Power Supply for SSB in a 24v Boat

[Dockhead]

I am starting to plan installation of my newly acquired M802 SSB radio, and have a pretty good idea about all of it except -- the power supply.

This devices uses a massive amount of power when you're transmitting -- up to about 300 watts. It want 13.5v power.

The obvious first choice is a DC-DC regulated power supply powered from the house batteries. This will give a stable, clean power supply, BUT -- in this size range it's very expensive.

The other choice would be a dedicated gel battery, charged by a DC-DC charger off the house batteries.

The dedicated battery would actually not be more expensive (and maybe less) than the regulated power supply, and does have the advantage that it will be a backup supply in case of failure of the main electrical systems.

What do you radio experts think?

[ka4wja]

Dockhead,
This subject comes up once in a while, and there is a pretty good discussion about it on the SSCA disc board....

SSCA Forum • View topic - ICOM/FURUNO SSB 24 Volt Installation



I wondering if your "newly acquired" 12vdc M-802 can be returned/exchanged for a 24vdc model M-801e??? (or 24vdc Furuno FS-1570 / FS-2570???)

Originally Posted by Dockhead

I am starting to plan installation of my newly acquired M802 SSB radio, and have a pretty good idea about all of it except -- the power supply.

This devices uses a massive amount of power when you're transmitting -- up to about 300 watts. It want 13.5v power.

As, I would always recommend using the radio designed for the main house voltage first, and then only if that is not possible, proceed with alternative power supplies (12vdc battery bank, DC-DC converters, etc...)


I hope this helps...

John
s/v Annie Laurie

[Dockhead]

Still struggling with this. RFI free DC DC convertor? Or a dedicated battery? I've got 2 separate 12v banks on board - engine start and genset start, but those batts are pretty far away from where the SSB will be installed. At 12v that kind of power will demand very fat cables.

[ka4wja]

Dockhead,
I was not aware that you had an existing 12vdc system on-board....that makes things a bit easier....

But, if the rest of your boat is 24vdc, is there a reason you did not choose a 24vdc HF radio??? And, have you queried whether you can exchange your "newly acquired M-802" for a 24vdc M-801e???
Providing low-current 12vdc for small items (GPS, etc.) is not too big of a deal, but as you're finding out providing 30+ amps for an M-802 ain't easy...




I assume you read what I wrote in the other thread, but for clarification, in my opinion you have 4 options...

a) use a 24vdc HF radio (assume you can exchange your "newly acquired" 12vdc M-802 for a 24vdc M-801e or 24vdc Furuno FS-1570 or Sailor System 5000)....

b) use your "newly acquired M-802", with your existing 12vdc system, change/add adequate amount of 12vdc deep-cycle batteries (do not use "starting batteries") which WILL work for "starting" purposes.....provide adequate power wiring for the M-802....

c) use a dc-dc converter to allow you to power the M-802 from your 24vdc battery bank....

d) tie into your 24vdc battery bank, taking 12vdc from that bank....


In my opinion, option A is best....

But, if can't exchange the radio, then you've got the other options...

--Option B is do-able.....assuming you have an adequate way to sufficiently charge the 12vdc bank....
--But, in many circumstances, this will not be the case, and option C will become a better choice....
--Option D is a workable idea, but it will require you to monitor the batteries more closely, and probably switch battery cables around some every year, in order to keep your 24vdc bank equalized....

And, let me be clear here....if you cannot do option A, then all other options are a compromise, and you must make your decisions taking into account how you are going to provide sufficient power to the radio....how you are going to provide charging to the batteries (other than engine alt)....and how you are going to monitor your battery bank(s).....

All-in-all, the more you look at the situation the more you may find that option A is REALLY the best choice....but if unable to do so, option C is the way to go....
These are the less complex and more robust options....



If considering Option B....
I have no idea what type, model, size of batteries you current have for your existing 12vdc starting system, nor whether you have any charging system for them (other than an engine alt.) so I cannot comment on whether you have adequate 12vdc battery capacity, nor whether you have adequate charging capability for them if used as a "12vdc radio battery"....

