stereo is dimming my lights, wasnt before.

[Convenienze]

my lights started dimming all of the sudden.
i have a 2400 rms amp in my miata, with 1 12 jbl gt5.

the amp is not pushing all the power, i have it set a bit low as the speaker doesnt need it all.
its been perfectly fine for 3 years, all of the sudden im getting crazy power drops when the bass hits and my car almost dies, rpms dip super low.

now, i made all new power wires for the system. and just today i put a new alternator from an nb in my na. 70 amps vs 65 amps. i know its not a big change but it will help a little.
it used to work fine.

could it be my battery? thats the only thing i havent checked. i dont have a meter to check it.

[JLBMX5]

Any autoparts chain store and even walmart can check your battery. The miata battery is no bigger than a lawnmower battery so its not really equipped to handle extra loads of bass. Even though the amp is not set to high when you hit a bass note its gonna want some power. To help out look at something called a battcap. Its made for short power burst that your amp needs.

[BoBo]

I would assume the battery is getting weaker, but to be sure a test has to be done. Sounds systems put added load to electrical components. Usually the alternator or battery would crap out prematurely, at least in my experience. The sub-woofer draws a lot of power, adding a capacitor would alleviate the problem with the lights dimming. I don't know if Optima makes batteries for our cars, but that would be sweet. You can go to Wally World and buy a "battery charger/conditioner". It usually has an option to test the battery and alternator if it's in good condition. I bought mine for only $100 maybe even cheaper...they come in handy.

[Convenienze]

well, i have a capacitor, and have been running it for the entire time. just recently took it out to see if maybe something was up with the cap itself. but it wasnt an issue with that.

i am however running a oem battery that was in the car when i bought it 3 years ago, and the system has been kicking its ass since day 1.. i wouldn't be surprised if that's my problem.

so i don't know how old the battery actually is, i have not looked for a date on it.

anywho, i will take it somewhere to get it tested soon. probably on friday there's an autozone right around the corner from my house, ill just drive in and take the battery out there.

[— Agent☣Orange —]

I'd suspect the battery as well but it would be worth seeing what your alternator is pushing. Should 14.4V running. Also, the advertised output of your amp isn't as important its amperage draw. In any case, since the car runs off the alternator once the car is running, you shouldn't be drawing anywhere near 65 amps. There's no need for an Optima battery unless you want a deep cycle to power extended parking-lot entertainment. A lightweight Odyssey battery would make more sense for a Miata. I wouldn't even run a cap either.

[BoBo]

well, i have a capacitor, and have been running it for the entire time. just recently took it out to see if maybe something was up with the cap itself. but it wasnt an issue with that.

i am however running a oem battery that was in the car when i bought it 3 years ago, and the system has been kicking its ass since day 1.. i wouldn't be surprised if that's my problem.

so i don't know how old the battery actually is, i have not looked for a date on it.

anywho, i will take it somewhere to get it tested soon. probably on friday there's an autozone right around the corner from my house, ill just drive in and take the battery out there.

Yeah, 2400 rms is a lot of power, maybe too much for a stock battery. I had a stock AC Delco/ Interstate on my MR2 SC and it would only last 1-2 years maybe 3 if I'm lucky. I was only running an old 1 10" MoMo Polk 350rms using a Kenwood 600 rms mono amp. That's why I upgraded to a Yellow top battery and it lasted me about 5 years, I could watch movies all night and still have enough juice. You're crazy for putting that kind of sound system on your Miata. I would be cool with a "8 Bazooka in a Miata. Did you have a custom box made to fit the tiny trunk? I used to be crazy about sound systems a few years ago. I had 2x 10w7 JLAudio subs inside my 91 Mr2 and that thing was a lot back them. It's an expensive hobby, I ended up parting everything out to focus on other hobbies and to save my ears lol.

[Convenienze]

i didnt have a box made, it just uses a 1sq ft box. it fits when sitting in the drop down area that fits the full sized tire when you have to put the spare on.

but i took the batt to autozone, they checked it and said its 100% fine.
alt is charging it, even did a test with the batt in the car while running.
however im putting the stock alternator back in as nb alts in an na will fry the harness due to not having a built in voltage regulator..
i did not know this untill it was already in.
also the nb alternator drains the battery for some reason when the car is off. i woke up to a dead battery and got off work with another dead battery. i unhooked it until tomorrow so i can move it in the morning to change the alt back over.

i think the dimming might be because my sub was on its way out. i fried it on the way to work earlier today. it lasted me 3 years plus it was used when i got it.

[Tkblazer]

Sounds like you've got some electrical issues.. maybe check your grounds

[davzway]

You are pulling more current than your battery (being charged by alternator ) is putting out which is drawing down your battery which shows in light dimming (grin, had BIG amp and did this back in 60's myself). Batteries don't last, 5yr gets 3yr or so in Florida,,, but even a 'new' alternator may not be PRODUCING what it should (and as said, miata batteries aren't giants in battery world). Sears or anyone selling batteries, should test running and not running. Running with no load and then running with EVERYTHING RUNNING especially your amp cranked up.
Likely battery since alternator is new, but have had 'new' stuff which wasn't working as it should. OFF they should check and ensure there is NO dead short which shows as power drain with everything OFF. Those get to be fun to track down. good luck. davzway (stereo nut who's installed a LOT of gear in more vehicles than I'd admit to).

my lights started dimming all of the sudden.
i have a 2400 rms amp in my miata, with 1 12 jbl gt5.

the amp is not pushing all the power, i have it set a bit low as the speaker doesnt need it all.
its been perfectly fine for 3 years, all of the sudden im getting crazy power drops when the bass hits and my car almost dies, rpms dip super low.

now, i made all new power wires for the system. and just today i put a new alternator from an nb in my na. 70 amps vs 65 amps. i know its not a big change but it will help a little.
it used to work fine.

could it be my battery? thats the only thing i havent checked. i dont have a meter to check it.

[MemphisMiata]

i think the dimming might be because my sub was on its way out. i fried it on the way to work earlier today. it lasted me 3 years plus it was used when i got it.

The sub has little or nothing to do with the dimming lights. The dimming is caused by too much current being drawn than what the electrical system can deliver. After checking the charging system, I would re-work & upgrade all the grounds in the car. If the lights were not dimming when you first installed the amp/sub, but are now, it is likely because of corroded or dirty grounds.
If replacing the sub takes care of the dimming, it is either a coincidence, or the new sub is more efficient, which means the amp is not working as hard & not drawing as much current.
Before you buy a new sub, invest in a decent Digital Volt Meter. A good investment for the future at any rate!