Constant Power to Stereo

[Howler]

Question from an electricity-challenged sailor:

I've installed a basic car stereo. The boat was pre-wired with standard DIN plugs so it was straightforward. The power is supplied via the DC panel so when the circuit is turned off, I lose my memorized radio stations and bluetooth pairing information. I don't want to hot-wire the stereo's constant power feed to the boat battery bank for fear of a constant trickle, and to avoid fishing wire around the boat. So here's the question:

Is it possible to connect the stereo's constant power to a dedicated battery?

I assume it draws very little so could one of those rechargeable 12V 3000mAh lithium ion battery packs work?

Which are the two wires that would need to be connected to the dedicated battery?

Thanks!

[Franziska]

Unfortunately I have no direct answer to you, but how about mounting a small solar panel to offset the drain from the stereo?

[Howler]

Originally Posted by Franziska

Unfortunately I have no direct answer to you, but how about mounting a small solar panel to offset the drain from the stereo?

Good idea. I would like to install small solar panel and I've read many threads about the subtleties of specifications, regulators, controllers, wiring, etc. I'm not good with electrics so if you could recommend a very basic "solar panel for dummy" reference, that would be great!

[Franziska]

If you want to add a small panel just for that purpose, any sort of traveller's panel which is used to charge phones on the go which is waterproof should do.

We talk about very little current.

If you want to use solar for more, it's a huge subject and costs can run from 100$ to 1000's of $.
I am sure others can recommend good small solutions. We have a big array on our arch, but will replace it eventually with a new big array.

[Lake-Effect]

Do you have the manual for the car stereo? It might list the "hold-up" current drawn when it's off.

Assuming it's miniscule, and your batteries are being charged regularly, why not just leave the stereo breaker on all the time? That's what is done in cars...

[smac999]

Your car stereo in your car is connected to the battery. It can be parked for weeks. The drain is small.

Most Likly the stereo power actually comes from that battery wire while on. (And the Acc panel wire just tells it to turn it on). So another battery would not last long.

[Diamond Life]

Check the wiring diagram, normally there is an additional wire (usually yellow) which is wired to essential power (fused) that maintains constant power for the memory.

I normally don’t worry about it as I don’t like non essential equipment going to my essential terminals.

[noelex 77]

The first thing to do is measure the power draw. It is generally (but not always) very small. I still like the options of disconnecting everything, but this can be done via a small switch, otherwise connect the yellow wire and let the house bank supply the power. The power would only be turned off if leaving the boat for many months. This is the best solution.

A small lithium battery will not work, as the supplied voltage will be incorrect for charging. A lithium battery will have a short life with a risk of more serious problems. You could add a small lead acid battery, but you need to think about fusing etc and you are still left with the hassle of periodic replacement.

A large capacitor is the most elegant solution if you are determined to avoid connection to the house battery, but it will need some experimentation.

Any power that is consumed by the stereo’s energy is likely to be replaced by the main battery bank anyway. For example, if you install a capacitor and while you are away from the boat it discharges 0.1 Ahrs keeping the memory alive. When you come back to the boat and turn on the stereo the main battery bank has to supply the 0.1Ahrs to charge the capacitor back up. So unless you are on shore power or have the engine started and the house bank is full, you have not saved any power or discharged the house battery any less despite the complication.

[moctrams]

Solar panel sounds like a good idea.

[Spot]

Originally Posted by Diamond Life

Check the wiring diagram, normally there is an additional wire (usually yellow) which is wired to essential power (fused) that maintains constant power for the memory.

I normally don’t worry about it as I don’t like non essential equipment going to my essential terminals.

On my Pioneer stereo, yellow wire is constant +12v for memory functions and red is switched +12v (so radio turns on/off when ignition is turned on/off in a car). As quoted above, check the manual for your stereo in case it is different.
On my RV I wired a lighted switch on the dash to act like the ignition since the stereo was on the house bank instead of the vehicle start battery.
Diagram assumes radio is fused on the unit. When switch closes, LED on switch and load terminal receive +12v.

[Tetepare]

Originally Posted by Diamond Life

Check the wiring diagram, normally there is an additional wire (usually yellow) which is wired to essential power (fused) that maintains constant power for the memory.

I normally don’t worry about it as I don’t like non essential equipment going to my essential terminals.

Me too. But are we being pig headed? We know it would take a long time to drain the battery. I suppose for me I don’t have the radio continuously powered because it’s “not the right thing to do” being a nonessential. Too conservative?

[Lake-Effect]

Originally Posted by Tetepare

Me too. But are we being pig headed? We know it would take a long time to drain the battery. I suppose for me I don’t have the radio continuously powered because it’s “not the right thing to do” being a nonessential. Too conservative?

It's possible to buy or build discharge protection circuits that will disconnect loads when the battery voltage drops below a predetermined value. So an always-connected but non-essential load like the stereo (or just its memory holdup) should not ever completely drain the battery.

[sailah]

I wired the yellow wire on mine, with a fuse, to a constant on bus that also feeds my bilge pumps. The drain is tiny, i don't even worry about it.

I have an ON OFF switch on my house bank if i truly want to shut down all power. But as it is, it bypasses my normal battery switch. Since i have Bluetooth on my stereo it's worth it to not lose the pairing, radio stations etc.

[stormalong]

This is a total non issue. The power draw to retain the memory is miniscule. Just leave the circuit breaker on.

[MV Wanderlust]

Originally Posted by stormalong

The power draw to retain the memory is miniscule. Just leave the circuit breaker on.

Well, that was my thought, too. Just leave that circuit breaker on and turn the stereo off. Our boat came with a car stereo wired to a breaker. We leave the breaker switch on all the time but turn off the stereo when leaving the boat. Everything starts normally when we return.

John