Greetings..... Marine electrical system upgrade

[oscarvan]

New to forum, not new to forums.

This is somewhat lengthy, but it's an intricate project. I own a 1978 Hatteras Motor Yacht. It's a labor of love, and it's in pretty decent original shape. In 1978 the cutting edge DC technology demanded 32VDC. Two Detroit engines, two alternators, and two 32V lead acid banks, consisting of 4 massive 8VDC batteries each, charged with a 120VAC charger when plugged in to shore power. The port bank is the "house" bank as well as starting bank for port engine, the starboard bank is start for the starboard engine. It can be paralleled to the port bank for starting backup. Pretty standard setup. Total battery weight 1200 pounds..... 8-(

Like Betamax lost to VHS, 32VDC lost to 12/24/48. Components for 32VDC are harder and harder to find, and they are expensive. (Water pumps, head pumps, bilge pumps etc). Most people rip it all out and start over with 24VDC. My problem is that it all works, quite well as a matter of fact, and it's a pretty complex system. I'm now changing light bulbs over to LED so finding the 32V bulb$ is a thing of the past.

Meanwhile all navigational/comm electronics are newer and 12V. So there's a separate 12V battery and charger for them. The generator is 12V starting (produces 240VAC) and has it's own battery on the aforementioned 12V charger. Then there is a bow thruster which is 24V also with its own charger.

So here I am with 12/24/32/120/240 volt systems...... The main problem is that the 12 and 24 system are only charged by their 120VAC chargers, which requires me to run the generator when underway. This is silly. Lastly I don't have an inverter.

Now there are MANY different ways with varying complexity and cost to make this system more functional. Because of cost a phased in approach is imperative. I'm still kicking various plans around, and I have a few questions (yes, finally) which is why I came here. I love Wills videos btw and showing me how to do stuff is going to be a major turning point.

At this point I plan on converting the SB bank to LiFePO4. In order to convert to 24V I would need a new starter, alternator and engine instrumentation. This gets costly. I would also lose the ability to parallel to the port engine in case I run my 32V port (house) bank low.

First question...... If I build a 32VDC bank (10 cells in series, multiple packs in parallel) is there any reason I cannot tap in at 24VDC to feed an inverter? 32V inverters are no longer made........

Second question: Does anyone know of a 32 to 24 transformer or robust enough MPPT controller to take 32VDC convert to 24VDC and feed a 2000W inverter?

 

[Q-Dog]

It is complicated, but no you cannot draw from only a few cells in a pack.

Look at 36 volt inverters. The ones I have seen can go down to 28 or 30 volts, and up to 40+

Talk to these guys and see what they suggest. https://shop.pkys.com

 

[FilterGuy]

First question...... If I build a 32VDC bank (10 cells in series, multiple packs in parallel) is there any reason I cannot tap in at 24VDC to feed an inverter? 32V inverters are no longer made........

That would not work.... Sorry. The charging would never work to get the cells back in ballance.

Second question: Does anyone know of a 32 to 24 transformer or robust enough MPPT controller to take 32VDC convert to 24VDC and feed a 2000W inverter?

That would be a huge controller. I don't know of anything that could take the kind of current you are talking about.

 

[FilterGuy]

My problem is that it all works, quite well as a matter of fact, and it's a pretty complex system. I'm now changing light bulbs over to LED so finding the 32V bulb$ is a thing of the past.

Marinebeam has some 32V bulbs..... but I don't know if it is the kind you need.

32V Edison Screw Base LED Bulb - for 32VDC Systems

THE ONLY 32V Edison style screw in LED replacement light bulb for 32VDC Hatteras Viking Train lighting and other applications

store.marinebeam.com

I would be tempted to see if there is a reasonable way to convert the Lights to 12 or 24 Volt.

 

[12VoltInstalls]

Goals:
- get away from 32V
- use commodity 12V and/or 24V accessories
- phase in gradually

First off is the 32V problem. Detroits are a common motor, and in trucking 24V is common for starter voltage. Starters are $275-$1300 each. Alternators are readily available. I think there were even 12V components for these items at one point?

Going to 12V might be achievable but probably 24V for starting makes the most sense. Then either an automatic 24V-12V charger could be used or an accessory 12V alternator could be installed if you don’t have that already.

The second alternator 12V makes sense to me because there’s SO MANY good 12V lighting, pump, accessories etc available at a decent price.
However, 24V makes sense, too, because it’s easily charged with your (new) alternators OR solar (or shore power). And stepping to 12V is doable: ‘distribute’ at 24V (less distance losses than 12V) and use 24V-12V DC converters locally where required.

