WHAT SIZE 12V RADIO BATTERY?

[Pelagic]

Star Gazer is all 24v except for Generator Start and a few 12v Furuno instruments and Radio.

Present system is one large 260ah 8D AGM that serves both.

I am going to replace with smaller individual batteries.
Start for Gen
Small Deep Cycle for Radio

Radio Battery supplied by new
Victron Orion TR DC/DC CONVERTOR 24/12 -30amp

You can see by board that the stereo with 4 speakers is probably the biggest draw.
What size and type of small reserve battery should I go with?


Datasheet-Orion-Tr-DC-DC-converters-isolated-100-250-400W-EN.pdf

[smac999]

If the dc to dc is always running. (As opossed to being charge voltage triggered). Then the size will not mater. As you would have the full size of the house bank (down to under 20v) to power the 12v. The battery is just a buffer. A little 10ah would be fine.

If you want more backup power if the house bank or dc to dc failed. Then you could go to a group 24, 27, 31. Etc. Depends how long you’d want it to last under a house bank failure.


Edit: Just noticed the ssb. In that case you need a bigger battery as the 30a dc to dc would not keep up. I’d say group 31. The ssb is the biggest draw. Not the stereo.

[Pelagic]

Originally Posted by smac999

If the dc to dc is always running. (As opossed to being charge voltage triggered). Then the size will not mater. As you would have the full size of the house bank (down to under 20v) to power the 12v. The battery is just a buffer. A little 10ah would be fine.

If you want more backup power if the house bank or dc to dc failed. Then you could go to a group 24, 27, 31. Etc. Depends how long you’d want it to last under a house bank failure.


Edit: Just noticed the ssb. In that case you need a bigger battery as the 30a dc to dc would not keep up. I’d say group 31. The ssb is the biggest draw. Not the stereo.

Yes, I had almost forgotten the SSB, since I doubt (hope) I never have to use it

[deblen]

In the olden days,to ensure that 12V was always available to VHF/SSB-


I supplied the radios with 12V from a 24V-12V converter via a 12V sub dist. pnl.


I also tapped the 24V bat bank @ 12V & fed this emerg 12V source to the 12V sub dist pnl via a "Emerg 12V Bat" switch.
No harm was done to the tapped bank,since that tap was never drawn from.


Cheers/ Len

[Bycrick]

The 30 amp power draw for the radio is PEAK power. Standby and receive draw is about 5 amps. For voice SSB, the duty cycle ir relatively low, probably less than 20%. For Pactor it will much higher. But a 100Ah battery (with DoD 50%) should run the radio for 3-5 hours of receive or a couple of hours of voice transmit. Add a 20-30 amp dc-dc charger to the feed and it will keep running indefinitely.

[Manateeman]

Hi. On some commercial vessels they is a battery dedicated for vhf /medical phone emergencies high up in the vessel so they can have a radio in case of flooding or fire. The captain has a good view of the aft deck and rescue boat
Sometimes an inexpensive GPS as well. Some of the wheel houses sit very high up. The thinking being that the vessel can keep radio contact or give position until abandon ship.
Mark

[Pelagic]

Originally Posted by Bycrick

The 30 amp power draw for the radio is PEAK power. Standby and receive draw is about 5 amps. For voice SSB, the duty cycle ir relatively low, probably less than 20%. For Pactor it will much higher. But a 100Ah battery (with DoD 50%) should run the radio for 3-5 hours of receive or a couple of hours of voice transmit. Add a 20-30 amp dc-dc charger to the feed and it will keep running indefinitely.

Thanks, I was about to look that up
The Orion 24/12 DC- DC converter I just bought for this purpose is 30a (360W)

https://www.victronenergy.com/dc-dc-...rters-isolated

[Bycrick]

I took a quick look at the Orión stuff. They seem to have both a 24-12 voltage converter and a different 24-12 battery charger. At first glance, I’d think you would want the latter one as rage converter will never raise the voltage high enough to charge properly.

[tkeithlu]

I second Manateeman, despite the totally unfounded and surrilous rumors that he has been bopping manatees on the side. I never believed that he is actually overcompensating for his compulsion to bop manatees by posing as their protector.

Realizing that my house bank of six size 27s is in the spot most likely to flood first, I added a size 24 behind the instrument panel. It normally is in parrallel with the house set, so it stays charged, but can be isolated to power the instrument panel and radios with an ordinary 1,2,both rotary switch.

