Low voltage/Dimming lights, please read this!!

**mxmissile** · 4-6-02, 23:50

Since the question keeps coming up in threads, and Steve and myself, and numerous others with whom I am regretably less familiar keep replying to them as the questions arise, I am starting this thread as a reference for people who somehow haven't read the FAQ's or found the answers they seek in a search. Feel free to reply, but this wasn't meant to start a discussion, only provide information.

Any guru's please feel free to back me up so that others know this is accurate and credible, or to expound on any part of it - if, in your expertise, you find any part of it lacking.

Not to be nasty, but if there be any individual who should feel compelled to disagree with this info based on what their "friend who knows a lot about this stuff" told them, I would ask said individuals to refrain from posting here without doing some heavy duty homework. This post is meant to clear things up for people who have heard different things from different sources and need help, not add to their confusion on the issue. That said -

The most frequently recomended step to help with a low voltage situation is to add a capacitor of one sort or another. This advice is given even by seasoned professionals in the industry. Unfortunately, it is more often than not the wrong advice.

Capacitors (caps) are a good thing - if they're used correctly. When added to an electrical system that can keep up, they provide the extra on-demand power a big amplifier craves. However, if the electrical system is already lagging, a cap helps until it's discharged, then it becomes one more thing for the already overworked charging system to keep up with. Once drained, a capacitor becomes a point of resistance in the system untill it is able to regain a voltage equal to or greater than that demanded "down stream", as it were. Since caps drain very quickly, and the demand that drained them in the first place will draw the current it wants with or without the cap, they do not recharge until the demand drops. So -

Make sure the alternator is in good shape. Then check the existing battery. If either of the above is wanting, replace it. If both are good, then add a second battery to reduce the load on the front end of the charging system. Upgrade the alternator if you are hard on your system to the point where even the 2nd battery is running behind. Once all this is in place, and your voltage no longer drops at the front, add capacitors as you see fit to bolster the amplifiers supply voltage. This is proper use of a cap.

Note that not all situations will call for the additional battery and/or upgraded alternator. If the power shortage is slight, as with a moderately sized amplifier added to a stock charging system in good condition and not overtaxed, a cap MAY be helpful. For most imports, that would be a sub amp fused at less than 40 amps, with few or no other additional components drawing significant power. There are no "exceptions" per se, but there are borderline situations where a cap may be benificial, and the preceeding was a VERY GENERALIZED example of such a situation.

As to what to add if you do in fact need to beef up the electrical system's foundation, here are some Cliff's Notes on what to do when.

When adding a second battery, try to mount it as close to amplifiers as possible. Avoid standard lead-acid batteries - for both safety and practicality. Gel Cell batteries (most popularly the Optima brand Red or Yellow Top units) are good, and will do the job. Redtops work best as a PRIMARY battery REPLACEMENT, Yelows are better as a second, dedicated battery. Drycell batteries (I prefer the Stinger brand, there are other very good ones out there) are better. They have a lower internal resistance, recharge faster, can discharge more current on demand, and are more durable.

Any time a second battery is added, the power wire connecting the two MUST be fused within 18 inches of BOTH batteries positive posts. A dual battery isolator or relay is not NECESSARY, but is a very good idea. It is OK to ground the 2nd battery to the frame if you'd rather not run two wires through the car, but all system components should be grounded to the system batteries negative post (this is usually more convenient install-wise anyway). It is not in fact necessary to have both batteries be of the same type - they will be wired in paralell, so the resistance will therefor average out as far as the alternator is concerned, although the battery with the lower internal resistance will charge faster.

Upgrading the alternator can be done two ways, by having your unit rewound to a higher amperage, or by replacing it altogether with a high output type unit. The former is less expensive, but typicaly less reliable, the latter usually more reliable - but MUCH more expensive. I am not going into adding additional alternators here, it is VERY seldom necessary, and if you need it, you need more help than would be useful here.

I REALLY hope there won't be many questions remaining after this, I tried to make it easy to grasp. Sorry it was so long, I hope it will be worth it!! Coming soon - Subwoofer enclosure types and their best applications. Stay tuned!!

**stifler** · 4-7-02, 0:09

I have a problem with my stereo, everytime the bass hits my lights dim, what is wrong. I can't figure it out......

