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Discussion Starter #1
PIONEER DEX P99RS.

I have a 2nd battery to run my system and this is split charged to the main system.

If I leave the face-plate in my headunit.. and do not run the car for a few days, I have noticed that the headunit will run the 2nd battery down..

There is no clock showing on the headunit when it is switched off and the memory settings are stored internally and need no power to maintain their use.

Is this normal that a switched off headunit can drain the power from the 2nd audio battery?

Normally on charge the battery reads 13.7v - 14.4v
When off charge and headunit is off - battery reads 11.9v - 12.3v

The 2nd battery will remain charged up to around 12v with no issues as long as the face-plate is off the headunit - if the face-plate is left on and system is switched off, the 2nd battery will show a slow voltage drop until it reaches 11v and this will trip an alarm and I will charge it up.

Could be any settings on this headunit that could account for this?

Thanks for any feedback.
 

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All head units should be hooked up to both switched, and unswitched power. They need some power constantly to keep settings. Hooked up correctly, this should not be draining a battery, it's more likely that simply letting the car sit for several days is what's causing the battery to drain. There will be parasitic loss, and some components within the car will need a tiny bit of power. This is why they make deep cycle batteries for things like boats, and recreational vehicles, a battery that is not charged frequently, and is left hooked up will drain, and eventually fail.

A healthy battery will read 12.6 volts with the car off, if the battery drops much below that after turning the car off, then the battery is on it's way out.
 

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Discussion Starter #3
All head units should be hooked up to both switched, and unswitched power. They need some power constantly to keep settings. Hooked up correctly, this should not be draining a battery, it's more likely that simply letting the car sit for several days is what's causing the battery to drain. There will be parasitic loss, and some components within the car will need a tiny bit of power. This is why they make deep cycle batteries for things like boats, and recreational vehicles, a battery that is not charged frequently, and is left hooked up will drain, and eventually fail.

A healthy battery will read 12.6 volts with the car off, if the battery drops much below that after turning the car off, then the battery is on it's way out.
I appreciate what you have just said.

What is strange is that for the last week or more, the 2nd battery has not had any use and still reads 12v.

The battery only drains when the face-plate is in place - take the plate off and there is zero drain.

The battery is a dedicated car audio battery and is about a year old.

Thanks for your feedback.
 

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12v is too low for a resting battery. If it's reading 12v, you probably need to replace it, or at least give it a proper trickle charge and see if it holds 12.6 volts.
 

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12v is too low for a resting battery. If it's reading 12v, you probably need to replace it, or at least give it a proper trickle charge and see if it holds 12.6 volts.
I will do that this weekend and see.. cheers
 

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The constant and ignition wires could be switched too. If the radio doesn't need constant power to saves memory, you'd never know if the wires were switched. Leaving the faceplate on could be enough to turn the radio on in some manner draining your battery.
 
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