But, in general the battery capacity can be small IF you have a continuous charging source available.....such as an "echo-charger" running from the 24vdc battery bank or a separate dedicated solar array just for the 12vdc batteries....(actually I'd recommend the "echo charger" arrangement, with your solar system charging the main 24vdc battery bank....)
If doing this, you'd probably be able to use a fairly small 12vdc battery bank, perhaps just one group 27 deep-cycle battery....

But, as you see here, even if using your 12vdc starting system you'd still need some sort of "dc-dc converter" / "echo-charger".....or alternatively you'd need to have a fairly decent sized 12vdc battery bank in order to reduce voltage drop under transmit.....

So, here you start to see why option A or option C, are the way to go....

I'm not saying that you cannot do either B or D, but they add complexity and complications that I'd not wish to recommend to anyone....




So, again Dockhead, not knowing how your boat is set-up, how your 12vdc system is set-up, etc....I cannot provide you with any exact recommendations, other than the above....

And again, if the rest of your boat is 24vdc is there a reason you did not choose a 24vdc HF radio????

Fair winds..

John
s/v Annie Laurie

[goboatingnow]

Shush John, Dockhead bought his in the states, hes sneaking it around the Hamble to avoid Ofcom or the RCA spotting him !!

dave

[Dockhead]

Originally Posted by goboatingnow

Shush John, Dockhead bought his in the states, hes sneaking it around the Hamble to avoid Ofcom or the RCA spotting him !!

dave

Heh, heh

Yes, Option A is the difference between about $5000 and, in my case, $1000 including antenna tuner and latest Pactor USB

I think using existing 12v banks is no good because of distance (probably 10 meter cables).

I don't want to 12v tap my 24v bank - I know it works, but I just hate the idea.

That leaves, I think:

1. DC-DC converter. IF I can find one with our RFI noise, this is the best option, I think.

OR

2. Separate battery charged by a 24v to 12v three stage charger like the Mastervolt Magic. I don't like this as much due to weight, space and complexity, but it is relatively cheap and should be noise-free. I have a place to put a battery box next to where the radio will be installed, but I would rather use the precious space for something else. Also, separate batt with charger will eat a lot more power.

[Zanshin]

I used a Newmar converter (Newmar’s DC-DC Converters – Standard Series – converts 20-50 VDC to 12 or 24 VDC for powering communication / navigation equipment, on negative ground systems. The standard DC to DC converters are ideal for powering voice, data and ) which was about $500 to convert the 24VDC to 12VDC for my ICOM SSB.

[Dockhead]

What about a small separate battery, continuously fed by something like this:

DC-DC Converter ? Model ST 240

This gives continuous 13.6 volts at up to 10 amps without noise. Would be enough to supply the radio when not transmitting, and would trickle charge the battery to replace charge lost when transmitting.

[Zanshin]

I think that you would, over time, ruin the 12V battery by using a DC-DC converter with fixed voltage rather than a battery charger. Think that the system will work, the battery will essentially be one big capacitor to regulate the current. A quick google looking for 12V chargers using 24VDC source rather than household current turned up no matches

[Dockhead]

Originally Posted by Zanshin

I think that you would, over time, ruin the 12V battery by using a DC-DC converter with fixed voltage rather than a battery charger. Think that the system will work, the battery will essentially be one big capacitor to regulate the current. A quick google looking for 12V chargers using 24VDC source rather than household current turned up no matches

I'm afraid of noise.

There are plenty of 24v battery chargers -- the Mastervolt "Magic" comes as a three-stage battery charger for 12v batteries, powered by a 24v source.

But it will probably be noisy.

I will of course, if I go this way, hook up a regular charger for when I have AC power, to do the regular charging and equalizing routines. I have a Newmar 12v charger on board already, which maintains my engine start battery, which has an unused second connection, which I could use.