JK my stereo works fine, I thought I would just poke fun

**scubasteve** · 4-7-02, 15:17

made sticky!!!

**mxmissile** · 4-12-02, 1:24

Quote:

made sticky!!!

Huh?

**Dex** · 4-16-02, 19:20

i would just like to understand the double battery a little more, what you are saying is that you wire them in parallel with one fuse between both batteries positive posts, or would you use 2 fuses, as in one for each battery? 2nd the fuses would be the equal to the main fuse for the car? or where would you get this amp rating?

**mxmissile** · 4-17-02, 1:47

You should definately have one fuse for each battery. More specificly, one for each positive wire coming off a battery.

Think of it this way - if a wire connected to the battery shorted to the frame, what would prevent it from arcing until the battery was dead? So if you have a wire connecting the two batts, and it grounds out, you need a fuse at each end - if one fuse blows, but there is no fuse at the other end, than the 2nd battery keeps sending power to the short. Make sense?

The fuse between the batteries can be any size you want, really - it just has to hold enough current to charge the second battery. Very little power will ever be demanded of that wire as far as pulling current for the amps. Theoreticly, a fuse equal to 1/2 the alternator output would probably hold. I usually go with a fuse equal to the alternators max output, rounded up. Like an 85 amp alt, I would use a 100 amp ANL fuse at each end. Again, these fuses are really just to provide short circuit protection for the two batteries, so I opt for a larger one to minimize both resistance and the chance of it blowing for any reason other than a dead short!

Thanx for the Q, hope this helped!

**scubasteve** · 4-17-02, 7:41

Quote:

Originally posted by mxmissile

Huh?

made sticky so that it will stay at the top of the list of the forum ....

**mxmissile** · 4-17-02, 16:23

Oh! Thanx Scube - I feel all warm and fuzzy now!

4-19-02, 13:17

you should post this up on mx6info.com or a website with pics and stuff. all this reading is making my head hurt

**mfp4073** · 4-23-02, 9:06

Is there any sort of rule as far as total amp wattage and approaching the need for caps, alternator upgrade, or extra batteries? I know there can not be a hard and fast one, but just the point where people have started needing more.

**mxmissile** · 4-24-02, 2:37

Generally speaking, if you are drawing less than 1/2 to 2/3 of your alternators rated output, you're probably OK, a cap might be benificial. At 1 to 1.5 times rated output, a 2nd battery is a good idea. Anything above 1.5x, and it's probably necessary. More than 2x rated output, and you should seriously consider upgrading the alternator.

To get your current draw, just add up all the fuse ratings for your amps. Not all amps will draw full power, but we're trying to make this simple, so the preceding makes a good general rule, assuming that some of the amps will not draw max current. If all your amps are running bridged to subs, or are amps that always run full power (the JL amps are the only ones that di this now), assume you're more likely to need an upgrade.

Hope that helped!

**Malicious** · 4-24-02, 7:30

JL amps always run full power? Oh damn... I have issues now with a 26A draw, part of the time... wonder what 50A will be like all of the time

I guess I really need a new alternator

**mxmissile** · 4-24-02, 14:28

The JL amps will draw less power at lower volumes, obviously, but the RIPS technology ensures that they put maximum output into any impedence between 1.5 and 4 ohms, regardles of whether or not they are bridged. Which means that at high volume, yes - they always pull close to their max fuse rating.

BTW, they are the best amps I have ever worked with....

I will not consider anything else for my ride at this point!!

mpyrol · 4-28-02, 22:49

Hello all.

