danmm7

iTrader: (1)

My car has close to 90k miles. It is well maintained, belts are new, runs fine...except this one electrical issue:

I have an Escort Passport Radar detector that shows current voltage while the car is running. For the last 2-3 months, i have noticed some very disturbing fluctuations in voltage and i would like to find out what could be the reason before i take the car to the dealer and they tell me that they "can't reproduce" the problem.

When engine is OFF with key on accessories ON, voltage reads at 12.1V or 12.0V. This should be normal since the alternator is not charging.

When car is running, Voltage is at 13.4 or 13.5V, sometimes...even 13.7Volts. I am not sure if 13.4V is normal for a running car, given that my 2006 RL, never shows less than 14.1V when car is running. ?!?

The big issue is that when my TSX is running, the 13.x voltage is not stable. At stop lights, often it goes to 12.1Volts. IF, i shift from "D" to "N", it goes to 13.x Volts again. This does NOT happen all the time, but often (3 out of 5 times). This cannot be normal, correct?

Sometimes, i am driving slowly around the city and i see my volt meter showing 12.1V again....even though my car is moving and i am not at a stop. Then, it jumps again, on its own, to 13.x.

Having the A/C or the Lights ON does not change the behavior. Sometimes it goes down to 12.0-12.1 sometimes is jumps back to 13.3-13.5V. Sitting at Idle brings the 12.x reading very often.

Why is all this happening?

Bad Alternator?
Bad Grounding?
Something else to check?

Battery is new, so i can't suspect it. Also, car has been starting "funny" for almost a year now. Sometimes in the morning it cranks for 5 secs before it starts (like the battery is weak or there is not fuel supply). This is why i replaced the battery, but the same voltage issues are still around and starting is still slow in the morning.

Where do i start?



Thanks!

curls

I would suggest bringing it in for a full charging system inspection. They should perform a number of tests 'under load' to check what components may be failing. Sounds like a weak alternator or voltage regulator, but frankly automotive electrical can be extremely frustrating and is better left to the pros. It could be something dead simple like a loose or corroding ground wire or battery connection, or, it could be something stupid like a failing contact in a harness plug @ a component such as the alternator. Who knows.

Good luck man, this might be fun.

Mskierki

This sounds like it could be a bad diode on the voltage regulator. They become intermittent and then fail. It could also be the wiring between the battery and the "not a cigarette lighter" power supply. Try checking the voltage with a multimeter at the battery terminals and see if it is the same as what is show on your radar detector. (It could also be something going bad with your device.) While you are checking under the hood check for continuity (with the automobile off) between the negative battery terminal, the chassis and the engine block. They should all be about the same resistance value.

Have you had any other symptoms of bad voltage supply: dimming lights at idle, etc?

Anything below about 13.2 is not enough power to charge the battery and no matter how new the battery is you will have hard starting problems.

danmm7

iTrader: (1)

One other issue i had with this car in the past (i still have it, but i gave up) is electrical noise/whining when i tried to add XM Radio player.

The noise i was hearing in the speakers was so bad, i just gave up. I tried everything, including, temporary connecting the XM radio directly to the battery and could still hear the electrical noise!!! It was like my entire TSX is one giant source of electrical noise. Yet, my built-in Navi/Stereo work fine.

I installed filters, changed the power source but i never could get rid of this noise.
Just to make sure it was not the XM radio.... i connected the same XM unit to my old Nissan Maxima and there was ZERO electrical noise! Clean and crisp sound at any volume level.

Ideas?

curls

I'd look at thoroughly cleaning the battery terminals and posts, then trying again. If you were experiencing ground-loop tyoes of problems it is possible that you have a bad ground somewhere, but a groun-loop feedback/noise symptom when direct-connected to the battery tells me you might have a bad connection right at the battery itself.

Lexx

Sounds like a weak alternator, buddy.

danmm7

iTrader: (1)

Is the voltage regulator on these alternators replaceable or it is "built-in" and i need to replace the whole alternator if the regulator is failing?

Thanks!

eg5

iTrader: (4)

it seems your acura was behaving the same way before you installed that little gadget. you do know voltage drops are normal in a car especially all this talk between all these modules that you didnt even know they were there let alone their functions and why a certain module talks to another module etc. i dont think youll ever get a steady voltage reading at idle, XXXXrpm etc.
about your cold starts did you notcied this before you had this cool radar? chances are you did but never gave it much thought since you didnt have anything to "suggest"(radar) you might have a problem there.

danmm7

iTrader: (1)

Actually, car never started right away. It was always cranking a bit longer in the morning, even when we got it with only 40k miles on. I kept thinking that the original battery is weak. Problem never got worse.
Later i noticed the fluctuating voltage.