You will need to decide what to do with those options. And that decision will drive everything else you do and make your choices for you in many cases. But the first jump will cost more than a few grand. (You could convert one motor to 24V at a time and make that a phase-in but you would lose the ability to switch starting batteries between motors until both were 24V)

The follow-up step I’d do is phase out the high demand 120VAC stuff. When those loads get updated, powering independent of shore power or the generator with solar becomes tangible.

In the fwiw department, when you do the phases, I would buy spares: an extra 24-12V converter, spare 24VDC-120AC inverter. Keep them NIB in zip-lock bags for Justin. Justin Case. Just like you probably carry spare belts, bilge pump, and alternator now. Luck favors the prepared, and Justin and Murphy don’t get along...

 

[oscarvan]

Thanks for the replies, I was afraid you were all going to say that. Strange as it may seem, there are no 32V inverters on the market, the last company that was making them quit a few years ago.

I'm doing a temporary fix with a Newmar DC to DC converter, 32V-24V-50A which will give me 1200W peak, 950W continuous to feed a 24V/1500 watt pure sine inverter. This will take care of the immediate need to charge the navigation equipment 12V battery (low consumption, easy to keep up with) and when not connected to shore power it will power the fridge at night.

Then I will just have to convert the starboard side to 24V.

Goals:
- get away from 32V
- use commodity 12V and/or 24V accessories
- phase in gradually

First off is the 32V problem. Detroits are a common motor, and in trucking 24V is common for starter voltage. Starters are $275-$1300 each. Alternators are readily available. I think there were even 12V components for these items at one point?

Going to 12V might be achievable but probably 24V for starting makes the most sense. Then either an automatic 24V-12V charger could be used or an accessory 12V alternator could be installed if you don’t have that already.

The second alternator 12V makes sense to me because there’s SO MANY good 12V lighting, pump, accessories etc available at a decent price.
However, 24V makes sense, too, because it’s easily charged with your (new) alternators OR solar (or shore power). And stepping to 12V is doable: ‘distribute’ at 24V (less distance losses than 12V) and use 24V-12V DC converters locally where required.

You will need to decide what to do with those options. And that decision will drive everything else you do and make your choices for you in many cases. But the first jump will cost more than a few grand. (You could convert one motor to 24V at a time and make that a phase-in but you would lose the ability to switch starting batteries between motors until both were 24V)

The follow-up step I’d do is phase out the high demand 120VAC stuff. When those loads get updated, powering independent of shore power or the generator with solar becomes tangible.

In the fwiw department, when you do the phases, I would buy spares: an extra 24-12V converter, spare 24VDC-120AC inverter. Keep them NIB in zip-lock bags for Justin. Justin Case. Just like you probably carry spare belts, bilge pump, and alternator now. Luck favors the prepared, and Justin and Murphy don’t get along...

Thanks for your thoughts. A lot of it is what I am thinking. One thing I do have to say is that stepping down to 12V is not doable because of wire size. There are hundreds and hundreds of feet of wire in the 32V system, and some of it is pretty hefty draw. (Head and water pumps for instance) As these die, (it's all working for now) they will be converted to 24V on the starboard side.

 

[yachtdweller]

Hey @oscarvan - fellow yacht owner here. Details on my boat toward the end of my post.

I joined the forum here with a similar line of inquiry in mind: feasible to drop in a 32v bank of LifePO4 as 10S?

I do like your thinking of splitting the banks, sounds more complex to keep track of but lets you move things over to a new voltage standard piecemeal. I'll keep it in mind as time wears on and other 32v stuff disappears from the market. Let me know if you're looking to offload any working 32vdc electrical other than bulbs!

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Replying generally to the above discussion,
The arguments for building from scratch with 12/24v are favorable, I think. Compatibilty, selection of devices, ease of replacement. No argument there.

If I had to start from scratch with new wiring, I'd build around 24v just because of the wiring run lengths involved on a boat this size - gauging wire runs from battery through load panel and then over to a 12v windlass motor (right at the bow) or mizzen mast-mounted winch (aft and aloft) is basically a non-starter in my particular use case. Some of the pumps and blowers are also far enough from the batteries where it is just an unreasonable amount of marine-grade wire to buy all at once.