[roland stockham]

SSB tends to be pretty sensitive to voltage drop, even .5v will significantly reduce range so I would want to be well within the continuous draw range, i.e. 4hr rate so 120a/hr. This is one place where AGM could be a good solution. As it is permanently connected to the 24/12v converter there are no problems with charging or dissimilar batteries and it can be located right next to the radio in any orientation. A better solution that may actually be cheaper would be Lithium. A plug in self contained lithium system would be able to supply enough power with minimal voltage drop so you could use a smaller battery. 100a/hr should give a couple of hrs transmit time at full power in an emergency.

[Pelagic]

Originally Posted by Bycrick

I took a quick look at the Orión stuff. They seem to have both a 24-12 voltage converter and a different 24-12 battery charger. At first glance, I’d think you would want the latter one as rage converter will never raise the voltage high enough to charge properly.

Voltage can be adjusted by 35%

English

Orion-Tr DC-DC converters, isolated


4. Adjustable output voltage:

The default values are 12,2V, 24,2V or 48,2V, depending on the model.

The output voltage can be set between approximately- 15% to + 25% of the default output voltage by turning the potentiometer.

Turn counter clockwise to decrease the output voltage.

Turn clockwise to increase the output voltage.

5. The output is overload and short circuit proof.

The converters can therefore be connected in parallel, and can be used to float-charge a battery.(always adjust the output voltage before

connecting in parallel or connecting a battery)

6. Connect the load. The converter is now ready for use.

[Bycrick]

My question about a "voltage converter" vs a "battery charger" version of the Orion was based on how one views the battery. At least in theory, the voltage converter will put a fixed voltage across the battery at all times, regardless of load or state-of-charge, while the battery charger will cut back the voltage when there’s no load and the battery is fully charged. So, I would think that from a system design point, your choice would be based on some questions like:
1. Is the battery designed to operate the radio for "long periods" without external power? That would imply a bigger battery with more need for a higher charging voltage when the battery was at lower SOC.
2. Is the converter turned on all the time, or only when the radio is in use? This would imply a smaller battery, but leaving it on charge with a fixed voltage and no monitoring is eventually going to damage the battery.

[Pelagic]

Originally Posted by roland stockham

SSB tends to be pretty sensitive to voltage drop, even .5v will significantly reduce range so I would want to be well within the continuous draw range, i.e. 4hr rate so 120a/hr. This is one place where AGM could be a good solution. As it is permanently connected to the 24/12v converter there are no problems with charging or dissimilar batteries and it can be located right next to the radio in any orientation. A better solution that may actually be cheaper would be Lithium. A plug in self contained lithium system would be able to supply enough power with minimal voltage drop so you could use a smaller battery. 100a/hr should give a couple of hrs transmit time at full power in an emergency.

I plan on placing this Fullriver 105Ah deep cycle AGM in my electrical locker, right beside the Orion and the 12v breaker panel
With 780 Ah @ 24v or 1560Ah @ 12v the draw will be insignificant and thus Orion has adjustable output voltage

[Pelagic]

Originally Posted by Bycrick

My question about a "voltage converter" vs a "battery charger" version of the Orion was based on how one views the battery. At least in theory, the voltage converter will put a fixed voltage across the battery at all times, regardless of load or state-of-charge, while the battery charger will cut back the voltage when there’s no load and the battery is fully charged. So, I would think that from a system design point, your choice would be based on some questions like:
1. Is the battery designed to operate the radio for "long periods" without external power? That would imply a bigger battery with more need for a higher charging voltage when the battery was at lower SOC.
2. Is the converter turned on all the time, or only when the radio is in use? This would imply a smaller battery, but leaving it on charge with a fixed voltage and no monitoring is eventually going to damage the battery.

Good points and I will clarify with the supplier who recommended the Orion Converter over the Charger...thanks!
Still not unboxed

If this 12v radio AGM is maintained at recomnended Float voltage via the Orion, will that damage the battery?
I can understand if over or under charged, don't understand if it is kept at float via a 30w output from the orion

[rslifkin]

If it's kept at float voltage all the time, that shouldn't hurt the battery. And if it does get discharged some, it'll recharge at float voltage, it'll just take longer to charge vs a proper 3 stage charger. As long as it's not getting cycled regularly, it shouldn't be an issue.

In this application, it sounds like the battery is just being used as a giant capacitor and emergency backup power.