Hello all, I recently got an oil change and the guy said I might want to change my battery soon. I figured this because I just recently installed a 2000 watt power inverter to my truck battery. What I would like to know is, what battery would be best for my needs. I need a battery that will be able to power a 500 watt sound system with 2 8in. sub, a 2000 watt power inverter, and last me a very long time. I should also mention that when I use the power inverter, I leave the truck running. I have done a little research and have narrowed it down to either the Optima red or yellow top or the Sears Diehard Platinum battery. Would I need a deep cycle battery if I still leave the truck running when using a lot of power? I am not set in stone which battery to go with so I open to suggestions. Thanks!

 

Red, you're actually asking a question that has a complicated answer and it's one that points out the fact that most people don't really understand the purpose of a battery in a vehicle.

It serves two purposes - period! It powers the starter to start the engine and then, it "smooths out" the output of the alternator. That's all it does. Once the engine has started, the electronics in the vehicle are powered by the alternator - the battery is absorbing energy from the alternator - no longer supplying power, and, it is acting a bit like springs and shock absorbers to smooth the voltage over the entire electrical system. The battery is doing nothing else.

With that in mind, you would be fine replacing your battery with anything that is capable of starting your engine. If you live in a very cold climate, you need one with a high Cold Cranking Amp (CCA) capacity. If the engine does not start easily and requires prolonged cranking, you need a battery with a high Cranking Amp capacity. Those are the times it is working on its own, and is using its reserves.

Now, IF you are in the habit of running that inverter or your sound system with the engine turned off, then the battery is supplying all the power too, and it would be drained fairly rapidly. You would need a deep discharge design to prolong battery life, but even then you would destroy the battery fairly quickly because NO battery likes to be deeply discharged too often.

However, I think you may need a higher output alternator. I don't know what is in your truck, mine is a 130A alternator since I have the tow package, but I did a couple "back of the napkin calculations" and here's what I determined: IF you ran the inverter at its rated output of 2000 Watts, it would be pulling at least 154 Amps, at 13 volts. The 500 Watt sound system would consume 39 Amps at the same voltage. (I use 13 volts here because the high drain would likely reduce the available voltage of even a high output alternator.

Now, you are NOT going to be running either of these items at full Wattage, or they won't last very long either. So, let's assume you MIGHT run the inverter at 1500 Watts and the sound system at 300 Watts. That would reduce the Amperage draw to about 100 A and 24 A respectively. So, that's 124 A which is very close to the rated capacity of my alternator. There would be nothing left over for my truck's other electronics. This would also shorten the life of the alternator and the battery would not be recharging.

So, look into at least a 200 A alternator and just replace your battery according to your starting needs.

And, if you run your two addons separately, and at lower output, you may be fine with what you have.

Hope this helps.

- Jack

 

Excellent explanation, Jack! You may be improving with age!

 

I'd like to think it's not all a decline! Thanks, Jim - and Merry Christmas to you and yours.

- Jack

 

If you do want a premium battery, go with the DieHard Platinum.

 

Get a big **** alternator .....

 

Yup ^^^^^^^^^^

 

great explanation, i have installed on my truck also a dual battery system with an isolator so i only draw from secondary battery when truck not running and an isolator bypass so if my main battery dies i can jump start off the second battery.