getting a 15v rating on a 12v system
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=118222
Printed Date: April 25, 2024 at 6:40 AM
Topic: getting a 15v rating on a 12v system
Posted By: still_walkin
Subject: getting a 15v rating on a 12v system
Date Posted: December 04, 2009 at 7:13 AM
I have a 1993 cadillac deville and it has a 800cc 1000c battery big 3 zero guage all stock and a 250a alt I got from highoutput alt.com . The alt was 240 but I had it beefed up after I broke it . So I'm messing wit my sitnger digital led read out on my battery and the car is on headlights on and I'm getting 14.25 thn 14.50/14.75 it jumps around then hits 15.01 for like two seconds then goes back down. Is this a good thing seeing how I haven't wired the system in yet. Post your thoughts thanks
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Replies:
Posted By: blackcivichatch
Date Posted: December 04, 2009 at 11:47 AM
I know that I wouldn't be complaining about gettin 15 volts. But if its jumpin around like that when youre just idling and no system on, it sounds like somethin might not be right.. Does you alt have an internal voltage regulator?
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UNLABELED Custom Car Club President
Posted By: yimke
Date Posted: December 04, 2009 at 12:24 PM
Ya check your voltage regulator. It sounds like it is working because it jumped it back down, but it might be going out because it spiked like that.
Posted By: still_walkin
Date Posted: December 04, 2009 at 2:27 PM
It has a internal voltage reg. in the alt.
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: still_walkin
Date Posted: December 05, 2009 at 7:19 AM
So I go out there last night and check the voltage after I crank and start the car I get a steady 15.89 and I'm thinkin my alts gonna die on me or my battery is gonna explode. So after work I check it with a regualr voltmeter and the battery cable and get these results below. I think those battery post are designed to boost your voltage from your orginal numbers giving you false numbers. Is there another way to boost your voltage .
Car off
Stinger batt post 13.70
Regular voltmeter12.80
Car on
Stinger 15.04
Volt 14.40.
What you all think.
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: oldspark
Date Posted: December 05, 2009 at 9:41 AM
It sounds like you have a voltage drop between the battery and the alternator's sense wire.
That shouldn't happen if it is a single-wire alternator - ie, (excluding the obvious ground/chassis & battery B or B+ heavy connections) it only has a charge-lamp connection aka D+.
If it's a 3-wire - typically Ig (+12V), L (charge lamp), & S (Sense), the S should be taken to the battery.
If it's a 2-wire - ie, L = charge lamp & S or I or Ig = +12V - then the latter S has to be connected to the battery +12V.
Instead of powering S from whatever power wire, insert a relay.
Actuate the relay with the power wire (ie, to #86 with #85 to chassis) and use #30 & #87 to connect the battery +12V to the alternator's S terminal.
FYI - battery 13.7V sounds like a typical 12V battery with its post-charge "surface charge". It should drop to ~12.7V after a some minutes with a reasonable load.
14.4V is a healthy maximum charge voltage (long-term - meaning not higher, but may drop to 13.8V "float voltage" once the battery is charged). This is expected wherever the alternator gets its "Sense" voltage from.
Erratic voltmeter readings may be due to normal AC fluctuations on the supply. Digital voltmeters tend to be "sample & hold" - ie, whatever instantaneous voltage (spike/dip). (That's another instance where where "True-RMS" meters are required.)
Analog meters tend to show an average (of any variation).
A "true-average" can be shown with an RC filter for the voltmeter.
Posted By: still_walkin
Date Posted: December 05, 2009 at 11:27 AM
They are both digital and I took the numbers from the battery . The battery is a double post. I took the readings from the top post. And these numbers came right when the car is off and right when it was started
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: oldspark
Date Posted: December 05, 2009 at 12:22 PM
So which voltmeter is showing the correct voltage?
The Volt indication is fine.
The Stinger reading is too high for a battery.
Posted By: still_walkin
Date Posted: December 05, 2009 at 3:26 PM
That's what I was thinking too when I first installed the terminals I used a regular digital meter and got around those numbers so I'm gonna rule out and ignore those stinger numbers and try another meter and see what I get
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: DYohn
Date Posted: December 05, 2009 at 7:23 PM
Forget about those crappy indicators built into your equipment which may or may not read correctly and test your system with a real volt meter. ------------- Support the12volt.com
Posted By: still_walkin
Date Posted: December 05, 2009 at 7:26 PM
Pretty much I was thinking if that meter was right which its not wouldn't the battery burst or give after this much over charging
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: i am an idiot
Date Posted: December 05, 2009 at 7:52 PM
Chances are the "Bling Volt Meter" you know the one mounted to the battery is inaccurate. Running 14.4 volts into a battery will not usually make it blow up. Seriously get a decent meter to see which of the 2 you have is inaccurate.
Posted By: still_walkin
Date Posted: December 05, 2009 at 7:56 PM
Yea I know My bling meter is wrong what I was saying about the battery is if it was charging constantly at 15v on a 12v battery what would happen to the battery
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: zerepdivad
Date Posted: December 05, 2009 at 8:11 PM
Just trust the multimeter. 14.4 is a healthy alternator.
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A DMM is a beautiful thing.
MECP Advanced Installer Certified.
Posted By: still_walkin
Date Posted: December 05, 2009 at 8:13 PM
Yea I kno I left the ground on the pos terminal unplugged.
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: oldspark
Date Posted: December 06, 2009 at 1:14 AM
still_walkin wrote:
what would happen to the battery
Above 14.4 Volts (long-term) cooks the battery (gassing etc).
It usually wrecks AGS (VRLA) & Gel Cels because they have no fluids to boil off. (And you can get thermal runaway on AGMs.)
Some AGMs claim they will tolerate above 14.4V provided they do not overheat.
Posted By: still_walkin
Date Posted: December 08, 2009 at 12:58 PM
Sounds crazy.
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: oldspark
Date Posted: December 08, 2009 at 4:59 PM
The truth often does.
(According to others. In that regard, I no longer judge.)
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