metroplex

The KAM is volatile memory so it is cleared/reset when the power to the PCM is disconnected. Upon reconnection of power, it will start over and just relearn the idle trim, adaptive fuel values, etc... The non-volatile/flash memory portion of the PCM does not depend on a constant power source (the important part of your PCM calibration, like shift schedules, spark tables, etc...) and stays put even without power.

I'm guessing that your Smart Junction Box is probably screwy. The SJBs are notorious for going out of whack when exposed to water that drips down from the cowl. I would not be surprised if one or more parts of your SJB were exposed to water and caused the SJB internals to short out the battery over time. Either that, or your PCM is faulty/bad. I've seen and heard of relatively new vehicles to have bad PCMs and they may be able to discharge the battery over a period of time.

I have not driven my Stang in the rain or let it sit in the rain. There's a high probability that the Stangs that are in the dealer parking lots have shorted out SJBs from the rain water that drains from the cowl and into the passenger compartment, which causes the battery to discharge.

m05fastbackGT

Well in that case, we can definitely rule out the SJB being exposed to water because I do not drive my Stang in the rain and it always sits in my garage when not in use so either something else must be shorting out the SJB ? or it's also a faulty PCM just as you mentioned.. so let's assume if it's a faulty PCM that's draining these batteries as the cause ? then how is it that my tender charger is preventing this faulty PCM or SJB from draining my battery...

metroplex

Did you factory order the Stang new and pick it up when it arrived? Or did you buy it off the lot? If it was bought off the lot, it *could* have sat out in the rain at one point.

Your battery tender is nothing more than a battery charger with a switching mode power supply that converts 110V AC into 12-15V DC with a current limiting circuit that switches off or reduces the current when your battery is fully charged (certain current draw is detected by the circuit). Essentially it is a smart "trickle charger" that keeps your battery fully charged. However much current is used up which causes your battery to deplete, is being supplied by the battery charger. Since we're not talking about a lot of amps here (1A-2A max from the charger) I suspect faulty electronics somewhere in the system: PCM, SJB, maybe even the regulator - assuming you've always gotten fresh batteries as replacements. You can normally use a 9V battery (like in a smoke detector) to keep the KAM alieve while you change car batteries, so you don't lose clock settings, idle trim settings, etc...

m05fastbackGT

I factory ordered the Stang and picked it up when it arrived so it definitely did not sit out in the rain..As for my automatic tender charger ? you're once again correct it's a 12volt/1.5 amp that automatically shuts off once the battery reaches full charge capacity.. but here's what I still don't understand ? if more current is being drawn from the battery than what the tender charger can put back in, then how is the tender charger able to keep the battery fully charged ? and here's something else you may also find as interesting.. before I purchased the tender charger, my Stang sat inside the dealership's service bay for a two week period in which the Stang's voltage was monitored by both the service manager and field service engineer to determine if the 3rd battery was defective ? along with looking for any unusual voltage drainage and here's what the results ended up as..CUSTOMER LEAVING VEHICLE FOR FIELD SERVICE ENGINEER TO INSPECT FOR BATTERY RUN DOWN, VEHICLE INSPECTED BY FSE FOR TWO WEEKS, BATTERY HELD DURING TEST @ 162 IMPS, SYSTEM POWERS DOWN COMPLETELY. BATTERY 13.58V. ALT CHARGING 14.01V. the text in blue are from the field service engineer's last comments. It tested out at .030 to .040 amps and 12.7v Per my meter. Still looks good. NO FURTHER ACTION TAKEN

metroplex

Your charger is supplying more than enough current to handle the consumption from whatever device(s) are drawing the current (along with the KAM) and maintaining the battery, which is why the battery does not completely discharge with the tender in place. Think of it as idling your engine 24/7 for 365 days. Without a constant fuel supply to replenish the gasoline supply in your tank, the engine would eventually die out. The battery tender is like a robot gas station attendant constantly filling your gas tank as you idle.

13.58VDC sounds acceptable for a warmed up engine, alternator, and battery while charging a battery (13.6VDC-13.8VDC is a bit better). The voltage is higher when it is colder due to the temperature compensation built into the voltage regulator. When it is hot outside (like 120F in a desert), the regulator reduces the voltage output to prevent boiling/overcharging the battery. AGM batteries like the Optima are extremely sensitive to this because thermal runway could occur. The VRLA aspect keeps recirculating the gases which is a big bonus, but there are safety vents to vent gases in case there is excessive pressure buildup.

