Fried electrical system?

Can the electrical system be fried if you hook up the battery backwords (poles reversed)?

I’m asking this because after taking the battery for a check at Advance Auto Parts, they offered to charge it. But when I took it back to the car and hooked it up (correctly) it sparked and everything went dead. I took it for a check at a specialized battery shop and they showed me the poles are reversed. Plus is actually minus and vice-versa. I told the guy the whole story and he said the guys at Advance Auto Parts reversed the cables when they charged the battery.

Could this be possible?

Is my car’s electrical system fried now, and how can it test it? I checked all the fuses and they’re good…



the poles of your battery are marked with a + and a -. the + is the positive terminal of the battery, the - is the ground terminal post. The leads from the battery to the car, are also plus and minus, but not generally marked as such. There is only one lead from the minus side, and that is the ground lead, and it goes from the battery to the frame or body of your vehicle. It is the shortest lead. the other lug ususally has two leads, one heavy lead that goes to the starter, and another smaller lead that goes to the fuse box and is called a fusible link. If you connect these leads backwards, you will ruin the alternator at the very least, and possibly other components of you cars electrical system, more so on modern cars with all the extras and computers and what not. You post is a little confusing about who did what and why. But the basic asnswer is yes you can.

Sorry for the confusion. I know all you say about leads and I’m certain I hooked up the battery correctly. That’s why I was so surprised when it sparked. When the guy from the battery shop put the battery on the bench and tested it, the pole marked (+) on the battery was actually the negative one and the pole marked (-) was the positive one. If the batteruy poles were reversed when recharged by hooking up the charger’s cables backwords, I intend to hold Advance Auto Parts responsible and get my car’s electircal system fixed for free.

if the battery terminals were marked with the wrong polartiy, then it is the battery manufacture you need to sue, not the service guys who cannot be expected to check this, as it is a standard no one expects to be violated. Sparks from a newly charged battery are a bad indication and if they hooked it up when they knew it was sparking then yes you do have a case aganist the service guys, but only for continuing to hook it up after they knew it was sparking. by the way, once it sparks off the leads being connected, most likely the damage to the diodes in the alternator has already been done.

Nope, the battery terminals are marked correctly by the factory. It’s been like this for the past few years and nothing like this happened. I did the hookup because the car was imobilized in a parking garage.
And BTW, you can’t hook it up backwords in the car because the leads are too short , even if place the battery 180 degreees from normal position.
Anyway, I have the battery with the revered polarity as prroof of their incompetence.

Im sorry, but you said the pole marked + on the battery was actually the negative one…etc. I read that to mean the pole was marked + but was actually the negative one. but now you say it was not marked wrong by the factory? I am having a very hard time following your post.

A battery CAN be charged backwards, that is possible…But most modern battery chargers will recognize this reversed polarity and refuse to charge the battery in the reverse direction.

When you installed it, yes, major damage is possible and probable. Take the reversed charged battery back to Advance, show them what they did, and file a claim for damages. Good Luck.

Ok now I get it. Geesse, do I have a red face.

I took the battery to the store and talked to the store manager. He wouldn’t admit anything despite their test printouts before and after the recharge showing the battery was good. More so, he tried to BS me when I showed to him, with my own voltmeter, the reading was -12.54 V, saying “See, the battery is bad.”. That after saying the battery was good, according to their own test printout. I don’t think he even knows what polarity is. That or he’s playing really dumb.
Anyway I realized I’m losing even more time with them and left. I’ll take it with their corporate management tomorrow.
In the mean time does anyone have any hints where I should start testng what’s fried in my system?

Yes a battery can be reverse charged. However, the battery must be almost completely discharged for a charger to do it otherwise the charger will overcurrent as the battery voltage will be added to the chargers potential causing excess current to flow. In fact, the way to correct the reversed charge is to completely discharge the battery and recharge it correctly. BTW, the reverse charging and the rereversal lowers the capacity of the battery so you might have the cranking amps of the battery checked.

As to the damage done, connecting the battery to the car’s electrical system with the polarity reversed would cause an immediate short circuit through the alternator diodes. If the electrical system of your car is sufficiently protected there is an alternator fuse or system fusible link that will open to protect the electrical system. During the time it took the fuseable link to melt out, there would have been ~1.5 volts negative on the positive side of the system. If you have an alternator fuse that blew, then you might have had a negative 12 volts on the positive side of the system. If so you may have colateral damage to any module that is wired ‘always hot’ i.e. ECM memory, radio memory, air bag SRS controller, etc. I assume you did not connect the battery with the ignition switch ‘on’.

I hope this helps.

Again Caddyman puts some sense into this one, I knew what the OP was talking about halfway through his inital post.

Batteries can be charged backwards, and damage will result.

The battery was almost completely discharged indeed and no, I didn’t install it with the ignition switch “on”.
The store is asking me now to come up with an estimate for the repair in order to file a claim. I guess I have to tow it to a shop and see.

If this is a 1995 Escort, luckily you do have a main master fuse 100A protecting the alternator, ABS, air bag controller, and other power distribution panels. There are separate fuses for ‘Head’? and ‘fuel injector’ of 30A each. So you might see if you can find these fuses and check their continuity with a meter – just check for 12 volts on each side of the fuse leads.

Let us know what damage did occur.