Dual Voltage (12 & 24) Electric Circuits

[LadyInBed]

That's because it isn't a battery charger.

That's good, I'm not going senile.

 

[fushion julz]

Just in case it helps...
My boat (Fairey Huntress with Perkins T6.354) came (to me) with 2 (12v) batteries wired for 24v...Engine is 24v alternator and starter. The added instruments/electronics were all 12v running off one half (one battery) of the 24v system with a common earth.
There was already a Sterling multimode 240/24v charger conditioner.

Over the winter I decided to wire the system up properly as the batteries needed changing anyway.
So the 2 starter batteries are now just that, retaining the shore power charge option in the Sterling unit.

I added a Victron 24/12v DC-DC 30A charger/inverter and a 12v leisure battery. It did necessitate a complete rewire of the dash panel and I needed a new (24v) temp gauge. The system now, effectively, is completely charged by the engine when running or the shore power when available. There is plenty of 12v current available from the leisure battery and it is topped up by the charger when needed.

This is the Victron unit I have:
Victron Energy Orion-Tr 24/12-30A (360W) Isolated DC-DC Converter - ORI241240110 – Battery Megastore

 

[jwfrary]

I would have thought the non isolated version non smart one would be sufficient for your needs.

I use victron gear a lot had one duff charger arrive which was changed out without any fuss at all, that's probably getting on for 40k in equipment over the last few years...

I also had a durite voltage converter that melted its insides out under a low load... Less than impressed. You get what you pay for!

 

[PaulRainbow]

I looked on Battery MegaStore at the Victron Energy Orion 12/24-20 DC-DC Converter IP20 – ORI122420020
but at £155 I'm reckoning that it is too sophisticated for my needs!
The items being driven are not sensitive to voltage stability or ripple, so I'm going to try the £30 version. If it doesn't do the job the lost outlay will only be small.

Victron Energy Orion-Tr 24/12-20 (240W) DC-DC Converter - ORI241220200R – Battery Megastore

 

[noelex]

A combined 24/12v system is quite common especially on larger sailboats. This system has several advantages over a pure 12v system.

I agree your boat system is unusual with, if I understand correctly, most systems running from 12v.

More commonly virtually everything on the house bank runs on 24v. Most modern marine equipment will run on either 12v or 24v straight from the box, and if not, 24v versions are readily available. There are exceptions such as the NMEA 2000 backbone and low cost VHF units. These exceptions are usually powered by a 24v to 12v converter rather than a 12v battery.

The engine start system can also be 24v, but is commonly kept as a completely seperate 12v system.

I suspect previous owners of your boat have created the rather problematic system you have inherited, but it is worth considering correcting these mistakes, perhaps gradually as wiring and equipment is replaced. You will end up with a superior system in the end.

 

[LadyInBed]

Victron Energy Orion-Tr 24/12-20 (240W) DC-DC Converter - ORI241220200R – Battery Megastore

Great if you want to go 24->12 but I'm going 12->24!

 

[LadyInBed]

I suspect previous owners of your boat have created the rather problematic system you have inherited, but it is worth considering correcting these mistakes, perhaps gradually as wiring and equipment is replaced. You will end up with a superior system in the end.

I agree, but as I said in #1, I've lived with it for 21 years, thinking about it, I must be a mug

 

[fushion julz]

Here you go
Victron Energy Orion-Tr 12/24-15A (360W) Isolated DC-DC Converter - ORI122441110 – Battery Megastor

 

[PaulRainbow]

Great if you want to go 24->12 but I'm going 12->24!

OOps, my bad.