07 Tundra Alternator, 13.8 and less ?

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Thread: 07 Tundra Alternator, 13.8 and less ?

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    Default 07 Tundra Alternator, 13.8 and less ?

    Hey all,

    I've been struggling since I bought my 07 Tundra back in March with its power system. I'm at my wits end and turning to you for help.

    I've added 2 yellowtop optimas to a truckbox in the bed of my truck.

    Cutting to the chase ... the 150A heavy duty alternator won't put out anything more than 13.8 volts, and most of the time it's more like 13.2. Charging additional batteries at 12.9-13.2 volts doesn't work unless I drive from here to Arizona every day. I really need 14.4 volts if I can get it.

    1. I assume the Denso alternator has internal sensing. If the stock battery is low (12.2v without charging) or fully charged (12.7v) I still only see about 13.8 volts being output. Is this because it's tuned to only charge the stock battery?

    2. I added an isolator from SurePower. This didn't work out since the alternator didn't sense the 1v drop and therefore the optimas never charged.

    3. I removed the isolator and put in a battery separator from SurePower. It's a little better, but I still only have 13.2 - 13.6 volts to charge these optimas, and that's not enough for a high amperage charging.

    4. I see a .2v - .3v drop from the front alternator to the back batteries, this is the 4 gauge wire. I am replace that with 0gauge wire tonight but that's still not going to get me more 14.4 volts.

    Main Question: Why does the Denso alternator only like to output 13.2 - 13.8 ? Can I get 14.4? Can I remove the sense wire and give it voltage from the back batteries to help with it determining what to output? Can I put a resistor in the sense wire to drive up the voltage ?

    The new 07 tundra is great, but I look stupid charging batteries in my driveway every day. Every other car on earth I've seen 14.4 volts coming from the alternator. If I remove my separator and put it back to factory, I still only see a max of 13.8 coming from the alternator. Is there anyone out there with an 07 tundra that can check the voltage for me ? Im wondering if the isolator fried my denso regulator somehow.


    Please help : )

    Sam


    2.

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    Quote Originally Posted by changeip View Post
    Hey all,

    I've been struggling since I bought my 07 Tundra back in March with its power system. I'm at my wits end and turning to you for help.

    I've added 2 yellowtop optimas to a truckbox in the bed of my truck.

    Cutting to the chase ... the 150A heavy duty alternator won't put out anything more than 13.8 volts, and most of the time it's more like 13.2. Charging additional batteries at 12.9-13.2 volts doesn't work unless I drive from here to Arizona every day. I really need 14.4 volts if I can get it.

    1. I assume the Denso alternator has internal sensing. If the stock battery is low (12.2v without charging) or fully charged (12.7v) I still only see about 13.8 volts being output. Is this because it's tuned to only charge the stock battery?

    2. I added an isolator from SurePower. This didn't work out since the alternator didn't sense the 1v drop and therefore the optimas never charged.

    3. I removed the isolator and put in a battery separator from SurePower. It's a little better, but I still only have 13.2 - 13.6 volts to charge these optimas, and that's not enough for a high amperage charging.

    4. I see a .2v - .3v drop from the front alternator to the back batteries, this is the 4 gauge wire. I am replace that with 0gauge wire tonight but that's still not going to get me more 14.4 volts.

    Main Question: Why does the Denso alternator only like to output 13.2 - 13.8 ? Can I get 14.4? Can I remove the sense wire and give it voltage from the back batteries to help with it determining what to output? Can I put a resistor in the sense wire to drive up the voltage ?

    The new 07 tundra is great, but I look stupid charging batteries in my driveway every day. Every other car on earth I've seen 14.4 volts coming from the alternator. If I remove my separator and put it back to factory, I still only see a max of 13.8 coming from the alternator. Is there anyone out there with an 07 tundra that can check the voltage for me ? Im wondering if the isolator fried my denso regulator somehow.


    Please help : )

    Sam


    2.
    Looks like std output is 13.2-14.8 Volts
    (a) Connect a voltmeter and ammeter to the charging circuit as follows.
    (1) Disconnect the wire from terminal B of the generator, then connect it to the negative (-) lead of an ammeter.
    (2) Connect the positive (+) lead of the ammeter to terminal B of the generator.
    (3) Connect the positive (+) lead of a voltmeter to the positive (+) terminal of the battery.
    (4) Ground the negative (-) lead of the voltmeter.
    (b) Check the charging circuit.
    (1) Keep the engine speed at 2000 rpm and check the reading on the ammeter and voltmeter.
    Standard current:
    10 A or less
    Standard voltage:
    13.2 to 14.8 V
    If the voltmeter reading is more than the standard voltage, replace the voltage regulator.
    "Gone" Replaced by 610+ ft lbs of CUMMINS Power 2007 Tundra Regular Cab Short Bed 5.7L 4x4 Ready lift , Magnaflow Cat back , TRD wheels , 285/65/18 TA Radials , Tow mirrors added , Airaid intake, Clear bra, Painted grille,,,

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    I'll follow '5.7rcbsb''s suggestion. I assume that's to check how many amps its drawing? I've amp clamped it and typically don't see it drawing more than 1-2 amps from the 2 back batteries, which during idle engine is probably just stereo stuff and the PC. I'll report back on that shortly when I can get the front tire off again to test... it's not an easy thing to get to : ) I did test the voltage right at the terminal at it was around 13.5 - 13.8 at the idle time. I'm thinking if I killed the stock battery so it had to recharge the sense wire would be giving less and it would up it's voltage, but havent tried that... that's next too.