I use this site fairly often and thought I would contribute. I work as an engineer for a manufacturer of automotive audio products. I have a few comments to make you guys should know.
1. Batteries give of noxious fumes; avoid adding batteries to the interior of your car. Gel cells may be used instead, however they have very limited life and when old will not charge above 12V after a year or so. Your amplifier needs the extra volt or two especially a regulated amp. There is a huge difference even with this small potential difference.
2. If your lights flicker after you add a capacitor and a new battery under your hood, the only way to alleviate your problem is an upgraded alternator. Under extended play your "added battery" will just die just as the battery under your hood is dieing.
3. A capacitor has to be big. These undersized caps are NOT 1 Farad.
4. Automotive electrical systems are capable of producing enough power to run a 200x2 watt amp, and this is with an adequate battery and capacitor. I recommend 300 watts. Trying to get more power to your speakers is futile. There is no more there to deliver unless you have three or four batteries and that is only for a few minutes.
5. A steady power source Is imperative to maintain the life of your amps, speakers and head units. Not only does your amp suffer due to excess heat (main symptom of poor current capability) but also your speakers see a nasty spike when your amp clips the top half of your signal.
To sum up, extra batteries are dangerous and very short lived. By the time you spend the money, time and effort you will agree, I should have bought an alternator. If this is out of your financial means, shoot for an efficient system. Buy quality not quantity; remember 200 watts is enough power to be heard. I'm working on a little system in a hobby car I just purchased. My goal is 150 Db with 300 watts of juice on two ten-inch speakers. I'll let you guys know in a few weeks how close I get. Good luck guys!!!!

**mxmissile** · 4-29-02, 4:47

You obviously come from a very technical background, and I respect that, so this is not intended to be a shot - but I will politely disagree with that last post on several notes.

While many gel cells have a lower than average life expectancy, that is usually because they are used in an application where they are constantly deep-cycled. Used in a car system where they will have a constant source of power, however inadequate, they last a VERY long time. The new drycell units use a better version of gel technology, and are even better. I personaly have a 4 year old Redtop that has been through 3 cars and 2 large systems with stock alternators, still strong. Also note - systems of the power discussed here shouldn't and usually don't play all the time at anywhere near full power, so the alternator has ample oppourtunity to "catch up" on charging the batteries.

I'll leave the fume issue alone, the point is made regarding non sealed batteries in any enclosed area. Anyone dumb enough to do so deserves what they get!! (J/K - sorta!)

I dunno where you get your info about power and speakers, all I can say is, 300 watts and 150 db? Unless you're using something other than a regular transducer in some magical enclosure - good luck! Running amps that claim 300 watts and put out 1200 doesn't count, either. I have seen ridiculous SPL #'s posted from single subs off comparably moderate power, but they use crazy huge TTL enclosures the likes of which are not anything like practical, even for most competition systems.

I personaly have three customers currently hitting between 150 and 155, the most "efficient" of which has around 1600 very real watts running 2 15" subs in vented chambers. Stock 115 amp alternator, dual batteries, 153 Db. Upgraded alternator is coming for that one. The other two are both running 200 amp alternators and dual batteries, one of them just over 2000 total watts to two 15's, the other a little over 3K to four 15's. Not one of them has blown a sub yet, two of the systems are well over 6 months old. I have a guy in NY who is still using the original 12" woofers I installed in 1995, running about 500 watts, now hitting around 139 - down from the 142 he posted when the setup was new.

On the cap issue, all I have to say is charge one up, get your hand wet, and smack the terminals. Keep me posted on the results.

I agree with you on the large scale view of things. By and large, electrical systems in cars are not strong enough to run a high power audio system - that's why I started this thread in the first place. And I see lot's of people trying to add power that just isn't there, in situations where more power isn't what they need anyway. This is another issue I am trying to address with this and other info threads. I just dunno where you get some of your #'s - 10 years of real-world experience in this industry leaves me disagreeing on a few things.

