couldn't pass it up, I knew that if I didn't like the amp, I could just as easily sell it and double my money so I pulled the trigger.

I hooked the amp up and noticed a big drop in output power, lights dimming badly, distorted sound.. I hooked a MM to the main battery got a reading of 11.8 (all this is just going from memory) At the alternator, I was getting almost 14 volts, at the Optima I was getting 11 and change, even lower than the main battery, when I used the chassis ground under the hood, I was getting an even worse reading.. The point is, I was getting ridiculous readings everywhere. Bad grounds, faulty wiring (98 Acura CL, Northern car, lots of rust)

I decided to get the Big 3 done. (put it off because I didn't have time and the Mmats amp was OK the way it was)

I removed all of the factory wiring from the alternator all the way to the main fuse box under the hood. I put nice 4 Gage from the main battery to the chassis and engine, put an extra 4 Gage from the engine to the chassis. Then I went 4 Gage from the + of the main battery to the fusebox under the hood. Went 4 Gage from the + out from the alt to the + of the main battery. Went 0 gage from the main battery to the Optima. Grounded the Optima to the trunk floor with 0 Gage. Then grounded the big digital cap to the trunk floor with 0 Gage. Ran 0 Gage to the Fosgate from the trunk floor, 0 Gage + from the optima to the cap, then to the Fosgate. After all the wiring was done, I put the MM on and got a reading from 13.4 to 13.6 anywhere I put the MM to.. This did the trick.

When I tuned the amp and put in Bass Mekanik, I couldn't believe my ears.. 30HZ and lower on the test tones from the Bass Mekanik CD were the only thing that made my lights slightly dim, that's with the Fosgate amp. (Fosgate is a serious current hog)

I took the Fosgate out, installed the Mmats D3500.1, it hit almost as hard as the Fosgate, but it never made my lights dim. I ended up blowing 1 of the surrounds clean off the cone with the same 30HZ test tone, destroyed one of my JLs.. This is despite the fact that the Mmats amp wasn't delivering its full payload, it is designed to do 2700 watts rms @ 1 ohm, the JLs were showing it almost a 2 ohm load which I was told was robbing me of nearly half its power..

I sold the Fosgate T30001BD for $750, now I am selling the Mmats D3500.1 and the 2 Matching Mmats 4 channels (SQ4150 and SQ4160)

Looking for PPI Art series amps, beat up for cheap if possible, the cheaper the better, don't care what they look like as long as they are functioning 100% and are all original inside.. Need an A600.2 and an A300.2 or an A404.2.

Anyone with beat up .2 Art series amps please send me a PM. The cheaper the better, prefer beat up amps because I am going to refinish them with custom powdercoat and graphics..

Anyway, back on the subject, you may have nothing to worry about. As long the voltage jumps when you rev, you should be alright. The only other thing I can think of is that you might want to check the voltage at the alternator when the car is idling, put a MM to the alt and chassis and check your voltage right from there. If you are getting a different reading at idle (different from your digital display) then pull the grounds off both batteries and check the voltage from each. If one is down on power, go back through your wiring. (But before you do that, make sure to pull the grounds and check both batteries.)

If it's not your wiring, and if your batteries are off, you may want to consider matching batteries. If one or both of your batteries is not up to snuff, it/they may be putting a heavy load on your alt, that is in addition to the current draw from your amps.. This will lead to bigger problems later..

Summary:

A) Check Alternator at idle. Use the Positive and Negative directly from Alternator for the first reading, if it's the same there at idle (same as the reading you're getting with your voltmeter) then it's the alt or regulator. If you are getting a different reading at the alt then go to step B

B) pull the grounds off both the batteries (with the car off) check voltage on both batteries. If one is off, then try a pair of matching batteries. Use Gelcaps front and back. If they are both good, then go to step C

C) Go back through your wiring, put a MM everywhere, find the bad connection or ground. Make sure that all of your grounds are as short as possible, put as many grounds from the main battery to the engine and chassis, alt to chassis, trunk battery to trunk floor, make sure all of your connections are solid, when grounding, make sure you grind till you have lots of bare metal, then use the special battery grease to keep it all from rusting..

Hope this info helped. Good Luck.

 

[audiolife 5,000+ posts]

You might need a smaller alt pulley.

 

[Xprime4 10+ year member]

What kind of batteries do you have and what's the weather like where you're at? Sometimes when you add a second battery, if it's in the trunk and the weather is cold, this may cause excess load on your alternator. This can also happen if your batteries are not matched, one may be losing charge quicker than the other, then your alt has to work overtime to get it charged up.
Also, this may be normal, you may not have noticed it in the past because of the fact that the Big 3 wasn't done so you may not have been getting accurate readings..

Check this out.

I decided to run a Fosgate T30001BD on a pair of JL12W7s.. I came across the Fosgate amp on Craigslist, picked it up for $300 BNIB. Some poor idiot bought it "WITHOUT HIS WIFES PERMISSION" (that shit cracks me up, grow a pair, anyway, his loss, my gain)

Until then, I was just running 4 Gage from the main battery to the Optima in the trunk, Mmats D3500.1 for subs.. Mind you, I had just installed the JLs about a month before, didn't have much time to do anything, just slapped it all in there rush job.

For music it was fine, the bass hit pretty hard but I knew there was much more in it.

When I came across the Fosgate, I couldn't pass it up, I knew that if I didn't like the amp, I could just as easily sell it and double my money so I pulled the trigger.

