12v versus 24v

[NB Esk]

Hi everyone, just looking for opinions/experiences of 12 and 24volt systems. I've looked thro' various old threads, using the search facility, but haven't come across anything that relates directly to this.

 

I need some food for thought, as I'm coming to the point of alternator mountings, etc (on my vintage engine) so the relative pros & cons would be of help, in knowing which system to go for.

 

Has anyone owned different boats, and experienced both 12v & 24v? What were the advantages(or otherwise)?

 

The engine electrics are 12v and will be seperate from the leisure electrics (except earth of course). Even so, is there any possible conflict, if the leisure electrics are 24v?

 

I work on vehicles with both systems, and understand things like voltage drop(though I'm not an electrician)

but I have the feeling there'll be a bit more to it.

 

So.........12 or 24?

 

Thanks for any comments............

[John Orentas]

Hi John.

 

The only advantage of a 24 volt system over 12 volts is as you have worked out is that of volt drop. You should however avoid having a dual voltage system unless you can arrange to drive two alternators. Why do you want to have 24 volt domestics when the engine is 12 volts.

 

At one time there were good reasons to fit 24 volt systems, there was equipment that was made for the 24v systems in commercial vehicles and coaches that was not available in the lower voltage but I don't think that is the case any more, in fact there are many things that are only available in 12v.

 

The difference in wiring cost and the potential problem of added bulk of the 12v system is very marginal.

 

There are ways of designing a dual voltage system using a single alternator, in fact I designed one for a member of this forum but it is very complex, I wouldn't advise it.

[NB Willawaw]

I have designed and wired systems for both 12V and 24V boats.

 

I presume that you are proposing fitting two separate alternators on your engine; one 12V for the starter circuit and one 24V for the domestic circuit.

 

The only advantage of 24V is the down-sized cables that can be used due to the reduced current draw and therefore volts drop.

 

Consider the availability of 24VDC equipment (including cabin lights) before making your choice.

Edited September 2, 2006 by NB Willawaw

[Yoda]

I have designed and wired systems for both 12V and 24V boats.

 

I presume that you are proposing fitting two separate alternators on your engine; one 12V for the starter circuit and one 24V for the domestic circuit.

 

The only advantage of 24V is the down-sized cables that can be used due to the reduced current draw and therefore volts drop.

 

Consider the availability of 24VDC equipment (including cabin lights) before making your choice.

 

One way to reduce the voltage drop is to run double cables everywhere. I think that there is more scope on the continent for different voltage products.

[Gary Peacock]

We have done quite a few 24v setups but in all honesty I didn't see any great advantage.

 

On a negative note the cost of 24v equipment tends to be inflated and the availability is less.

[NB Esk]

There are ways of designing a dual voltage system using a single alternator, in fact I designed one for a member of this forum but it is very complex, I wouldn't advise it.

 

Hi all & thanks for the replies................pretty much as I thought, so it looks like 12v and combat voltage drop, as much as possible.

 

Twin alternators, John...............don't want to go the way of complication for the sake of it.............just wondered if there was anything I'd overlooked, to give 24v the edge.

 

12v it is, and thanks again for the replies..............

[John Orentas]

Hi all & thanks for the replies................pretty much as I thought, so it looks like 12v and combat voltage drop, as much as possible.

 

Twin alternators, John...............don't want to go the way of complication for the sake of it.............just wondered if there was anything I'd overlooked, to give 24v the edge.

 

12v it is, and thanks again for the replies..............

 

 

John.

 

The twin alternator option is the simple one, no split charge relays, two totally independent systems. As a bonus you will always have spare generating capacity if one of them jacks it in. And as someone said 12 volt lighting and other appliances are more easily available.

 

Next best option, one alternator with split charge for starter and domestics. It really isn't that involved.

 

The complication I mentioned was a system I designed with 12 volt alternator and domestics and 24 volt starter motor, but don't go there.

[DHutch]

We have a 24v system though our boat.

 

Fittings are fairly avalable. Basicaly everything is made in both 12 and 24v, but often only stocked in 12v with a few 24 items.

- So its not too bad. Theres usally 2/3 24v bildge pumps and other staple items. But light fittings, chargers, inverters, etc usally have to be ordered.

 

Other electric items on the boat are the fridge, which is easy with all shorelines prducts being 12/24v anyway. (although ours is an older engle)

- Bow thruster, defonatly better being 24v for the current draw. But then again the cable runs are only 2ft, fo could have been doubled easly.

- 24v filament bulbs for navb lights etc are widely avalable from coaches/lorry outlets, (and most chandelers tbh)

 

 

If i was doing it again, i would be tempted to go for 24v again.

- If i was doing a boat now, i would have a victron charger/inverter combi unit, with and extras being mains anyway.

- Then its basicaly just the lgihts, pump, and fridge, which are all widly avalabe, even if it takes a few days to get them in.

 

 

 

Daniel