battery or alternator

96 Mazda Pickup, 4 cyl, manual transmission.

About 3 weeks ago the truck wouldn't crank without being boosted off after the weekend (not driven during that time). Last week, it got to the point where it needed boosting almost every day, then by Friday it was needing a boost every morning. Not after being shut off, but only in the mornings. My first thought was the voltage regulator. Saturday my husband and son decided to just get a new battery. They took the old one up there, did NOT have it tested and got a new battery.

However, when they hooked the new battery up they didn't pay attention to the fact that the battery hookups (+/-) were the opposite of the old battery so they proceeded to hook it up backwards. Yes, there was smoke.

The truck cranked this morning without a boost. However, when we removed the red cable from the battery, the truck would die. My husband's brother insists that this means the alternator is bad. I am not sure, but it seems that if you break the circuit, that the power to the truck is gone.

I will take the alternator tomorrow to have it tested since DH will probably just go buy a new one without having this one tested. I still think that the regulator was bad since the truck didn't need a boost until after about 12-14 hours of sitting idle.

Kay

 

it is always a good idea to have ur alternator tested unless u already know it is bad as for it dieing after disconnecting the battery not nescessarily sumthing wrong not sure of the case with urs but sum vehicles need to have a battery hooked up in order to run but not all of them which is why they may think ur alternator is bad in any case u r doing the right thing having ur alternator tested it will help u avoid problems in the future

 

The new battery may have fixed the problem...not sure why the cable was unhooked unless he was trying to test the alternator but its not the best idea to unhook it while its running. I agree with backyardhndyman with the battery needing to be hooked up on some cars. I believe the old cars, before they had computers would run fine if you disconnected the battery or even jumpstarted the car with the battery disconnected, but todays cars are different and may need the battery connected. The engine runs from the alternator voltage anyway, not the battery, so unhooking the battery wouldn't tell you anything about the alternator.

You may have other electrical problems since the battery cables were hooked up backwards. Check for burned insulation on battery cables and other wires and repair them. There might be a fuse that goes to the voltage regulator. Check that, if it exists. A wire from the regulator should go right to it.

 

Thanks for the responses. This has just been bothering me. I thought it was strange about pulling the red cable from the battery, while the truck was running, too. I have a little too much respect for electricity to mess with batteries on a truck while its running.

His brothers are kind of funny. They will tell you to lay a metal object across the two posts of the battery to see if its shorted out. If it pops or shocks you, then it wasn't shorted out, but it is now. If nothing happens, then the battery was already shorted out. Either way, you end up having to get a new battery.

This is why I don't like my husband listening to them. And he will listen to them even if he knows better. I'm still amazed at them (my son and husband) hooking the battery up backwards. I was really upset with them Saturday, but now it is kind of funny. I guess they aren't stupid, just lazy.

DH has apparently taken the alternator with him to work. I was going to have it checked today. Thanks and I will post back the results of this little mis-adventure.

Kay

 

All gasoline powered vehicles will run with the battery disconnected, unless there is a problem in the charging system. IT is not a good idea to disconnect the battery on todays highly electronic cars as it can cause problems with some electrical components. Hooking up the battery backwards can be very dangerous. I have seen a battery explode when this kid hooked it up backwards. It was my battery and he stuck it in his car to get him started and he hooked it up backwards and it exploded when the ignition was turned to the on position. He ended up with a face full of battery acid and several large pieces of plastic sticking in his skin. It was not a pretty sight. There could be some wiring damage as well as some fuse(s) that were damaged due to hooking the battery up backwards.
I would bet that the alternator is bad, but there are a couple of other things that can cause the same thing to happen. Like the main fuse or wiring. And the regulator is inside that alternator.
Hope this helps ya,
Billy

 

Thanks Billy. I discovered that VR's are inside the alternator on my 79 Blazer. My first experience with a VR was years ago and on an El Camino. Had to pop the hood and disconnect the VR when I'd stop somewhere, or else it would allow the battery to drain.

I'm going to have the alternator tested now. He had put it in the bedroom?

I'm really grateful that nothing bad happened to the guys when they hooked the battery up backwards. That would have been a really bad situation. Those two are REALLY lucky that didn't happen.

Kay

 

They've gone now to get the new alternator. Its $92, which is okay I guess. Sure miss my old 79 Blazer. The alternator was $40. My son had taken it up to the shop to have it tested and they said it was bad. Not sure if the VR was bad, or the whole alt. No matter, it has to be replaced.

Thanks for the answers. Keep up the good work everyone! Appreciate you more than you will ever know!

Kay

 

Sounds like a situation gone from bad to worse.Sounds like a simple battery replacment would have solved the problem until the battery got hooked up backwards.
The alternator will keep the truck running even with a weak battery it is hard on it because it is always on.The battery is kind of like a shock absorber for electrical loads.
Who knows what got fried hooking it up backwards I am willing to say the alternator was one of the casualties of not paying attention and maybe if you are lucky the only thing.
Putting a metal rod across the posts is not a good idea batterys have lots of amps and will blow up and they have so much power they can weld things.
I hope that your computer or other electronic items did not get cooked but I guess you will find out once you install the new alternator.

 

I do consider us extremely lucky. One, my DH didn't blow the battery and himself up, and two nothing else was damaged, except for a wire. He didn't discover that until he cranked the truck and let it run for a bit. It died, and the battery was dead. My son, who knows a little more about cars today, checked the wiring and found the burnt wire. He fixed it, and now the truck is cranking fine and holding a charge. I'm sure over time that we will start seeing more side effects from this. Or, by grace, maybe the melted wire saved everything else? We shall see.

Thanks again everyone. I have to say that I have been super-stressing lately, and you helped to calm me down on this issue. Now, is there someone that can help me with my accounting homework ? College is getting harder.

Have a great day everyone!

Kay

 

That "melted wire" could have been a fusible link, which is a kind of fuse. Ask son about it. If he doesn't know, find someone who does. If so and it was replaced with common wire this could cause a severe problem down the road.
Mike A

 

When Lee (son) was checking the wires he noticed when he ran his hands up and down this particular wire that it was soft. Lee was a mechanic for awhile so I trust him when he fixed this.

I also found out that Lee had nothing to do with hooking the battery up backwards. At first I was shocked, thinking he was standing there when it happened, but he was putting windshield wiper blades on my car.

I really appreciate everyone's responses. You all are great!

Thanks again!

Kay