I hooked the amp up and noticed a big drop in output power, lights dimming badly, distorted sound.. I hooked a MM to the main battery got a reading of 11.8 (all this is just going from memory) At the alternator, I was getting almost 14 volts, at the Optima I was getting 11 and change, even lower than the main battery, when I used the chassis ground under the hood, I was getting an even worse reading.. The point is, I was getting ridiculous readings everywhere. Bad grounds, faulty wiring (98 Acura CL, Northern car, lots of rust)

I decided to get the Big 3 done. (put it off because I didn't have time and the Mmats amp was OK the way it was)

I removed all of the factory wiring from the alternator all the way to the main fuse box under the hood. I put nice 4 Gage from the main battery to the chassis and engine, put an extra 4 Gage from the engine to the chassis. Then I went 4 Gage from the + of the main battery to the fusebox under the hood. Went 4 Gage from the + out from the alt to the + of the main battery. Went 0 gage from the main battery to the Optima. Grounded the Optima to the trunk floor with 0 Gage. Then grounded the big digital cap to the trunk floor with 0 Gage. Ran 0 Gage to the Fosgate from the trunk floor, 0 Gage + from the optima to the cap, then to the Fosgate. After all the wiring was done, I put the MM on and got a reading from 13.4 to 13.6 anywhere I put the MM to.. This did the trick.

When I tuned the amp and put in Bass Mekanik, I couldn't believe my ears.. 30HZ and lower on the test tones from the Bass Mekanik CD were the only thing that made my lights slightly dim, that's with the Fosgate amp. (Fosgate is a serious current hog)

I took the Fosgate out, installed the Mmats D3500.1, it hit almost as hard as the Fosgate, but it never made my lights dim. I ended up blowing 1 of the surrounds clean off the cone with the same 30HZ test tone, destroyed one of my JLs.. This is despite the fact that the Mmats amp wasn't delivering its full payload, it is designed to do 2700 watts rms @ 1 ohm, the JLs were showing it almost a 2 ohm load which I was told was robbing me of nearly half its power..

I sold the Fosgate T30001BD for $750, now I am selling the Mmats D3500.1 and the 2 Matching Mmats 4 channels (SQ4150 and SQ4160)

Looking for PPI Art series amps, beat up for cheap if possible, the cheaper the better, don't care what they look like as long as they are functioning 100% and are all original inside.. Need an A600.2 and an A300.2 or an A404.2.

Anyone with beat up .2 Art series amps please send me a PM. The cheaper the better, prefer beat up amps because I am going to refinish them with custom powdercoat and graphics..

Anyway, back on the subject, you may have nothing to worry about. As long the voltage jumps when you rev, you should be alright. The only other thing I can think of is that you might want to check the voltage at the alternator when the car is idling, put a MM to the alt and chassis and check your voltage right from there. If you are getting a different reading at idle (different from your digital display) then pull the grounds off both batteries and check the voltage from each. If one is down on power, go back through your wiring. (But before you do that, make sure to pull the grounds and check both batteries.)

If it's not your wiring, and if your batteries are off, you may want to consider matching batteries. If one or both of your batteries is not up to snuff, it/they may be putting a heavy load on your alt, that is in addition to the current draw from your amps.. This will lead to bigger problems later..

Summary:

A) Check Alternator at idle. Use the Positive and Negative directly from Alternator for the first reading, if it's the same there at idle (same as the reading you're getting with your voltmeter) then it's the alt or regulator. If you are getting a different reading at the alt then go to step B

B) pull the grounds off both the batteries (with the car off) check voltage on both batteries. If one is off, then try a pair of matching batteries. Use Gelcaps front and back. If they are both good, then go to step C

C) Go back through your wiring, put a MM everywhere, find the bad connection or ground. Make sure that all of your grounds are as short as possible, put as many grounds from the main battery to the engine and chassis, alt to chassis, trunk battery to trunk floor, make sure all of your connections are solid, when grounding, make sure you grind till you have lots of bare metal, then use the special battery grease to keep it all from rusting..

Hope this info helped. Good Luck.

ok thanks for that, i'll have to check that pretty soon since the batt upfront ain't the same as the one in the rear.

All i need is the one upfront rest at 12.4 and the agm in wheel pit rest at 12.8v. There was an isolator prior, but it blow.... and i don't know why. I didn't bother buying another one ever since

i wish i could get the batt at your price. Agm are rare over here and they sells at sick price.

 

[dman4486 5,000+ posts]

check your numbers with a dmm at the batt and again at the alt....just to be sure it isn't a gauge issue.

 

[Xprime4 10+ year member]

check your numbers with a dmm at the batt and again at the alt....just to be sure it isn't a gauge issue.

i don't think. I've just added some more wire to the stock one.

problem is now everyday. if the car is stopped... not charging.. if i release the brake pedal slowly... it starts charging, if i push the pedal, then it charge quick

 

[AlterEgo99 5,000+ posts]

I'm only running 1000W RMS and typically never get anywhere near full tilt at that. My '08 Silvy's PCM regulates the alternator output anywhere from 11.5 to 15.5 volts. This is normal for my truck per GM technicians. I have a Kinteik HC 2000 up front and will be adding another under the hood in the next couple of weeks. I'm looking at some of the aftermarket voltage regulators from Missing Link Audio or XS Power (not out yet) to keep the voltage at around 14 volts. So, I think you are OK unless you do the same and get one of the aftermarket voltage regulators.

 

[Xprime4 10+ year member]

i've got alot of power on tap, but i'm not using it at all....

i mean, even if i ride 15min with amps off... the voltage will still stay in the hi 12ish when i'm completly stopped. If i release the brake pedal and the car move slowly... voltage get up a little, if i press the gaz pedal, it goes up quickly

 

[Xprime4 10+ year member]

while i was riding back from school, i noticed the alty wasn't working at stoplight ... but once i got home to put the dmm on it , it was working //content.invisioncic.com/y282845/emoticons/mad.gif.c18f003ab0ef8a0d9c27ca78d77a6392.gif

i hate that shit