4-6-02, 23:50	#1 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 32 iTrader: (0)	Low voltage/Dimming lights, please read this!! Since the question keeps coming up in threads, and Steve and myself, and numerous others with whom I am regretably less familiar keep replying to them as the questions arise, I am starting this thread as a reference for people who somehow haven't read the FAQ's or found the answers they seek in a search. Feel free to reply, but this wasn't meant to start a discussion, only provide information. Any guru's please feel free to back me up so that others know this is accurate and credible, or to expound on any part of it - if, in your expertise, you find any part of it lacking. Not to be nasty, but if there be any individual who should feel compelled to disagree with this info based on what their "friend who knows a lot about this stuff" told them, I would ask said individuals to refrain from posting here without doing some heavy duty homework. This post is meant to clear things up for people who have heard different things from different sources and need help, not add to their confusion on the issue. That said - The most frequently recomended step to help with a low voltage situation is to add a capacitor of one sort or another. This advice is given even by seasoned professionals in the industry. Unfortunately, it is more often than not the wrong advice. Capacitors (caps) are a good thing - if they're used correctly. When added to an electrical system that can keep up, they provide the extra on-demand power a big amplifier craves. However, if the electrical system is already lagging, a cap helps until it's discharged, then it becomes one more thing for the already overworked charging system to keep up with. Once drained, a capacitor becomes a point of resistance in the system untill it is able to regain a voltage equal to or greater than that demanded "down stream", as it were. Since caps drain very quickly, and the demand that drained them in the first place will draw the current it wants with or without the cap, they do not recharge until the demand drops. So - Make sure the alternator is in good shape. Then check the existing battery. If either of the above is wanting, replace it. If both are good, then add a second battery to reduce the load on the front end of the charging system. Upgrade the alternator if you are hard on your system to the point where even the 2nd battery is running behind. Once all this is in place, and your voltage no longer drops at the front, add capacitors as you see fit to bolster the amplifiers supply voltage. This is proper use of a cap. Note that not all situations will call for the additional battery and/or upgraded alternator. If the power shortage is slight, as with a moderately sized amplifier added to a stock charging system in good condition and not overtaxed, a cap MAY be helpful. For most imports, that would be a sub amp fused at less than 40 amps, with few or no other additional components drawing significant power. There are no "exceptions" per se, but there are borderline situations where a cap may be benificial, and the preceeding was a VERY GENERALIZED example of such a situation. As to what to add if you do in fact need to beef up the electrical system's foundation, here are some Cliff's Notes on what to do when. When adding a second battery, try to mount it as close to amplifiers as possible. Avoid standard lead-acid batteries - for both safety and practicality. Gel Cell batteries (most popularly the Optima brand Red or Yellow Top units) are good, and will do the job. Redtops work best as a PRIMARY battery REPLACEMENT, Yelows are better as a second, dedicated battery. Drycell batteries (I prefer the Stinger brand, there are other very good ones out there) are better. They have a lower internal resistance, recharge faster, can discharge more current on demand, and are more durable. Any time a second battery is added, the power wire connecting the two MUST be fused within 18 inches of BOTH batteries positive posts. A dual battery isolator or relay is not NECESSARY, but is a very good idea. It is OK to ground the 2nd battery to the frame if you'd rather not run two wires through the car, but all system components should be grounded to the system batteries negative post (this is usually more convenient install-wise anyway). It is not in fact necessary to have both batteries be of the same type - they will be wired in paralell, so the resistance will therefor average out as far as the alternator is concerned, although the battery with the lower internal resistance will charge faster. Upgrading the alternator can be done two ways, by having your unit rewound to a higher amperage, or by replacing it altogether with a high output type unit. The former is less expensive, but typicaly less reliable, the latter usually more reliable - but MUCH more expensive. I am not going into adding additional alternators here, it is VERY seldom necessary, and if you need it, you need more help than would be useful here. I REALLY hope there won't be many questions remaining after this, I tried to make it easy to grasp. Sorry it was so long, I hope it will be worth it!! Coming soon - Subwoofer enclosure types and their best applications. Stay tuned!!
	Car audio guy and resident domestic 4 banger advocate

4-7-02, 0:09	#2 (permalink)
stifler Join Date: Sep 2001 Location: Calgary Age: 30 iTrader: (0)	I have a problem with my stereo, everytime the bass hits my lights dim, what is wrong. I can't figure it out...... JK my stereo works fine, I thought I would just poke fun
	Stifler http://photos.yahoo.com/bc/stifler0877 new:black-cherry repaint/red-pearl flame design,CRX Combat sides,Z3 fenders, Clarion 925 CD,Brembo drilled/slotted rotars,Bosal Headers, 2.25" exhaust, high flow cat,17" Primax rims, Hercules low pro tires,neon underbody,momo steering wheel

4-7-02, 15:17	#3 (permalink)
scubasteve Join Date: Aug 2001 Location: southern indiana right outside louisville Age: 27 iTrader: (0)	made sticky!!!
	-KLZE, Ported Heads, Authentic KLZE PCM w/ J-spec VAF,- -Hotshot CAI, Erubuni Style 44 kit- -Stevenbishop79@insightbb.com-

