Possible Voltage Regulator Issue
 

Ok guys I need some help. I did a search to see if any of you experienced this issue in the past but I found a few things that were close but not close enough. So here is my description...

About a month ago I started noticing that the electronics in the car we're intermitantly running slow or dimming. In other words my head lights would dim even regardless if the AC compressor was already running. This mostly happened when I tried to raise and lower the windows or even when I applied the brake and the rear brake lights would eluminate. Recently though things have gotten much worse. I can attempt to raise/lower the window and the motors will slow during the process if there is a drain in voltage. This mystcal drain in voltage is happening frequently now to the point that at times it will shut off the radio.

The thing is the car is running fine. So I took a voltage meter to the battery (Braile 11lbs battery...1 year old) and I recieved a constant 12 to 13 volts. My next idear was the alternator was going bad so I turned the car on. I took 2 seconds and it turned over like normal. I checked the voltage at the battery terminals again which read 12 to 14 volts...usually @ 13 volts. This too is normal. So I turned on all the accessories and took a reading. Again voltage read 13 volts. Next my friend rev'd the engine. Voltage was closer to 14 volts.

Mods: Exhaust, K&N air filter, Racing Beat Ram air duct, Braile Battery.

I simply don't get it. What is causing this mystical voltage drop and why can't I replicate it? I have a feeling that during driving conditions the voltage regulator is failing intermitantly causing the issues but I am not 100% sure. Anyone know how much and where I can get one? If its cheap maybe changing it would not be a bad thing to do? :Eyecrazy: :banghead:

Mileage: 56k+

I know its lunch but sheesh...:)

Your alternator should be charging around 13.5 volts so, based on your measurements it looks OK. I'd venture that you have an intermittent short or, more likely, a bad ground connection somewhere. Of course, this is going to be very hard to isolate. First, look at the easy things. Make sure your battery terminals are tight. Second, take out your battery and get it tested under load - that will tell you if its really good or not. Have you added any accessories? Check to see if you have a good ground connection between the engine and chassis. You can then start pulling accessory fuzes one at a time to see if one of the circuits corrects your problem. You'll have to drive around after disconnecting each circuit to see if it has an effect.

The voltage regulator should be INSIDE your alternator. It's not a separate part.

I honestly can't see there being a short since no modification was made to any part of the electrical system. Actually I also installed the P.I.E. (dont know what it stands for...LOL) input device for the radio which allows for an axuilary input but this did not involve any exposed wires or grounding...Plug N Play.

As far as ground is concerned even if there was a faulty ground wouldn't all accesories be running ok while the engine is running?

Just brain storming before I go testing the car again. Please also remember that all systems are being affected...lights, radio, dash/gauge lights, etc.

No added accesories or stereo equipment except maybe a radar detector and an iPhone charger.

Do your accessories dim when then engine's NOT running? If they do, I'd suspect the battery first. A voltage measurement does not tell you the full story on battery condition - that's why I said to get it tested under load first. Next is the ground between the engine and chassis - that's the ground that most of your accessories are connected to. Didn't you have to pull your radio to install the P.I.E.? Make sure you didn't pinch someting in the re-install.

Accessories diming when engine not running...Hmm, I thought of that after the fact and in fact I was going to test that when I get back to my car this afternoon.

You know, I hope its the battery. That would be a much easier and cheaper solution. I guess I could take it to Pepboys and have them load test the battery. Another part of me would be pissed if it was the battery. An 11lbs Braile Carbon Fiber battery is not exactly cheap...Bummer!

As far as the radio is concerned...I did have to pull it out to connect the PIE but this was well over a year ago with zero issues till now so I am confident that is not the issue.

Your car starts fine----This takes a lot of amps and good connections. Therefore your battery should be fine, as are the connections to it. The ground connection to your engine is OK as well.

You have 13+ volts at the battery with the engine running and most of the current drawing accessories on------your alternator should be OK.

If in fact the above is actually true, and a particular accessory (power window for example) operates as if it is not getting enough voltage, and in particular, if operating this accessory causes some other accessory to appear as if it is also starved for voltage (radio), then you have a common resistance in the line delivering voltage to those accessories. That resistance is either in the voltage side or ground side (could be in both, but not likely).

