Adding a second battery for audio and accessories
Thread Starter
Junior Member
Joined: Jul 2022
Posts: 10
Likes: 3
Adding a second battery for audio and accessories
Hi, before I go on another rabbit hole, I wanna pick y'all's brain on some things.
So I have a 2015 F-150 Crew Cab 4wd and I've been thinking on adding a 2nd battery for my audio gear and possibly other things. At present, my two amps are connected to the main battery, as you do, and like I presume other car audio enjoyers I tend to sit with the engine off jaming to music or listening to my audiobooks and podcasts while I eat lunch. I'll sometimes sit for like 30-40 minutes with the engine off. In that time, battery voltage drops to like 12.2-12.3. I know that's not good on the starter. I just had to replace the starter last weekend and the battery 14 months ago.
So it got me to thinking. why not add a battery just for the audio system. mount it under the bed or inside the bed under the tonu cover. have a isolator solenoid thing so the truck isn't drawing on it when I don't want it to but can charge it while the engine runs. I'd have a switch in the cab to toggle it in the event that the main battery can't start the engine. my question is, would this require a alternator upgrade? the big 3? I'm also thinking of running a wire to the radio's fuse location to run it off the secondary.
the amps are nothing special. a 400W rms 4 channel for the doors and a 500W rms mono for the 2x 8" subs.
thoughts?
thanks.
So I have a 2015 F-150 Crew Cab 4wd and I've been thinking on adding a 2nd battery for my audio gear and possibly other things. At present, my two amps are connected to the main battery, as you do, and like I presume other car audio enjoyers I tend to sit with the engine off jaming to music or listening to my audiobooks and podcasts while I eat lunch. I'll sometimes sit for like 30-40 minutes with the engine off. In that time, battery voltage drops to like 12.2-12.3. I know that's not good on the starter. I just had to replace the starter last weekend and the battery 14 months ago.
So it got me to thinking. why not add a battery just for the audio system. mount it under the bed or inside the bed under the tonu cover. have a isolator solenoid thing so the truck isn't drawing on it when I don't want it to but can charge it while the engine runs. I'd have a switch in the cab to toggle it in the event that the main battery can't start the engine. my question is, would this require a alternator upgrade? the big 3? I'm also thinking of running a wire to the radio's fuse location to run it off the secondary.
the amps are nothing special. a 400W rms 4 channel for the doors and a 500W rms mono for the 2x 8" subs.
thoughts?
thanks.
Junior Member
Joined: Feb 2024
Posts: 8
Likes: 4
I know nothing about car audio but I do have an auxiliary battery setup similar to what you're thinking of doing.
I ended up mounting the batteries in the bed as I couldn't find a good spot underneath to mount multiple batteries. I use a 30 amp DC to DC charger with the stock alternator and no big 3 upgrade. Never have had an issue with charging the aux batteries or the truck battery.
I ended up mounting the batteries in the bed as I couldn't find a good spot underneath to mount multiple batteries. I use a 30 amp DC to DC charger with the stock alternator and no big 3 upgrade. Never have had an issue with charging the aux batteries or the truck battery.
Junior Member
Joined: Feb 2024
Posts: 8
Likes: 4
The invertor that comes with the truck is a totally different system. The DC to DC charger gets it's power from the starting battery and sends the correct charge to the aux batteries. Since F150's have smart alternators you need the DC to DC charger to isolate the batteries and send the correct charge profile to the aux battery. Without it the batteries wouldn't charge correctly and I would think you would have codes and a battery light on your dashboard.