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Hypothetical 48 volt system (not Hypercritical...)


ditchcrawler

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OK people come on here and ask about electrical generation , storage, voltage etc. and we often all go off half cocked about other things so this being a hypothetical request can go anywhere, even in the bin.

 

How about having a 48 volt battery bank and inverter and as a charging system two isolated return alternators connected in series?

 

Sorry about the heading the auto correct went wild and I didn't notice

Edited by ditchcrawler
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Why does your thread title say "Hypercritical"?!

 

OK people come on here and ask about electrical generation , storage, voltage etc. and we often all go off half cocked about other things so this being a hypothetical request can go anywhere, even in the bin.

 

How about having a 48 volt battery bank and inverter and as a charging system two isolated return alternators connected in series?

 

Sorry about the heading the auto correct went wild and I didn't notice

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Many electrical driven boats have 48v systems with an AC generator providing the power.

Yes, but I was looking from a different angle

edit

But then maybe a Travel power with suitable charger.

 

 

 

Again SORRY about the header, I could ask a mod to change it but they have enough to do with real problems

Edited by ditchcrawler
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Difficult/impossible and expensive to get a range of 48v equipment.

 

Potential problems with the alternator regulators working in series, would maybe need a bespoke controller.

 

Lack of redundancy/unreliability, total loss of charging when either alternator fails.

 

Little electrical advantage unless doing propulsion.

 

..................Dave

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As said most boat equipment is either 12 or 24v.At 48v you would be able to get a bigger inverter it depends if you are going for a 240v equipped boat running off the inverter. there are some very good 24 and 48v generators out there rated at 5kw plus at a

constant load, don't know about a 48v alternator can you get them ?

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I wouldn't say bad - especially if the output is mainly for powering inverters, however everything else is so 'challenged' as to be a no-no.

For example most alternators have an earth return so don't lend themselves to running in series (24V are common, 48V I've never seen).

If you can't charge the batteries the idea is dead in the umm - water.

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Well it's bad insofar as you wouldn't be able to find any equipment (pumps, lights etc) that's rated at 48V and you won't be able to charge the batteries with an alternator.

 

A 48V bank that can't be used or charged becomes... er... well... bad ;)

 

Bear in mind that I'm being hypercritical as requested :lol:

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Hypothetically, its not such a good idea from the regulatory/safety point of view because "they" deem over 50 volts to be different than under 50 volts, in terms of electric shock hazard etc. With a %age over when charging, a 48 volt system would probably actually be 52-56V during charging.

 

There was talk a while ago of moving over to 42 volt for car electrical systems, but its yet to occur and I suspect it won't anytime soon. Historically, they did of course changeover from 6 volt to 12 volt though. And there's plenty of crossover with certain commercial vehicles being available with both 12V and 24V for different variants/models.

 

Airplanes use 28V DC (amongst others....there is a similarly unique AC voltage too, I think).

 

So in theory, there is no technical reason not to but in practice the barrier of regulations and the non-availability of components will not make it occur. I personally don't think the technical advantages (of smaller wiring and/or lower voltage drop etc) are enough to justify the changeover. What might be more likely is a changeover to more widespread 230V AC use, ie more or most items powered by 230V AC, since (for example) a fridge might be that voltage and thus there's already a large inverter which is on most of the time. Indeed some boats are already like this.

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I would also point out that the charging voltage for a 48v bank is going to be about 58 Volts which is getting to be a bit high and your wiring should probably be to a higher standard than a 'normal' 12V or 24V system.

 

Added - I was a bit slow typing this - see above clapping.gif

Edited by Chewbacka
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Him Spartacus has got it right,if the Boat was powered by an inverter it can have all kinds of 24 and 12 Volt supplies driven by it

 

CT

Yebbut... how you gonna charge the bank? Have a genny in addition to the propulsion engine?

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Well it's bad insofar as you wouldn't be able to find any equipment (pumps, lights etc) that's rated at 48V and you won't be able to charge the batteries with an alternator.

 

A 48V bank that can't be used or charged becomes... er... well... bad wink.png

 

Bear in mind that I'm being hypercritical as requested laugh.png

clapping.gif

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As I said I am sorry about the title. It was meant to be HYPOTHETICAL most of you seam to be sticking with the norm.

 

A little more thought

24 volt isolated return alternaters are commonly available, its standard marine kit.

48 volts would be better for feeding an inverter

The starter batter could be charged from a small 240 volt battery charger, they dont need much charging.

Why use 12 volt lights, I don't have 12 volt lights in my house. You can buy 240 volt water pumps.

Tunnel light and horn can easily be powered from the starter battery.

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48 volt systems are being looked at and designed for cars. They will probably coexist with 12 volt systems.

 

Autoblog:

Mercedes-Benz engines with 48-volt systems coming in 2017

The industry is moving toward 48-volt power, with the SAE working on a standard for the systems and Delphi claiming a 10-percent increase in fuel economy for cars that make the switch. The supplier is said to be working with two major automakers to implement 48-volt systems, and most companies are rumored to be working on adding the technology to next-gen vehicles.”

http://www.autoblog.com/2016/06/14/mercedes-benz-2017-engines-48-volt-electric/

 

 

The Economist:

At last the 48 show

http://www.economist.com/news/science-and-technology/21704778-upping-volts-will-make-hybrid-cars-much-cheaper-last-48-show

 

Autoweek:

The 12-volt car battery is about to be a thing of the past

48-VOLT POWER IS COMING, OFFERING A BIG ADVANTAGE TO AUTOMAKERS

http://autoweek.com/article/technology/48-volt-systems-are-bringing-more-power-and-better-fuel-economy

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As I said I am sorry about the title. It was meant to be HYPOTHETICAL most of you seam to be sticking with the norm.

 

A little more thought

24 volt isolated return alternaters are commonly available, its standard marine kit.

48 volts would be better for feeding an inverter

The starter batter could be charged from a small 240 volt battery charger, they dont need much charging.

Why use 12 volt lights, I don't have 12 volt lights in my house. You can buy 240 volt water pumps.

Tunnel light and horn can easily be powered from the starter battery.

 

If you needed to go via a inverter to power the pumps/lights you would be adding another point of failure as well as the additional power used for inverting itself. At home you have 240v coming into the house so you don't need to convert anything. It would be like converting to use 24v for lights in your house!

 

With the 48v boats, they primarily used 48v because of propulsion, and guessing use a DC-DC converter to drop to 12/24v for the boat appliances, of course that's another source of failure so going to 240v for pumps has some real benefits.

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There's some 48V automotive equipment avaliable, but its mainly alternators, motors and inverters. It's been used for some stopstart / mild hybrid applications. The attraction is that it's below the 60V cut off for low voltage - 4 batteries in series are Ok, 5 is over the threshold when charging.

This was going to be the big thing in automotive and re-appears every few years. Most systems are now either 12V DC or > 300V DC.

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There's some 48V automotive equipment avaliable, but its mainly alternators, motors and inverters. It's been used for some stopstart / mild hybrid applications. The attraction is that it's below the 60V cut off for low voltage - 4 batteries in series are Ok, 5 is over the threshold when charging.

This was going to be the big thing in automotive and re-appears every few years. Most systems are now either 12V DC or > 300V DC.

 

 

It must be over 20 yeas ago that I was working with Jaguar and LucasRists (Rists Wires & Cables - known as 'Twists, Lies & Fables' before they became Lucas SEI (Sumitomo) We were looking at 48v systems even then.

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