Battery seems to be low if truck isn't used for a while

[91Ranger_MO]

I've been having this problem for about 2 weeks now and I simply can't figure it out. In the morning when going to work and other times when the truck has been sitting a couple hours I will go to start it and it will start no problem, but the voltage gauge shows on the very very low side of Normal (the needle is pointing near the N) my lights are dim and all...when I go to take off it studders a bit, sometimes even dies on me. After I get it going if I stop at a light the gauge will go down low again near the N but once I press in the gas it goes right back up to where it should be.

I've had the battery and alternator both tested at an O'Reilly store and he told me the battery was good, and the alternator was good as well but that it wasn't putting out as much of a charge as it should be. It was putting out around 12.5v instead of the normal 13-14v

I put the truck on a battery charger tonight for a few hours and then went to start it and it did the same thing as I explained before where it would start out with a low voltage.

I've looked all around and don't see any lights that are constantly turned on so I really have no idea what could be causing this. Just looking for suggestions on things to check so that I can get this resolved ASAP.

 

[91Ranger_MO]

Wow...thanks a ton for all the help guys!

 

[Ronald Hribar]

i had a glove compartment light that drained my battery

 

[Blee1099]

What your dealing with is parasitic draw.. It does occur commonly on 1st & 2nd gen Rangers & Explorers.. Pretty much any vehicle can.. If you search parasitic draw on the forum, you'll come up with some ways to determine what is causing the issue.. My 91 won't start if its been sitting for 2 weeks without starting. I've determined it to be a bad diode in the alternator.

 

[coppe]

also it might be that your alternator´s inner works (carbons, brushes or whatever) are beginning to die, so your battery is not getting enough charge during the running period, and also you might notice that the most electronics you use (lights, wipers, etc) the more the drop will be and the less time the car is going to be able to sit and start. You already know the charge is not what it should, (that couple of volts difference can cause problems) and i´ve had the exact same pronblem before, and after troubleshooting a lot of stuff (even disconnected my aftermarket alarm and sound sys.) replacing the alternator was the answer. I´m not saying parasitic draw isn´t present, but you might have both problems.

 

[coppe]

ohhh and also after putting it in the charger... it will start because you have indeed charged the battery, but remember the battery indicator in your dash is just like the battery light in every car, but with a gauge, it is not going to show the real voltage or charge in the battery, it shows the presence of a charge current from the alternator, so you can have a new fully charged batt. but if the alternator is faulty the needle will be down. Also the fact that the charge (needle position) improves as you rev the car, is another signal (most of the times) of a dying alt., this happened decades ago with cars that had generators instead of alternators, the latter one is able to give continious charge at any normal revs. within the engine normal range. (iddle or floored) but generators charge more when rev´d. hope this helps.... you might be able to purchase a rebuilt alternator pretty cheap, or if you can, get a new one from a place that takes devolutions, just in case the alt isn´t your real problem.

 

[91Ranger_MO]

Finally got some replies...thank you!

My ranger is equipped with manual doors so that can't be the problem. My dome light shuts off when the doors are closed, the glove compartment light shuts off when the switch is pushed in, the light under the hood shuts off before the hood is even shut, and I have not seen any external lights on with the key off. I have been trying to figure this out for over a week and I've had absolutely NO luck.

I'm afraid that if I don't solve the problem soon I'll probably resort to just buying an alternator...and if that isn't what the problem is I'll just be out the money because the parts store doesn't accept returns on electrical parts.

 

[patrick112390]

well i would say at least replace your alternator. it should be charging around 14.23 volts.......also take an amp meter and unkook the battery cable, with the amp meter in-line, to rule out any parasitic draw....

 

[Dan Whitaker]

When O'reilly's tested the alternator was it on the vehicle? If so have it bench tested.

What are your battery cables like? That could be the cause.

 

[91Ranger_MO]

When O'reilly's tested the alternator was it on the vehicle? If so have it bench tested.

What are your battery cables like? That could be the cause.

Yes it was still in the vehicle...didn't see any need to take it out just to put it back in, plus it was the only way for me to get there to have it tested.

I'm unsure what you mean by what are my cables like....are you asking if they have corrosion on the ends of them? If so yes, a little but it looks like it's mostly on the outside of the connector, doesn't really look like it is interfering with the post connections but I guess I will clean them just for the hell of it tomorrow.