Can my poor alt handle it?

[Oldbasshead]

2019 Mazda 3 sedan. Stock 130A alternator. Big 3, done with 1/0 OFC. Stock lead acid battery but looking at AGM. 1/0 single run of 15' OFC from battery to amps. Voltage drop is minimal but can fluctuate +/- 1V with heavy bass drops. No light dimming but 1V does seem a little excessive. Possibly bad ground?

Gear currently is Memphis 1500.1D running at 1 ohm to two Skar EVL 12's, subs and port facing at backseats. I tried so many variations and this gives me the best bass response to my ears and zero trunk/license plate rattle since majority of bass is in the cabin. Sealed that up best I could and it sounds surprisingly awesome.

I also have a Kicker 800.1D that I would like to run to a Kicker downfiring solobaric in a factory box, probably 2 ohm, so >400 RMS? Rest of my stereo is factory Bose premium, so not upgrading it yet, but would like a little more mid-bass. Hence the little Kicker. Only place for it is in the trunk which is fully soundproofed with Kilmat.

Ideally not looking to upgrade to HO alt and would prefer to run it all from a single battery. If I decide to go 3K or bigger, then this conversation changes. But this is a daily driver, so I'm looking for some power here and there, but SQ with a potential for a kick in the face is my goal. Am I being reasonable here for a mostly stock electrical?

Click to read more...

 

[HardofWhoring]

I won't look at your amps in particular, but here's the theory.

So let's say 1500watts and 800watts. (=2300watts).

2300watts / amp efficiency, which we will use 80%, although you should look for yourself.
2300 / .8 = 2875watt draw for your amps to produce 2300watts.

Divide by operating voltage, 12v off, standard used to be 14.4v running, but it's not all that standard anymore, so maybe your vehicle is different.
2300 / 14.4 = 199 amps.

So when your music is maxed out, and the bass is hitting, it's drawing 199amps. That's on top of what your vehicle is using, (which is generally 40-100 amps depending on if you are using your AC, electric fans, headlights, taillights, radio, cigarette lighters, horns, fuel injection, computers. With AC and electric fans being about 1/3rd each). At absolute max, you would be close to 300 amps draw, but that's overkill, because your amps aren't playing test tones to where there is a constant max draw.

The type of music you play matters. Between bass hits, your amp is doing next to nothing, and your alt is charging more than you are using. Generated bass tracks and rap, have less time between. Rock and country has more time between.

Now you can do this power from a good single battery (but you're getting close to needing something better). You're not going to get away with it on a stock 130 alt. A battery stores energy, and an alt produces it. If you start playing yours on max, your alt wouldn't keep up, and you're going to slowly start draining battery. You can then turn the volume down, or off, and it will charge back up again. My guess is somewhere in the 15-45 minutes to kill depending on the music.
You WILL need an upgraded alt for that so that isn't your weak point. Again depending on the music, and assume you are setting those amps at RMS power, then you're probably wanting a 200-250 amp alt. If there is a small difference in price to upgrade, and there's even a whiff you might want something more, than buy that one the first time. An alt is also going to produce that amperage you need. If you listen to your music with the engine off, you need more battery. If you need more power while it's running, you need a larger alternator.

For what you want, I wouldn't spend the money on an AGM battery, spend that money on an upgraded alt.

 

[Oldbasshead]

I won't look at your amps in particular, but here's the theory.

So let's say 1500watts and 800watts. (=2300watts).

2300watts / amp efficiency, which we will use 80%, although you should look for yourself.
2300 / .8 = 2875watt draw for your amps to produce 2300watts.

Divide by operating voltage, 12v off, standard used to be 14.4v running, but it's not all that standard anymore, so maybe your vehicle is different.
2300 / 14.4 = 199 amps.

So when your music is maxed out, and the bass is hitting, it's drawing 199amps. That's on top of what your vehicle is using, (which is generally 40-100 amps depending on if you are using your AC, electric fans, headlights, taillights, radio, cigarette lighters, horns, fuel injection, computers. With AC and electric fans being about 1/3rd each). At absolute max, you would be close to 300 amps draw, but that's overkill, because your amps aren't playing test tones to where there is a constant max draw.

The type of music you play matters. Between bass hits, your amp is doing next to nothing, and your alt is charging more than you are using. Generated bass tracks and rap, have less time between. Rock and country has more time between.

