Critical DC components not available in 12v / 24v

[Bruce K]

If I was to new built or completely redo electrics it would most certainly be in 24v. Avoid dual 12/24v systems!!!!!!

[Manateeman]

Hi. We run 24 volt house and 12 for gen set starter and a few electronics. In both the military and commercial sectors, 24 volt is very common...almost the norm. Never found the need for voltage converter. We keep a small 12 volt system seperate. For larger vessels, 24 volt is simply more economical. In addition, you can find excellent prices for new military surplus equipment in 24 volt. Tuff stuff.
Toy boat = 12 volt.
Happy trails to you.
Mark the manatee

[Chotu]

I have been looking into a dual voltage system where at the very minimum, all the things requiring large cables see 24v from the battery bank. Things such as chargers, inverters... I have also been considering distributed type systems where a pair of monster cables are run down the boat and smaller takeoffs with their own small breaker panels are located near the devices.

My overall goal is to reduce the weight of the wiring.

[NaClyDog]

Originally Posted by smac999

most things are available as one or the other. very few things are both. not sure where you are seeing all these dual voltage things. a 12/24 windlass? no way.

You are correct, I didn't look at a windlass specifically but did look at winches. Incorrectly assumed they would be the same.


So, currently we have windlass, marine radios and electronic networking that do not come in dual 12v/24v versions.

[noelex 77]

There is reasonable amount of equipment that has separate 12v and 24v versions. Most equipment with an electric motor for example. So water pumps, electric bilge pumps, autopilot drives etc will need to be purchased in a 24v not a 12v model.

There is no shortage of choice. It is rare to find any marine equipment that is available in 12v that does not have an otherwise identical 24v model.

[nfbr]

Low power DC-DC converters are very cheap and efficient now
I would just put one per device or group of devices.

[Manateeman]

Hi. Well I’m not so sure “avoid 12/24 volt systems” is always good advice. For example, new large commercial vessel have a dedicated battery (usually 12 volt ) for emergency communications in the wheelhouse. If your engine room is on fire or you are half sunk and going down fast... it’s kind of nice.
Happy trails to you.
Mark the manatee

[Statistical]

I have been looking at this myself. Be sure to check spec sheets and owners manuals very careful. B&G Zeus (chartplotters) are 12V/24V but B&G Vulcan is 12V only.

God only knows why. There is no good reason why low powered electronics aren't universally dual 12V/24V at this point. Same thing with NMEA 2K powered devices. Some actually are but if even 1 NMEA 2K device is 12V only you are going to need to power the NMEA 2K network at 12V.

If you are converting a boat check your existing solar charge controller, battery charger, and inverter. These sometimes are dual voltage but usually are 12V or 24V specific. Replacing all three is trivial but not cheap.

Also keep in mind that if your house systems are 24V but your starter(s) are 12V you will need a method to charge them. A simple ACR or A/B switch isn't going to work. One option is to use the engine alternator for just charging the starter battery but it means you lose it for the house bank. Another option would be dual alternators. A third option would be a DC-DC charger to charge the starter bats off the house bats.

[rslifkin]

Originally Posted by Statistical

Also keep in mind that if your house systems are 24V but your starter(s) are 12V you will need a method to charge them. A simple ACR or A/B switch isn't going to work. One option is to use the engine alternator for just charging the starter battery but it means you lose it for the house bank. Another option would be dual alternators. A third option would be a DC-DC charger to charge the starter bats off the house bats.

Or, depending on what the engine is, you might be able to convert to 24V starters.

[Lake-Effect]

Originally Posted by NaClyDog

In preparation for getting our boat, I've been taking "mini" boat courses put on by our local yacht club. Basic diesel engines, basic boat plumbing, basic DC power, etc... It seems to just be enough knowledge to try and prevent you from doing anything too stupid while away from the dock.

Everything pointed to 24v being better but it just seemed to not be that common and I wanted to try to see if there was a reason I was missing.

What size of boat are you contemplating? If it's 30' or smaller, I'd stick with 12v just because it's going to be easier to find equipment and parts wherever you go.

If you're planning on a bigger boat, and to carry more spares with you, then it makes more sense to think harder about 24v. IMHO.

[glenn.225]

It is very simple to pull 12 volts off a 24 volt bank, just run a + lead off half the bank. Wouldn't do it for high draw uses as it will unbalance bank but light loads are no problem.

[Bycrick]

12v autopilot drive motors are often used on 24v systems. I know the Simrad line allows this. Since the voltage to the motor is pulsed, they just reduce the pulse width to produce the correct average power.

[Jammer]

Originally Posted by Statistical

Also keep in mind that if your house systems are 24V but your starter(s) are 12V you will need a method to charge them. A simple ACR or A/B switch isn't going to work. One option is to use the engine alternator for just charging the starter battery but it means you lose it for the house bank. Another option would be dual alternators. A third option would be a DC-DC charger to charge the starter bats off the house bats.

Originally Posted by glenn.225

It is very simple to pull 12 volts off a 24 volt bank, just run a + lead off half the bank. Wouldn't do it for high draw uses as it will unbalance bank but light loads are no problem.

Or use a Vanner equalizer or similar. The marine world appears to be unaware they exist. They allow taking a 12v tap off the midpoint of a 24v bank while still keeping the state of charge equal across cells.