Car Audio Memory Retention during Battery Disconnect

[g-reno]

I have a car stereo head unit in a boat that only has the marine batteries connected when the boat is in the water. When the boat is on the hard the batteries are disconnected and therefore the head unit is always losing it settings.

I'm thinking of using a little A23 12v battery connected to the Yellow Wire and through a diode to hold the memory while the marine batteries are out of the boat. Has anyone done something like this?

Head Unit
\---- Red Wire (switched 12v) --- Ignition Switch
\---- Yellow Wire (12v) --- +A23 --- 10A diode --- Accessory Circuit --- +12v Marine Battery
\---- Black Wire (gnd) --- -A23 --- -12v Marine Battery

The diode prevents the little A23 from trying to power anything else in the Accessory Circuit except for the stereo head unit.

So I found that the A23 has about 55mah of power. That's not very much and possibly not enough to do the job here. Need to find out how much current these head units draw when they are off.

 

[BadActor]

If your boat has an 12v accessory plug:

http/www.ebay.com/itm/Kastar-9-Volt-Automotive-On-Board-Car-Computer-Memory-Saver-/231309996441

 

[g-reno]

If your boat has an 12v accessory plug:

http/www.ebay.com/itm/Kastar-9-Volt-Automotive-On-Board-Car-Computer-Memory-Saver-/231309996441

Yeah, I've seen those before but the boat doesn't have a 12v accessory outlet. The 9v does have more power than the A23 though so that might be useful.

 

[g-reno]

So I built this circuit with the A23 and diode in it and the diode works fine.
The A23 on the other hand only holds the memory for about 2 hrs.
This is on a Pioneer AVH-X5800BHS double-din unit.
So this head unit must be drawing a good bit of current (~27ma) to hold the memory.
That's means it's going to take a fair size battery to do what I'm trying to do which sort of defeats the purpose of just using a small battery for memory hold.

 

[g-reno]

Even a RBC2 UPS battery would only hold the memory for about 10 days.
These Pioneer head-units are great but do they ever suck a lot of power when turned off.