4-16-02, 19:20	#5 (permalink)
Dex Join Date: Jul 2001 Location: Ab/Canada, Canada Age: 26 iTrader: (0)	i would just like to understand the double battery a little more, what you are saying is that you wire them in parallel with one fuse between both batteries positive posts, or would you use 2 fuses, as in one for each battery? 2nd the fuses would be the equal to the main fuse for the car? or where would you get this amp rating?
	87 626 Factory LXT winter/project car 92 mazda mx6 project car 90 mazda mx6....LXT 1st block made 24000 km...then broke a rod...now on 2nd LX block...and running... http://www.cardomain.com/ride/2173605 There is a replacement for displacement; it's called technology

4-17-02, 1:47	#6 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 32 iTrader: (0)	Fusing You should definately have one fuse for each battery. More specificly, one for each positive wire coming off a battery. Think of it this way - if a wire connected to the battery shorted to the frame, what would prevent it from arcing until the battery was dead? So if you have a wire connecting the two batts, and it grounds out, you need a fuse at each end - if one fuse blows, but there is no fuse at the other end, than the 2nd battery keeps sending power to the short. Make sense? The fuse between the batteries can be any size you want, really - it just has to hold enough current to charge the second battery. Very little power will ever be demanded of that wire as far as pulling current for the amps. Theoreticly, a fuse equal to 1/2 the alternator output would probably hold. I usually go with a fuse equal to the alternators max output, rounded up. Like an 85 amp alt, I would use a 100 amp ANL fuse at each end. Again, these fuses are really just to provide short circuit protection for the two batteries, so I opt for a larger one to minimize both resistance and the chance of it blowing for any reason other than a dead short! Thanx for the Q, hope this helped! Last edited by mxmissile : 4-17-02 at 1:50.
	Car audio guy and resident domestic 4 banger advocate

4-17-02, 16:23	#8 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 32 iTrader: (0)	Oh! Thanx Scube - I feel all warm and fuzzy now!
	Car audio guy and resident domestic 4 banger advocate

4-19-02, 13:17	#9 (permalink)
wariow Location:	you should post this up on mx6info.com or a website with pics and stuff. all this reading is making my head hurt
wariow Location:

4-23-02, 9:06	#10 (permalink)
mfp4073 Join Date: Sep 2000 Location: Winter Park, FL/Hells Ditch iTrader: (0)	Is there any sort of rule as far as total amp wattage and approaching the need for caps, alternator upgrade, or extra batteries? I know there can not be a hard and fast one, but just the point where people have started needing more.
	We do not ask for your poor, or your hungry. We do not want your tired and sick. It is the corrupt we claim. 1967 mustang coupe 289/4speed, 1970 mustang mach 1 fastback 351c/auto, 1994 MX-6 LS 2.5 v6 5 speed Green/black and tan interior!!

4-24-02, 2:37	#11 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 32 iTrader: (0)	Generally speaking, if you are drawing less than 1/2 to 2/3 of your alternators rated output, you're probably OK, a cap might be benificial. At 1 to 1.5 times rated output, a 2nd battery is a good idea. Anything above 1.5x, and it's probably necessary. More than 2x rated output, and you should seriously consider upgrading the alternator. To get your current draw, just add up all the fuse ratings for your amps. Not all amps will draw full power, but we're trying to make this simple, so the preceding makes a good general rule, assuming that some of the amps will not draw max current. If all your amps are running bridged to subs, or are amps that always run full power (the JL amps are the only ones that di this now), assume you're more likely to need an upgrade. Hope that helped!
	Car audio guy and resident domestic 4 banger advocate

4-24-02, 14:28	#13 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 32 iTrader: (0)	The JL amps will draw less power at lower volumes, obviously, but the RIPS technology ensures that they put maximum output into any impedence between 1.5 and 4 ohms, regardles of whether or not they are bridged. Which means that at high volume, yes - they always pull close to their max fuse rating. BTW, they are the best amps I have ever worked with.... I will not consider anything else for my ride at this point!!
	Car audio guy and resident domestic 4 banger advocate

