Cap or additional batt or ho alternator?


Bass Xploder

CarAudio.com Newbie
Apr 27, 2020
12
3
Jersey
Ive done some research and I'm finding mixed reviews on what direction I should proceed in.

I currently have 2 10" skar audio subs at 600rms each wired down to 1ohm and connected to a jl audio 1000 watt amp with 4ga and a 80amp inline fuse about 8 inches from the battery and a bass knob in cabin. I cant have the bass all the way up hitting hard during an entire good song because the idle rpm jumps down if I'm at a red light and makes vehicle jerk a bit from the rpm drop and rise.

I'm adding a 4channel 400w amp also and upgrading speakers and adding tweeters as well as a big 3 upgrade, and considering how the vehicle is acting now, I want a stable experience once I add everything.

I'll be removing all the current wiring and adding a distribution block with 0ga from the front battery with an inline fuse about 6inches from the terminal back to the rear of vehicle with another inline fuse before the distribution block and then 4ga to amps also with their each inline fuse.

Still waiting on rest of equipment to arrive, so I need to figure out my next action plan.

Question I want to ask, along with the big 3 upgrade, how should I proceed?

Should I be replacing stock alt with a ho or replacing battery with a yellow top? Or should I add a cap or a 65ah+ agm battery in rear?
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
32
United States
What vehicle do you currently have? Stock alternators are usually able to keep up with that much of a demand in my experience. I would expect maybe some headlight dimming, but it sounds like either your alternator is pulling too hard on your drive belt or your battery is on death's doorway.

That being said, assuming your problem is caused solely by lack of power I'd say getting a HO alt is the more effective solution long term that you won't regret. While getting a higher quality battery will be expensive for a less long-lived part and your charging system will still have to deal with the heightened demand of the amplifiers regardless. It's perhaps worth looking into getting a second standard battery before a yellow top unless space is your primary concern, as that's the more economic way to deal with a higher amperage draw than your primary battery can handle.

With capacitors it's possible that it would address your immediate issue but while it would improve things from your alternator's perspective, it's only for very special cases where it's teetering on the edge of not being enough to handle the demand of the system with the resistance losses of charging a lead acid battery. Also capacitors are a very scammy business in car audio, I don't trust a lot of the farad values they list because they know getting testing equipment and know-how means you're willing to pay more than the cost the scammy ones are selling for. It's worth considering as well that if you're having issues without the additional amplifier then a cap is not nearly enough to address the situation.

Bottom line: If you have the money, get both the HO and either yellow top or additional battery, but ultimately I'm still most concerned that there's something wrong with the belt system if it's dragging your car's engine down enough to turn the music off. The engine should not be so phased by what sounds like a low amperage, like 90A load. Maybe more details from you will clear up why that's the case.
 
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Bass Xploder

CarAudio.com Newbie
Apr 27, 2020
12
3
Jersey
What vehicle do you currently have? Stock alternators are usually able to keep up with that much of a demand in my experience. I would expect maybe some headlight dimming, but it sounds like either your alternator is pulling too hard on your drive belt or your battery is on death's doorway.

That being said, assuming your problem is caused solely by lack of power I'd say getting a HO alt is the more effective solution long term that you won't regret. While getting a higher quality battery will be expensive for a less long-lived part and your charging system will still have to deal with the heightened demand of the amplifiers regardless. It's perhaps worth looking into getting a second standard battery before a yellow top unless space is your primary concern, as that's the more economic way to deal with a higher amperage draw than your primary battery can handle.

With capacitors it's possible that it would address your immediate issue but while it would improve things from your alternator's perspective, it's only for very special cases where it's teetering on the edge of not being enough to handle the demand of the system with the resistance losses of charging a lead acid battery. Also capacitors are a very scammy business in car audio, I don't trust a lot of the farad values they list because they know getting testing equipment and know-how means you're willing to pay more than the cost the scammy ones are selling for. It's worth considering as well that if you're having issues without the additional amplifier then a cap is not nearly enough to address the situation.

