Battery killer...
 

My '98 Explorer 4x4 v-6 goes through a Sam's Club battery every six months or so. They get so they won't charge full and if I run around town with the A/C going full blast and the automatic daylight headlights on, the battery gradually loses power. The latest one just gave up this week after about 8 months. The alternator is putting out plenty. At idle the battery voltage shows 13.5 with the ac and headlights on. After forty or so town miles I put the battery checker on the battery today with engine off and it showed 10.7 volts no load and about 5.8 volts with the starter engaged. When I jumped the battery with a fresh battery the load voltage hung at 11.5 with the starter engaged. When I put a good 15 amp charger on the mostly dead battery it would only take 4 to 5 amps and tapered down to zip after barely an hour. That leads me to believe that the battery is bad and won't accept sufficient amperage. I don't believe the starter is dragging. Or no more than normal considering the 140000 miles on the unit. I have ran the starter for a while with the ignition open and then felt the starter case and it is barely warm. I do have a small battery drain with ignition switch off. Even a new fresh battery will go dead after a week or so. I think it may be the auto door locks. Maybe a leaking diode. I suppose with a cheap battery the constant drain down and recharge wears them out faster. Still 6 to 8 months seems a lot.
Question: Who makes a better battery? Consumer reports sez that NAPA has a good 65 group for $79.00. A performance select 8465. Anybody try it?
Also, how can I unhook the daylight headlights? Fuse? Pull the plugs behind the lights? Thanks for your help and the web site for being here.

its hard to believe you get a rash of bad batteries. something to think about... 20 years ago i had a small chevy car that the alternator put out about 15 volts. it would slowly cook the battery and kill one each year. since you have a small "leak" that could be a diode inside the alternator, and also causing some overcharge. i know you said 13.7 volts was measured, but maybe that is not the case at 2000 RPM running down the road. if the alternator is "old" it might be something to think about.

Check the old battery and see if there is any water in it. It could be that your are boiling the battery dry and causing it to fail. Your alternator could be shot with the regulator not operating properly. Get the alternator checked at an auto electric shop and then you will know.

All cars have a little drain. The modules and security system need this to stay alive(about 25-50 mA). Anything over that is a parasitic draw. How is your belt? The belt could be slipping on the alternator causing an under charge after it heats up. Or is the tensioner failing? If the belt and tensioner are good, I'de throw a new alternator in. It could be failing after it heats up....

check'n
 

Thanks for the quick response on my battery problem. I put a new serp. belt on when I had to replace an idler about 10k back. And it's torqued right by the new tensioner I also replaced at the same time. As far as batt. acid, the plates are covered with acid.
I know I get a small current drain from the alarm system and door lock rcvr and I also have a remote starter wired in that sucks up some juice.
Yesterday after posting I borrowed a fairly new battery from my F-350 7.3ltr Diesel (talk about a battery killer) which checked full and tried it on the Explorer. The starter whirled like new.
I've got a cig. lighter volt meter which is easier to read than the Ford dash gauge. After I get a new battery, I'll plug it in and check it around town with all accessories on with engine cold and engine hot. Also going down the road at high revs. Usually when the alternator is overcharging the battey will boil off water pretty fast. It hasn't lost any since I put the battery in in jan. '07.
I think my next move is to see exactly how much current is being drained by putting a volt/amp gauge in line from the pos. side of batt. with engine off. Any more than .1 amp at 12.5 volts would be a lot I would think. That would be close to 2.5 amps each 24 hours and 17 to 20 amps per week. With a weak group 65 battery that's down to a max capacity of 40 to 50 amps. at 6 to 7 cranking volts, that would be a deal breaker.
I do notice that when I re-attatch the pos. cable the door lock servos make a pretty good noise. I also get some temperary fuel injector whine, which would be normal I think.
I live on a ranch with a wash board road and have read that battery plates can seperate with the jolting. I keep the tires at normal pressure but you Explorer pilots know how the machines ride on rough dirt. I doubt that's the problem or all my rough riding Ford trucks would be needing batts.
I'll know more when I find out how much drain there is and start pulling fuses to isolate the bad line.
Meanwhile I'm going to plug in a cig. lighter trickle charger every time I intend to let the great little green beast sit for more than a few days. I've got 5 Fords and like to drive them all. So sometimes the Xer has to wait. Thanks for the help. I'm open to any more ideas. Meanwhile Sam's club is getting their el cheapo battery back tomorrow. NAPA has one for $90 bucks that gets best review in Nov. '07 Consumer's Reports. Also WalMart's MAXX 65s 850 cca gets a good review for some less dough. I'd like to try a Optima but can get 2 regular good batts. for the same price.

Fully charged battery will read 12.7 volts at the batt..12.5 is half discharged. The alt should read 14.5 volts at idle everything off fully charged battery..At any time if you rev it up and the charging voltage doesn't go over 14 volts the alt is bad. I'm sure the batteries are fine...Any drain over 30 ma is an indication of a problem.

good advice, thanks!
 

