[Amel Yacht Owners] Re: M801E HF/SSB Radio power Supply

Nick Newington

My only worry with using the engine starting battery for the Icom is the negative ground. 
The radio will be grounded  onto the plate located by the rudder and the power to the radio at the engine. 
Not sure what this implies.

On 17 Dec 2018, at 11:13, trifin@... [amelyachtowners] <amelyachtowners@...> wrote:


Hi Nick,
That’s great information. I’ve always hated trying to get that smoke back inside the box!

There are some isolated DCDC converters available which would produce 30A each, so like your system, two would be needed. I don’t much care for the faililure mode you describe. As you say it’s the high voltage that would have blown up the caps (probably electrolytic or tants), and probably some IC’s would not take kindly to overvoltsge, so the fuse would do nothing.
If the same thing happened with a 24V bank being connected via failed DCDC Convertor, to a 12V battery, the first thing that would happen is high current flow, and the fuse would do its job.
The other thing I don’t like about running two DCDC converters go directly power the Icom is the possibility for conducted emission harmonics to interfere with the RF signal. The converters will run switching in the hundreds of kHz, so it doesn’t take many harmonics to start interfering with the MF band.

Your story has lent weight to the the 12V battery based solution.

I could of course install a dedicated battery, and echo charger, but the engine battery is right there begging to be used. I’d change my engine battery to a deep cycle type, but other than that it’s a simple and elegant solution.

Hmm, where’s the gotcha?

SY Stella

Alan Leslie

The negative of the engine start battery is only connected to the bonding system during starting of either the main engine or the Onan  i.e. for seconds at a time.
I don't think that's an issue.
The more important issue is keeping that 12V battery charged up, if as you say you're going to pull 60A from it when you use the radio.
Elyse SM437