Higher-Voltage House Banks:
The Real Costs, Benefits & Pitfalls Nobody Tells You About

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Preface:

I get so may questions on this topic I decided to discuss. A lot of these questions arise because in Europe 48V inverters etc. are about half the price as North America. Going 24V is much easier as more 24V equipment exists than 48V. Pricing will come down and converting to 48V will become more affordable we are just not quite there yet in NA. This is no different for those of us who started with LiFePO4 in 2007 and had to wait patiently until the industry matured.. It will happen faster than LFP just understand that today we are on the very forefront of 48V house banks..

Introduction

For more than sixty years the marine  RV, marine & automotive world has standardized on 12V DC. Pumps, lights, autopilots, chart plotters starters, alternators, VHFs, refrigeration—nearly everything on boats & RV’s expects 12 volts. With LiFePO₄ now the most popular deep-cycle battery option, boat owners naturally ask:

“Should I upgrade to 24V or 48V?”

On paper, high-voltage systems look incredible and they can be. In real-world installations, however, compatibility and conversion cost are the real deciding factors.

A very simplistic  48V Installation looks like this:

Additional charging or loads can be connected to the Lynx  fused Bus. If additional high current loads are desired Lynx Distribution busses can be daisy chained.

In this image I have chosen Epoch 48V 100Ah batts that have Victron Communication. These are marine-duty 48V batts

This article features a Victron  48V -3000-35 Multiplus inverter/charger.  Why? Because, Victron is very reliable and the most full featured brand out there.  Feature for feature their pricing is very aggressive. It has now been 10 + years since Victron took over the MPPT Solar market by adding Bluetooth to  their controllers. The industry today still does not know what hit them. We went from brands like Morningstar, BlueSky & Genasun  who owned the market to Victron being #1.Everyone of the companies are still, to this day, clinging to life. Why? Because Victron innovates the rest stagnate.. They also stand behind what they sell with a five year warranty and the Victron support community is huge worldwide.

Purchasing Victron Components?

Purchasing Victron Equipment means choosing a good dealer. With Victron’s model, all tech support & warranty-processing  flow through their massive world-wide network of factory trained dealers.

Victron does not offer consumer level tech support because all their dealers are trained to do this locally. This keeps Victron insanely competitive and allows them to keep pricing in line, as tech support is insanely expensive. It’s one of the reasons they literally own the marine market when it comes to inverters etc. and a major reason to avoid purchasing Victron from eBay, Amazon etc. as there is zero support. Victron can track down the reseller by serial number but, this process can take weeks. With a Victron dealer you pick up the phone and the ball is rolling instantly.

We highly recommend purchasing your Victron Components from Bay Marine Supply. They have amazing support and we get a very small commission for sending business their way to help keep this site FREE.

Buy Victron Components – Bay Marine Supply

 
As for Epoch Batteries, we advise buying through LFP Experts. LFP experts is owned by ABYC techs, Andre Cormier & Ben Stein (Panbo)  & Allen Jones, who know what they are doing and by far have the most experience of any Epoch dealer I know of.

Buy Epoch Batteries from LFP Experts

Equipment 48V vs. 12V 

As can be seen the 48V  & 12V units are nearly identical size wise. The difference here is the 12V Multiplus (MP) unit is doing far more work than the 48V  as evidenced by the dual positive &  neg terminals  on the 12V unit. The 48V unit retails for $1,184.90 & the 12V for $1,088.00. As we can see in North America  the 48V is actually a little more expensive.

In this photo we can visually see the difference in the work 12V unit is doing. Just above the pos & neg terminals is the H-Bridge mosfet rectifier with 6 black wires. Compare that to the 48V on the left.

Low Frequency Transformer:

It should be noted that Victron uses  very large/robust Toroidal  transformers  not inexpensive, noisy EI transformers.

What is an EI transformer?

An EI transformer uses a core built from laminated steel shaped like the letters “E” and “I.” This is  a cost-effective, easily wound design is common in power supplies, industrial machinery, and lighting—offering simple, reliable voltage transformation at scale. Victron chooses Toroidal because it is just a better transformer.

Benefits of  Toroidal vs. EI transformers:

*Toroidal  transformers are more efficient, 90-98%
*Toroidal transformers are naturally self-shielded and emit very little EMI
*Toroidal transformers are compact and lightweigh, up to 50% lighter for the equivalent power rating.
*Toroidal transformers are very quiet; with low hum and vibration compared to EI transformers.

Why Higher Voltage is Attractive

1. Higher Voltage = Lower Current (Smaller Wire)

 

Lower current means:

• Smaller wire

• Less voltage drop

• Less heat

• Longer allowable wire runs

• More efficient inverter performance

Voltage vs Current at Same Load

The Catch 22, 60+ Years of 12V 

Once you leave 12V, almost every major DC device needs replacement, or you run as much as you can on AC voltage via the MP.

