Hi. I have an 88 TII. I just got a new battery for my 7, and twice now when I hooked up the negative cable I get some good sized sparks and the main 80 AMP fuse blows. The battery I got was listed in the store's computer as a battery that would work in my car. Battery specs: Auto Craft Gold, part # 35/75-2, cold crank amps 650, regular crank amps 813, reserve cap 93. I cannot figure out what could suddenly be causing this other than the battery???? Is this amperage rating too high for the 7? Could the battery be defective? What are some simple tests that I could do to find out what the problem is? I have a generic multimeter that I could possibly use to check circuits, but I'm not sure how to go about it. Thanks for any help in advance!!

....also, please don't ask me if I had the pos/neg mixed up, I did not.

 

CCA will have no affect on the rest of the system. The starter is the only component that could pull such a large amount of current, and it is not powered through the main fuse. The main battery cables just run directly to it. If the main fuse is popping, it's bound to be a short or the cables are hooked up backwards. Since you seem sure it's not the second, scour the area around the (+) battery cable terminal for anywhere it might be grounding.

 

okay, I'll check the cables. I just thought it was weird that this problem only now occurs with this new battery. It makes me feel like the manufacturer somehow mixed up the poles in the battery. Anyway, thanks.

 

Definitely sounds like reversed terminals.

I've done this a few times by mistake.

Nice big pop and a spark when you immediately complete the circuit until the fuse blows.


I've learned to fuse anything you connect to the battery through the idiot method of reverse hook up. Not fun....

 

I've triple checked my connection, positive to (+) pole on battery first, then negative to (-) pole on battery second. If this is in fact a reverse hook up situation, then the battery was not labeled correctly. I'm taking it back to the seller today to have it checked or replaced.

 

You could just use a DMM to check it.

 

?? Get a multimeter and see the current direction.

OR a very simple one time check is to get a LED and touch the terminals with it.

It's a diode so one direction will not light it up due to no current flow. The other direction will light it up and then fry it immediately as they are only 3v and the batt should be 12.

A sturdy tester would be an LED with a 550ohm (or close to it) resistor.

 

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If it'll help, the POSITIVE cable is composed of two cables. One of those two cable is much smaller, and that smaller one goes to the engine bay fuse box to feed those fuses.

Negative cable should be composed of only one large cable.

 

Check to make sure your top mount inter cooler (TMIC) is not grounding out the alternator or something stupid like that. It happens more often than not and people sell their car for super cheap due to a "no crank" or "huge electrical" problem.

 

Is your new battery the same size dimension wise as the previous battery or is it taller in height and if so, are you using the black plastic top of the battery case to prevent the battery from coming in contact with the underside of the hood?

 

my friends rx7 is having the same problem pretty much ...did u ever figure out what the issue was?

 

the negative is the one with the yellow stripe!

 

Yes. Black with yellow stripe is gnd cable.

Note that the large output wire on the alternator is also tied into that battery positive cable and if shorted out can cause the main fuse to pop. One post above mentioned this already. I've done this to myself by letting the intercooler touch the alt output terminal.

So? Remove the large cable from the alt and then reattach the cables to the battery with a good main fuse and see what happens.

 

One other possibility is there is a black wire with connector just below and inboard of the engine bay fuse box. If there is some problem with its insulation touching the chassis that wire can also cause the Main Fuse to pop.

 

I think that battery has screw terminals on the front as well as posts on top - you can see them here (Round black and red covers)



If that's the case, be sure that the plastic covers are there and are in good shape. Also be sure there is nothing touching the front terminals like the rad support or the battery tie down.

 

Its not very common but the post could be switched INSIDE the battery, I have run into this twice. where the (+) is actually negative, and the (-) is actually Positive, i would suggest what someone said and check the current flow.