Constant Power to Stereo

[Danm1]

I bought a boat where the previous owner had direct wired the radio for this reason. I didn't realize. Had an outboard with an alternator to recharge the battery, but sailed from the mooring most often and the battery would run down every few weeks...drove me nuts until one evening I spotted the little red light on the radio indicating a power draw. Disconnected it and never had battery problems again. So, it may not be much, but it is something.
That said, around the same time I added a 10 watt Coleman solar panel that connected to the battery with alligator clips and sat in the cockpit when I left the boat. Worked great.

[stormalong]

Originally Posted by Danm1

I bought a boat where the previous owner had direct wired the radio for this reason. I didn't realize. Had an outboard with an alternator to recharge the battery, but sailed from the mooring most often and the battery would run down every few weeks...drove me nuts until one evening I spotted the little red light on the radio indicating a power draw. Disconnected it and never had battery problems again. So, it may not be much, but it is something.
That said, around the same time I added a 10 watt Coleman solar panel that connected to the battery with alligator clips and sat in the cockpit when I left the boat. Worked great.

I don't know what brand of radio you have. I have never seen an indicator light on mine unless it is turned on. That indicator draws more power than the memory.

PS. An LED indicator would not discharge a battery in two weeks unless it is a very small battery. An LED draws about .02 amps.

[a64pilot]

Measure it if you will. But the power draw is minuscule, I’m sure there is some odd ball radio out there that somehow has significant draw, but I’ve never seen one. So minuscule that for example most computers use a small coin battery to retain memory and it usually last for years.
The current draw when things are off is called dark current, and it’s not a bad idea to measure the draw from the whole bank as it could alert you if for example you have a current “leak” from your bilge pumps or something. If I had an Amp of current draw when everything was off, I’d track it down.
The keep alive power draw for a stereo ought to be about 1 milliamperes or so.

[mlydon]

Car stereos (and marine ones) have a straight to battery. Onnection (the larger one) and an ON wire. Both the stereo's main power and the memory come through the allways on connection. The other wire simply turns it on, so as others have stated, run it as intended. The memory draw is in the nature of 10 milliamps.

Other devices in hour boat will suck constant current as well, like smart bilge pump switches, etc.

My boat draws a constant current of 250ma daytime between 2 smart bilge pump switches, battery monitor, r stereo memory, vhf memory, and whatever else. With an auto anchor light im into over half an amp an hour. A small solar panel & controller at less than $200 total keeps everything topped off at all times. Better for batteries, no sleepless nights, well worth it.
Matt

[noelex 77]

Originally Posted by mlydon

The memory draw is in the nature of 10 milliamps.

10ma is a typical number from the units I have measured, but there is considerable variation.

This is a very tiny draw and can usually be ignored.

If the boat is left for 6 months it is only 43 Ahrs.

However, if leaving the boat for a long time, self discharge, indicator lights, stereo memory, battery monitor etc etc do add up so do not ignore these small loads completely, especially on a small boat with a correspondingly small battery bank. The best advice is to measure the numbers, and then estimate the self discharge to decide if any action is needed.

There are some potential loads that will require significant power input, for example some automatic bilge pumps (even if there is no water in the bilge). Solar is ideal for this power input, but even solar panels can be covered in snow or develop a fault.

[S/V Illusion]

Originally Posted by stormalong

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

Correct - this is a solution in search of a problem.

If this trivial draw is a concern, his battery bank isn’t adequate for the boat.

[Maine Sail]

The last stereo we installed for a customer, where this was a concern, was a Kenwood. The customer was overly concerned about the memory draw so I inserted our Fluke 289 into the circuit and the draw was 4mA or 0.004A

0.004A X 24 = 0.096 Ah Each Day
0.096 X 7 = 0.672 Ah Each Week
0.672 X 4 = 2.7Ah Each Month

If your house bank is in the range of 400Ah, actually pretty small these days on a 41 footer, this means that in an entire month your stereo memory will eat all of 0.675% of the banks Ah capacity.

If your stereo memory is causing your house bank to die you may want to consider a new hobby as your really not using your investment...

[freakytiki]

Yes.. on my Cal 35 I set up a separate battery and a solar panel. I listen to music for hours and hours so I wanted to be sure I never used my house or starter batteries. I added a small fuse panel with usb ports and use a small fan with it. Dont worry about anything

[Howler]

Thanks for all the great suggestions.

Leave it on and don’t worry seems to be the consensus!

[martinz]

Attached is the circuit diagram for a solution I built 5 or so years ago, and is still functioning as intended. The battery charges while the stereo is being used. The unit holds power to the radio memory (yellow wire) for about 3 weeks, then the protection unit in the 18650 cell cuts in to protect the cells. This unit retains the isolation from the house battery that the boat owner wanted to retain when boat is not in use.

This solves the problem discussed for up to 3 weeks.

It all sits in a black box with an orange LED to show when its charging.
I'm sure someone with more electronics experience could improve on this design.

[DameGravey]

I had the same concerns as the OP and while I rationalized that the stay alive radio draw on the batterries would be less than the LED that indicates that the auto bilge pumps are connected.
I fitted a low battery cut out switch set to just above 12 volts, https://www.jaycar.com.au/battery-discharge-protector/p/AA0262 if the batteries drop to the preset voltage the switch shuts down the radio. I know it's not needed, but it does help me sleep that little bit better.

[Stu Jackson]

Originally Posted by 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.

^^^


Just what I did. Four times with different stereos. BT now.


If running the wire is the OP's issue, or one of them at least, then he could run it to the 1-2-B switch (or his house bank on), which is simply the other end of the same wire to (i.e., from!) the battery. Done and it's already fused. This assumes the switch is closer than the battery for running the wire.


Good luck.

[Boatwright]

There is equipment on boats that needs power at all times:

The bilge pump is one.

Electronic device memory is another.

All circuits must of course be properly fused. The usual deal for the bilge pump is an inline AGC (glass) fuse holder, often a poorly made item of the sort that one finds at West Marine.

Do yourself a favor and get a quality ATC style fuse block. We use one directly connected to the battery for the bilge pump, radio memory, and solar input. The yellow wire (standard color for the always hot connection on most car radios) is the one you want.

Don't worry about the power draw on your radio memory it's around 1/4 AH per day or a year or two before it would drain your battery. The stories you hear about radios draining car batteries are due to weak starting batteries that are ready to give up on the first cold day anyway.

[Nicholson58]

Originally Posted by 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!

I wired in a 12 volt sealed lead acid rechargeable lantern battery with a diode. You could use a relay as a better way of isolating this battery from the house. The battery is always charged under way and isolated when the charging system is off. Plenty of power for the memory for months.

[hamburking]

Another approach would be to install a dedicated battery just for running the stereo. Does not need to be large, maybe a utility (lawn mower/motorcycle) battery. Then the switch on your DC panel is to recharge the dedicated battery, like when the engine is running. Maybe not what you wanted to hear, but I think a good solution.