Equipment That Needs to Match Bank Voltage

The trusty old Blue Sea Systems (BSS), Perko, Guest etc. switches are not rated for 48V (really a 60V rating). This is not an easy change as UL is required and 60V jumps a much bigger arc than 32V.. We are still patiently waiting on Blue Sea Systems  to address this.

On the other side of the corporate structure BEP/Marinco, BSS sister company, has addressed this and with my favorite manual battery switch. This switch is 60V rated, Victron also now offers a 60V rated Switch. The point is, very few boats have 60V rated switches. Even the top notch BSS remote battery switches are only 12/24V.

Upgrade Cost Reality Check?

The cost of replacing 12V components with 24V or 48V almost always exceeds the cost of simply using heavier 12V wiring. Sure, In Europe 48V 230V inverters are less costly than 12V, by about 1/3, but that is simply  not the case in North America.

This—more than anything—is why 12V remains the dominant marine voltage.

Let’s assume you already have a 12V  Maxwell Windlass. Just buying  the 48V windlass motor is going to run $572.00 for one 12V device swap. Of course you then need to source a 48V solenoid too, and we’re still on the windlass. Notice how they cant even provide a picture.? The harsh reality is that 48V equipment is still bleeding edge, with low volume, hence companies not putting too much marketing effort into selling 48V windlass motors.. Some manufacturers sill don’t even offer 48V windlasses..

Keep 12V add 48V?

If had a dime for every time I have been asked about this I’d be sipping margaritas on a beach. Perhaps the easiest way for a high voltage conversion is to leave your engine 12V, add a second 48V  alternator to directly charge the 48V bank, Yanmar, Volvo & Beta all have brackets for second alternators.

Once you dive into converting the engine to 24V or 48V it gets more complicated. If leaving the engine 12V you will need to remove any combining battery switches or VSR’s and be 150% sure 12V and 48V shall not meet anywhere onboard, or the smoke monster escapes!A benefit to this method is you retain a 12V battery for any tough to convert items as your buffer battery.

What About DC-to-DC Converters

DC-to-DC converters work well for small  non motor loads:

• Radios

• LED lighting

• Navigation electronics

But they typically cannot safely power inductive or DC motor loads.

Why DC-to-DC Converters Fail for Motor loads

DC motors have in-rush current at startup— in-rush is typically 5× or more of the motors “rated” load.

Example:

• Windlass: 700A in-rush

• Large DC-DC converter: 35A intermittent, 20A continuous

The Problem With In-Rush Current

A DC-to-DC converter cannot be used for heavy loads without risking converter failure unless you buffer the in-rush loads with a 12V battery.

This is easy if you use a 48V to 12V  DC converter/charger as pictured.

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Charging Higher Voltage Banks

The Arco Zeus Alternator’s &  regulators can work up to 48V, but:

• True 48V alternators are currently quite expensive and very few actually exist. Most still require 12V for the field signal.. The ARCO alternators are true 48V alts including the proprietary stator. alts like the Mahle and Balmar 48V alts are still running a 12 volt rotor.

• Replacement parts for 48V alts are scarce in far away places

It’s absolutely possible, and 48V equipment availability grows daily but,  it is  not not necessarily cheaper or easier.

Which Boats Should Consider Higher Voltage?

A high-voltage bank makes sense when:

• You run very large inverter loads eg: cooking, climate control etc.

• Your boat already uses 24V or 48Vhigh-voltage thrusters/windlass

• You’re doing a full electrical refit

• You can source all DC components in the new voltage

• You’re building a brand new boat

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Which Boats Should Consider Sticking With 12V?

Stick with 12V if:

• Your boat already has a plethora of 12V devices, that work.

• You want affordability and global replacement availability

• You value world wide simplicity and serviceability

• You don’t want a multi-voltage DC system

• You cruise internationally where 24V or 48V equipment is scarce.

Bottom Line

Higher voltage banks offer real benefits:

• Smaller wire

• Reduced current

• Conversion Efficiency

But…

Most of the cost is not in the wire, as we hear repeated so often. The real  cost is in replacing nearly every major 12V component on your vessel.

While 48V equipments is on the rise, driven mostly by the RV& off-grid industry, we are still bleeding edge just like it was in 2007 for LiFePo4. Give it a few years and we’ll see a ton of needed growth in 48V equipment!

12V remains the most practical, affordable, and supportable voltage. For new builds, 24 or 48V makes a ton of sense or for the boat that wants to run on AC power for most items.

Good Luck & happy Boating!

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