The purpose of the unit I linked to is that it is a zero noise (claimed) power supply. It would supply all the power needed during receive operations, and the radio would dip into battery power only when transmitting. The noise-free 10 amp power supply would replace the power used when transmitting fairly quickly, so the battery would not get run down. For a good absorption charge to get the battery fully topped off, I would use the Newmar charger off shore or generator power (while not using the radio!).

I still don't like this as much as a real noise-free power supply. But it needs to be capable of 30 amps!! So far have not found such a beast.

[conachair]

Originally Posted by Dockhead

I
The purpose of the unit I linked to is that it is a zero noise (claimed) power supply.

You might need to be a little careful with that, it says clean power but doesn't mention airborne interference. Both my fridge and mains charger are noisy bugg$rs but it's all airborne, not down the power feed.

For batt/batt chargers, sterling seem to have a good following.

Sterling Power Products: Battery to Battery Chargers

Prob noisy as well though.

[Dockhead]

I have written to Samlex:

Home

Who apparently produce some Ham radio power supplies. Maybe they have something suitable.

I have been cruising ham radio forums, and apparently this is a bigger problem than I thought

This would be a good application for a small 12v lithium-ion or LiFePo battery -- no voltage drop. I could entirely shut off the charging source for lowest noise when needed.

[Dockhead]

It's obviously a really big challenge to get a clean power supply like this.

I read this on one ham forum:

"Off-Grid DC-DC Converters

Yes, Neil, thought that I placed FILTERING in the post, before shielding. Was a quick post. Sorry.

YES, Common-Mode filtering should be placed on the input and output of the converter. My recent experience is that almost all of the RFI from switching devices is line-conducted. These emissions then radiate into the antenna(s) from the leads connecting the switching device. This often means that shielding of the interconnects can be very effective. If possible, try using type 31 Ferrite material for HF frequencies. Generally, the lower bands are those most affected. And if necessary, place a common-mode choke on any coax feedlines. Avoid open wire antenna feedlines if possible.

Manufacturers often omit the RFI filtering from their switching devices, as the materails in the filter are expensive, and often slightly reduce the efficiency of the device. Some use filtering to get emissions compliance, and then omit the filters in production to save $$.

Suppose that the OP should contact the manufacturer(s) of the subject device regarding the emissions compliance if any. Then buy the unit and test it. Then do any/all things needed to make the system work. Some switching devices have such HORRIBLE emissions that suppression by mortal persons is very difficult.

At my comm site, have tried to do as much shielding as possible, as it is more difficult to do after construction is complete, and have tried to do the best job on filtering as I can. It is all experimental. The MPPT CC's are difficult as the PV array interconnects twix each solar cell are also antennas, and I have made no effort to shield each of my solar panels -- there are limits.

Good Luck, and any results would be of general interest."

Off-Grid DC-DC Converters - Page 2

Argh, I really didn't know I was getting into something so fiddly . . .

[Dockhead]

In view of all these complications, starting to think again about long fat cables from my generator start battery . . .

I have a "leisure" battery there now, not a regular starting battery, a big 110amp/hour one. I can easily put in a DC/DC charger to supply power to it fro the 24v house system.

The cable run is a PITA but compared to all these other problems . . .

Plus with nothing else running on that circuit, it should be much easier to control noise.

[Nicholson58]

Originally Posted by Dockhead

Still struggling with this. RFI free DC DC convertor? Or a dedicated battery? I've got 2 separate 12v banks on board - engine start and genset start, but those batts are pretty far away from where the SSB will be installed. At 12v that kind of power will demand very fat cables.

Perhaps you might consider operating the SSB off the engine start battery and plan to run the engine while using the SSB. This might be logical since it uses so much power.

On our boat, the SSB is 30 volts. The boat is 24. We have one of those expensive DC-DC devices but it was there when we bought the boat. I have located this supplier that might interest you. Murata Power Solutions | DC-DC Converter, AC-DC Power Supply, Digital Panel Meter, Inductor, Common Mode Choke and Pulse Transformer | Murata Power Solutions