Change from 32 volt to 24 volt (or even 12 volt)

[Navatech]

Hi, my recently purchased 1985 46'6" Bertram Convertible has the standard (for the time) 32 volt system.

However, as the boat does NOT have the batteries, the Raritan Electro Scan MSD treatment units (2) and a lot of other electrical stuff (e.g. chargers, inverters etc) is highly suspect at this point I'm wondering whether this wouldn't be a good time to change (or, at least consider changing) to a 24 volt (or even 12 volt) system for which all kinds of equipment can be had easier (and cheaper).

Yes, I know that I'd have to get new/rebuilt alternators and starters. I'm not even sure they work so that's not a problem. Much of the other stuff is either MIA or dodgy at best.

I'm OK on mechanical matters (former marine grease monkey) but electrics are pretty much an enigma to me. Especially the relationship between volts, amps and wire thickness.

I do NOT want to rewire the boat. I want to use the existing wires. What can come and bite me in the ass?!...

Which would be better? 24 volt or 12 volt?

Also, would it be possible to rebuild the existing alternators and starters to 24 (or 12 volt)?

[CaptPatrick]

I do NOT want to rewire the boat. I want to use the existing wires. What can come and bite me in the ass?!...

The main problem will be that by reducing the voltage you'll be increasing the current and much of the wiring would have to be increased in size to handle a 12 volt current flow. Failing to rewire, fire is the ass bitter... 12 volts DOES involve major re-wiring as the current increases over 60%.

Converting to 24 volt is more do-able since the current flow only increases 25% and less existing wiring would have to be replaced, but there would still be the need to replace primary wiring, especially on long runs like to the anchor windlass. Then there's replacing all the 32 volt equipment with 24 volt equipment.

Overall, I think that the time and expense outweighs the advantage. Adding some 12 volt equipment, especially electronics and other lower current demand items like bilge pumps could be done using voltage reducing transformers, but again the cost/advantage ratio may not be very good...

While finding 32 volt items like light bulbs, bilge pumps, and such is a PITA, converting is a far greater PITA. Conversion would also be something that should ONLY be undertaken by a qualified marine electrician and not as a DIY on the job self training exercise.

[captbone]

All depends on your plan for the boat. If you are keeping the boat for the long run and can see yourself owning the boat for 7+ years then I would say the time and effort is well worth the cost.

Since most of the systems are suspect right now, you will need to review them anyway.

[Navatech]

The main problem will be that by reducing the voltage you'll be increasing the current and much of the wiring would have to be increased in size to handle a 12 volt current flow. Failing to rewire, fire is the ass bitter... 12 volts DOES involve major re-wiring as the current increases over 60%.

OK, so 12 volt is NOT an option.

Converting to 24 volt is more do-able since the current flow only increases 25% and less existing wiring would have to be replaced, but there would still be the need to replace primary wiring, especially on long runs like to the anchor windlass.

I was planning to change a lot of stuff to less demanding stuff. E.g. LED's for lightening thereby reducing the current. Thereby compensating for the increased current due to the voltage change. The "hotel" stuff (AC, fridge, range, oven, microwave) are all 110 volt anyway. Not sure about the outside ice maker and freezer.

Then there's replacing all the 32 volt equipment with 24 volt equipment.

I suspect that a lot of the 32 volt equipment will need replacing anyway. So, I guess it's mostly a question of seeing what works and what doesn't work. Tally it all up and crunch the numbers.

Overall, I think that the time and expense outweighs the advantage. Adding some 12 volt equipment, especially electronics and other lower current demand items like bilge pumps could be done using voltage reducing transformers, but again the cost/advantage ratio may not be very good...

The thing is that a lot of stuff simply isn't available in 32 volt anymore whereas 12 & 24 volt stuff is common. I still remember the troubles my friend had with his (very) old 6 volt VW Beetle... He was a very happy camper after we converted it to 12 volt.

While finding 32 volt items like light bulbs, bilge pumps, and such is a PITA, converting is a far greater PITA.

I'm not disagreeing on principle. However, finding 32 volt items will be an ongoing (and increasing) PITA whereas a conversion would be a one time PITA.