I put a battery checker on the old Sam's club battery after charging it with an ac batt. chrgr to a tapered down zero. After running the surface charge off it read 12.3 volts and with the built in 'load' it dropped to 8.3. That would indicate 'bad' to me. The plates must of sulphated or a cell is bad because it will only take 5 amps from a good new 15 amp battery charger. The voltage reads too high too fast. That charger will almost pin the needle on a good battery that's low with the voltage gradually coming up to spec.
With the borrowed battery the voltage at rest and fully charged with engine off and surface charge off, is 12.7 volts. Under the starter load it only drops a volt or so. I think the alternator may be putting out a little too much voltage or the borrowed battery isn't in as good of shape as I thought. At normal idle the voltage at the battery with accessories off reads about 15. The battery doesn't 'boil' though as the old battery never needed water. The Ford dash voltage gauge puts the needle about half way up, well with-in the normal range. Lights at night aren't too bright like they can get with a run away voltage regulator.
With the headlights and AC on the voltage only drops to about 14.5.
I did run into a alternator once in a reciprocal engined plane that put out a high voltage AC spike and chewed up batteries and electronic equipment. Had a bad capacitor as I remember.
The more I learn about lead-acid batteries the more I realize I don't know.
I hate to start changing 'black boxes' as we used to say in Naval Air. It's quick but not cheap when Unc. Sam ain't buying. I'll get the local auto parts store to put their machine on the alternator and see what's what there.
Sometimes a big electrical problem turns out to be a bunch of small problems. Bad cables, bad grounds, bad alternator/regulator, dragging starter, bad solonoid etc.
Working on my own stuff beats book rate at the dealer. By about a hunderd or more bucks an hour.
I'm new to this site but as I've got a bunch of Ford products I imagine I'll be here a lot.
Thanks for the response.

Up to 15.5 is ok. Yes that batt sounds bad it should charge 10 amps or more. Check for overnight draw...

I have an Aviator which has been giving me the same problems. The dealer disconnected a Lo-Jack type device that I did not know I had. Apparently it came in the package but was not listed (or maybe my wife had it put in to track me). In addition to the regular alarm system this was drawing another 15 to 20. I'd leave the car at the airport for 2 or 3 days and it would be absolutely dead. Compounded witht he fact that I take a lot of short trips no battery could stand the pain. I had the device disconnected and got a new heavy duty battery. That worked for about 2 years but now I need another battery. So I have been given a lot of ideas but the mystery continues.

As others have stated, look for a battery drain. Pull the pos cable off the battery and run a mutlimeter between the post and the cable. There will be a small amount of draw. IF you feel the draw is too high, start pulling fuses/relays to isolate the circuit that has the draw. You mentioned the door lock servos, so maybe start there. Also, remember to disconnect the hood light when doing this procedure to eliminate that circuit.

You might want to also carefully inspect the battery cables to make sure there is no loss due to cracking or corrosion.

You need to do a parasitic current drain test. Insert an ammeter between a battery post and the battery cable. Set to at least 10 Amps range. Close all doors except drivers door. Flip the door striker on the drivers door in to turn off the dome/ courtesy lamps. At first you should see about 200 to 250 ma. draw on the battery. After 45 minutes the G.E.M. module should go to battery saver mode and the current draw should drop to 15 to 50 MA. 50 MA is the absolute max spec. My 98 Expy goes to 17 MA. If not in spec you can start pulling fuses in the fuse panel to find which circuit is drawing too much. Other possible sources of excess draw are the alternator and the cruise control switch on the master cylinder - if it is leaking and about to possibly cause a fire and courtesy and interior lamps stuck on. Also any add - in stereo amplifiers may have a large current draw when turned off - pull their fuse to check.

The alternator should charge at 13.8 to 14.8 at 2000 rpm, depending on temperature.

Short trip driving can kill a battery by constantly under charging. It is wise to drive at least 20 minutes once a week to fully charge the battery.

Hope this helps

Scucci

I know this isn't addressing the cure, just the problem. If the shortened battery life has anything to do with your driving conditions (rough roads leading to premature shortage in the plates) you may try one of the spiral-wound type batteries, i.e. Optima and Exide. There are plate separators between them to prevent the vibration woes. You may also consider one of the dual purpose, cranking/deep cycle batteries, that Optima sells. The deep-cycle aspect should help offset the higher-than-normal parasitic draw you have.

Just a thought-
Randy

Ok, as opposed to discussing it further on this forum, here is what I suggest. Drive to a local auto parts store, and they can do a free charging system check. This will tell you exactly what the problem is, so you can stop throwing batteries at it. There is obviously something wrong, and no doubt, you battery is now bad, but it was good when you installed, it, it is no longer working because it has been damaged by something else in the charging system.

A bad alternator will destroy batteries.

Use a VAT-40 to check your charging system....your alternator is crud.

Over on the "serious Explorations" forum, there are many threads about teh door switch wire bundle chafing in 2000-2007 Explorers and Aviators. Pulling the rubber boot back and a flashlight may let you see the bundle.

The door open/closed trickle test is most often used to see this.

Keep us in the loop. I'm on my 3rd battery in 2 years myself.......