LOW VOLTAGE DESTROYS ALL ELECTRONICS
NOT JUST YOUR AMP

"Do No Harm" - Hippocratic Oath - Adding High Current Aftermarket Electronics

• Below is for guesstimate purposes.  To not guesstimate use an Ammeter  on the particular vehicle.

• Lets say you add 800 WRMS of amplification which draws 80 amps of current at full volume and the vehicle.   
  -  65 Amp Hour Under hood Battery  /    80 Amp alternator   /    Vehicle draws 30 Amps to run (Without heater fan (+10a) or Head lights turned on (+10a))
  - Running with heat and lights  1 Hour 15 min //  Running  without heat or lights-  2 Hours Full Volume  before main battery is depleted and potential voltage drop damage to any/all electric components in the vehicle begins.    Is their vehicle drive by wire or brake by wire?    This assumes highway driving.  Under 2000RPM  the alternators output is severally reduced.   
  -  The alternator will enter a state of constantly running  under the heavy load and the battery will only have a surface charge which will effect starting. 

Some more  Examples 

• Lets say you add 1200 WRMS of amplification which draws 120 amps of current at full volume and the vehicle.   
  65 Amp Hour Under hood Battery  /    80 Amp alternator   /    Vehicle draws 30 Amps to run
  While running  -  1 Hour 45 minutes Full Volume  before main battery is depleted and potential Voltage Drop damage to any/all electric components in the vehicle starts.

• Lets say you add 1800 WRMS of amplification which draws 150 amps of current at full volume and the vehicle.   
  65 Amp Hour Under hood Battery  /    80 Amp alternator   /    Vehicle draws 30 Amps to run
  While running  -  40 Minutes Full Volume  before main battery is depleted and potential Voltage Drop damage to any/all electric components in the vehicle starts.

• Lets say you add 2400 WRMS of amplification which draws 200 amps of current at full volume and the vehicle.   
  65 Amp Hour Under hood Battery  /    80 Amp alternator   /    Vehicle draws 30 Amps to run
  While running  -  30 Minutes Full Volume  before main battery is depleted and potential Voltage Drop damage to any/all electric components in the vehicle starts

• Rule of thumb:  WHEN A SYSTEM GOES ABOVE 80 AMPS FUSED AT THE BATTERY THE ELECTRICAL SYSTEMS CAPACITY NEEDS TO BE CONSIDERED. 
  Vehicle charging systems typically only have 20 to 30 Amps of reserve capacity to add accessories without over cycling the alternator which can severely reduce its lifespan. 

Does your customer need  battery?    
- Do halogen headlights dim with the bass turned up?  
- LED bulbs flickering?
- Bass doesn't hit when the heating fans are on?

Does your customer need an alternator?  
- Are they installing a 800Wrms sound system fused at 80 Amps ->  With the engine running they would have to blast it  for 2 hours straight wile
    driving using the example above.  Do they go on Road trips?  
- Did their alternator recently need to be replaced?  Or is constantly running & getting hot?
- Are they are installing a 4000Wrms sound system fused at 300 Amps  ->  Are they going to drive around slow, frontin,  banging hard?    Yes they
    need an alternator and batteries.  Basic Physics Watts Law discovered in 1765.    

CUSTOMERS ONLY HAVE SO MUCH MONEY 
So you explain to your customer not to blast their new dream stereo because can damage their new amp and all the other electrical components in the car.  You tell them they should upgrade the alternator and/or add batteries to maintain proper voltage and not damage anything       

Customer A
"No man, I won't turn it all the way up more than a few minutes.  When the headlights dim I'll turn it down" 
Offer your customer a way to actively manage their situation with Voltage meters they can see while driving  

Add 2 -LED Voltage Meters 
- 1 at Main Battery in vehicle 
-1 on the Power-feed within 14" of the amp(s)

Mount the LED  meters where they are visible to the driver.  You can also add a latched push button switch to turn off If they wish to turn off the glow of the meter.  Wire with a relay to accessory power so It turns off with vehicle.  

Now you customer can see to take appropriate action to not damage their vehicle

Customer B
"My new sound system only  draws 140 Amps - Can't we just add a battery"

If the total (Vehicle+System) draw exceeds the output of the alternator it's not a matter of if you can have an issue but when.

Glassmat battery's  make an excellent choice because they can discharge  quickly like a capacitor and have the reserve storage of a battery.    They can keep  up with heavy current transients audio amps make allowing the amp to sound their best and operate properly.    

Keep in mind you can also increase your reserve with a larger AHR starting battery. 
Adding a glassmat wired in parallel to your amps will not only protect your amps but also enhance their performance.

Examples of AFTER ADDING a  Sealed Glassmat battery 

- 80 AMP current draw  with 20 Amp Hour Battery Model: SK-BT20  - up to 1000 Watt amps
    - Reserve battery adds 15 Minutes at Full Volume.  
    -Vehicle running -   1 Hour Full Volume  before potential damage.  Assuming 60 AHR Main Battery .

- 120 AMP current draw  / 28 Amp Hour Battery Model: SK-BT28  - up to 1300 Watt amps
    - Reserve battery adds 15 Minutes at Full Volume.  
    -Vehicle running - Assuming 60 AHR Main Battery while Vehicle running -  45 minutes Full Volume  before potential damage

- 140 AMP  current draw  / 35 Amp Hour Battery Model: SK-BT35  up to 1900 Watt amps
    - Reserve battery adds 15 Minutes at Full Volume.  
    - Vehicle running - Assuming 60 AHR Main Battery while Vehicle running -  45 Minutes  Full Volume  before potential damage

- 180 AMP  current draw  / 45 Amp Hour Battery Model: SK-BT45  up to  2340 Watt amps
    - Reserve battery adds 15 Minutes at Full Volume.  
  - Vehicle running - Assuming 60 AHR Main Battery while Vehicle running -  35 Minutes  Full Volume  before potential damage

- 240 AMP  current draw  / 60 Amp Hour Battery Model: SK-BT60  up to  3120 Watt amps
  - Reserve battery adds 15 Minutes at Full Volume.  
  - Vehicle running - Assuming 60 AHR Main Battery while Vehicle running -  30 Minutes  Full Volume  before potential damage

FOR HIGH AMPERAGE SYSTEMS

Best / Correct route eliminate potential damage to the vehicle is to upgrade the alternator to increase the amperage by what you are adding draws as well as adding extra batteries allowing your new alternator to correctly  run cycle/cool during operation.    

You should not guesstimate and use an Ammeter on the particular vehicle to find out what AMPERES
- The alternator is putting out.
- The battery is putting out to run the vehicle.    Try with & without lights on / heater blower/  Wipers on etc to get an idea how many amperes the car consumes
- The total fused power draw of what you are adding to the car.

then do some math ...
(Amperes The battery is putting out to run the vehicle) +  (The fused power draw of what you are adding to the car)  =  Minimum Total or Ampere output needed from an upgraded alternator.   

Alternators are designed to cycle on and off in order to cool and not burn out.   A typical cycle ratio would be about 30% off //  70% on
Keep this in mind when selecting additional batteries.   The total combined AHR for batteries in the car should be 30% higher than you total anticipated draw.
IE.  for a  300 Ampere total vehicle draw you should have 428AHR of batteries in the vehicle for the new Altenator.

EXAMPLE CHART BELOW SHOWS HOW LONG WILL IT TAKE AT FULL VOLUME WITH ENGINE RUNNING BEFORE DAMAGE CAN OCCUR