using32v wiring to run 12 volt stuff

[ron6785]

Guy on my dock with a 53 told me he was swithching out his 32 volt for 12. I indicated that would be a big job what with pulling all the 32v wiring. He said not "I'm going to use the the 32 wiring to run all the 12 volt except the engines". I'm not a electrician but it seems to me that except for low voltage Items, he could be in for some trouble. Can any of you electricians weigh in on using 32v wiring to run 12 volt. What specific items would he be in trouble with?????

 

[SKYCHENEY]

I don't understand exactly what he is doing. Is he just changing out the house bank to 12v and leaving a 32v banks for starting the engines? What about the windlass? If he has only one start bank, he loses the ability to parallel to the house bank if the start bank goes down. Generator? Inverter? Chargers? Fan motors? Wiper motors? I hope he has thought this through.

Hatteras used wire size that was bigger than needed in many cases, but I would not just go to 12v without looking at the potential load on each circuit first and making sure he wasn't creating a fire risk.

The more you mess with the original setup, the more difficult it is for future owners to figure out. It may also lead to problems during survey (for sales or insurance purposes). When you see these ridiculously low sales prices for old boats, you wonder why. Sometimes it's the "re-engineering" that contributes to that.

 

[Brian Degulis]

Some circuits were wired heavy enough to handle the aditional amps required for 12V Some were not. I often thought instead of converting to 12V why not ad an inverter and go 120V as much as possible. The wiring would be more than enough and on many Hats even the 32V circuits are 3 wire they have a seperate ground. So you leave your engines and big loads like winches and toilet pumps 32V and convert all the lighting and small stuff to 120V. With a 32V inverter everything still runs on the house bank. You would still have the 8V batteries to deal with but most of the expensive hard to find 32V stuff could be eliminated?


Brian

 

[REBrueckner]

When I bought my 48YF I found all the bunk lights were 120volt. As I anchored out all summer and rarely use a genny I did not want that!!!

So I changed them to 12 volt by exchanging bulbs and in most cases running new wire as I passed most of the fixtures with other rewiring I was doing. (so I just pulled another pair of wires along) In a few cases I used most of the original wiring and extended it to 12 volt circuit breakers. All was well for 11 years until I sold her.

Almost certainly there is a touch more voltage drop due to IR losses (wire resistance (R) stays constant and current (I) increases so losses do as well) and I used 15 watt or 25 watt bulbs instead of the originals (maybe 40 watt??) ...in general for such light duty circuits the original wiring should do.

 

[Canuck Dennis]

Newmar makes a 32x12 converter, I have a 15 amp one and have converted most of my 32 v lighting to 12 v .mind you the thing ain't cheap !! it came with the boat or I would never have bought it. Still used the 32 v wiring.

 

[GJH]

Just an FYI, I saw a NewMar 32-12 50 amp converter at Jarrett Bay Surplus the other day for $250, probably negotiable.

I am in the camp that the old wiring should only be used if it meets the size requirement for the amperage load of the circuit at 12 volts. Fudging can be fatal.

 

[Canuck Dennis]

Somebody should snap that up real quick. Also, 12.ga is way good for 12 v 60 watt bulbs

 

[Canuck Dennis]

32 V inverters are not cheap, i bought one here in Vancouver for our 70 ft Yacht, 32 vx240 v 15 amps....$3K. and boy, do they suck juice, approx 90 amps of 32 v to give me 12 amps of 240 v, as this one has twin cooling fans which also takes juice. I try to only use it when running as the 150 amp alternator helps when making coffee etc, can run one major appliance at a time, i.e. dishwasher or microwave or one stove element or large fridge/freezer, along with TV and one small 120 v motor, so does save me genset use when cruising.

 

[SKYCHENEY]

I run everything on our boat with a 32v Outback 3200watt inverter. It only outputs 120v, but if we need 240v, we just start the generator. It seems very efficient as I can run 24hrs on just the house bank of Rolls batts.

The cost for the Outback is about $1500.

 

[MikeP]

Ditto re the Outback - one of the very best purchases I've made since owning the boat...maybe THE best.

 

[Glory]

I switched my 58YF to 12 volt a few years ago, everything except the windlass it is 24 volt.

Starters, alternators, shut down solenoids, crossover solenoid, blowers, bulbs, wiper motor, heads, bilge pumps, water pumps, horn relays, tacks, volt meters, (all of the other gauges are mechanical, chargers and several breakers were changed. Also added were some starter relays mostly for the bridge run distance.

The only wires that I needed to change would have been the bait well pump circuit, my sea water wash down is delivered by a 220 volt well pump and the DC supply wire to the panel was increased as was the supply to the bridge.

. Even the speaker wires are 12 gauge on my boat.

My objective was to never have to wrestle with 8D 8volt batteries again. I now have 16 group 31 950 CCA batteries, 3 for each engine, 2 for the generator, with a selector switch, 2 for the 24 volt windlass bank, 1 for the electronics and 3 for a house bank and 2 spares.

Now the boat 3 chargers, windlass 24 volt, house and mains, and the generator. I like the generator to completely stand alone.

The heads I used are Jabsco quiet flush, only a 25 amp draw and the #6 wire provided for the Raritan heads is over kill even for the aft head.

Every couple of years I save about $500 $600 on batteries and I can change them without help, hired or otherwise.

I’m pleased with my results.

