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Running amp off a 2nd battery in my trunk?

Old 02-23-2016, 07:39 AM
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Join Date: Feb 2016
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Running amp off a 2nd battery in my trunk?


I should start off by saying that I know very little about car audio. I have a 2006 Ford Fusion.

I bought my current 600w amp and pair of 12s in a box from my cousin. This was 9 years ago. For 7 years it was working great.

I got it installed by a car audio place. Worked nicely with my original car radio and when that went kaput, it worked fine with the pretty basic Pioneer deck I bought after that. An electrical guy in a shop installed that for me 4 years ago.

I only use my system from the months of Nov. to Apr. as I need the trunk space for summer activities.

However, my amp has always been screwed into the back of my backseat and the power cable attached to the battery.

One winter ago in Nov 2014 I noticed that when I connected the woofers to the amp again, I was getting really big bass but the lyrics and what not were all mumbled. I played around with it a bit and it would work for like 30 seconds and then same problem. I wondered if I had a bad amp.

In Jan. 2015, my car battery started giving me problems. Couldn't start car sometimes. But hey that's winter right? Well that battery was only 11 months old.

In Feb. 2015 I got my battery tested and the mech said it wasn't holding the right amount of power. I disconnected the power cable of the amp from my positive terminal and continued with that battery for 3 more weeks. But continued having problems. So I replaced it with a much higher end battery that cost a hundred bucks more. And I did not connect the amp back to the battery for the rest of the winter or even spring and summer.

Nov. 2015 I try my woofers again and connect them to the amp. And connect the amp power cable to my high end battery that is now 9 months old. Same problem of really big bass and mumbled lyrics and even some feedback. Now I'm thinking my amp is bad. Anyway, I take out the woofers until Jan. 2016 but leave the amp cable connected to battery.

Jan. 2016 my car won't start. Battery problems. Get a boost and it's fine. Good for another 3 weeks. Then it does it again but boost didn't even start it. So I trickled charged it for an hour with a battery charger I use for my deep cycle boat battery. The manual says I can use it for car batteries. This time I disconnected amp cable from battery. It's fine again for the next 2 weeks.

Feb. 2016 my car doesn't start. This top of the line battery is 1 year old. My car won't even try to crank or anything. This time I get it towed to the same mech. who sold and installed my battery. He says it's not holding the charge it should be. Says the alternator is fine. I get battery replaced under warranty for free.

Mech. said it is possible I could have a bad amp that is drawing power on my battery even when my car is off. But he cannot say it definitively.

So this got me thinking. Should I get a separate battery and keep it in my trunk to power my amp? I actually have found 2 old amps from 2 other people who had them stored in their garages after they had kids. They were working fine when they were last used 3 and 6 years ago. One is only 400w while the other I don't know because it doesn't say on the top of it but it is bigger.

So should I take off the old amp from my back seat and drill in one of the others and connect the cables, and then run a new power cable from it to a new car battery in my trunk? And then charge that battery every few days with my charger that I use for my boat battery? I actually spend a total of 30 minutes a day in my car during the working week.

Does this make any sense? I don't want to connect one of the other amps to my brand new battery I just got and have the hassle of what I've been going through again later on in the year.

Would it have to be a car battery or could I use a general purpose battery?

And I'm trying to keep the costs down since I only use my setup for 5 months a year and want to have kids soon so my trunk space would disappear.

Thx for the suggestions.
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