Keeping FM radio stations coded

CPD

CPD

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I want to be ablke to walk away from the boat with all the batteries isolated and am thinking of ways (perhaps a very small battery with small solar panel perhaps) to keep the programmes in the unit. Its a small job to find them when I get on board, but I would rather have a better solution. Any ideas ?
 
But I might not visit the boat for weeks on end, and desopite the minimal amp draw, its a principle thing.
 
Your radio should have a separate 'permanent live' feed for this purpose, the current drawn by this is very small, no harm in measuring it, but its probably much less than the batteries lose by self discharge anyway. A fuse is a good idea.
 
If you are concerned with discharge, which can be large over time, it would be simple to add one of those solar trickle charge jobbies from argos or maplin etc.

I have my bilge pumps, radio on 24hr, but then I have 100A of solar and a wind gen. I did leave an old digital (not DaB) radio on for memory retention before self charging and did flatten a battery after leaving for 3 weeks.
 
If it's anything like mine, the unit will draw most of the operating current from the 'permanent' (yellow) wire when in use. The 'ignition' (red) connection is just used to sense the ignition is on. So you will need some kind of diode logic if you provide an alternative standby power source.

Figures from my book of tedious facts:
The standby current (yellow) is 10mA but this increases to 0.25A when the 'red' connection is on even if the unit is turned off! Playing a CD it uses around 1.25A.

Why don't they spend an extra 2p on non-volatile memory? You don't have to retune your TV when you unplug it!
 
[ QUOTE ]
Your radio should have a separate 'permanent live' feed for this purpose, the current drawn by this is very small, no harm in measuring it, but its probably much less than the batteries lose by self discharge anyway. A fuse is a good idea.

[/ QUOTE ]

Yes ... that is what I referred to ..........
 
I have a car radio from an M reg Honda installed in the boat. It is unpowered when the battery is switched off, but it still remembers the station presets.
How does that work ?
 
The trickle feed to the radio will discharge even a large battery in the end. On principle I have everything isolated when I leave the boat. However there is a solution.

I use a small Yuasa gel-cell burglar-alarm battery to power up the radio when everything else is off. A couple of diodes stop the radio battery discharging into the main system, but when the main system is switched on and the engine is running the Yuasa gets charged. The Yuasa can run the whole radio if necessary without hooking up the main batts if you are on a brief visit to the boat. A 4.7 ohms resistor is necessary to limit any surge current if the battery ever does get really low. I fitted this two years ago and it has worked faultlessly ever since.

Regards, Mudhook
 
Re: Keeping FM radio stations coded(re Dylan)

The early push button presets physically moved the tuning selector when pressed (rather than tuning electrically) - if yours is one of these then it probably requires a hefty push to select (and can miss if you do not push in all the way) - Perhaps yours is one of these?
 
Re: Keeping FM radio stations coded(re Dylan)

No it's electronic not mechanical. Perhaps it's like a TV or has a very long lasting internal battery.
 
Re: Keeping FM radio stations coded(re Dylan)

[ QUOTE ]
No it's electronic not mechanical. Perhaps it's like a TV or has a very long lasting internal battery.

[/ QUOTE ]
Same principal as a USB memory stick. Bits are store as an infinitesimally small charge on a semiconductor junction.
 
Re: Keeping FM radio stations coded(re Dylan)

[ QUOTE ]
[ QUOTE ]
No it's electronic not mechanical. Perhaps it's like a TV or has a very long lasting internal battery.

[/ QUOTE ]
Same principal as a USB memory stick. Bits are store as an infinitesimally small charge on a semiconductor junction.

[/ QUOTE ]

Damned clever, these Japanese /forums/images/graemlins/smile.gif
 
Hi

It might be worth measuring what it actually takes for standby power with a multimeter. My bet is that it will be something pretty miniscule and not really worth worrying about in the overall scheme of things (all batteries have self discharge anyway eg 3% per month), so just connect it to the main battery (eg if taking 1mA or less).

Whether to have a solar cell is then kind of a seperate decision, and if you do, you might as well have a reasonably big one (with a regulator) rather than just something that covers this radio discharge.

Of course this assumes that the measured current draw is small. But then if its bigger eg 50mA I'd be tempted to say its not worth powering the thing up for months on end to keep the memory anyway; considering that it then needs a reasonably decent solar cell and battery capacity....so then the solution is to use the boat more often /forums/images/graemlins/wink.gif or disconnect it....

Just my thoughts anway

Chris
 
Computer motherboards have always had the same problem. Their silver alloy cells last several years, so you may have to connect several in series to get the required voltage, They recharge when the radio is on, but should give you six months without charge
 
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