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Another Alternator and RockAuto Shout-out

bpdutton

bpdutton

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I replaced the original alternator on my '07 at 85k miles in 2016 with a remanufactured unit. That alternator lasted 49k miles to June of last year. I replaced that one with a new Delco REMY unit and replaced the battery at the same time. Well, this past Thursday, 16 months and 10k miles later, the "Service Battery Charging System" light came on in the DIC and the alternator gauge on the dash was on the line between 9 and 14 volts. I got home and tested the battery - 12.5v with the truck off and 12.5v with the truck running. I then tested resistance between the alternator body and the negative battery post - zero resistance so grounds check out. Thankfully I ordered the REMY unit from RockAuto and it carried a 2 year warranty. On Friday morning, after a few clicks of the mouse and a tracking ID from USPS for shipping the defective unit back, my warranty replacement alternator was on its way. It showed up on Saturday, installed it and have 14v with the engine running. (y)

So, #1 - shout-out to RockAuto for their excellent customer service and warranty handling. #2 - could there be something going on with my truck that is causing the alternator to go south so quickly? I have no added accessories that require extra power - pretty much a stock LT Z71 in that regard. The serpentine belt is relatively new, tight and quiet and tracks straight. I was reading in another thread about the Battery Current Sensor, but seeing as how a new alternator solved my problem I figure that component should be OK.

Thoughts on this would be appreciated. Otherwise I will just chalk it up to a poor quality replacement alternator.
 
Hi Brian,

I have the same problem currently.
Is Rock Auto just a USA company?
C.
 
Reviving this thread. Well, it looks like my warranty replacement alternator has STB now after a little over 2 years and 14k miles. Seems like that isn't very long for an alternator to last. Of course, it only had a 2 year warranty so no free warranty replacement this time.

It noticed the voltage gauge dropping and then the "Service Battery Charging System" warning came on along with the battery light. Then the gauge went back up to a little over 14 where it usually is. Then back down and back up. So I parked the truck. Now the gauge goes up when you start the truck but comes immediately down to about 11v on the gauge and the warnings come on.

I did the same tests I did last time - battery 12.5 v with the truck off and a little less than that with the truck running. Still have good solid grounds with no resistance. I just replaced the serpentine belt, idler pully and tensioner. I also replaced the battery current sensor - still no joy.

Is there something else that could be trashing the alternators in my truck or causing the alternator not to charge the battery? Replacing them every couple of years seems kind of ridiculous. If not, looks like I'll be ordering a new one tomorrow.

Thanks in advance for any and all info provided.
 
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Just a guess, but it's a remanufactured alternator. I learned when working at a parts store in college to always buy new. Remans are produced using as many of the old parts as possible, and they failed regularly. Some more than others.
 
How many amps does the alternator put out. It's stamped into alt. Housing. It should say something like 105a145a 160a etc.
Also have you added things like aftermarket radios, headlights, alarms etc.
 
Well, you have me on this one. I understand they are 2 different Battery Current Sensors which one you need, I can't tell.

I would take it to a shop so they can monitor the system to see what is going on. Yeah its going to cost around 100 per hour but that beats throwing parts at it.

bcs.PNG
 
Mine has the 2nd design - matched the number of the old one.

I'm calling Rock Auto tomorrow to see if they'll give me a break on a new alternator.
 
If you're destined to replace it every few years anyway, due to some gremlin in your truck, you might consider buying a store brand alternator from Autozone or O'Reilly or some other parts store that have a lifetime warranty. It won't last any longer but you can keep getting it replaced for free whenever it fails.
 
Another shout out to Rock Auto. Emailed them about my situation and they replied with a return shipment label to send the bad, now out-of-warranty Remy alternator back to them. They are giving me store credit for the full amount of the price of the Remy once they receive it. I already ordered and received a replacement from them (TYC with a lifetime warranty) and installed it last night. All back to normal and the truck is running great.
 
That should do it, not too big.
 
Are you by chance using Optima batteries? Those will eat alternators. They were designed to be used in off road vehicles to give them better boost to pull with the winch. They were never designed to be used in daily driven cars. They became popular because they could discharge a lot of power fast which was desirable for big power audio systems.

The quality of those batteries has dropped dramatically and the amplifiers of today incorporate large capacitors in their power input stage that gives them the same quality as when people used to add 1 Farad capacitors to their systems. So incorporating a Capacitor, or an Optima battery in any daily driven vehicle, even one with a big sound system, is a waste of money. A standard good quality battery is enough. I use AGM batteries in my truck as they can handle more abuse.

The main issue with the Optima battery is the low internal resistance. This is nice for booming base of old or for pulling out something with a winch as it will allow the whole power of the battery to be used at once. You will notice your starter turning over quicker as well. The problem comes in when the battery is low. The Red tops are supposed to be what you want for a daily driver, Yellow tops are for Deep cycles, ie where you constantly take the battery to low power. Deep cycle batteries are designed to not loose capacity when they get close to dead. A normal battery loses part of its life as soon as your voltage is low enough to need a jump.

Talked with a now defunct alternator company engineer and he told me they tested the Optima red tops and the lower the voltage drops in the optima the more of a draw it will pull. When they are greatly discharged they act as a 450 amp draw. Most alternators and even trickle chargers that don't limit the amperage they put out, will see this as pretty much a dead short. If you HAVE an alternator that can put out that kind of power the battery will explode as it can not accept that much power that fast. So even a 160 amp alternator will have problems charging an Optima if it is taken too far down, will overheat and burn out things. When I ran the red top optimas, my alternators only lasted about 6 months which is why I got into the conversation in the first place. Thought I was using substandard alternators.

There are other batteries out there that are much better than the Optima, but the reason why they are not more popular is because the class D amplifiers, with the much more efficient power supplies they use, and the optimum capacitors in the power supplies they have now, you can get all of the thump you want with normal batteries as long as the wire you use is big enough.

If you are not using an Optima battery, make sure your grounds are good and possibly do the big three wire upgrade to add durability to your electrical system. And know that getting an Optima battery won't help your situation.
 
redheadedrod said:
If you are not using an Optima battery, make sure your grounds are good and possibly do the big three wire upgrade to add durability to your electrical system. And know that getting an Optima battery won't help your situation.
Click to expand...
I am running a NAPA Legend battery. Can you elaborate on the "big three wire upgrade"?
 
Do a google search for "big 3 wire upgrade". It is a common upgrade for just about any car. There is a thread here somewhere so feel free to search for it. Thats what I would have to do.
 
Found via search:

A new ground wire from the battery to the body of the vehicle, a new ground wire from the battery to the engine, and a new power wire (+) from the alternator to the battery.
 
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