Photo credit to Chris Allen, Limitless Lithium One of the common questions we get as installers is "Hey what alt/batteries do I need?" I've answered this a few ways but I've always had a good idea of what would be an easy way to define this yourself. While this may not be the end all answer as various companies rate differently, there are efficiency changes between amplifier types and varied ohm loads etc etc. However I find this to be a simple solution for the common installation.
Let's start by taking your wattage in RMS. Add this up by using real world ratings. If your amplifier produces 1500wrms at 2 ohm but 3000wrms at 1 ohm use the wattage at the load you are wired for. Lets say 5000 watts RMS and go from there. While amplifiers may not always produce their rated RMS during music play (ask about impedance rise and maybe another blog post will follow!) we still want to address that no amplifier is 100% efficient. While efficiency can range we are using the rating of 80% to get our results. So, 5000WRMS at 80% efficient would look like 5000/.8=6250WRMS. To determine the correct batteries we will need we can divide our WRMS by the voltage at which we will be providing to the amplifiers. Typically we would want a 14.4 volt input however this isn't always the case so we will be using 13 volts. This would look like 6250WRMS/13volts=480 amps. Translated into batteries we would need 480aH of battery power at 13 volts with adequate alternator charging. We would at this point recommend a min of 4) 110aH AGM batteries.
Now for how to keep these batteries charged during play. We can reuse some of our previous math and skip right to our requirements of 6250WRMS after amplifier efficiency. We are going to find what amperage our alternator system needs to produce by dividing our wattage by 14 volts. This looks like 6250WRMS/14volts=446.42 amps. Being that our charging system still needs to adequately support our OEM vehicle electronics we are going to add 30% to this. However if adding an alternator system NOT being tied into the OEM systems and ran solely to our aftermarket gear we would skip this step. This looks like 446.42 amps x 1.3 = 580 amps of required alternator charging. This could be broken up across 2,3 or however many alternators. (Note that not all engines can support the high demand and load of larger alternators and may require you to increase your idle by various methods so not to have engine stalling when the alternator(s) kick on).
With the increasing popularity, huge costs, and weight savings of lithium technology we must address these separately. Lithium is not AGM and are rated differently. We have found a safe rule of thumb for lithium is roughly 200WRMS for every 1aH of lithium being used. So using our same math above this would look like 6250WRMS/200WRMS=31.25aH of required lithium battery. I'll also take this time to point out how much weight, space and costs this saves over traditional AGM.
For the manufacturers we have come to trust we recommend Limitless Lithium, Northstar Batteries and Singer Alternators for the best in product quality, customer support and warranties. For more information visit the following links or click our store above to purchase!
Thanks!
WCCA_Nick
http://limitlesslithium.com/
http://www.singeralternators.com/
https://www.northstarbattery.com/
Now for how to keep these batteries charged during play. We can reuse some of our previous math and skip right to our requirements of 6250WRMS after amplifier efficiency. We are going to find what amperage our alternator system needs to produce by dividing our wattage by 14 volts. This looks like 6250WRMS/14volts=446.42 amps. Being that our charging system still needs to adequately support our OEM vehicle electronics we are going to add 30% to this. However if adding an alternator system NOT being tied into the OEM systems and ran solely to our aftermarket gear we would skip this step. This looks like 446.42 amps x 1.3 = 580 amps of required alternator charging. This could be broken up across 2,3 or however many alternators. (Note that not all engines can support the high demand and load of larger alternators and may require you to increase your idle by various methods so not to have engine stalling when the alternator(s) kick on).
With the increasing popularity, huge costs, and weight savings of lithium technology we must address these separately. Lithium is not AGM and are rated differently. We have found a safe rule of thumb for lithium is roughly 200WRMS for every 1aH of lithium being used. So using our same math above this would look like 6250WRMS/200WRMS=31.25aH of required lithium battery. I'll also take this time to point out how much weight, space and costs this saves over traditional AGM.
For the manufacturers we have come to trust we recommend Limitless Lithium, Northstar Batteries and Singer Alternators for the best in product quality, customer support and warranties. For more information visit the following links or click our store above to purchase!
Thanks!
WCCA_Nick
http://limitlesslithium.com/
http://www.singeralternators.com/
https://www.northstarbattery.com/
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