DENSO ALTERNATOR OVERCHARGING?
#2859936
12/14/20 04:52 PM
12/14/20 04:52 PM
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Joined: Jan 2010
Posts: 1,442 NW Chicago suburban area
Mopar Mitch
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OP
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I recently installed the lighter weight ~1986 Toyota 4-Runner alternator onto my new SB stroker 410, cast iron heads. I also installed a new AutoMeter Volt meter gauge... by-passing the rally dash alternator gauge. I've also purchased a new Optima Red Top battery (trunk located.. replacing the old one after past ~12 years).
I purchased a brand new DENSO (not remanufactured) from AUTOZONE... lifetime warranty. This alternator has an internal voltage regulator, so, I removed the firewall voltage regulator.
I also purchased the AR Engineering Pigtail (AR016), as well as the AR022 SB mounting brackets.
Headlights and turn signals are much better (no more dimming or slow blinking at idle). But, I've observed the voltage reading on the new AutoMeter gauge to be about 15-15.5 most of time, slightly lower... about 14.5-15 with heater and lights on.
I tested the alternator and it reads the same as my new voltage gauge,,, 14.5-15.5... avg 15.
Any suggestions what could be the problem? Shouldn't the voltage read only between 12.5-13.5 at most?
Advice truly appreciated.. I don't want to have electrical problems.
Mopar Mitch
"Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers!
Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: roadrunninMark]
#2860234
12/15/20 10:55 AM
12/15/20 10:55 AM
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Joined: Mar 2006
Posts: 9,894 MI, usa
dvw
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15.5 v is to high. If the ground side (alt case) has voltage drop to the negative terminal of the battery it will overcharge. Same issue if the power cable to the positive of the battery has voltage drop. The voltage sense circuit of the regulator reads the battery voltage as being lower than it actually is. If this condition occurs, the field current will increase. This will cause output voltage to rise out of range. Doug
Last edited by dvw; 12/16/20 11:28 AM.
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: moparx]
#2861287
12/17/20 01:26 PM
12/17/20 01:26 PM
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Joined: Aug 2004
Posts: 139 Mass.
dartmadness
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The location of your sense wire is key. If located at your starter relay it should sense the voltage currently be demanded. If the demand is light it should charge less. If your battery has a weak cell it will rmain high. I think the charge wire from alt. should go direct to batt. or starter if stock setup and not running a ford soleniod .This is a good read to explain . http://www.madelectrical.com/electricaltech/remotevoltagesensing.shtml
Last edited by dartmadness; 12/17/20 01:29 PM. Reason: Added info.
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: dartmadness]
#2861322
12/17/20 02:49 PM
12/17/20 02:49 PM
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Joined: May 2019
Posts: 6,358 nowhere
Sniper
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Battery charging voltages will change with temperature, not sure if that alternator you have has that ability though. https://batteryuniversity.com/learn/article/charging_at_high_and_low_temperaturesCharge voltage will be higher than the float voltage, 14.8v @70 degrees F. Once you start the car the charging system has to top off the battery quickly so the charging voltage will be high, automotive starting batteries are designed for this. Once it gets close to fully charged it'll drop down to what's called a float voltage, this is the13.8v @70 degrees F or so you see bandied about. As temps rise both of those voltages will drop, as temps get lower both of those voltages will rise. There is no one voltage that should be correct all the time.
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Sniper]
#2861386
12/17/20 04:31 PM
12/17/20 04:31 PM
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Joined: Jan 2010
Posts: 1,442 NW Chicago suburban area
Mopar Mitch
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pro stock
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OP
pro stock
Joined: Jan 2010
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NW Chicago suburban area
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All -- I truly appreciate everyone's replies and advice. Once I get it figured out, I'll let you know.
Mopar Mitch
"Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers!
Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: fourgearsavoy]
#2863012
12/21/20 04:26 PM
12/21/20 04:26 PM
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Joined: Jan 2010
Posts: 1,442 NW Chicago suburban area
Mopar Mitch
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OP
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Joined: Jan 2010
Posts: 1,442
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fourgearsavoy... T/Anks for the input... that sounds encouraging.
