mzilvar

iTrader: (3)

Curious if anyone has any experience with aftermarket options for the alternator.

Last few days I noticed that my TL was cranking a little slower than normal and almost didn't want to start. Checked the battery voltage with a DIMM & ensured connections were tight, it's sitting at 12.6V.

With my android tablet in the car I used torque w/ my OBD2 scanner to further diagnose, while driving I noticed the voltage was fluctuating from 12.6V to 15V but mostly stable at 14.3V while driving.

I changed the serpentine belt tensioner with a new one since I knew that was going out and had recently ordered it (it was wobbling with the AC on, so I just drove on it w/o the AC on for a while until I got the new tensioner in, had to trim a rib on the lower TB cover for the new one to fit as well for those that are familiar with it).

Thought maybe that would fix the problem, but it didn't.

I drove quite a bit today, and still notice the voltage occasionally going from 14.0 - 14.3V down to 12.6V. It usually happens when the car is no longer under a load and comes down to idle, at a stop-light or something like that. Then kicks back up to 14.0-14.3V eventually while driving.

I'm thinking the voltage regulator is failing and it also is looking like I need a new battery soon so probably going to replace that as well.

So my question, which alternator to go with. I'm looking at DENSO and ACDelco.

Anyone recently swapped an alternator have any input? Maybe someone familiar with reliability of the aftermarket reman'd units?

dcmodels

This may actually be a problem with the starter, rather than the alternator. But, of course, it is almost impossible to diagnose this type of problem "by internet".

Did you correctly check the battery voltage? the battery must be left sitting 8-12 hours, without either starting the car, or any voltage/ current draw, before checking the battery voltage. Even the dash lights will give a false reading. So you must open the hood, and close up the car (doors closed), and wait 8-12 hours, then check the battery voltage without opening the car doors.

And you must check to the hundreth of a volt, i.e., 12.65 volts is the correct voltage, at 80 degrees, for a typical battery. The battery in my RDX is fully charged at 12.60 volts, while the battery (different brand) in my Chevy is fully charged at 12.75 volts.

Checking the voltage after driving, even a few hours later, will give you a completely false (high) reading. That voltage is called a 'surface charge'.

It is possible that unless you have correctly, and carefully, checked the voltage of your battery, that the battery is actually not fully charged.

For more on this see this link:

https://acurazine.com/forums/showthread.php?t=890429

My RDX does this normally, and I too thought there was a problem with my alternator. But this is caused by the ELD (electrical load detector), which most Honda/ Acura models have had for the past 15 years. So I would assume that your TL has an ELD as well.

Unless there is a constant electrical load, such as the HVAC system (either the fan motor or the AC compressor), headlights, etc., the voltage in my RDX actually drops to 12.3 volts at idle. That is less than the battery voltage, engine off. So I definitely thought something was wrong with the alternator, and made a visit to my dealer.

The service manager there is very nice, and spent almost an hour with me, driving around with complete laptop (with diagnostic software), and wireless sender unit hooked into the OBDC-II port, so that I could see exactly when the ELD was shutting down the alternator output.

Unfortunately, the ELD is not explained in the RDX FSM (factory service manual). There is a completely separate manual, which I was allowed to read (over the SM's shoulder, so to speak). He had never completely diagnosed the ELD before, so that is probably why he spent so much time with me (for FREE).

So I cannot provide further info on the ELD, nor do I know where you can find a description of how it actually works, or the specifications of how it controls the alternator output.

---eof

mzilvar

iTrader: (3)

I read something about the ELD elsewhere but not much at all on a different car forum.

I have used torque with my OBDII adapter before with my N7 (it's fixed in the console) and one of the standard gauges I have it display is the battery voltage, taken off of the OBDII connector.

It's never fluctuated that much at any time in the past when using it, was always around 14.0 to 14.3V even when the car wasn't under load.

Only way really is to have it tested, I suppose. It is the original alternator, 8 years old now and 105k miles.

Also I'd say if that were the case for testing the battery voltage you'd also have to pull the battery cables. As long as it's connected there is always some draw on it in these cars. The little red security light on the driver door for example.

It did start up normally later in the evening as well, after driving around some. I'm guessing the battery has more of a charge on it now. Really don't want to pull the alternator to have it tested for free or go somewhere and pay a diagnostic fee.

I went ahead and pulled the trigger and bought an AC Delco alternator, figured it's probably about time anyhow. Just have to wait now, bought from amazon.

Project_CLean

iTrader: (2)

I'm curious to see if your voltage reading changes, or if your problem persists?

dcmodels

Disconnecting the battery cables will give a true OPEN CIRCUIT voltage reading, but the difference with the cables connected is not significant, so long as the doors are closed, and the battery has *rested* overnight. The parasitic current draw is just not significant, or the battery would quickly discharge.

For my own RDX, with a CostCo battery, the difference is about 0.04 volts. A difference in ambient temp of 40 degrees would produce that same battery voltage difference. That would equal a difference between 12.65 and 12.61 volts. Again, this is explained in the link I posted above.

However, the difference between the voltage of a *rested* battery, and one that has been charged by recent driving, IS significant, if the battery is old, and weak. Or new and weak (sulfated). Yes, even new batteries can be sulfated and become weak by constant short trips.

dcmodels

For those reading this thread, who also have an alternator problem, SEARS and my Acura dealer have always tested my alternator (and battery) for free, and without removal from my car(s). Also, most any parts store in my city will test for free. FYI

mzilvar

iTrader: (3)

Thanks for the advice and help, I'm sure that you're correct with the voltage reading.

So I'm positive I fixed the problem, here's what happened today..

- This morning car was a bit weak starting, started fine but I could tell the battery wasn't full, I was able to get it started and get to work, put gas in the car and park it at work.

- I ordered a battery from sears, since I could tell it was going to die soon. I picked the Diehard Gold, didn't feel like springing for the platinum for another $112 more with only 1 year more of warranty on the platinum over the gold. I'm sure it's a better battery though - I know some people have posted that it's a really solid battery.

- Around lunch when I left work to pick up the battery my car - barely - started. I could tell it almost didn't start, but ran fine once it was on the alternator. I got to sears and pulled the battery & replaced it, pretty much knew mine was on the way out, an interstate megatron II, with 2 years on it. The sides were bulging and it looks like some of the electrolyte came out of it on the top.

- Car started fine and I let it idle for about 10 minutes to do the idle re-learn after replacing the battery.


The alternator voltage stabled out with the new battery.

Today it ran from 14.2 - 14.3V under load after starting it back up for my trip home and 14.1-14.2 while idling.

After what I'm assuming is the battery recharging from starting the car it was sitting at 14.0 - 14.1 at idle and 14.1 - 14.2 under load.

No fluctuations down to 12.6V or up to 15V.

I'm pretty certain it was just my battery going out. I did also purchase the alternator which is on the way. Since amazon has no core fee and I picked it up for $196 or so shipped I'll probably just hang onto it until mine does, eventually, fail since it is already rather old.

Some pics attached, the shot of my tablet is after doing the idle re-learn.


I'm sure I could've had it tested, but really don't like the hassle of having to take it in to have it tested.

silverstreaktsx

I was having the same issue in my 2010 TSX base model. I recently installed a 1000 watt rms system. I have a voltmeter that plugs into the cigarette lighter. It keeps dropping from 14.2 V to 12.5 at idle. I was freaking out and confused. Even more confused when I turned on the lights and the voltage jumped back up to 14V. This pdf of the technical document explains the ELD system in detail.