Conversion would also be something that should ONLY be undertaken by a qualified marine electrician and not as a DIY on the job self training exercise.

I would have thought that the conversion DESIGN would have to be done by a qualified marine electrician whereas the actual EXECUTION is another matter. I have successfully rewired/modified cars, RV's and other such equipment. IMHO it's the design that requires the professionalism whereas the execution is doable for a competent DIY person.

you will need to review them (electrical systems) anyway.

The problem there is that, AFAIK, in order to do that I will have to invest in the old system (e.g. new batteries) thereby further reducing the economic atractivity of the change... I can't see a way around that (aside from borrowing a set of batteries)...

The real question IMHO is the starter. If I can simply have the 32 volt starter refurbished as a 24 volt or, if it has the same gear wheel (pinion?) as the OEM 24 volt starter then I'm good. Otherwise I'll have to change the flywheel and that's NOT an option at this time.

[CaptPatrick]

The real question IMHO is the starter. If I can simply have the 32 volt starter refurbished as a 24 volt or, if it has the same gear wheel (pinion?) as the OEM 24 volt starter then I'm good. Otherwise I'll have to change the flywheel and that's NOT an option at this time.

I kind of doubt that the starter gearing would need changing. As to whether or not they could be rebuilt to change voltage requirements I don't know; that'd be a question to ask a shop that rebuilds electrical motors.

Again, you might only need to re-wire with heavier guage cable the primary items which require a high current load... At this stage, enlisting the services of that qualified marine electrician to "design" a safe system seems like your next move. Dropping voltage and increasing current on a 46' boat is just a tad different than increasing voltage and decreasing current on a vintage 13' VW Beetle...

[Navatech]

I kind of doubt that the starter gearing would need changing.

That happened to be the case with the VW as well as with another (200 KW diesel generator) engine that I was involved with.

As to whether or not they could be rebuilt to change voltage requirements I don't know; that'd be a question to ask a shop that rebuilds electrical motors.

Just as soon as I'm back in Puerto Rico (where the boat is) as I'll need a local outfit to do it.

At this stage, enlisting the services of that qualified marine electrician to "design" a safe system seems like your next move.

I was hoping that somebody here had done something similar and could share with me some of their real life experience. Basically I'm engaging now in some preliminary homework.

Dropping voltage and increasing current on a 46' boat is just a tad different than increasing voltage and decreasing current on a vintage 13' VW Beetle

I would never claim otherwise. And there's another factor, if one gets stuck with a car it's a simple matter of calling AAA. In the middle of the ocean it's another proposition altogether...

I think that I should start a blog about this adventure. That way I can share my experiences, lessons and what have you not...

[micky]

Navatech, where is the 46 located?? I'm also in PR. I know a guy that has the same boat over in Guayama and he converted everything to 12V except the engines, he left them 32 V.

[Navatech]

Navatech, where is the 46 located??

Fajardo. Not that far from Guayama I believe. A little over an hour traffic permitting?

I'm also in PR.

Nice!...

I know a guy that has the same boat over in Guayama and he converted everything to 12V except the engines, he left them 32 V.

It would certainly be worth it to me to meet him. Is he on-line?

[Navatech]

OK, assuming I'm going forward with the existing 32 volt setup, what was the original battery setup on these (1985 46'6" Bertram Convertible) boats?

16 x 2 volts? 8 x 4 volts? 4 x 8 volts? I think it's the latter as there are (what I think) 2 double boxes on each side of the battery space. Should I keep to the original setup or should I consider something else?

Also, I assume I should get two banks of those (one bank for each engine)?!...

What about "house" use? Would that require an additional bank? Where would those batteries have originally been located (I don't recall having seen them or a space where they should have been but maybe they're still there)?

Any pointers about what kind of batteries to get? Acid/Gel/AGM?

[mike ohlstein]

I would guess that there were 4 eight volt batteries. Plenty of golf cart batteries around, and probably dedicated marine batteries.

Try Exide.

Or here http://www.powerstridebattery.com/marin ... -batteries

[Navatech]

Any idea of what kind of battery capacity I should be looking for?