Mopar Mitch
"Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers!
Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Mopar Mitch]
#2863015
12/21/20 04:35 PM
12/21/20 04:35 PM
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Joined: Jan 2003
Posts: 5,450 So Cal
Sinitro
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A crucial point is the tolerance of DC voltage measuring device...For example, a precision Fluke multi-meter has a tolerance of +/- 0.5%.. But a typical automotive DC voltage gauge has a much wider tolerance up to +/- 5.0%.. or up to a 10% window..... Just my $0.02...
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Sinitro]
#2863020
12/21/20 04:41 PM
12/21/20 04:41 PM
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Joined: May 2019
Posts: 6,358 nowhere
Sniper
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A crucial point is the tolerance of DC voltage measuring device...For example, a precision Fluke multi-meter has a tolerance of +/- 0.5%.. But a typical automotive DC voltage gauge has a much wider tolerance up to +/- 5.0%.. or up to a 10% window..... Just my $0.02... It is certainly true of the AutoMeter voltage gauge I have. Compared to my work Fluke, which is regularly calibrated, it's way off.
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Sniper]
#2863113
12/21/20 09:07 PM
12/21/20 09:07 PM
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Joined: Jan 2003
Posts: 5,450 So Cal
Sinitro
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A Fluke multi-meter is guaranteed to have a tight tolerance... If your Fluke is off significantly even when recalibrated... I would question the calibration procedure, by whom? And if still off alot perhaps the Fluke is an older 1 that has some internal components changing value... Just my $0.02...
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Sinitro]
#2863159
12/21/20 10:40 PM
12/21/20 10:40 PM
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Joined: May 2019
Posts: 6,358 nowhere
Sniper
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A Fluke multi-meter is guaranteed to have a tight tolerance... If your Fluke is off significantly even when recalibrated... I would question the calibration procedure, by whom? And if still off alot perhaps the Fluke is an older 1 that has some internal components changing value... Just my $0.02... My fluke is fine, it's the Autometer gauge that's off. I used to calibrate test equipment in the Navy and it's been my experience that Flukes are either right on or replaced, there were no adjustments to be made.
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Sniper]
#2863412
12/22/20 03:37 PM
12/22/20 03:37 PM
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Joined: Sep 2003
Posts: 19,687 north of coder
moparx
"Butt Crack Bob"
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"Butt Crack Bob"
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A crucial point is the tolerance of DC voltage measuring device...For example, a precision Fluke multi-meter has a tolerance of +/- 0.5%.. But a typical automotive DC voltage gauge has a much wider tolerance up to +/- 5.0%.. or up to a 10% window..... Just my $0.02... It is certainly true of the AutoMeter voltage gauge I have. Compared to my work Fluke, which is regularly calibrated, it's way off. i was just thinking about the gauge reading [slightly ?] high, maybe it's the gauge and the alternator should be tested with a fluke meter. [i have several flukes] you guys must have read my mind. [what LITTLE is left. ]
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Re: DENSO ALTERNATOR OVERCHARGING?
[Re: Mopar Mitch]
#2863642
12/22/20 10:40 PM
12/22/20 10:40 PM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
top fuel
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top fuel
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Posts: 2,094
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I have a rebuilt 14668 Denso alternator. it runs at just below 15V pretty much the whole time I'd guess it's a 14.9V set point on the regulator). This is on my old truck though and I don't drive it often, the big battery might not be fully charged. I've had this alternator on my truck for atleast a year and it's been fine, the battery is fine, I bypassed the Ammeter and installed a voltmeter. Another thing to think about, the Voltage Regulator set point. Here is one for the same style alternator and it's a 14.6V set point... https://www.maniacelectricmotors.com/80904406.htmlI also found this, notice they seem to set their alternators to 14.9V https://www.powermastermotorsports.com/why_run_an_alternator_a.html
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