Bottom line: If you have the money, get both the HO and either yellow top or additional battery, but ultimately I'm still most concerned that there's something wrong with the belt system if it's dragging your car's engine down enough to turn the music off. The engine should not be so phased by what sounds like a low amperage, like 90A load. Maybe more details from you will clear up why that's the case.

Space isn't an issue, vehicle is a 15 ford explorer. I've had same amp running a jl 12 w7 with no problem but soon as I switched to the new subs, I noticed the issue with the engine rpm.
If I'm driving, some songs can be full bass the entire song and some good ones cant. If I'm at a red light or sitting idle wether in drive or park, the engine rpms drop and rise as the big bass notes hit. I should have checked the voltage drop at the battery but made this thread while inside for the night. I'll check that tomorrow since I dont have an incabin volt guage or meter so this way I'll figure out where my current battery stands.

I didnt think a cap would help in this situation since this issue arises without the additional amp.
Big 3 kit is still being shipped so if it's the battery on it's way out, I'll be replacing that and the big 3 at the same time. Will do a ho alt if needed, but after those 2 I'll be adding an additional battery in rear to help out with the system.

Any recommendations for a specific battery to go with in this scenario?
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
32
United States
Space isn't an issue, vehicle is a 15 ford explorer. I've had same amp running a jl 12 w7 with no problem but soon as I switched to the new subs, I noticed the issue with the engine rpm.
If I'm driving, some songs can be full bass the entire song and some good ones cant. If I'm at a red light or sitting idle wether in drive or park, the engine rpms drop and rise as the big bass notes hit. I should have checked the voltage drop at the battery but made this thread while inside for the night. I'll check that tomorrow since I dont have an incabin volt guage or meter so this way I'll figure out where my current battery stands.
From what I can find online it looks like you've got either a 175A Alternator (base model) or 200A Alternator (XLT) OEM. Honestly both of those seem powerful enough to handle that demand without killing your RPMs. I know that vehicles with higher output OEM alternators also have increased demand, but not that much. I currently have a 110A alternator OEM and a 1200W RMS Rockford Fosgate amp. Even at clipping my lights barely dim and my RPM is able to stay steady idle or at speed. My engine is also likely smaller than yours, a 2.4L I-4 or at least puts out less horsepower if you have a turbo. I don't think this is related to the subwoofers as much as it's just highlighting an issue with your electrical system and/or engine. Does your AC lower your RPMs dramatically as well? The AC compressor should tug the engine harder than an OEM alternator. In my non-professional opinion, your engine is weaker than it should be at idle, and perhaps it's because it's lacking airflow. Explorers seem to be kinda well known for these air-related problems (especially IACVs or idle air control valves going out/getting dirty) but that's speculation on my part since I haven't experienced your issue myself.

It could be a weak battery that's causing the alternator to be at maximum power, but if it's so bad that you're worried about your engine stalling then no alternator draw should do that. Your vehicle should have the ability to regulate its power based on the load, even at idle. If you've ever watched an SPL demo on a fully loaded SUV or something and checked out the RPMs you'll notice that the vehicle works its ass off with 4 HO alternators tugging on the belt but it doesn't come close to stalling. I would swap out the air filter since it probably needs a new one anyways and then if no improvement consider cleaning some of the air intake parts or having someone else do it.

Checking voltages is a good first step, it shouldn't drop below 12.4 no matter how high it's turned up. A continually declining voltage means the alternator can't keep up while dramatic drops means the battery can't supply enough amperage. It's a good idea to do this at the amp terminals since that's where it will be most dramatic, even fat cables will result in about a .3-.4v drop from the battery to the trunk.


Any recommendations for a specific battery to go with in this scenario?
I don't have any specific recommendations on batteries, but obviously yellow tops are very good (just expensive).


This Youtuber does amazingly useful videos on different products and car batteries appear to be one of the products that you don't necessarily get what you pay for if you splurge on name brands.


