QuestionI have a Jeep Grand Cherokee Laredo with Alpine head unit. I am currently trying to buy 1 Alpine type R 12" subwoofer 500wRMS at 2ohm and 1 Alpine amp to push it. That is not my question though. I have read and read about how much power this will use and am scared I'll break my alternator and ruin my car. Will I be ok without anything? I read on one site and the guy said buying a new high output alternator is my best bet. I am on a budget and am running it tight with the sub and amp. What do I need to do to ensure everything runs smooth and my car stays running? thank you.
AnswerAll you need to do is do the "Big 3" - that is to replace (or add to) the power wire between the battery and alternator, the ground from the battery to the chassis and the ground strap from the engine/tranny to the chassis with at least 4 AWG wire, 2 AWG would be better.
Also upgrade to a yellow top battery.
This will be the most you will have to spend UNLESS the stock alternator is below 75 amperes. Then you have to get an upgrade or only run the system at half volume or less.
To find out what you have, look for a replacesment stock alternator on Autozone.com or wherever. The amperes are usually listed.
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For the record, the truth is it depends on a few factors whether an alternator upgrade is required - things like the RMS power output and, most importantly, the efficiency of the amplifier is required to determine the current draw on the electrical system. The formula is as follows:
((RMS power X (1/amp effiency))/car voltage @1500 RPM) X 0.667) + 40% of your existing alternator ampereage @3000 RPM.
If the final number you come up with is within the total amperage output of the alternator, you need do nothing.
However, if the number you come up with is higher....this is where the recommendation for a high output alternator comes into play.
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If you can post this on one the sites you read the information, you could be a big help to others there.
