Anyone using 24 Volts or higher?

[Boyntonstu]

Solar panels can charge a 24 V batteries using thinner wires than needed for 12 V.

Are the 24 V appliances, inverters, etc?

Does it make sense to go to higher Voltages?

 

[jonsun]

someone was setting up a 48v system

 

[RVtrek]

Solar panels can charge a 24 V batteries using thinner wires than needed for 12 V.

Are the 24 V appliances, inverters, etc?

Does it make sense to go to higher Voltages?

Yep, that's me.  I haven't actually starting the build yet, but I am planning on 48v for the main system and a DC-to-DC converter for some light 12v loads.

The basic premise is that yes, with higher voltage, thinner wires are needed.

Volts x Amps = Watts

Amps determines the required thickness of wire.  If you keep the load the same (watts) and increase the volts, then amps goes down, and so does wire thickness.  Most of the RV'ing community though lives on 12v, with the exception of some bus conversions.  I think it's easy interoperability with automotive systems is why, and perhaps tradition.

If you're looking at what kinds of equipment to use with 48v:

Solar Controller: Outback Flexmax 80
Inverter/Charger: Magnum Energy MS4448PAE
DC-DC Converter: 48V Step-Down to DC 12V 30A 360W

All of the equipment above is either directly compatible with 24v or has a 24v version as well.  And these are just my favorites, there's other brands that sell this stuff too.

Edit: And I forgot to mention the biggest reason I'm going with 48v!  The mini-split A/C unit that operates completely off of 48v.  Highly efficient, quiet, and generally awesome.

 

[highdesertranger]

BradKW has a 48v system. and yes the make 24v appliances. some are 12/24v. the military stuff is all 24v. but not everything is available in 24v. also jumping vehicles becomes difficult, you can't just hook jumper cables up. highdesertranger

 

[user 15722]

I decided on a 24vdc system with the main inverter because everything is more efficient. This will be used for some specialty devices and computer/electronic equipment I care about a lot. Series parallel bank with MPPT controller and a 1500w sine wave inverter.
We will also have a much smaller 12vdc system for led lighting, which does not draw much juice, and a few other things with a PWM controller and 800w modified sine wave inverter.
and the toothbrush charger... a third 12vdc system just for that with PWM controller and 400w inverter with a pair of small panels! lol

Redundant systems built on the cheap to substitute for a hi-dollar proper system... all to eliminate genset run-time. wheels

 

[frater secessus]

also jumping vehicles becomes difficult,  you can't just hook jumper cables up.  

Good point. And alternator charging doesn't work unless the vehicle is 24v.

 

[CityWoman]

Why can't you jump a vehicle that is set up with a higher than 12v system? I thought all these power systems are supposed to be separate from the car battery. If you have solar panels feeding a battery bank that powers higher voltage appliances, how does that affect being able to jumpstart the car battery if it isn't even part of that loop?

To whoever mentioned that buses don't always use 12v, what do they use? And for what?

I'm glad this thread was started, btw. I've been thinking of starting my own with the title "Why 12v?" It seems like 12v is the holy grail, and I've been wondering why that is.

 

[highdesertranger]

because 24v will fry the electronics in any new vehicle. back in the day before computers you could do it if you knew what you were doing. everyone uses 12v because that's what the vehicles use, so there is a large aftermarket support for 12v systems. you can get 24v or 48v stuff but your choices are limited. I have a Ready-Welder it runs on 24v or 36v so it's kinda a pain in the ass, I have to remove my batteries and series wire them for 24v. but it's worth it to have a portable welder, believe me I have used it. highdesertranger

 

[Boyntonstu]

Good point. And alternator charging doesn't work unless the vehicle is 24v.

Why can't you jump a vehicle that is set up with a higher than 12v system?  I thought all these power systems are supposed to be separate from the car battery.  If you have solar panels feeding a battery bank that powers higher voltage appliances, how does that affect being able to jumpstart the car battery if it isn't even part of that loop?

To whoever mentioned that buses don't always use 12v, what do they use?  And for what?

I'm glad this thread was started, btw.  I've been thinking of starting my own with the title "Why 12v?"  It seems like 12v is the holy grail, and I've been wondering why that is.

You have a pair of 12 Volt batteries is series and you use your solar panel for charging.

A double pole double throw isolation switch would break the 24 Vseries connection and parallel the 2 batteries for 12 V alternator charging.

Like this:  +  -  +    -     Series 24 Volts

                 _______
to this:      +   -       +    -       Parallel 12 V
                     ^-----------^

To jump start from a 24 V series Battery: Jump your leads from the middle +  to the end - for 12 V.

Not too difficult.

 

[highdesertranger]

the above post is why the majority of people go with 12v. you are just adding expense, complications, and headaches to your system. highdesertranger

 

[Boyntonstu]

"the above post is why the majority of people go with 12v. you are just adding expense, complications, and headaches to your system. "

Let's break your statement down,

Expense:  12 V cabling to the solar panels is more expensive than 24 V cabling.
                Perhaps a DPDT Transfer switch is more expensive than a SPDT switch?  I dunno.
                 Batteries:  The same cost.
                 Complications:  Any wiring can confuse. Series to parallel is not terribly confusing.
                 Headaches?   I dunno.