Edit: I suppose if your voltage dipped low enough it could affect your sparks, but your amp should be going into protect mode before that. They usually go into protect at around 11.8v or under with very minimal tolerances for the duration of those dips. I seriously doubt that's the issue, but it would point to a severely bad battery, like a dead cell.
 
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Popwarhomie

Team Lethal Pressure
10+ year member
Jan 22, 2010
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Optima batteries are shit.

Get an XS power or Northstar AGM in the front and do the big 3 upgrade.
 
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Bass Xploder

CarAudio.com Newbie
Apr 27, 2020
12
3
Jersey
From what I can find online it looks like you've got either a 175A Alternator (base model) or 200A Alternator (XLT) OEM. Honestly both of those seem powerful enough to handle that demand without killing your RPMs. I know that vehicles with higher output OEM alternators also have increased demand, but not that much. I currently have a 110A alternator OEM and a 1200W RMS Rockford Fosgate amp. Even at clipping my lights barely dim and my RPM is able to stay steady idle or at speed. My engine is also likely smaller than yours, a 2.4L I-4 or at least puts out less horsepower if you have a turbo. I don't think this is related to the subwoofers as much as it's just highlighting an issue with your electrical system and/or engine. Does your AC lower your RPMs dramatically as well? The AC compressor should tug the engine harder than an OEM alternator. In my non-professional opinion, your engine is weaker than it should be at idle, and perhaps it's because it's lacking airflow. Explorers seem to be kinda well known for these air-related problems (especially IACVs or idle air control valves going out/getting dirty) but that's speculation on my part since I haven't experienced your issue myself.

It could be a weak battery that's causing the alternator to be at maximum power, but if it's so bad that you're worried about your engine stalling then no alternator draw should do that. Your vehicle should have the ability to regulate its power based on the load, even at idle. If you've ever watched an SPL demo on a fully loaded SUV or something and checked out the RPMs you'll notice that the vehicle works its ass off with 4 HO alternators tugging on the belt but it doesn't come close to stalling. I would swap out the air filter since it probably needs a new one anyways and then if no improvement consider cleaning some of the air intake parts or having someone else do it.

Checking voltages is a good first step, it shouldn't drop below 12.4 no matter how high it's turned up. A continually declining voltage means the alternator can't keep up while dramatic drops means the battery can't supply enough amperage. It's a good idea to do this at the amp terminals since that's where it will be most dramatic, even fat cables will result in about a .3-.4v drop from the battery to the trunk.




I don't have any specific recommendations on batteries, but obviously yellow tops are very good (just expensive).


This Youtuber does amazingly useful videos on different products and car batteries appear to be one of the products that you don't necessarily get what you pay for if you splurge on name brands.


Edit: I suppose if your voltage dipped low enough it could affect your sparks, but your amp should be going into protect mode before that. They usually go into protect at around 11.8v or under with very minimal tolerances for the duration of those dips. I seriously doubt that's the issue, but it would point to a severely bad battery, like a dead cell.

It's a 15 explorer limited trim with a 4.6l v6. Occasionally when the ac goes on, the rpms do a drop then go back up then drop and back up etc. Usually only once because I'll give it some throttle and it stables itself and idles perfectly fine. My lights barely dim at all honestly.

At rest, the battery is 12.80 with no load and the amp is at 12.60. Once on with just radio no bass the battery is at 14.40 and the amp is reading 14.39.

With the volume turned up like 3/4 and bass turned up the battery drops down to 13.26 and amp also drops down to 13.26 and rpms vary from around 750 dropping down to 500 and back up and down.
 

jt4x4

CarAudio.com Enthusiast
Jul 22, 2019
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12
ND
4.6L v6 or v8? Either way, that should have enough torque at idle to turn the alternator. If you own or know anyone with an OBD II scanner with live monitoring, you could monitor engine load when it's happening. That would tell you if it's really that bogged down or if you have mechanical issues. Since you aren't blowing fuses, that tells you you've added less than 80 amps of draw.

For reference, my off road vehicle's idle barely drops when I use my 12k winch that pulls up to 400 amps, and that's with a 130 amp alternator.
 
