I have a 91 ford ranger 4 cyl, no power windows or locks, just a basic truck. The battery dies every few days?

There's 2 basic causes.

Most Obvious is simply a Bad Battery.

Which is not necessarilly an "Old Battery"

Less obvious but very common is a "Bad Alternator".

Or more correctly stated,,,the RECTIFIER in the alternator.

Get Alternator Checked for a Bad Rectifier Condition,,not just "alternator output".

A simple,,"Non-Conclusive test" is to chech the Battery Positive terminal for any presence of AC Current while engine is running.

A Cheap Voltmeter set on a Low Voltage (10V or 50V AC scale) can indicate AC is SOME instances.

Results:

*If it shows NO AC reading,,it's Not necessarily OK

*If it shows ANY AC reading whatsoever,,Alternator's rectifier is Bad.

Whatever you do,,Best to Not replace Battery until Alternator's condition is verified

......................................................................

The rectifier has a set of Diodes in it which are semiconductor devices.

They function as Electrical One-Way CHECK VALVES.

They Conduct electricity in One Direction,,but block it's flow in the opposite direction

Their job is to convert the alternator's Alternating Current (AC,,,like House current),,

into Direct Current (like battery current)

Several Diodes are arranged & connected to form the Rectifier..

Diodes can Fail in 2 basic ways.

1)OPEN--they just burnout like a Litebulb or Fuse,,,,Nothing gets thru them in either direction.

Resulting in NO CHARGE,or LOW CHARGE to the battery.

That simply DRAINS the Battery while in Use,,,'cuz it's not being Recharged properly.

2)CLOSED--aka shorted,,,this is when the Diodes sorta fuse together internally and create a Short inside themself.

That destroys their 1-way Blocking function,,

and allows Current to move in Either direction Thru it.

Result is...As the Vehicle Sits,,,and everything is OFF,,,with no current drain from battery,,,

The Faulty,,Internally Shorted Diodes allow Battery Voltage to BACK FLOW to Ground.

It's same effect as having a small lite bulb or other type eletrical device Running and drawing current from Battery.

SO it eventually drains battery dead...

BUT,,it's effect is even WORSE.

Because the Diode is "Leaking" in a direction it should be Blocking,,,,

the Alternator which Charges the Battery is

No Longer sending Pure DC direct Current.

It leaks thru a small,continuos amount of AC to battery when engine is running & Alternator is Charging.

That AC current will DESTROY a Battery...physically damage the Batt.

Draining a Batt is "normal" operation.

They're made to be Drained and Re-Charged.

But allowing AC Current to reach a Battery will Damage the batt.

TRicky part is,,,,Battery,Alterntor,Charging System TEST EQIPMENT ranges in Complexity,Capability,,,and PRICE.

Lots of Test Equip wont Find Bad Rectifiers.

Battery can test GOOD,,,while it's slowly & surely being Destroyed by AC charge.

Or,,Alternator can test GOOD,,,because it IS "charging" and it's output is within accetable limits.

But NOTHING in a Quick Test/Cheap Tester shows the presence of AC current where there MUST BE ONLY pure DC.

Rectifier Section of the Alternator must be purposefully and deliberately Checked.

Procedure is SIMPLE,,,

the physical ACT can be difficult.

Vehicles' wiring gets "ganged" at or around Positive Battery Cable.

So even though you remove Cable from Battery,,,,there is often Other ciircuitry connected to the CABLE.

The Charging Output wire or Terminal From the Alternator MUST be isolated from All Else in order to test properly.

A Simple Ohmmeter can then be used to test Continuity between Alt's Output and Ground.

If there's ANY "connection" whatsoever between Ground and the Alternator Output,,,,there's the Parasites at work.

Actual Cause of that is almost exclusively a Leaking Diode.

99.9999% Certain.

It's possible to replace Only the Diode/Rectifier assembly in Most alternators,,,,which usually saves some money.

But,it requires a somewhat bit of "advanced" level of skill to work Inside an alternator.

Zillions of home mechanics Can & DO,,,it's not a bad project overall.

Lots of folks simply replace the entire alternator assembly,,,it's pricey in many cases,,,but certainly the quick & easy,most convenient method.

When everything is OFF especially on vehicles without a bunch of continuous running electronics,,,

The ONLY drain source is a Faulty Alternator Diode.

It's a "separate" control device BETWEEN Alternator and Battery,,,but in Practice they are "built in" to Alternator.

So the Fix is either Replace or "Rebuild" The Alternator.

First off, how old is the battery? After a few years batteries tend to "wear" internally. They can develop tiny shorts between the cells, and can even lose voltage through the case to the battery box itself.

You can take the truck to an auto parts store and ask them to put a load test on the battery. Also, have the alternator checked for low output. Both tests can be done quickly and will tell you if the alternator and battery are ok to start with...

Then you can isolate possible circuit drains...have an electrical multi tester handy, disconnect the negative battery cable from the battery, set the meter for low to medium amps, connect the leads between the cable and the battery post, write down the reading. Then pull one fuse at a time, recheck your reading. When the amps drop, you found a circuit that "might" be causing the problem. Remember, the clock uses a small amperage to keep time, even with the power off.

As you can see, there are a lot of possible causes, but a methodical investigation will usually turn up the problem fairly fast...

Your truck may be fine, you may just have an old battery. Try cleaning the battery terminals and terminal connectors first. If the battery still discharges then take it to a parts store that can test your battery, if it tests bad you will need a new battery. The next and less common problem is the alternator, again, you can get that tested for free at some auto parts stores but you are going to have to take it out of your truck. Finally, it could be a fault in your wiring; if this is the case I suggest you take the thing to a qualified mechanic as these problems can be a real pain to track down.

have battery alternator checked if good disconnect the pos battery cable use a volt meter set on dc volts one lead to the pos post on battery the other to the pos cable with everything off you should read 0 volts if reading any thing else you have something draining the battery start pulling fuses one at a time until the reading goes to 0 volts(reinstall the fuse if the reading does not change) the problem will be in that circuit(if when pulling the fuse for the tail lights the reading went to 0 check the tail light wires (circuit) for problems or shorts)

I had similar trouble with an old Toyota truck. It was something really simple - battery low on water, and cold winter weather. Topping off the water helped. But eventually, the battery needed to be replaced, and then the trouble never came back.

How old is your battery?

Disconnect it.

Charge it up with a car charger for the maximum charge.

Disconnect it.

Measure the voltage. If it drops off by itself, you need a new battery.

Otherwise, assuming you have a good battery, you may have to enjoy the thrill of tracking down a 12 volt short circuit. If you suspect a damaged light or a dent might be pinching a wire, check there. Otherwise, start replacing electrical components in order of likelihood and cheapness.

bummer.

1

get a load test done on ur battery, if it is good check ur charging system, might not be charging enough. If this is no fix you have a battery draw prob that could be expensive to find and fix

Glove box light staying on?

go to s10forum.com ur gonna need to create an account no money needed then go to the top it says forum chat news stuff like that go to the chat and ask if anyone knows deeze49686 or ask for Neal Lamp and your gonna need to leave him a message