Using accessories, car now runs rough

[pfhappy]

I have a 2006 Hyundai Elantra with 44,000 miles on it.I've never had any problem with it. This past winter, I thought it would be a good idea to put a new battery in it, since the original one was getting old. A friend, who worked in a "forklift repair shop" got me a battery he said he could get for cost. It was much bigger sizewise than the orig battery, but once I had it installed the car seemed to run a little better.

Then when really cold weather hit, I had to use my accessories more, I noticed the car was running rough when I ran the rear defroster, headlights, - well just about most things. Without the accessories on, it runs ok again. It seems to. This roughness is esp noticable at red light idling, that type of thing with the accessories on.

The newly installed battery was an Interstate and might not have anything to do with this shaking, right?

I don't want to burn up my harness - I don't have money for repairs in particular. What do you think?

Thank you in advance.

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[juanmgarza26 10+ year member]

could be your alternator is getting weak, happened to my brothers truck, now it could also be a bad battery, go and get it checked at autozone to see if its bad, my brothers truck would do the same thing, at red lights his rmps would go down and at night his lights would dim down and the truck tugged alot, gave him money to have his alternator rebuilt and problem solved

 

[Kingstroker 10+ year member]

new or not battery could be bad or too big for alternator to charge properly.

 

[pfhappy]

OK, went to AutoZone as suggested. A fellow tested my battery with a handheld gadget - it read "good". Guy made the comment "This battery's brand new! Maybe something else is wrong". Yes, well that is possible. It's not an Interstate brand - the battery is a Deka - I never heard of Deka batteries - the AutoZone sales guy didn't much else about batteries except what the battery tester told him.

Alternators are $100 and up for rebuilt ones and $150 for new ones, and that's not installed.

As long as the wiring harness is not frying, I'm going to have to live with the problem for now. No money to spare...

Thank you so much for all your great advice.. thank you.