Again, assuming what you say in the above two conditions are true, you have to first find out where the source of parasitic voltage drop is occuring. The most direct way to find out on which side it is, is to measure voltages to battery ground right where the the power and return lines enter the accessory with the accessory turned on. The fuse could also be used for the power side. If the voltage measurement on the power side is significantly less than battery voltage then the voltage is being robbed on that side. If the ground side measurement shows significant voltage relative to battery ground (zero), then some common ground is the problem.

there's your problem the brailee battery. They are not made for daily driving.

I can't agree with this statement. I spoke to the resaler and the manufacturer. The 11lbs battery is perfectly suitable for daily use. They did however tell me that the 6lbs battery should not be used in a daily driven application.

Description:
Braille B14115C Carbon Fiber Sealed battery
Weight: 11.5 lb/5.2kg
Volts: 12 AmpHr: 15
Pulse Cranking Amps: 904
Exterior Size L:5.8" W:3.3"H:5.9"

Recommended Uses:
Daily or Race Use in Small to Medium Displacement Motors.
Weekend Track Warriors
Show Vehicles
Custom Cars and Vintage Vehicles – No Acid to Spill protect and enhance your vehicle!


Uses: Sport Compact Vehicles Street Use Warm Climates; 4 & 6 cylinder Race Vehicles; Custom Multi-Battery Audio

http://www.brailleauto.com/images/indexB14115.jpg

Well either way I will be taking the car to Pepboys so I can use there battery tester. I want them to test the battery under load to make sure the voltage doesn't drop.

Is the 15 AH rating a typo? If not, that is not even close to what you need.

I was thinking about getting the same battery. Cause honestly, I really dont want something yellow like that in my engine bay. But whats with the 15AH? interesting...now i dont know....but im no battery expert. So can someone clear this up.


Update: Ok so after a little bit of research I think I have found an answer. Optima leaves their AH ratings a 20hour rating and Braille is the per hour rating. So in reality a 15AH rating by braille may be that its 20hour rating (to make it the same standard as Optima) is 300. Again I may be completely wrong. As I usually am. But I could not find a lot of info. So please. Someone tell me if I'm right or wrong.

If you look at the physical size of the Braille battery, it is pretty small compared to the size of the OEM battery. I believe that with lead-acid batteries, size is more or less directly proportional to capacity. So, the 15AH rating for a battery that size is not surprising to me. I wonder what the OP finally found out about his problem?

Here are a couple more sites with info on AH ratings:
http://www.allaboutcircuits.com/vol_1/chpt_11/3.html
http://www.dcbattery.com/faq.html

Interesting that the OP is having issues as I've had similar issues with the same battery.

Most of my problems have been related to initial starting of the vehicle which might be related to the 15 AH figure. When the car sits for 4+ hours, starting the vehicle sounds like the battery is drained.

The car starts, don't get me wrong. I've never had any issues with the vehicle not starting, even after it sat for 48 hours without being driven (a rare occurance for me). I even went as far as to purchase a Braille protector switch in the event that the battery drains low enough to leave me stranded. So far, that switch has never tripped due to low voltage on the battery.

Does anyone know a minimum amp hour rating for the RX8? I've been told the PCM takes a larger amount of power than other vehicles.
(Edit) Answered my own question as the stock battery has a 40 AH rating.

I'm curious to know if the OP had problems with the battery. The carbon wrapped battery was $200+ so it's not something I can just toss.

Keep in mind that battery was the battery installed on the early cars. A service bulletin that addressed hard starting, called for the replacement of that battery with a beefier one (along with a larger starter motor), so the rating is more like the cold weather rated battery in the shop manual.

Update:

My car would not start this weekend...I was set on taking the battery to Pepboys this weekend but I just could not believe that all voltage readings were above normal. So I toyed with the battery and it turns out the Negative battery post was loose. Initially I checked it by hand and it appeared to be tight but when I put an allen wrench to the post it was clearly loose.

So I go into the car and viola...the car started. Well, this is a good thing and a bad thing. The good news is technically I never had an issue with the car starting right up with this battery until this weekend but that was my fault for not keeping the posts nice and tight. The bad news is I am still getting an excessive voltage drain.

The hunt continues... :banghead: I might just buy a standard battery if I don't get a solution soon.

The only two voltage draining items I can come up with are my security system which is factory and the PCM.

Glad to hear you got that small issue taken car of. I had similar issues with the battery terminals not being tight enough on the battery. I actually had the positive terminal slip off at one point which wasn't very exciting at all!