Boat life note: Siting batteries with the current draw requirement of starters, inverter, etc. is non-trivial in any boat and 4/0 gets costly even when you can make it reach given ABYC spec for conductors and current. This gets more costly and challenging the lower you go with system voltage. Hopefully we all recognize that with decreasing nominal voltage, larger conductors are mandatory at a given load current over the same distance. Lower-voltage motive loads also draw more amps vs. their higher-voltage counterparts, exacerbating the matter. V=IR yadda-yadda.

As you've said, it isn't quite as simple as it sounds going away from 32v entirely. Depending on the size of vessel, there may be several hundreds of feet (my case) of 2-conductor wire which are not gauged appropriately for 24v or especially 12v use. Voltage drop and fire risk from overheating conductors become major considerations, the conversion implies replacing nearly all of the original wiring for 32v systems, not to mention any lighting+fixtures (fixture internals and grounding will also typically be sized to 32v from the builder!). Add to that all of the blowers, pumps, any original accessories or electronics, instruments, load panels and circuit protection... we quickly realize it isn't merely a matter of swapping out the alternators and starters. More than a few $$$$s of gear by my estimation, just to keep the same functionality already available on 32vdc.

A further pointer I received on the starters - I am told any motive electrical shop worth it's salt should be able to redo the windings in your existing starters for a reasonable fee (more reasonable than a whole new 24v truck starter, at any rate), but you would still need to change out the solenoid for one with the appropriate voltage - some savings is possible this way if you do end up going the route of changing your system voltage.

For inverter needs, consider finding a NOS Outback VFX3232M if at all possible. It was only recently discontinued so there are hopefully still some in stock out there. I have this inverter and it is very well made. I believe it works with the various Outback "Mate" control modules still sold for their 12/24v model inverters. I run every 120v AC load from it (but no 240 without shore/gen). I'm going to run this until I can't any more but I do expect it to last a good long while. Don't install it where it can get sprayed by leaking water (ask me how I know).

Regarding step-down to lower voltage for nav and instrument electronics:
I've just replaced my Newmar 32-12-25A with a heavier yet more compact 28~52v input to 12v 60A out brick which is IP67-rated whereas the Newmar had open end ventilation. The old one still powers on but started having problems keeping my Fusion stereo's subwoofer adequately supplied (the dang bass kept cutting out while I'm rocking out!) after an incident. As with the inverter, I'd recommend putting your Newmar unit somewhere it isn't ever going to even catch a fine mist, mine was bulkhead-mounted but not in the best of locations.

One idea I've been toying with: there are Amazon-available, protected circuit step-down and step-up DC-DC converters featuring Ingress Protection (e.g. IP67 or IP68) ratings thanks I believe to the golf cart market. I want to use these at point-use loads which need to be 24 or 12v (for example if you want reasonable options for nav equiment or even just color LEDs you give up on sticking with 32v). Their current ratings seem ample enough with 5/10/20/30A possible when going from 28~56v input to 24v or 12v. I think this will let me wring new life out of all the near-ubiquitous 32v accessory/outlet circuits which are serviceable but no longer have any devices to plug into them. The wiring is already there!

-----

I've got a custom 57ft 1964 Alden twin diesel trawler (though not quite a one-off design, there is a single-screw sister ship out there somewhere) and some similar electrical considerations to @oscarvan
I too have 32v primary systems original to the boat with dual starting banks (as with your vessel one doubles as the house bank). At 220ah and flooded lead acid tech they aren't anything to write home about, but they manage the ship loads adequately and I have no complaints under the type of use the boat sees. I've also got an isolation transformer for shore power at 30A or 50A, 15kw single-phase genset, as well as 120/240v loads with 32v 3200w inverter for the 120 branches, plus a growing collection of 12v accessories and electronics. Mostly I just want more capacity so I can benefit more from renewables and stay off the aging (1984) diesel genset for longer periods when away from dock.

Upshot of all this is that for now I'm going to maintain 32v on both banks - it certainly has its advantage (OK, mostly just for voltage drop over long runs) and as in your case, everything wired to it still works.

I want to build a 10S bank with BMS soon, ideally at a form factor that can drop right in where those 8x massive 8v cells are currently installed - possibly leaving room at the end closest to the starters for a supercapacitor module to even more handily serve inrush current demands like starters, pumps, and compressors.

 

[yachtdweller]

The 32v model of this charger is also still available:

Sentry Battery Chargers 12V 24V 36V Dometic

Sentry FR Series Battery Chargers 12V 24V 36V Dometic, Sentry FR Series Battery Chargers 12V 24V 36V Dometic, Sentry FR Series Battery Chargers 12V 24V 36V

yachtaidmarine.com

The link says 36 but the product details and voltage selection say 32, the actual device is a 32v.