truck’s battery drains in 2 days

I have a Ford Lightning that's relatively stock with the only exceptions being the stereo and the alarm. Amplifiers and processing are as follows:

2 Linear Power 3.2HV's
1 Linear Power 2.2HV
1 Linear Power DPS500

Alpine D301 head unit
Alpine H701 processor

Optima Yellow Top battery

1/0 wiring throughout.

Anyway, the crux of the problem is that my truck's battery will stay usable for starting a maximum of two days.  Following that, the truck is completely dead.   I've started troubleshooting by measuring the battery's voltage last night night prior to going to bed with the truck connected and stereo disconnected at 12.13V. This morning I measured it at 11.33V. This is with the truck off and alarm unarmed throughout the night.

Is this an excessive drop in voltage in one night? Would further troubleshooting look to eliminate the stereo from the cause of the problem, and possibly focus it on the truck or alarm, specifically?

Let me know what you think. Thanks in advance.

If you're battery is discharging that much overnight with nothing connected, you've got battery problems.

I would start simple. Disconnect everything from the battery terminals before going to bed and check the voltages. I'm guessing it will be fine so long as the optima is relatively new.

When you said you disconnected the stereo, how did you do it (at the battery or at the amp?) Something must be staying on and draining your battery provided it worked fine before you installed the stereo.

Take it one step at a time and I'll bet you'll find the culprit.

Good luck!

I should claify that it is not a new battery, nor is this a new problem...I'm just now getting around to fixing it.  The problem has been present for over a year

Well, that's interesting since it eliminates any known good items.

I'd still go forward with disconnecting everything from both battery terminals overnight and measure the voltage drop. Should at least let you know if you have a good battery. If so, only connect the car stuff, no stereo. Verify that the alternator is charging correctly and the battery will work without the stereo.

Good luck.

is the amp always on?? even when the car is off??

Instead of focusing on battery voltage you should be looking at current draw.  With an ampmeter connected in series with your battery and nothing else on (dome lights, etc) see what the draw is.  If it is high (above 50mA) start disconnecting stuff until its below 50mA.  Start with aftermarket equipment and if that doesn't help start pulling OEM fuses.  Keep us updated!

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Kevin Pierson

Maybe your battery has seen it's better days (although 12.13volts is not low by any means). What is concerning is that you are almost losing a full volt in one nights time, which points to the first and most obvious question: There is current being drawn from somewhere. The full proof way would be to do what mjwood0 mentioned. You will then know for a fact that nothing can be drawing any current with nothing connected to the battery terminals. Re-check every light, amp, etc. It could just be something that you overlooked. Or it could be time for a new battery...

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