how to calculate how much ah you need for your amp

[TaylorFade]

This is one of those questions that you are going to get alot of different answers to.

Personally I like to take the alternator out of the equation and figure out how much battery power it would take to run my amp/s with the vehicle off. Figuring it this way will be overkill, but that is what has lead me to 30 14v XS batteries.

With XS Power I dont pay as much attention to the ah ratings as I do the batteries wattage rating. I usually take what the company rates the battery to handle and cut it in half so I give myself extra head room for reserve capacity that will allow me to play longer.

So lets say I am planning a 5kw system and amp planning to use the D3100s that are rated for 4000w/5000w+. What I want for battery power is going to be enough to technically support double the power I am running. So taking the 5kw rating of the D3100 and cutting it in half to 2500w, I would need 4 D3100s to give me enough battery power for my 5kw system.

I know there is no math to back up what I am saying, but my experience using this method has proven to work.

Good lord. (4) d3100's for 5k? I guess it does work. Lol.

[Kyblack76]

As a general rule of thumb (and a starting point)... I always say RMS of the system divided by 10 is how much amperage you need.

2,000w = 2,000/10 = 200A

Your alt counts in there so you'd need a 100A alt and 100Ah of batt.

Obviously your alt won't provide all 100A to the system and it's not a perfect calculation, but there's a fudge factor built in and it's just a reference.

This is exactly how i do my needs. And, what i do quickly in my head when some asks about reserve, or fusing need. I do the divide by 10 deal also.

When looking at bats, i look only at amp hours.

Just my own way of doing it....