Do you remember 6V cars?

Today's news:  48  Volt cars are coming:

https://www.extremetech.com/extreme/247889-cars-moving-48-volt-electrical-systems

 

[CityWoman]

You have a pair of 12 Volt batteries is series and you use your solar panel for charging.

A double pole double throw isolation switch would break the 24 Vseries connection and parallel the 2 batteries for 12 V alternator charging.

Like this:  +  -  +    -     Series 24 Volts

                 _______
to this:      +   -       +    -       Parallel 12 V
                     ^-----------^

To jump start from a 24 V series Battery: Jump your leads from the middle +  to the end - for 12 V.

Not too difficult.

Not difficult for anyone who already understands this stuff, I suppose. However, difficult for me. I still don't get it. I was under the assumption that the point of solar or any battery bank is to power stuff (like fridges, A/Cs, computers, etc.) with its own standalone system that doesn't involve the vehicle's battery so that it doesn't get drained. So, if it's all separate, wouldn't the battery that starts the car and runs things in it that would be used for a normal, non-nomad driver still be able to do its thing unaffected? Or am I wrong in assuming that the power systems everybody talks about here are meant to be separate from the battery and system the vehicle came with?

 

[Boyntonstu]

wouldn't the battery that starts the car and runs things in it that would be used for a normal, non-nomad driver still be able to do its thing unaffected?  Yes if that is the only battery in your vehicle.

This may help you understand Parallel and Series Batteries.

http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel

 

[highdesertranger]

Boyntonstu, if you want to go with a 24v system fine, build it and give us a report on how it's working out for you. but you are glossing over the downside and your info is confusing for newbies. I was just trying to point out the downside, something you should be doing. highdesertranger

 

[CityWoman]

It's not the type of battery that is confusing me. It is what gets hooked up to the system it runs.

Here is an example. Let's say I have a car and it is an average car with a battery under the hood. That battery is there for all the usual things car batteries use.

Now, let's say there is a boombox in the backseat. The boombox has its own set of batteries that powers it. Of course, the strength or capacity of the batteries in the boombox have no affect on the vehicle's battery, what the car battery powers, nor its ability to be jumpstarted. The six batteries in the boombox are solely responsible for operating the boombox.

Now let's say I want to set up a charger for those boombox batteries and I construct something that draws power from the sun and somehow charges them. The car battery and everything powered by it are still not affected by what I do to the system I've devised for the boombox battery, because it's not hooked up to my boombox system. They are separate.

So, am I wrong in thinking of a solar panel and the bank of batteries it would charge for using larger appliances as something like my boombox in the backseat, a totally separate entity/system from the car battery and the system connected to it in the vehicle?

 

[highdesertranger]

so now you can't use the cars charging system to charge your other battery system and without disassembling something you can't use your other battery to jump start your car in case you need to. what happens in a week long rain storm were you get very little solar charge, you have no back up. some people know what they are doing and have planned for all this. also some people like BradKW has 2 separate house systems a 48v and a 12v but he has a box truck so plenty of roof room for panels and the payload to handle the batteries. there are trade offs for everything, just pointing out the good points does no good for newbies. highdesertranger

 

[user 15722]

Yes, agree w hdr... money is what gets in the way.
Any sort of power when boondocking is a bonus and improves quality of life.
The small 100w panels are dandy for weekenders.
Full-timers are installing the full sized panels with serious battery banks and quality MPPT controllers with pure sine wave inverters.
Design a system for your needs. Then you may improve upon it for what you might want.
Best, wheels

 

[John61CT]

> I've been thinking of starting my own with the title "Why 12v?" It seems like 12v is the holy grail, and I've been wondering why that is.

For the same reasons you'd be bonkers to wire your S&B home with 240V AC.

Yes it is technically superior, and since it's widely used outside the US (like big yachts use 24V) you **can** get some version of desired appliances in that voltage.

But much fewer choices, much higher costs, much more hassle.

Doing it the way 99.99% everyone else in your situation does it has its benefits.

Lower cost for long wire runs doesn't come close to balancing those benefits for a small yacht, much less a van

 

[CityWoman]

But why 12? Where does that number come from? That's what I'm curious about. Who decided that vehicles should all use 12v and why?

Oh, and about keeping battery systems separate from each other - I give up. I thought keeping them separated was the point and now it looks like, with all the reading on forums and blogs that I've done over the last year, I understood squat. I guess I will have to look for some kind of course in electrical systems and study hard to grasp the basics. I plan on making a notebook full of cheat sheets to keep handy anyway.

 

[John61CT]

But why 12? Where does that number come from? That's what I'm curious about. Who decided that vehicles should all use 12v and why?

Gustave Planté gets the initial credit, from 1859.

Has to be a multiple of 2V, inherent in the chemistry (when full actually 2.1V), like LiFePO4 is 3.2.

12 is divisible by 2, 3, 4 and 6.

Early cars were 3 cells @6V, then industry upgraded over time to 12V, took decades.

At one time, when copper got too dear they tried increasing again, but the price went back down.