[blackgts2002]

Good point. I will make sure to test that for you.

 

[changeip]

thank you for checking, i appreciate it. If i hear another 1-2 people with the same result I know mine's not broken at least. I assume the max is 13.8, and only if the stock battery needs extra juice - and things are cold. Typically I measure 13.2, sometimes 12.9 even. I could have sworn my battery needle used to sit in the middle at all times ... now its always 1-2 notches to the left it seems. I'm going to fool with the sense wire on the alternator to see if I can give it 1v less to trick it. Bad idea ? I was thinking of running a long 16ga wire to the back batteries for the sense.

 

[blackgts2002]

Yeah, I couldnt find my multimeter. I will keep looking, but my gauge is a little to left of center. center being 14v I think

 

[changeip]

anyone know a product to boost 12v to 14v ? It would have to handle 20-50 amps or so since it would be charging batteries.

 

[kd5byb]

Well, I just measured mine - '07 CrewMax 5.7L. Started it up in the driveway after about 2 hours since it was last driven and put the meter across the battery terminals:

Got 13.98 volts immediately after starting and as the engine speed came down to idle, it came down to 13.90 volts. I suspect that if I let the engine warm up fully and let idle speed fully drop, I'd probably be at 13.8 volts or less.

You may want to check the voltage output of the alternator with the engine running at your typical cruising speed - I'll bet you get closer to 13.8 volts, or more. I've noted that many Japanese designed alternators seem not to have full output voltage at idle speeds. In my wife's Lancer, you can see the headlights dim ever so slightly and the A/C blower slow ever so slightly when the engine is idling. This may be an emissions thing, but that's pure speculation on my part.

I do know that my Ranger ran about 14.2 volts at idle and that that was within Ford's specs.

It's worth noting that 13.8 volts will charge a battery, just not as fast as if you were to apply 14.0 or more volts. 13.8 volts is the automotive standard for a 12 volt system voltage...

later,
b

 

[kd5byb]

Here is a link to a voltage booster that may be what you need. Not sure it has enough current capacity, however...

Battour

later,
b

 

[joshp]

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.

For most mobile equipment you won't have a problem if you aren't hitting 14 volts. 150*13= 1950 watts which is plenty for anything I'd be doing. I guess my recommendation if you have sensitive electrical equipment ot tons of electrical equipment would be to go to an aftermarket alternator.

 

[Pbbobkanobi]

I dont think so - no cold package that I know of... In Southern California.

I have a 5.7L Crewmax with the Cold Kit here in San Diego. It comes with:

Heavy-duty battery
Heavy-duty starter
(Double Cab and CrewMax include windshield wiper de-icer grid with timer)

With the Towing, TRD Off Road and Cold Weather Package my Tundra is good to go.

 

[eusasc]

I've got the cold package and the alternator's putting out 13.4 at idle

 

[changeip]

I've got the cold package and the alternator's putting out 13.4 at idle

Exactly! If you look at the specs of any deep cycle battery they need at least 13.8 for a cyclic charge (fast charge). Some even say 13.5 minimum for a trickel charge (odyssey). I wonder if the cold package alternator is set lower for some reason?

For most mobile equipment you won't have a problem if you aren't hitting 14 volts. 150*13= 1950 watts which is plenty for anything I'd be doing. I guess my recommendation if you have sensitive electrical equipment ot tons of electrical equipment would be to go to an aftermarket alternator.

Correct, all of _my_ equipment will run fine between 11-15 volts. I even have a carnetix dc-dc power supply that fixes that voltage so it's stable. The problem is with battery charging. I have to drive 1000 miles in one trip to trickle charge the battery to 12.7 volts (fully charged). I understand that 12v is plenty for equipment, I just can't run on 11.5 for more than an hour. My goal is 24 hours on batteries drawing 4A... 55ah yellowtop should get me around 9-10 hours each battery.

Thanks all for your help. I've been stuck in this project for too many months now. This Tundra is great, I love it, but I also hate it because of this. There has got to be a internal regulator I can swap out or something to get the standard 14.4 reference output, even if the stock battery has to be replaced to handle the higher voltage.

 

[changeip]

Here is a link to a voltage booster that may be what you need. Not sure it has enough current capacity, however...

Battour

later,
b

That's exactly what I need, however I can't find anyone who makes one that you can actually purchase.

 

[jamesdewitt]

This might work for you:

MFJ-4416 Super Battery Booster

 

[changeip]

Excellent... I wonder if its the same problem though, they don't recommend charging batteries with it, only temporary resistive loads up to 25A. Anyhow, I have a SurePower 11020C00 (20A trail charger) on its way that might just do the trick. Seems silly to have to do this, but I guess there's no other way. I just wish I had a real alternator - a 150A alternator that won't even cyclic charge batteries seems odd to me.

Yesterday while playing some hard hitting bass just for testing I would see my voltage drop to 11.0v during loud music (5-10A draw from amps) and the alternator did nothing to try to increase that. I would figure that the alternator sense would be telling it to increase but I guess not. I still think there is something wrong with these alternators.

Thanks for the help - I will post back Monday after I've installed the trail charger to see if it's a viable solution.

 

[ROZ]

It's been my experience in car audio that alternators generally have an output of about 13.8 - 14.8.... I would have used a PAC iso-relay to add the battery and called it a day...

 

[changeip]

Correct, they generally do, but not 07 Toyota Tundra's. They output 13.2 typically. Trickle charging batteries is never going to work for a car stereo drawing 1000w. I meant to call it a day back in February when I was done wiring and installing it. . . been futzing around with the stupid power output since. There is just not enough voltage coming out of the alternator... plenty of amps if I could get the voltage up to 13.8.

 

[changeip]

Wooo hoo! Received my second SurePower TrailCharger today in the mail. The first one was dead on arrival - of course, I paid for Saturday UPS delivery. Received the replacement today. This unit does exactly what I needed. Compensated for line voltage loss and outputs 13.8 - 14.4v at 20A to charge my back batteries. I just wish I didn't have to spend $350 to compensate for Toyota's trick with the internal regulator voltage output. I can see all the problems ahead for others, hopefully this thread will be found and help someone out. Deep cycle batteries will be ruined if you don't boost the voltage on these trucks.

 

[changeip]

one followup request to you all - is there not a single 07 tundra out there that outputs 14.4v ? I am wondering if I swapped out my heavy duty alternator with the standard one I would get 14.4v... even if I don't have the same amperage. Can some more of you measure your voltage at idle ? Cold and hot ...

 

[blackgts2002]

Call me crazy but isnt amperage more important in what you are doing...???

And I found my meter I'll test soon. I expect 13.8

 

[changeip]

amperage is important, but not ruining my deep cycle batteries is also important. Plus, most batteries will not draw _high amperage_ unless they have > 13.8v... if you feed them with 13.2v they will draw < 1a, even if mostly dead. I just ruined 2 optima yellow tops because of that. The whole point of getting higher voltage is so I can take advantage of the high amperage.

Solution: Place a 2200-2500ohm resistor in the fuse box inline with the ALT/S fuse. I used a 5k linear potentiometer to find the right value. This will lower the voltage that the alternator is sensing and it will output more to compensate. I am now getting 14.4v! Woooo hoooo, finally! I can see my parallel odyssey 2250 batteries drawing around 100A to charge now - awesome! Note: do not try this at home if you are not experienced with electronics : ) I think I need to find a alternator charge controller to manage it possibly - at the field connection bypassing the regulator, will look into that more.

 

[ROZ]

Guess you can send the trail charger back