Stereo memory wire to hot bus

[ualpow]

One of my spring projects will be installing my new stereo. I have been reading this and other forums about current draw and couldn't find a definitive answer about draining the battery. I ran different combinations of the red (power), yellow (memory) and RF remote power wires through my ammeter and here are the results.
All three connected with stereo on=.91 A
All three connected stereo off=.79 A
Red + Yellow, stereo off =.75 A
RF + Yellow, stereo off =44.8 mA
Yellow only, stereo off = 12.9 mA
No wonder the people on the other forums were draining their batteries. The general consensus was to wire the red and yellow wires together to the battery and just turn off the radio to kill power.
So my red and RF remote power wires will be on my switch panel but I'm not sure about the yellow memory wire.
I can wire it with the rest to the panel and re-set my presets, bass, treble etc each time I turn on the stereo.
I can also wire the yellow wire the the hot battery bus and live with the 12.9mA current draw. I wonder how long that would take to discharge my everstart maxx-29 battery?
I guess I could always rip apart one of my solar walkway lights and use that to run the memory circuit....

[yukonbob]

You've got a stereo in your car/truck right? You don't have to jump it after it sits for a month do you? Just make sure to put it a main power kill switch (on panel or by stereo like mine) kinda like the ignition in your car, and have the mem on continuos feed so you don't have to reset each time. Unless you're constantly powering the internal (or external) amp (stereo powered but 'off' still powers the amp thats why it gets warm) it won't really draw anything for power.

[seahouse]

Hey ualpow!

I don’t know exactly what the number is, but assuming your battery is average at 70 amp-hour (they’re higher at lower drain rates), your time to fully drain would be 70/.0129= 5,400hrs or 226 days on the yellow wire.

But you don’t want to fall below 50% depth of discharge on your battery, assuming it’s a deep cycle (less if it’s a starting battery) so you would reach that after 113 days, or 3 – 4 months. Tolerable, especially if you visit your boat once every week or two.

I was going to suggest simply connecting a 9V battery to it for the memory, but the power draw is too much for that. That amount of draw for the memory alone actually surprises me - it's likely not Energy Star rated?

You would need about 8 of your solar walkway lights just to get the voltage you need, and assuming 1amp-hour for them, idealy you would get about 3 day’s memory power on a full charge out of them. Around here, and in practice, those solar lights don’t often get fully charged, though.

-Brian.

[ualpow]

Thanks for the replies. I thought something was fishy on the other forum when guys were draining their batteries. I just didn't think it would draw that much on the power wire when off! So memory wire and bildge pump to the hot battery bus it is. (fused of course)

[Russ]

You've got a stereo in your car/truck right? You don't have to jump it after it sits for a month do you?

Exactly. Drain is teeny for memory.

There are many places where batteries are drained from leaking power, but I doubt it is from radio/clock memory circuits.

[mastreb]

You could install a 5 watt solar trickle charger that will keep your battery topped off including powering your memory wire. It'll keep any minor (<200ma) parasitic loads from killing your battery, and is likely the cheapest way to prevent deep discharge.

[Uncle Jim]

Thanks for the replies. I thought something was fishy on the other forum when guys were draining their batteries. I just didn't think it would draw that much on the power wire when off! So memory wire and bildge pump to the hot battery bus it is. (fused of course)

Looks like your compairing apples and oranges here, or Amps and MilliAmps. Big difference.

All three connected with stereo on=.91 A
All three connected stereo off=.79 A
Red + Yellow, stereo off =.75 A
RF + Yellow, stereo off =44.8 mA
Yellow only, stereo off = 12.9 mA

12.9mA is 0.129A and 0.91A is 910.mAthe yellow memoy wire draw is very small

[ualpow]

I wasn't confused about milliamps and amps. I was just surprised that so much current would flow on the power wire with the stereo off. .91A with stereo running and .79A with stereo off seemed odd to me.

[Catigale]

I think that your .79 amp with the stereo off is too high. That will drain a group 24 battery to 50% in about 2 days.

Are you catching the right scale on your ammeter? Make and model?

[yukonbob]

It sounds right. If your in your vehicle with the ignition on you can turn the deck off but it is still powered (mostly the amp and a little for the display) when you turn the ignition off only the memory is powered. This is the same reason you have to have the key in the on position or the engine on in order to turn you car stereo on and why your presets are still available every time you start your car. Wire the main power through the panel or another on off switch

[Crikey]

I think that your .79 amp with the stereo off is too high. That will drain a group 24 battery to 50% in about 2 days.

Are you catching the right scale on your ammeter? Make and model?

Unless it runs the subwoofer channel on the 'tremor' setting to keep the coils heated up, and the overall hysteris drain low.

The drain for maintaining a ROM memory should be close to negligible. Some systems power displays as well as station and settings memory, which could be the problem with this particular model.

[ualpow]

Ok sorry for the delay. Grabbed my true RMS meter from work and here are the reading all in amps.
Memory wire only is .013A
When I add the red power wire (which is supposed to be a 12v switched wire) some of the faceplate lights up and it pulls .772A. Like yukonbob said, it must be powering the amp circuit as well.
When I turn on the stereo with volume all the way down it pulls .902A
Bottom line is, wire it how the manual says. The guys on the other forum were having problems because they assumed that with the stereo off the only thing drawing power was the memory circuit.

[Catigale]

Thanks. Now I remember why my stereo is on a power switch!!!