Now you can do this power from a good single battery (but you're getting close to needing something better). You're not going to get away with it on a stock 130 alt. A battery stores energy, and an alt produces it. If you start playing yours on max, your alt wouldn't keep up, and you're going to slowly start draining battery. You can then turn the volume down, or off, and it will charge back up again. My guess is somewhere in the 15-45 minutes to kill depending on the music.
You WILL need an upgraded alt for that so that isn't your weak point. Again depending on the music, and assume you are setting those amps at RMS power, then you're probably wanting a 200-250 amp alt. If there is a small difference in price to upgrade, and there's even a whiff you might want something more, than buy that one the first time. An alt is also going to produce that amperage you need. If you listen to your music with the engine off, you need more battery. If you need more power while it's running, you need a larger alternator.

For what you want, I wouldn't spend the money on an AGM battery, spend that money on an upgraded alt.

This definitely isn't for competitions. I just like to feel the music and I also drive 50k or more miles a year. I was hoping not to have to upgrade alts but I guess I'm stuck there. I looked at a few 250A that would fit my car but haven't jumped on it yet.

If you only had to change one, would you pick a quality AGM or a HO alt?

 

[Oldbasshead]

Edit: Sorry, I also didn't answer about my music. It's a healthy mix of rock/metal and bass boosted trap/trance. The latter definitely stress my electrical.

 

[HardofWhoring]

An AGM would have a better discharge rate, and since you can mount them in other directions, they help with install, you just don't need that. A good stock battery should be fine, especially considering an upgraded alt is going to produce more amperage to help with that draw.

If you're really up for it, here's what you can do:
Install the system you have and don't buy a batt or alt.
Set it up, play it, and see when you start to have trouble. If you can max it out on your stock electrical, then you 100% don't need a battery.
Dimming lights is going to be a sign that your draw is higher than you can handle.
Your battery voltage dropping means your alternator can't keep up.

Set it up, drive it around, and start with about half volume on the stereo. Play 3-4 heavy songs, (about 15-20 minutes). Then turn your volume up by one number, and start again. Keep going until you notice your electrical can't keep up. (If you wanted to really test your draw, turning your AC on, will work it a little harder if you do that in the summer).
Then you can use this to see how, and test your AC voltage.


That will tell what your wattage is, and you can then tell what your amperage draw is when you start to notice problems. You can then compare it to where you will end up when you max it out. Your alternator will need to be a little more than that difference. Your alternator will add that amperage to the draw.

 

[djdilliodon!]

The good news about doing an alt upgrade is these days it doesn’t cost a ton, and if you can install it yourself, it’s even more of a reason to do that upgrade. It’s almost certain that if you enjoy having a system, an upgrade is only right around the corner and that usually means more power too. If you plan on keeping this car, I would do the alternator upgrade.

 

[Oldbasshead]

The good news about doing an alt upgrade is these days it doesn’t cost a ton, and if you can install it yourself, it’s even more of a reason to do that upgrade. It’s almost certain that if you enjoy having a system, an upgrade is only right around the corner and that usually means more power too. If you plan on keeping this car, I would do the alternator upgrade.

I don't disagree. This is just a tiny little engine bay we're talking about here, so changing it will be a pain. I've been sourcing some and the best I'm finding price-wise is about $500. Gonna give it a shot with the above mentioned power diagnosis but I see now that I will be pulling more than my alt is really even designed to handle in the first place. I don't think not swapping it out will be an option. Oh well...

 

[HardofWhoring]

I don't disagree. This is just a tiny little engine bay we're talking about here, so changing it will be a pain. I've been sourcing some and the best I'm finding price-wide is about $500. Gonna give it a shot with the above mentioned power diagnosis but I see now that I will be pulling more than my amp is really even designed to handle. I don't think not swapping it out will be an option. Oh well...

$500 is not unreasonable, but just know about alternator shopping:
There are two numbers that matter:
The amp output at or near idle (what's it going to do at a red light). &
The RPM needed for max output, (what RPM do you need to be at to get it's full rated power).

A good alt will do most at idle, and full output around 2K rpm.
A cheap alt will do less at idle then your stock, (even if its rated for twice as much), and won't do full output until over 3K rpm.
That's the difference between a $200 alt, and a $5-600 alt. Know what RPM you cruise at, and if they can't or won't give you those numbers, that's a red flag. $500 for a 250 amp alt, is what a quality alt would cost. Up to you to compare numbers.