Boat Stereo Memory Supply

[Andrew_Trayfoot]

I have just replaced my car radio cassette with a new Bluetooth FM radio/Media player.

http://www.ebay.co.uk/itm/300757580357?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649


It was a straight swap out as both the old and new units have the same standard plug. Am very pleased with it.

On the old unit I just wired the memory feed in with the switch supply and lived with the fact that it lost the programmed stations – I can remember the frequency for R4!

As the new unit is Bluetooth it needs to remember the paring to my Android tablet (with Navionics – fantastic!), or Windows Phone with all the music on….

So I was thinking how I could provide a supply to the memory circuit without connecting it to the main battery bank. I am loathed to do this as I have a policy of no permanent drain on the battery which has served me well for 15 years.

So the options I have thought of:

• A bank of 8 NMiH Batters in a holder with a diode to block them from discharging into the main system. Take home once in a while to charge.
• As above but use an Alarm battery from CPC/Maplin etc
• Use a caravan split charge relay to charge one of the above when the engine is running.

I already have a relay controlled only on with the engine supply near bay that powers the electric cool box.

Any ideas?
Andrew

 

[pvb]

So I was thinking how I could provide a supply to the memory circuit without connecting it to the main battery bank. I am loathed to do this as I have a policy of no permanent drain on the battery which has served me well for 15 years.

The memory circuit current drain is minimal, maybe 10mA, so there should be no worries about it flattening your battery. A permanent live feed from the battery must of course be fused as close to the battery as possible.

 

[elton]

The memory circuit current drain is minimal, maybe 10mA, so there should be no worries about it flattening your battery. A permanent live feed from the battery must of course be fused as close to the battery as possible.

As above.

 

[Cardo]

Many modern radios have a built-in battery rather than require a permanent feed to maintain memory.
Have you tried it to see if the memory sticks after switching off the power?

 

[makingplansfor]

Many modern radios have a built-in battery rather than require a permanent feed to maintain memory.
Have you tried it to see if the memory sticks after switching off the power?

+1

I have just installed a Sony Bluetooth Radio and it remembers the pairing information after removing power.

 

[nigelmercier]

Many modern radios have a built-in battery rather than require a permanent feed to maintain memory.
Have you tried it to see if the memory sticks after switching off the power?

Note that if so, you may need to leave it powered for a few days first.

I've often considered having a small SLA 12V battery mounted up high to act as an backup for the VHF, so this may be an option. Charging it via a resistor and a diode should be sufficient.

 

[FWB]

Many modern radios have a built-in battery rather than require a permanent feed to maintain memory.

I always wondered how the car radio in the boat kept its memory ! Now I know thanks

 

[prv]

I always wondered how the car radio in the boat kept its memory ! Now I know thanks

May well not be an internal battery - after all, the memory cards you use in your camera don't have a little battery in them either. There are solid-state storage technologies now that don't need to be supplied with power to remember their data.

The outward effect is identical, of course

Pete

 

[William_H]

If indeed you are considering a small battery for stereo memory power then I would recommend 10x NiMh batteries (not 8) they are basically 1,2 volts each. I found that sub C size give the most AH for the money. (6AH) Get the type with tags and solder together. (from China) This could be charged by a diode and resistor of about 100 ohms to give a few milliamps charge from the circuit that is on when charging. Check the current into the NiMH around 50 ma I think would be good and should recharge battery depending on charge time versus discharge time into radio. increase charge current up to 600ma in necessary
However if you have a big battery bank then a permanent connection is least trouble. good luck olewill

 

[nimbusgb]

Decent car radios will use flash memory to hold configuration data and should not need standby power.

I have a blaupunkt unit with bluetooth and other stuff but the unit draws almost 200ma! on standby. Its being replaced.

 

[Ex-SolentBoy]

My new stereo, a Clarion one, remembers everything and it definitely has no permanent power source.

 

[Cardo]

May well not be an internal battery - after all, the memory cards you use in your camera don't have a little battery in them either. There are solid-state storage technologies now that don't need to be supplied with power to remember their data.

The outward effect is identical, of course

Pete

Good point. I guess I'm going back a few years when car stereos with backup memory batteries were all the "rage". Seeing as how flash memory is now so cheap, I'd be surprised if this isn't what's going on, these days.

I've had a read of my Fusion's manual, but it doesn't say what it uses. Needless to say, it does remember the settings even after months of sitting without power.

 

[sailorman]

that`s what we have also the nasa navtex is permanently on as is the auto bilge pump sensor

The memory circuit current drain is minimal, maybe 10mA, so there should be no worries about it flattening your battery. A permanent live feed from the battery must of course be fused as close to the battery as possible.

 

[Cardo]

that`s what we have also the nasa navtex is permanently on as is the auto bilge pump sensor

But not the bilge pump itself? Why?

 

[chrisbitz]

I wonder if a simple 9v battery might be enough? I don't think the internal circuits actually work on 12v, aren't they stepped down to more like 5v internally anyway?

Don't know how long a 9v would last though, but it would be a lot simpler than 10 batteries in a block!

 

[nigelmercier]

Don't know how long a 9v would last though, but it would be a lot simpler than 10 batteries in a block!

As would an SLA.

 

[William_H]

As would an SLA.

I have gone right off small SLA batteries compared to NiMH. Mainly because the NiMH are far more robust in the face of abuse. Especially if you completely discharge the batteries. I found also that 6 x Sub C at 6AH are far cheaper than a small SLA. Not any reall difficulty soldering the tags together. olewill

 

[readings]

My new stereo, a Clarion one, remembers everything and it definitely has no permanent power source.

Hmmm, Clarion sounds like a good solution. Do you have the model number pls?

 

[Rigger Mortice]

Personally I would just wire the memory line to the main battery but, if I went the separate battery route I would go for one of these; http://www.ebay.co.uk/itm/230819766...AX:IT&_trksid=p3984.m1438.l2649#ht_5324wt_904. At nearly 10AH it would last a fair time.