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Lasherž

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It's a 15 explorer limited trim with a 4.6l v6. Occasionally when the ac goes on, the rpms do a drop then go back up then drop and back up etc. Usually only once because I'll give it some throttle and it stables itself and idles perfectly fine. My lights barely dim at all honestly.

At rest, the battery is 12.80 with no load and the amp is at 12.60. Once on with just radio no bass the battery is at 14.40 and the amp is reading 14.39.

With the volume turned up like 3/4 and bass turned up the battery drops down to 13.26 and amp also drops down to 13.26 and rpms vary from around 750 dropping down to 500 and back up and down.
Yeah 500 rpm under idle load sounds like classic airflow control issues. There's three parts that control that, the most commonly failing one I already mentioned is the IACV, but the air bypass channel opening could have crud in it as well. The third part will trigger a check engine light in most cases. With a cheap OBDII bluetooth module you can watch airflow problems graphed out on your phone (using the torque lite app). The voltages you mention seem okay, it's unlikely to be the battery or an alternator regulator. Also the fact that the AC compressor is doing the same thing pretty much guarantees it's a vehicle problem. If you're not comfortable disassembling and using brake cleaner on the air intake parts (spraying into the intake won't work), particularly the bypass then it's best to visit a garage and ask for an air induction cleaning or throttle body cleaning. It's mostly the cost of labor 1-2 hours, but there's always the possibility that the part will need replaced if it's the IACV -- not all of them are salvageable.

Your system obviously affects your car's electrical, but I highly doubt your issues are caused by that. As I said earlier, a stock alternator won't drag on an engine as badly as an AC compressor, so in terms of engine idling it should be behaving as normal right now with or without the system. You can tell in my car for example when the AC kicks in, but it doesn't drop half the RPM, just a little bit of shaking and the RPM goes from 1k to 1.2k, barely a 50 rpm drop on the needle before it recovers.
 

MattinMO

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Dec 31, 2017
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St.louis, MO
I’m not reading all this hoopla above but do the big three and see what happens, if Voltage is still dropping add a 2nd battery. Johnathan Patrick of brand x and formerly ces alternators wrote this up not too long ago:

Reasons why you NEED a big 3 BEFORE installing an HO alternator EVEN IF YOU DONT HAVE THE SYSTEM INSTALLED YET!

There are numerous reasons the alternator can generate hundreds of amps of current over your factory fuse rating. This is especially common in late model Honda, Hyundai, Toyota, and kias. This can blow the factory fuse on the top of the battery, this isn’t a cheap part, sometimes costing 100+$ from the dealer. *Autozone and advance generally don’t carry these parts.* you can damage your computer as well from the voltage spike associated with the fuse blowing, the regulator in the alternator, the rectifier in the alternator as well.

Reason 1: if your battery ever gets low enough from starting or sitting long enough the alternator is not smart enough to *slow charge* your batteries, due to this you can blow the fusing / mega fuse/ breaker associated with the factory electronics / fuse terminal on the battery.

Reason 2: if you jump someone’s car, or receive a jump you can damage all of the same components referred to above.

Reason 3: you didn’t follow your other directions with the install and your batteries were not charged before firing it up.

Reason 4: you don’t need a reason 4, be smart. Install your alternator according to directions... you’ll have a way better time with it I promise.
 

Popwarhomie

Team Lethal Pressure
10+ year member
Jan 22, 2010
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Voltage is not dropping below battery resting voltage....

So like I said add an XS power or Northstar front AGM with big 3 and you are good to go.

No need for an HO alternator for 1000 watts.....

Your idle RPM is going to drop when a load is placed on the alternator. Period.
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
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So like I said add an XS power or Northstar front AGM with big 3 and you are good to go.
That post must have been deleted. AGMs are much better for car audio, but the RPM drop isn't normal and it's pretty common on his vehicle. That will likely solve all of his other issues without buying a 250 dollar battery plus make his car run better. You expect some drop from an alternator, but this is a 2015 vehicle, not 1990. Modern ECUs adjust readily to handle loads by increasing idle when it needs to and with very little delay, old cars had higher idles that didn't adjust and so you'd see drops like that all the time.
 