4-28-02, 22:49	#14 (permalink)
mpyrol Join Date: Mar 2002 Location: USA,Ga. Age: 41 iTrader: (0)	More Power Stuff Hello all. I use this site fairly often and thought I would contribute. I work as an engineer for a manufacturer of automotive audio products. I have a few comments to make you guys should know. 1. Batteries give of noxious fumes; avoid adding batteries to the interior of your car. Gel cells may be used instead, however they have very limited life and when old will not charge above 12V after a year or so. Your amplifier needs the extra volt or two especially a regulated amp. There is a huge difference even with this small potential difference. 2. If your lights flicker after you add a capacitor and a new battery under your hood, the only way to alleviate your problem is an upgraded alternator. Under extended play your "added battery" will just die just as the battery under your hood is dieing. 3. A capacitor has to be big. These undersized caps are NOT 1 Farad. 4. Automotive electrical systems are capable of producing enough power to run a 200x2 watt amp, and this is with an adequate battery and capacitor. I recommend 300 watts. Trying to get more power to your speakers is futile. There is no more there to deliver unless you have three or four batteries and that is only for a few minutes. 5. A steady power source Is imperative to maintain the life of your amps, speakers and head units. Not only does your amp suffer due to excess heat (main symptom of poor current capability) but also your speakers see a nasty spike when your amp clips the top half of your signal. To sum up, extra batteries are dangerous and very short lived. By the time you spend the money, time and effort you will agree, I should have bought an alternator. If this is out of your financial means, shoot for an efficient system. Buy quality not quantity; remember 200 watts is enough power to be heard. I'm working on a little system in a hobby car I just purchased. My goal is 150 Db with 300 watts of juice on two ten-inch speakers. I'll let you guys know in a few weeks how close I get. Good luck guys!!!!

4-29-02, 4:47	#15 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 32 iTrader: (0)	You obviously come from a very technical background, and I respect that, so this is not intended to be a shot - but I will politely disagree with that last post on several notes. While many gel cells have a lower than average life expectancy, that is usually because they are used in an application where they are constantly deep-cycled. Used in a car system where they will have a constant source of power, however inadequate, they last a VERY long time. The new drycell units use a better version of gel technology, and are even better. I personaly have a 4 year old Redtop that has been through 3 cars and 2 large systems with stock alternators, still strong. Also note - systems of the power discussed here shouldn't and usually don't play all the time at anywhere near full power, so the alternator has ample oppourtunity to "catch up" on charging the batteries. I'll leave the fume issue alone, the point is made regarding non sealed batteries in any enclosed area. Anyone dumb enough to do so deserves what they get!! (J/K - sorta!) I dunno where you get your info about power and speakers, all I can say is, 300 watts and 150 db? Unless you're using something other than a regular transducer in some magical enclosure - good luck! Running amps that claim 300 watts and put out 1200 doesn't count, either. I have seen ridiculous SPL #'s posted from single subs off comparably moderate power, but they use crazy huge TTL enclosures the likes of which are not anything like practical, even for most competition systems. I personaly have three customers currently hitting between 150 and 155, the most "efficient" of which has around 1600 very real watts running 2 15" subs in vented chambers. Stock 115 amp alternator, dual batteries, 153 Db. Upgraded alternator is coming for that one. The other two are both running 200 amp alternators and dual batteries, one of them just over 2000 total watts to two 15's, the other a little over 3K to four 15's. Not one of them has blown a sub yet, two of the systems are well over 6 months old. I have a guy in NY who is still using the original 12" woofers I installed in 1995, running about 500 watts, now hitting around 139 - down from the 142 he posted when the setup was new. On the cap issue, all I have to say is charge one up, get your hand wet, and smack the terminals. Keep me posted on the results. I agree with you on the large scale view of things. By and large, electrical systems in cars are not strong enough to run a high power audio system - that's why I started this thread in the first place. And I see lot's of people trying to add power that just isn't there, in situations where more power isn't what they need anyway. This is another issue I am trying to address with this and other info threads. I just dunno where you get some of your #'s - 10 years of real-world experience in this industry leaves me disagreeing on a few things.
	Car audio guy and resident domestic 4 banger advocate