JM

 

[REBrueckner]

" 32 V inverters are not cheap, i bought one here in Vancouver for our 70 ft Yacht, 32 vx240 v 15 amps....$3K. and and boy, do they suck juice, approx 90 amps of 32 v to give me 12 amps of 240 v.."

Only in your dreams is an inverter over 100% efficient! Your figures ( 90 x 32= 2700 watts in, 12 x 240= 2880 out) are impossible and that's never going to happen. (100 amps input would be pretty good, 2880/3200 or 90% efficiency.) Apparently 32 volt inverters ARE expensive, but should be no less nor more efficient than 12v inverters.

Figure a 10% or 15% inverter loss depending on load ....and with wet cell batteries, you lose another 15% or more when charging batteries to heat losses....so in general, running an inverter for high power applications, unless for brief periods, like a coffee maker, will offer only marginal cost savings.

On board electrical power is generaqlly an expensive proposition and is an unavoidable aspect of boating away from dockside power. Figure your typical cost per KWH and you'll likely find its three or four times commercial power....

 

[bigbill]

i am with jim (glory) on this one, i switched to 12v and used the group 31's. the batteries give me more cca than the old ones, and the are much lighter. than the 8volt ones. i didn't change any wires in the boat, and, for about one and a half years, no problems. i did change some breakers though. bigbill

 

[Canuck Dennis]

Dc to ac conversion factors as follows....

Approx 10 to 1 at 12 v dc..therefore..100 amps of 12 v dc will convert to 10 amps ac minus 10% efficiency factor.

at 36 Volts dc ..100 amps converts to approx 3 times that of 12 v minus efficiency.

So, Rob, where did I go wrong at 96 amps 32v dc input gives me 12 amps 240 v out ????

 

[GJH]

You're getting more CCA because it is 12 volt, but likely less wattage, which is what power is. You need 2.75 times the amps at 12 volts to deliver the same wattage as at 32.

As for a 12v conversion, without knowing wire sizes and loads and round trip circuit distances, hard to comment whether what has worked so far for you is also safe, or likely to continue to work.

I have occasionally thought about some sort of 24v conversion for the main banks, since I have a lot of 24v ancillary stuff on board: inverter, wash down pump, bow thruster, navigation electronics. Just haven't been able to cost justify it; certainly the battery savings is not enough for me. So I have to weigh what the simplicity and redundancy conveniences are worth.
Maybe some day...

 

[ron6785]

I switched my 58YF to 12 volt a few years ago, everything except the windlass it is 24 volt.

Starters, alternators, shut down solenoids, crossover solenoid, blowers, bulbs, wiper motor, heads, bilge pumps, water pumps, horn relays, tacks, volt meters, (all of the other gauges are mechanical, chargers and several breakers were changed. Also added were some starter relays mostly for the bridge run distance.

The only wires that I needed to change would have been the bait well pump circuit, my sea water wash down is delivered by a 220 volt well pump and the DC supply wire to the panel was increased as was the supply to the bridge.

. Even the speaker wires are 12 gauge on my boat.

My objective was to never have to wrestle with 8D 8volt batteries again. I now have 16 group 31 950 CCA batteries, 3 for each engine, 2 for the generator, with a selector switch, 2 for the 24 volt windlass bank, 1 for the electronics and 3 for a house bank and 2 spares.

Now the boat 3 chargers, windlass 24 volt, house and mains, and the generator. I like the generator to completely stand alone.

The heads I used are Jabsco quiet flush, only a 25 amp draw and the #6 wire provided for the Raritan heads is over kill even for the aft head.

Every couple of years I save about $500 $600 on batteries and I can change them without help, hired or otherwise.

I’m pleased with my results.

JM

So do I understand that you are running all of the above items on the original 32v wiring???? Ron

 

[MikeP]

"My objective was to never have to wrestle with 8D 8volt batteries again. I now have 16 group 31 950 CCA batteries, 3 for each engine, 2 for the generator, with a selector switch, 2 for the 24 volt windlass bank, 1 for the electronics and 3 for a house bank and 2 spares."

I guess everyone has there own view on this subject but this seems needlessly complicated just to avoid horsing around the 8V batts every 5-6 (or 15 if they are Rolls) years. The oem 32v system works great and none of the components are hard to find (except at West Marine )

Regardless of the alleged "success" folks have had going to 12v on the oem wiring, it can't actually meet the specs for ampacity on anything other than extremely light loads if that. Just looking at ampacity tables shows that a 30 ft run (one way) at only 5 amps at 12v would require 12ga wire and would still be more than a 3% voltage drop. 5 amps at 12v isn't much power - only about 60 watts. If you start looking at longer runs, which would be common on these boats, I can't see how 12v is viable at all other than for LED lighting using the oem 32v wiring.

But, as I said, everyone has their own view of what "works."

 

[Glory]

So do I understand that you are running all of the above items on the original 32v wiring???? Ron

Execpt for the supply to the DC panel and the bridge supply that is correct and the windlass is on it own 24 volt bank.

The heads, as I indacated, Jabsco and run on a 25 amp breaker, I also added a relay for the starter buttons. If I stuck with Raritan I would have needed 2.0 for the aft heads.

I'm peaseed with the Jabscos.

The battery wires were all 4.0.

The one thing I didn't mention yesterday is the engine alarms also had to be changed, I wound up using a truck back up alarms, 96 BDs.