24v & 12v systems

[wooslehunter]

I have both 24v & 12v on board with two alternators. I'd like to get rid of the 12v alternator as its not mounted on the engine & a bit of a bodge.

I can replace all bulbs with 24v types but then need to convert 24v to 12v to power the electronics: instruments, VHF, plotter etc.

Anyone with a 24v system have any recommendations on a converter to do the job? BTW I used to design switched mode PSUs so understand the technology. Just looking for a mnufacturer recommendation. Load will be small but peak load much higher when the VHF is transmitting & the autopilot is running.

 

[BGW]

I have both 24v & 12v on board with two alternators. I'd like to get rid of the 12v alternator as its not mounted on the engine & a bit of a bodge.

I can replace all bulbs with 24v types but then need to convert 24v to 12v to power the electronics: instruments, VHF, plotter etc.

Anyone with a 24v system have any recommendations on a converter to do the job? BTW I used to design switched mode PSUs so understand the technology. Just looking for a mnufacturer recommendation. Load will be small but peak load much higher when the VHF is transmitting & the autopilot is running.

24V to 12V droppers are commonplace - I use a 20A one to power my 12v navigational equipment and radio.

Just get a good quality one with plenty of capacity.

 

[savageseadog]

Have a close look at the specs for all the electronics, you may find a few that will work on a range of voltages up to 24V and beyond.

 

[pvb]

Have a close look at the specs for all the electronics, you may find a few that will work on a range of voltages up to 24V and beyond.

Yes, lots work on around 10-30v.

 

[Deleted member 36384]

BEP DC/DC Converter

I have a BEP 12/24 20A converter for my system. It has been very reliable and provides circuit protection as well as voltage reduction, all in one box, therefore no need for other levels of protection on the main 12v supply to the 12v distribution panel.

http://www.bepmarine.com/home-mainmenu-8/product-402/dcvr-20a-dc-dc-converter-20a

 

[David2452]

Take care with the spec when choosing, some of the cheaper 24 - 12 converters work fine when at 24v or slightly above but if on full charge either alternator or shore power will cut out on over current protect.

 

[William_H]

24 and 12v system

You have lots of options for the system.
If you choose to fit a 12v battery then you can have lower current converter to charge it off the 24v battery.
Fit a VSR so it only charges of 24v battery when 24v is on charge. This battery can then supply the added current of VHF on tx but can also double as domestic battery quarantining the 24v start system from discharge. Take all your domestic needs form the 12v battery. That is what I would do.

You might find one of the alternator to battery chargers that will work on 24v input. Or you could make one using one of the smart charger type chips to control 12v charge current.

If however you don't want an added battery and are not concerned about domestic discharging the engine battery system then a converter is what you want. It is fairly simply a switch mode pulse width supply into an inductor and capacitor with fly back diode. Any should be fine you will need about 5 amps I would imagine for VHF and nav gear. Run everything possible off 24v.
Yes get rid of extra alternator. Definitely not needed.
good luck olewill