My 98' is equipped with the OE automatic supply disconnect switch that detects when there is too long of a draw on the battery and is supposed to shut off power to the vehicle. It does not seem to be working. In the recent -10 to -20 F below weather we've had over the last couple weeks the battery went dead just sitting there for that period of time. We were not using it because of a monster snow storm and medical reason also. The only draws I know of are the OE security system and the radios clock and memory presets. The switch is supposed to shut off power from the battery once it reaches a certain amount of discharge. I have a 4 year old Interstate MTP N65 that I keep topped off and has been great until this last stint of low temps. Do these modules go bad, wear out, or fail after years or what?

Thanks, have a very safe and Merry Christmas

 

...I know of no auto switch like your inquiring about.
...The only auto shutdown is for the interior lights.
...The battery has to be connected at all times for the computer to retain is program values as learned from your driving cycles.
...You likely are seeing the accumulated effects of an aged battery, and the very low temperatures.
...First thing to do is either replace the battery or at least have it capacity tested to eliminate it as a source of failure.
...Second is to test the charging system for performance and static discharge from a leaking diode stack in the alternator.
...Third is to check over all the cables for corrosion and do a cleaning of them at each connection.
...Always be alert for some other drain beyond the normal computer, radio memory and any other options that need to be 'kept' alive as needed.
...If you don't do these tests to be sure there are no performance problems you will keep having the same issues of no start.
...-10 and -20 will absolutely bring out any problems in the charging/starting system that has to turn over the drag of a cold motor that has set for some time..
...A discharged battery at your temperatures can freeze and break the case.
...Also be sure you are using 5W20 weight oil in the motor.
If you tend to all these items there won't be an ongoing issue with cranking and a discharged battery unless there are issues with the starter or the start relay..
...I would hope you see all this as a reliability factor, you need.
Good luck.

 

I just went thru all this with mine. I have a less than 3 year old battery that would discharge in about 3 days sitting in the garage. First I put my meter across the terminals with it running and got 14. somethin' volts....so that was OK. Then I set my meter to 20 mA scale and in line on the negative side I got 0.24...tested with the hood light pulled out and 45 minutes after disconnect....so that was OK for parasitic draw. So then I pulled the battery out and put it on the bench and charged it for 2 hours with a 3amp. charger. Let it sit a day and the next morning it was like 11.98 or something. So took it back and they tested it and right away said the battery was bad. It had a 3 year 100% warranty so I walked out with a brand new one at N/C. I have never had a battery go bad that fast...it was a 1000-850 battery so it was a rather expensive one. I would just pull the battery and have it tested on those machines they use. I am in Minnesota also and we are looking at like -20 below tonight IIRC. As you know we have had a nasty December, and as mentioned by others anything marginal can't take that extreme cold for long. Good luck and let us know..

 

A guy put a Knife Switch on his Positive Batt terminal. That worked.

 

BF, there is no "autu disconnect", but during the discussion last week someone brought up that when you shut off the truck, after an hour or so it goes into a "low battery usage" mode and draws very little current. That makes the battery last a month when truck is not used. Im not sure what the "low usage mode" is called, but remember Bluegrass talking about it.

 

IIRC brother Project SHO 89 called it a "battery saver relay" and it shuts off at about 40 minutes.

 

I would still go over the whole system for good measure to be sure.
The saver relay could have sticky contacts so address that possibility as well.
Good luck.

 

That's it. I read about it in the owners manual and the factory FORD workshop manual.

 

I'll check to see on availability of the BSR and the other items you mentioned. We got hit with winter temps and frozen ground back in Oct. A little bit early this year! Ironically the large snowfall we got 2 weeks ago covered all the lakes and slowed the ice freezing process tremendously, putting ice fishing and driving on the lakes this season in a precarious position. We're already on pace to beat the all time snow accumulation record for Dec. Tonight we're seeing -33 F just north of here. I did disconnect the battery and gave it a three 2.5 hr sessions at 10 amps. I had years ago installed a green twist lock on/off switch on the neg. bat. terminal that I use for servicing the truck when needed to minimize pulling the battery terminals off. It's a great convenience that has worked fine so far.

I just checked my records and the battery is 5 yrs. old now with an 85 month prorated warranty. I'll probably bring it over to the Interstate Battery distribution center for a test and replacement if needed. I did not know that the trucks CPU was drawing off of the battery when the truck was turned off. Indeed, I did see several vehicles up the alley with battery chargers plugged in after that cold snap. I'll see if the guys at Interstate can check the other systems quickly for ma as well?

In the old pre-computer days we used to see 10 years of use out of batteries when nothing was drawing them down and they started frequently in -25 deg F weather, some times with a short blast of either down the carb. I wonder what happened to all that talk a few years ago about switching modern day automotive electrical systems to a 44 volt power supply instead of 12v to better handle all the new demands of modern electrical systems?

We're supposed to see -20s this weekend to.

Note: I wonder if my Edge Evolution is drawing when it's turned off?

 

You can measure draw even with a cheap meter.....like the ones they give you at Harbor Freight for free when you buy some cheapo tool. Set it to 20mA and plug the positive lead of the meter into the 10amp. port. Pull off the negative battery cable and put your meter in series with the cable and the negative post. 0.25 or less is somewhat normal, though I have read 0.25-0.50 is OK also...I am no expert on this. If it has a hood light pull the bulb out so that does not mess with the results. If you think it may have a battery saver relay, take the initial reading and then wait an hour and take another one and compare results. The hood lamp alone will run a 0.24 to a 0.80 so be sure to pull the bulb. Good Luck...stay warm.

Speaking of old cars and cold weather...I went to college in Bemidji in the early seventies where temps. regularly were -20 and lower much of the time at night. Had a 67 Firebird with a 400 and it would sit for weeks. Couple shots of Ether down the snorkel and she would come to life.....I don't ever remember many battery problems either.

 

I'll give that a try just to see what it's drawing?

 

I tried charging it one last time and the next day it turned over about 1 revolution and clicked once. It was dead. I located a new one and when I pulled the 4 3/4 year battery out it was frozen solid. I got a pro rated price and for 56 months of the 85 month warranty and it starts great now. We've had really cold weather here this winter. I went for a drive last night and it was -32 F (no wind chill) on my IAT in one low lying area north of town. I also had to replace my ground on/off **** switch that broke in half when I tried to take it off the old battery. While driving around last night the truck was so cold, it was expanding and contracting all over the place, though the windshields was going to break. When i got that -32 F reading I was only getting 14 mpg at 55 mph, that's cold! The engine temp ranged in the 188 F to 194 F area. Heater worked great though. Interstate has the new AGM batteries set to slowly start replacing current production over the next several years. They're supposed to be lighter and hold their voltage longer. I found out the CPU, energized remote door locks system, radios clock and presets, and the factory security system all drain on the battery when it''s turned off. We were snowed in for over a week with 28 inches and I couldn't get out to start it up. Starts great now, I guess that the way the cookie crumbles on newer vehicles with all these systems dragging off them. Good piece of mind for the next few years though.

Thanks guys!