Alternator or fuse

ford
expedition

#1

I have a 97 ford expedition the alternator test good so i bought a new battery but it still wont stay charged does anyone know if it could be some kind of fusei need help


#2

What makes you think the battery won’t hold a charge? B/c it won’t crank? You don’t hear that rr rr rrr sound with the key in “start”? Do you hear a click at least? The battery is just one reason why a car won’t crank. There are others. But let us know about the symptoms.

If you know how to use a volt meter, you could do the following measurements, and let us know what they are

  • Before starting the engine, the battery should measure about 12.6 volts.
  • After starting the engine, the battery should measure 13.5-16 volts.
  • After running the engine for 15 minutes, the battery should measure 13-14.5 volts.
  • With the engine running, the voltage between alternator output post and the battery positive post should be less than 0.3 volts.

#3

See if fuse #19, 10 amp in the junction box fuse/relay panel has blown.

If that fuse is good, there’s a 20 amp in-line mini-fuse in the charging circuit that may have blown.

Tester


#4

It’s impossible to tell from here.

  • under what conditions is the battery running down; while driving or while parked?
  • Have you checked all of your car’s courtesy lamps (domelamp, entry lamps, etc) to ascertain that none have been left on?
  • do you drive the car far enough every day to recharge the battery of the energy used to start the engine, or is your driving simply to the corner store and back?
  • how long is it taking for the battery to drain? Overnight? A day? A week?
  • did you change the battery yourself? Did you (or the shop) check all eth connections for corrosion?
  • have you checked the fuses?

If everything was tested and checked, and you’re driving far enough every day to replenish the battery, and all the courtesy lamps are off, you may have a “parasitic drain”. That’s an unwanted current draw when the engine is off. You’ll need a shop to measure the current draw with everything turned off and try to isolate the offending circuit. It may be as simple as removing fuses one by one until the current draw drops, or as complicated as pulling a schematic and a wiring diagram and getting into some serious electrical testing… or both. The former you could do yourself, the other two will need either a good shop or even a shop that specializes in automotive electronics.

Oh, and if you have aftermarket installations like an aftermarket security system, a 2,000 watt audio system, or “Xmas tree lighting” on the vehicle’s exterior, those would be really good places to start looking. Especially if the problem started after the installation.


#5

It ran fine untill the other day all the guages droped and it died and had to get jumped off to start then it kept doin it the rest of the day i had it tested at auto zone and they said the alternator was good and the battery was bad so i bought a new one and it still wont hold a charge as soon as u take the jumper cables off it dies


#6

Also where are these fuses


#7

If it starts fine and runs fine when jumpered, then I doubt it is a fuse. I’d check the battery connections, both ends, and the battery cables for internal corrosion.

Warning, this could damage your new battery… Fully discharging it causes damage.

Get a charger and let it sit overnight charging and see what happens.


#8

My favorite link to post on battery drain :cat:


#9

The OP states the following.

Tester


#10

Check you owner’s manual. If you don’t have it, try the Ford website. They may offer a pdf version there for your vehicle, gratis. Many vehicles the main fuse box is located on the inside of the car, to the left of the driver’s left knee. But not all fuses are located there, and alternator fuses often are in the engine compartment. Often located in boxes on top of the wheel wells. The owner’s manual should have a picture what those fuses are located and what they are for too. Tester mentions an in-line fuse, that one might not be in the owner’s manual. Sometimes that type of fuse is located near the battery positive post.


#11

When i put the new battery in it ran for about 2 hours now it want stay started unless on jumper cables the battery guage dropes and nothing works like windows or anything


#12

That sounds like the alternator is not charging the battery. Indeed, a fuse could cause that. If the fuse replacement idea doesn’t pan out, try the voltage measurement test above. If you don’t have the necessary experience to do that test, ask a shop to do it for you. I doubt they’d charge much just to do that, it would only take 10-15 minutes.

It would make sense btw to charge the battery overnight using a battery charger in the meantime. Not a good idea to allow a battery in terms of battery long-life to allow it to become fully discharged and stay that way.


#13

I charged it today to try and make it to a shop and only made it 5 mins down the road and had to be jumped 3 times to make it home…about a week ago my electric back windows stopped workin then everything else happen


#14

It can take as long as 24 hours to fully charge a totally dead battery. How long did you charge it?


#15

About 6 hours


#16

Start the charger up again, and let it run overnight. If you happened to have a shorted diode in the alternator, that could prevent a proper battery charge unless you disconnected the battery from the car first, or at least disconnect the battery negative connector. Maybe disconnect the battery and charge it that way overnight. It’s an experiment that might be enlightening to help solve the problem.


#17

Thank u ill try


#18

Your owner’s manual will show you where all your fuses are.
But I think you’d be wise to take it to a shop. They’ll have the experience, knowledge, test equipment, and access to your car’s technical data to check everything out properly.
I usually avoid mentioning store names, but I would not trust AutoZone for this. My experiences with them have not instilled in me a sense of confidence. I’ll buy a new headlight lamp from them, or a tube of lamp lube, but that’s about it.