MattinMO

Senior VIP Member
Dec 31, 2017
817
179
St.louis, MO
That post must have been deleted. AGMs are much better for car audio, but the RPM drop isn't normal and it's pretty common on his vehicle. That will likely solve all of his other issues without buying a 250 dollar battery plus make his car run better. You expect some drop from an alternator, but this is a 2015 vehicle, not 1990. Modern ECUs adjust readily to handle loads by increasing idle when it needs to and with very little delay, old cars had higher idles that didn't adjust and so you'd see drops like that all the time.
Oh wow you’re the new guy on the forum that knows everything...get fuk’d
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
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Oh wow you’re the new guy on the forum that knows everything...get fuk’d
You act like I was born when my first post occurred lol. There'd be a lot less drama in the world if people didn't get offended on other people's behalves. If I'm wrong, argue a point, otherwise you're just spreading drama you have nothing to do with on a post about helping someone. Take a chill pill.
 
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jt4x4

CarAudio.com Enthusiast
Jul 22, 2019
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You act like I was born when my first post occurred lol. There'd be a lot less drama in the world if people didn't get offended on other people's behalves. If I'm wrong, argue a point, otherwise you're just spreading drama you have nothing to do with on a post about helping someone. Take a chill pill.
Honest advice is not to engage with people like that. This forum is full of them. People with a lot of posts think they are kings, and there's an equal amount of fanboys who will jump to defend their king and throw out generic insults. Even if you prove them wrong or have a sound counterargument, they will just jump to a different topic to call you wrong about, and believe me, they spend a lot more time behind a keyboard than you do and they have a lot more "need" to be right.

Been there; done that.

- Joe
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
32
United States
Honest advice is not to engage with people like that. This forum is full of them. People with a lot of posts think they are kings, and there's an equal amount of fanboys who will jump to defend their king and throw out generic insults. Even if you prove them wrong or have a sound counterargument, they will just jump to a different topic to call you wrong about, and believe me, they spend a lot more time behind a keyboard than you do and they have a lot more "need" to be right.

Been there; done that.

- Joe
Yeah, starting to see that now. Thanks for the advice. I've had my fair share of arguments about capacitors among other things and I forgot what I learned from those until you reminded me: If your advice speaks for itself then trust that it will.
 
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Bass Xploder

CarAudio.com Newbie
Apr 27, 2020
12
3
Jersey
So it's been some time and I've ordered the big 3, a 120ah agm battery a second 4channel amp, new wiring for everything, replacing the original power and ground with 0ga and new speakers and tweeters for the 4ch amp and I'm making a battery and amp box in the spare tire location because I need the third row seats to still be functional. So far I've done the big 3, but still waiting for my battery to come in. Of course everything else arrived already and all supplies are good to go. Once everything is ready this week I'll be redoing it all on saturday with weather permitting since I dont have access to a garage. I'll send updates and let everyone know how it's going, but I'll probably start another thread for the actual build and add pictures and some details and instructions.
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
32
United States
So it's been some time and I've ordered the big 3, a 120ah agm battery a second 4channel amp, new wiring for everything, replacing the original power and ground with 0ga and new speakers and tweeters for the 4ch amp and I'm making a battery and amp box in the spare tire location because I need the third row seats to still be functional. So far I've done the big 3, but still waiting for my battery to come in. Of course everything else arrived already and all supplies are good to go. Once everything is ready this week I'll be redoing it all on saturday with weather permitting since I dont have access to a garage. I'll send updates and let everyone know how it's going, but I'll probably start another thread for the actual build and add pictures and some details and instructions.
Awesome, thanks for the update. Good luck on the process, try and stay patient and thorough. At least if that doesn't fix the rpm drop issues you'll have a very good battery which is never a bad thing. I'm still sticking to the likelihood an air intake part being dirty.
 
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