    Toxarch: I've got a minipc, routerboard, other radio equipment, gps, stereo, etc ... In the beginning I didn't want to mess with any factory stuff so I ran my own batteries for everything. I never wanted to be stranded on top of a mountain because I ran the test equipment for too long or something. With 240 RC I should be able to get that PC to run overnight in my driveway at least - as it stands the battery never charges fully and so it only runs for a few hours.

    Thanks again for the help. I've worked with auto electrical in the past and never had such a hard time getting something like this to work smoothly. I mainly wanted to know if I'm crazy only seeing 13.2 - 13.8 on the alternator output (at idle or revving up, doesn't matter). It seems the only time I see 13.8 or so is right when I start it in the morning (colder?), otherwise its about 13.2. I can't remmeber for sure, but I thought the dash needle was in the middle when I bought the thing, but now it's 1-2 ticks to the left almost always. Is there anyone else willing to just put a volt meter to their battery while at idle to see if its 13.2 - 13.8, or 13.8 - 14.4 ? I'm starting to think my regulator is bad.

    Sam

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    I installed a P3 brake controller in my CM. It has a troubleshooting option that allows you to monitor system voltage. You are correct, I've never seen it over 13.8V 13.5V is usually where it hangs out at. I too thought it was odd since my Civic would run at 14.4V

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    From a cold start 72* this morning 13.5v

    Hmmm ?

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    do you guys have the cold package? just curious

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    I dont think so - no cold package that I know of... In Southern California. I'm guessing Toyota has done some tricks to try to get the battery to last longer by only trickle charging it or something. This is the first auto I've ever seen that doesn't produce enough voltage to fast charge a battery. The battery won't draw high amperage until it hits around 14v. I don't understand why this Tundra won't put out the juice I need : ) There has got to be something that I can do to get the right output from this HD alternator - 150A does no good if you can't draw it outta there. It's a Denso 27060-0S020 alternator.

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    Hmm I thought that the cold kit that I have has the 150 amp alt. are you sure yours does?

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    i assume the label looks like this? I havent looked at mine..


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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    I was looking at Tundras at Escondido Toyota, pretty sure I saw some with a cold weather package. Double check yours. Either way, not sure how it relates to your problem, since it adds only: Heavy duty battery, heavy duty starter, and deicer grid on windshield. /Mike
    2001 2WD Silver Tundra: 4x4 TRD springs, Camburg Uniballs with adjustable Bilsteins, Carson AAL, red/blue Bilsteins in rear, 265/75 Yokohama A/T, IS kit(minus bumper) and rims(hand polished), Billet Wing Window Latch Upgrade, TC Steering Bushings, RF851X amp, Alpine HU, JL 6.5"XR comps, Qlogic with JL 8W3V2 subs. Stebel 300Hz Air Horn.
    202k miles and counting......

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    oh i thought it added HD alt. sorry

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    I don't have the cold weather package, but it does have the heavy duty towing package... which adds the 150A alternator I guess. The label on my alternator shows Denso 27060-0S020, which I couldnt' find much info on. Im wondering if I can introduce a resistor into the sense wire or something to get it to pump up a bit ... or replace the internal regulator all together. If the stock battery isn't supposed to charge at more than 13.8 I'll replace it if need be. Just seems weird that Toyota would change that from the standard 14.4 volts on mosts denso's.

    I'm mostly trying to decide if my alternator / voltage regulator is faulty (have you guys verify yours is also low) and I should take it in for service, or if I should just replace the alternator with another one (if even possible).

    blackgts2002: do you get 13.8 or less or the standard 14.4 ? Maybe I should put the smaller alternator in : )

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    I wonder if the tow package is only pumping out 13.8 at the trailer connection? That's not going to charge the trailer battery very well.


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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    Quote Originally Posted by changeip View Post
    I don't have the cold weather package, but it does have the heavy duty towing package... which adds the 150A alternator I guess. The label on my alternator shows Denso 27060-0S020, which I couldnt' find much info on. Im wondering if I can introduce a resistor into the sense wire or something to get it to pump up a bit ... or replace the internal regulator all together. If the stock battery isn't supposed to charge at more than 13.8 I'll replace it if need be. Just seems weird that Toyota would change that from the standard 14.4 volts on mosts denso's.

    I'm mostly trying to decide if my alternator / voltage regulator is faulty (have you guys verify yours is also low) and I should take it in for service, or if I should just replace the alternator with another one (if even possible).

    blackgts2002: do you get 13.8 or less or the standard 14.4 ? Maybe I should put the smaller alternator in : )
    I will throw a volt meter on it today and let you know later on.
    This interests me alot too since I want to add my car audio battery to the rear as well.
    -Joe

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    Default Re: 07 Tundra Alternator, 13.8 and less ?

    Ive tested voltage at the rear trailor connection, it seems to be about .2 - .5 volts less than at the battery, mainly because of the thin wire they used and the distance. Trailor battery won't charge unless you drive across country.

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