Ensuring Stable 12v DC

[sv.BlueLagoon]

I am remolding my boat and will start on my electrical system soon. I am leaning towards a 12 DC boat. Meaning terminate my shore power / AC Generator / Solar / Wind ..etc at the batter charger. My 120 V AC would run through a DC / AC Converter. The question is whether I should use a buck converter or DC / DC converter that would stabilize my 12v DC output. I am just wondering if it's worth the investment?

Cheers,

[ccannan]

It depends on your 12vdc equipment sensitivity. Most 12vdc equipment will happily accept from 14v to 11v. Each device has its electrical requirements listed on it, and in its' manual.

BTW, a common name for a DC to AC converter is inverter.

[Privilege]

..and you will need different chargers; one for your A/C, one for your solar and one for your wind.

[travellerw]

Originally Posted by sv.BlueLagoon

I am remolding my boat and will start on my electrical system soon. I am leaning towards a 12 DC boat. Meaning terminate my shore power / AC Generator / Solar / Wind ..etc at the batter charger. My 120 V AC would run through a DC / AC Converter. The question is whether I should use a buck converter or DC / DC converter that would stabilize my 12v DC output. I am just wondering if it's worth the investment?

Cheers,

Personally I think a DC/DC converter is a waste of money and power. Pretty much all devices on our boat are tolerant from 11-16V. A DC/DC converter doesn't really offer any benefits. I guess the only real benefit I could see is surge supression.

I wouldn't bother with it. Instead put the money into quality connectors, wires and terminal blocks. Thats a much better investment.

[Viking Sailor]

One exception is the Ham radio transceiver. These units are much happier when powered by 13.8 volts from a car alternator/battery system.

[Colin A]

Originally Posted by Viking Sailor

One exception is the Ham radio transceiver. These units are much happier when powered by 13.8 volts from a car alternator/battery system.

Yep Radio equipment tends to prefer a more stable power source. Certain electronics as well. But for 90% of boat stuff kind of a non issue.

[Bean Counter]

If you have big electric winches, the power draw can be high enough to temporarily drop voltage down to instruments below their cutoff and so they switch off and then reboot. Particularly disconcerting when using your radar in fog or driving rain, all of a sudden you can't see anything for a couple of minutes. This can happen if batteries have been run down when sailing all night. We installed a Victron DC ~DC stabilizer (Orion isolated 18 amp - $116) that powers all the electronics and radar and have not had a problem since.

[travellerw]

Now I don't know anything about HAM radios, but I really doubt the new generations would work any better on higher voltage. Modern radios would be designed with a stable power supply built in and should operate exactly the same on any voltage listed in thier range. That would also hold true for any electronics. As long as you aren't running electronics from the 80s, they will operate exactly the same on 11 - 16V.

The only modern device on a sailboat that may benefit would be the windlass or an electric winch. They do operate better when the voltage is higher, BUT, you would need a hell of a DC/DC converter to run them (with probably %10 loss to heat).

[hellosailor]

Most "12" volt gear is designed for a specific range, often "13.8 volts plus or minus ten percent" and often it is expected to run from 14.4 volts (the maximum output from an automotive alternator) down to around 11.5 volts, that being a dead 12 volt battery.

Aside from radio transmitters sometimes getting unstable at 11.5 volts or less, and cheap LED lights or filament bulbs varying in brightness with voltage changes, I can't think of what on your boat would care about "stabilized" DC. There are a lot of FUD "stabilizers" sold to the car audio crowd but they are mainly pointless. Especially if you take care of your batteries and voltage drops in the wiring.

[smac999]

that is what a battery is for.... it goes between the AC charger and the DC loads...

[S/V Illusion]

Originally Posted by travellerw

Now I don't know anything about HAM radios, but I really doubt the new generations would work any better on higher voltage. Modern radios would be designed with a stable power supply built in and should operate exactly the same on any voltage listed in thier range. That would also hold true for any electronics. As long as you aren't running electronics from the 80s, they will operate exactly the same on 11 - 16V.

The only modern device on a sailboat that may benefit would be the windlass or an electric winch. They do operate better when the voltage is higher, BUT, you would need a hell of a DC/DC converter to run them (with probably %10 loss to heat).

Actually, most radios ( ham or marine) have no power supply but rather depend on external power. If unregulated, they behave poorly below 13 volts. The same is true of other electronics, most commonly autopilots which are unreliable with lower voltage.

A reasonable (read - cheap) alternative to whole boat converters is single unit voltage stabilizers which have the added advantage of supplying a selectable output voltage regardless of supply voltage such that a 12 v source can be raised to 13+ where necessary.

[travellerw]

Originally Posted by S/V Illusion

Actually, most radios ( ham or marine) have no power supply but rather depend on external power. If unregulated, they behave poorly below 13 volts. The same is true of other electronics, most commonly autopilots which are unreliable with lower voltage.

A reasonable (read - cheap) alternative to whole boat converters is single unit voltage stabilizers which have the added advantage of supplying a selectable output voltage regardless of supply voltage such that a 12 v source can be raised to 13+ where necessary.

Hmmm.. News to me.. Both my VHF (pretty sure that is considered marine) and autopilot that died during our lightening strike had built-in power circuits. Since I have an EE background I took both apart to discover the damage and see if they could be repaired. I will agree to disagree with you..

However... Yes autopilots can perform poorly below 12.4V since they usually have a large electric motor used for moving the rudder (either as an actuator, or a pump for the hydraulics). The electronics, however do not care if the voltage is 12V or 15V.

[hellosailor]

" If unregulated, they behave poorly below 13 volts."
And you are basing that on what?

The radios I have worked with, documented by their manuals, usually say 13.8 volts plus or minus either 10% or a more generous 15%.

So for the one it is 12.42 volts minimum, for the other 11.73 volts. And if the ship' s battery is down to 11.73 volts, that's effectively a dead battery anyway. Some, like the old Drake radios, were actually quite happy at twelve and below. Others, including some popular Icom's, are notorious for misbehaving at "twelve". (Which is still a 60% discharged 12-volt battery.)

It is one thing to run a voltage booster when and if the battery bank is down, quite another to need it all the time.

[travellerw]

Originally Posted by hellosailor

" If unregulated, they behave poorly below 13 volts."
And you are basing that on what?

The radios I have worked with, documented by their manuals, usually say 13.8 volts plus or minus either 10% or a more generous 15%.

So for the one it is 12.42 volts minimum, for the other 11.73 volts. And if the ship' s battery is down to 11.73 volts, that's effectively a dead battery anyway. Some, like the old Drake radios, were actually quite happy at twelve and below. Others, including some popular Icom's, are notorious for misbehaving at "twelve". (Which is still a 60% discharged 12-volt battery.)

It is one thing to run a voltage booster when and if the battery bank is down, quite another to need it all the time.

Sometimes I really wished CF had a "LIKE" button!

[john61ct]

Deal with the root cause, not bandaging symptoms.

If big loads are pulling your voltage that low, you should probably get your genny fired up beforehand.

Or get a bigger bank, or go to LFP.