Running a 12V VHF Radio off a 24V system?

[s/v Jedi]

So with other messages about 24V radios, better dc-dc converters etc., let me describe the ultimate setup, based on commercial requirements:

From your 24V house bank, install a Victron Smart Orion Isolated 24 -> 12 converter.

Connect the output to a small AGM battery, like this 35Ah one: https://www.amazon.com/dp/B00K8V2VD0

Configure the Orion to charge that AGM battery at all times.

That is all easy, now comes the hard part: connect the VHF radio to this battery, making sure that the negative stays isolated from the 24V negative. Take extra care with antenna selection and installation as many have metal parts that are grounded to the radio negative. Also take extra care when connecting NMEA etc. which may have shielding connected to negative.

When this is done, you have hardened your communications against transient surges on the power system caused by lightning storms or man made events near you. Also, when house battery power is lost, the radio keeps working.

You can extend this by bringing all electronics into this isolated system.

[s/v Jedi]

There were some comments about these converters being used at 100A capacity for a windlass, as well as questioning the likelihood of that actually working.

Well, this person posted that they have that and that it works for them, so why would one question that? Just for the sake of arguing? Also, it was being reported that these are not available in that high capacities. Well, Victron sells them up to 70A and these can be connected in parallel, but on Amazon you can easily find these at high capacities all the way up to 200A. See the options offered here: https://www.amazon.com/Cllena-Conver.../dp/B07RGLDX61
The point is that the cost of this has to be compared to the cost of a new motor for the windlass that takes 24V. I bought this one on Defender during a sale for a lot less than this price it is listed at now: https://www.defender.com/product.jsp?path=-1&id=2656373
Note that you still need 12V for the solenoid controls… unless you upgrade those to 24V as well, which can be a good idea when they are as old as mine were (30 years…)

[ForeverDes]

Originally Posted by s/v Jedi

There were some comments about these converters being used at 100A capacity for a windlass, as well as questioning the likelihood of that actually working.

Well, this person posted that they have that and that it works for them, so why would one question that? Just for the sake of arguing? Also, it was being reported that these are not available in that high capacities. Well, Victron sells them up to 70A and these can be connected in parallel, but on Amazon you can easily find these at high capacities all the way up to 200A. See the options offered here: https://www.amazon.com/Cllena-Conver.../dp/B07RGLDX61
The point is that the cost of this has to be compared to the cost of a new motor for the windlass that takes 24V. I bought this one on Defender during a sale for a lot less than this price it is listed at now: https://www.defender.com/product.jsp?path=-1&id=2656373
Note that you still need 12V for the solenoid controls… unless you upgrade those to 24V as well, which can be a good idea when they are as old as mine were (30 years…)

I looked into swapping my windlass motor for a 24v replacement. It was going to cost a LOT more, if it was even feasible. And void my warranty. (Not a huge consideration, I distrust warranties in general, but it was a factor).
I did a brand new install of my windlass (Lewmar 700) 3 seasons ago, and started using the buck transformer 2 seasons ago, when I changed to a 24v house bank 2 seasons ago, I honestly think it runs better. In theory, since the 12v leads are <1' long from the transformer to the windlass, there's practically no voltage drop. I do have oversize wire from my battery to the transformer, the same that used to directly power the windlass.

Of course, I haven't anchored in anything deep at all, so perhaps hauling 150' of rode in will overheat or overwork the transformer, but I doubt it.
BTW, all of my other 12v loads, including a vhf, have been handled by a 40 amp buck transformer for the last 2 years. No problems there, either.

[coopec43]

I knew I had read it somewhere (This excerpt comes from a Noonsite article).

If I have to install a DC-to-DC converter I want it to be powerful enough to be able to handle other electronic gear.

"Installation guidelines
• Be sure to use correctly sized power feed wires to serve the unit, especially in consideration of restricting voltage drop to a maximum of 3%. Based on ABYC E-11, you will need a minimum of 6 AWG (13 mm2) wire to supply power to a 12V SSB set over a 20-foot cable run.

• Adhere to voltage supply parameters. Most if not all SSB units operate at a nominal 12V. For a boat with a 24V or 32V system, you will need a DC-to-DC power converter. Over voltage supply to the transceiver will damage the unit quicker than you can snap your fingers! A typical l2V (nominal) SSB has a voltage operating range of 13.6VDC, ±15% maximum. Consider this 15% an absolute maximum because performance will definitely be affected if power falls below -15%."

https://www.noonsite.com/report/inst...-an-ssb-radio/

[Wotname]

Dunno how noonsite gets their 'facts' but it took me 30 seconds to find a 24V SSB...
I suspect there are others.
Icom GM800
https://www.icom-australia.com/produ...0_brochure.pdf

[Wotname]

Originally Posted by s/v Jedi

So with other messages about 24V radios, better dc-dc converters etc., let me describe the ultimate setup, based on commercial requirements:

From your 24V house bank, install a Victron Smart Orion Isolated 24 -> 12 converter.