A 40 mA current draw isn't too bad. If you figure the Group 96R has a 50 A-h capacity, a 40mA constant draw should deplete the battery in around 30-50 days of not being charged (you have to factor in colder air temperatures and the lower open circuit voltage of the battery). One way to find out what's going on is to log the current draw over the entire length of time to see if the current demand actually increases at a point. It doesn't make sense for your battery to be completely drained from a 40 mA draw, so it actually must increase at some point. KAM is not new (heck it is used by practically all fuel injected Mustangs) and should not try to commit suicide by completely discharging your battery once it reaches a certain voltage.

m05fastbackGT

The test results that I posted during the 2 week period, was monitored without the vehicle being started so unless somebody at the dealership was up to something ? neither the engine, alt or battery should have been warmed up at anytime during the 2 week test period..I also agree that it doesn't make any sense as to how a battery could be completely drained from just a 40mA draw within a 2 week to 30 day period, so for some reason either somebody from Ford missed something ? or is withholding info.. If by any chance you still suspect faulty electronics such as the SJB, Voltage Regulator or the PCM ? I'll have the dealership test all 3..In the meantime, how would I go about logging the current draw, to find out if the current demand should increase at anytime, and should I also leave the battery tender on during the log time, or should I disconnect it ? because this is something I've never done before so if you could walk me through step by step ? I'd really appreciate it and I'm also very grateful for all the input and support that you've provided as well..

Cali HP addict

It was posted earlier but no one seems to have acknowledged it.
The Shaker system is for sure a likely candidate.
I have the Shaker 1000 and began getting dead batteries within a week.
I started turning off the radio before I turned off the ingition and I do not have dead batteries anymore. I have went a whole month and she started right up.
I'm not saying that this is your particular problem and I am not saying this is the only problem out there.
What I am saying is that you should give it a try!

metroplex

Good call Cali HP addict. I recall someone mentioning that before as well. I normally turn off my Shaker 500 before I turn off the ignition anyhow. I was taught to shut off all accessories before shutting off the engine.

m05fastbackGT

The shaker was the very first that was tested over a year ago. They took the entire head unit out and checked the wiring harness, along with the amp itself plus each fuse in the engine bay and everything checked fine voltage wise and mind you this was the second dealership I took the Stang which still didn't solve the problem, so I can pretty much rule out the shaker 500 as the problem and I always make certain to shut it off manually before shutting the car down..

m05fastbackGT

If by any chance you still suspect faulty electronics such as the SJB, Voltage Regulator or the PCM ? let me know and I'll have the dealership test all 3..In the meantime, how would I go about logging the current draw, to find out if the current demand should increase at anytime, and should I also leave the battery tender on during the log time, or should I disconnect it ? because this is something I've never done before so if you could walk me through step by step ? I'd really appreciate it..

metroplex

If it's not too much trouble, the dealership ought to check the SJB, PCM, voltage regulator, active anti-theft system, and Shaker (just to double check).

If you want to log system standby current draw, you don't want a battery charger hooked up because you'd be charging it. I hope you did NOT take your current measurements with the battery tender attached because that would just measure how much current you are supplying to the battery. You are more interested in how much current is LEAVING the battery and into your car when the engine is OFF and nothing is charging the battery (standby/parasitic draw).

You can either use a hall-effect style sensor on the positive battery wire, or hook up an ammeter in between the battery positive terminal and battery positive cable. If the value reads negative, it just means the current is flowing the opposite direction of how you hooked it up with the meter (not a big deal unless you are charging the battery).

don_w

I really hate to break up the techno talk here , but to go back to the original post, I have an Optima Yellow Top in my car, and it's been awesome. I bought it at PepBoys.

m05fastbackGT

I'll make certain the dealership does a thorough check on all 5 once the Stang is out of storage in April..In the meantime, how long should I leave the ammeter hooked up when logging for battery parasitic draw ?

metroplex

You don't need it hooked up 24/7, but you could take readings every day or so just to see if there is a trend (more draw as time goes on, or if it stays consistent).

I would recommend just measuring the current draw (without the battery tend or a charger attached, and without the engine running) once or twice and keep an eye on the voltage across the battery terminals.

m05fastbackGT

I appreciate all the input and support and will post the results..

ski

My car's battery bit the dust. Dealer replaced it today. They said it was defective. Hope the new one fares better, but I will not be surprised if it also fails.
The car would not start after it sat idle for a week back in January. The lights & radio worked ok, but the starter began clicking after the engine cranked for only about a second. Voltage was less than 12V. Jump started it, drove for 20 miles, voltage went up to 12.6V. Sat for 2 days, started right up, drove for 10 miles. Sat for 2 more days, started up, drove for 10 miles. Sat for 4 days, would not start. Jumped started it, drove it for 30 miles, next day it would not start. Called the dealer.

However, this is not the 1st time it had a starting problem. The same thing happened about a year ago. But at that time everything was dead, lights, radio, everything. Battery voltage was less than 10V(deep discharge?). Jump started it, took it to the dealer, they said everything checked out ok, and they recharged the battery.
(I must also note that I had been manually turning off the stereo unit prior to turning off the ignition for approx. 6 months before this initial starting problem occurred, as I had read on the various Mustang forums that one possible cause was the stereo's amps staying powered up if this procedure was not done.)
So it's possible that my battery was damaged by this single deep discharge, which was caused by who knows what.

karman

Here's my little winter test:
No starting for 3 weeks. Kept in an above freezing garage. Doors unlocked.
Started as if there was no battery drain (40ma of course).
I have the alarm (which I don't use in the garage) with the upgraded battery.
Stock radio never on.
It is a Johnson Controls battery ( It states this on the battery).