Connect the output to a small AGM battery, like this 35Ah one: https://www.amazon.com/dp/B00K8V2VD0

Configure the Orion to charge that AGM battery at all times.

That is all easy, now comes the hard part: connect the VHF radio to this battery, making sure that the negative stays isolated from the 24V negative. Take extra care with antenna selection and installation as many have metal parts that are grounded to the radio negative. Also take extra care when connecting NMEA etc. which may have shielding connected to negative.

When this is done, you have hardened your communications against transient surges on the power system caused by lightning storms or man made events near you. Also, when house battery power is lost, the radio keeps working.

You can extend this by bringing all electronics into this isolated system.

If I was setting a 24V cruising boat and wanted to use 12V radios, I would do it like Jedi suggests and take note of the emphasised section.

[Uncle Bob]

Originally Posted by Wotname

If I was setting a 24V cruising boat and wanted to use 12V radios, I would do it like Jedi suggests and take note of the emphasised section.

Just a question re this suggestion, would it not be better to utilise this secondary circuit for all the nmea instruments as well as the radio, ensuring that all nav equipment is totally isolated from the 24v circuit, or is this not really advantageous?

[coopec43]

Originally Posted by Wotname

If I was setting a 24V cruising boat and wanted to use 12V radios, I would do it like Jedi suggests and take note of the emphasised section.

OMG! I can't handle this anymore.

Did you bother reading my comment #30?

[coopec43]

Originally Posted by Wotname

Dunno how noonsite gets their 'facts' but it took me 30 seconds to find a 24V SSB...
I suspect there are others.
Icom GM800
https://www.icom-australia.com/produ...0_brochure.pdf

Well aren't you clever?

The Icom GM800 is a 12V radio with a DC to DC Converter. If you don't believe me have a look at this below!

(I think you are saying if a radio works off 24V then it is a 24V radio. But I say it is most likely a 12V radio with a DC to DC Converter allowing it to run off 24V)

[goboatingnow]

I had a 24 v boat. I had 7 various capacities Dc dc converters for various 12v things , vhf , nmea2000 etc.

[coopec43]

Originally Posted by goboatingnow

I had a 24 v boat. I had 7 various capacities Dc dc converters for various 12v things , vhf , nmea2000 etc.

That is what I'm hoping to avoid.

All my engine instruments work on 12V or 24V so they aren't a problem. But what about depth sounders, radar, cameras, sound equipment, navigation equipment etc.

[goboatingnow]

Originally Posted by coopec43

That is what I'm hoping to avoid.

All my engine instruments work on 12V or 24V so they aren't a problem. But what about depth sounders, radar, cameras, sound equipment, navigation equipment etc.

The simplest is dedicated converters. Cheap easy to replace without major system shutdowns, no dedicated wiring looms or runs. Run the system voltage everywhere and convert as needed locally.

[coopec43]

Originally Posted by goboatingnow

The simplest is dedicated converters. Cheap easy to replace without major system shutdowns, no dedicated wiring looms or runs. Run the system voltage everywhere and convert as needed locally.

"The simplest is dedicated converters" That approach really appeals. Maybe that's the way to go?

I'm an adherent of the KISS (Keep it Simple Stupid) principle these days as I I've destroyed a $300 battery when I complicated everything by using 1/2/both switches. They have now been banned on my yacht (I'll carry a set of jumper leads instead!)

[Wotname]

Originally Posted by coopec43

Well aren't you clever?

The Icom GM800 is a 12V radio with a DC to DC Converter. If you don't believe me have a look at this below!

(I think you are saying if a radio works off 24V then it is a 24V radio. But I say it is most likely a 12V radio with a DC to DC Converter allowing it to run off 24V)

You might notice it says it has a 'build in DC DC convertor'. It is not possible for a user to make the GM8000 operate of 12 volts.

Now I dunno about being clever, I'm pretty sure I am not however I have managed over the years to repair all sorts of commercial, marine and aviation radios and whatnots to component level (back in the day when they had replaceable components) so I know my around a power supply. But don't take my word for it, ask Icom Australia, they are a friendly bunch and they will put you straight.

[goboatingnow]

Originally Posted by coopec43

"The simplest is dedicated converters" That approach really appeals. Maybe that's the way to go?

I'm an adherent of the KISS (Keep it Simple Stupid) principle these days as I I've destroyed a $300 battery when I complicated everything by using 1/2/both switches. They have now been banned on my yacht (I'll carry a set of jumper leads instead!)

It is , firstly it’s cost effective , doesn’t require separate 12v wiring runs from a centralised convertor and it’s redundant design, as a single failure doesn’t result in looking all 12v units.

It’s also easy to mount as the small dc dc unit converters can be often just mounted in the same enclosure as the 12v appliance or nearby.