12v vs 24v

[edlittle]

I'm having so much decision anxiety between 12V vs 24V for my Transit build. I'll be traveling with my wife for a few months, and our plan is to use propane for water heating and cooking and no A/C. This makes me think I should stick with 12V due to the availability of appliances and loads, but I'm considering 24V so that I could run smaller cables and possible add more batteries/loads later on. My only components so far are 2x 200W 12V Rich Solar Panels, which I believe I can work with a 24V MPPT anyway?

Has anyone else made this decision?

 

[fratermus]

I see no particular need for 24v in this use case unless you just want it. OTOH if you were running 2000w-3000w inverter loads loads 24v would make a big diff in wiring sizes and maybe inverter efficiency.

12v bank also leaves open the possiblity of direct-charging from the alternator if you were thinking about that.

2x 200W 12V Rich Solar Panels, which I believe I can work with a 24V MPPT anyway?

With a 24v bank the 12v nominal panels would need to be run in series to get enough voltage to charge. Assuming one has a normal bucking MPPT and not an exotic boosting one.

 

[Rocketman]

If you will have a microwave on an inverter- go with 24v (or any other high load 120v items - hairdryers,etc).

If no large inverter go with 12v.

The difference between 6ga wire and 10ga will not be significant.

 

[edlittle]

Thanks, there probably won't be high load 120v items, I'm thinking the highest load will be our kettle for coffee which maxes at 1200W. I'll stick with the 12V system

 

[12VoltInstalls]

If you will have a microwave on an inverter- go with 24v (or any other high load 120v items - hairdryers,etc).

Yes. To a point.

This makes me think I should stick with 12V due to the availability of appliances and loads, but I'm considering 24V so that I could run smaller cables and possible add more batteries/loads later on.

If you ever add a microwave don’t buy a huge one. 12V is good to 2000W; 3000W steady is past what you should do for 12V systems.
An intermittent load like a smaller microwave could require 3000W inverter for startup surge, but run at 1200W or maybe less.

That you don’t have a microwave now, and you were traveling in a native 12 V system vehicle, I couldn’t come up with any reason to go 24 V in your situation. In my opinion, even if you add a microwave in the future, I would still stay with 12 V in your situation.

Yes the cable cost will be significantly higher by percentage. However, on the grand scale of things the dollars really aren’t that significant to cable up for 250 Amps. If you never can imagine adding a microwave then staying 12 V is a no-brainer.

In my experience a 2000Watt pure sine inverter will more than handle anything you could throw at it from a shop vac to a refrigerator. And with the 12 V native system there’s lots of components like cell phone chargers etc. to be had inexpensively for quality pieces to meet your needs – never mind the plethora of 12V lighting options in LED.

You may say you don’t need a 2000 water inverter and that is probably true. However, having the availability to run a vacuum or have plenty of headroom for a coffee maker or whatever combined with the fact that halfway decent inexpensive 2000W psw inverters are readily available with 11W idle consumption up to say -26W for AIO stuff I’d just do it.

I’d suggest your 400W of solar should be adequate for you. Not overly sufficient, but adequate and possible depending on your batteries/type and expected loads. A 140Ah lfp battery will live under that acceptably re: charging capacity. Two 140Ah lithiums might want 600W of panels unless your daily Wh are fairly modest and you merely want a couple days of buffer. Each 200W of panels matches up adequately per 100Ah of usable battery storage.

 

[edlittle]

In my experience a 2000Watt pure sine inverter will more than handle anything you could throw at it from a shop vac to a refrigerator. And with the 12 V native system there’s lots of components like cell phone chargers etc. to be had inexpensively for quality pieces to meet your needs – never mind the plethora of 12V lighting options in LED.

I'm planning on the 2000W Victron Inverter/Charge so this is perfect.

I’d suggest your 400W of solar should be adequate for you. Not overly sufficient, but adequate and possible depending on your batteries/type and expected loads. A 140Ah lfp battery will live under that acceptably re: charging capacity. Two 140Ah lithiums might want 600W of panels unless your daily Wh are fairly modest and you merely want a couple days of buffer. Each 200W of panels matches up adequately per 100Ah of usable battery storage.

I'm thinking of grabbing 2 100Ah batteries, would it make more sense to size up and add solar later on or start small and then add capacity later if the buffer isn't working out?

 

[12VoltInstalls]

Perfect. You’ll know if it works or doesn’t- then compensate with your future decisions.
Too many people look for a perfect one-time spend with no vision for flexibility and are disappointed because they have unrealistic expectations- and then blame the equipment. A lot of businesses that make it past four years but close in ten have suffered for six years because they don’t have vision or flexibility.

An eye for a possible upgrade - vision- frees your mind so much the likelihood of success is many factors higher.

With lithium batteries you can add later- solar as well. From my shoes I’d run what you’ve got because I think you’ll be fine for stated usage (although you didn’t specify daily Wh). If using an AIO you might need more battery and a panel but with typical small system components idle consumption is like not even worth considering. I could run full time (other than Nov to March-ish) on 400W of panels and 200-300Ah of batteries- and have. Not ideal but can be done.

I’d use what you’ve got and try it but leave expanding room if that reveals itself to be needed.

 

[edlittle]

With lithium batteries you can add later- solar as well. From my shoes I’d run what you’ve got because I think you’ll be fine for stated usage (although you didn’t specify daily Wh). If using an AIO you might need more battery and a panel

When you say AIO, you mean an Inverter/Charger?

 

[RoadTurtle]

If you will have a microwave on an inverter- go with 24v (or any other high load 120v items - hairdryers,etc).

If no large inverter go with 12v.

The difference between 6ga wire and 10ga will not be significant.

If the wires are properly sized, then why would running a microwave drive you to 24v or 12v?

 

[John Frum]

When you say AIO, you mean an Inverter/Charger?

An AIO is an inverter/charger plus solar charge controller.

 

[edlittle]

An AIO is an inverter/charger plus solar charge controller.

Ah I see. I'm planning on the Victron Multiplus + Victron MPPT, so I'm assuming the idle consumption will be less (especially since I plan on having an inverter shut off switch)

 

[John Frum]

Ah I see. I'm planning on the Victron Multiplus + Victron MPPT, so I'm assuming the idle consumption will be less (especially since I plan on having an inverter shut off switch)

If Victron made an AIO it would have similar idle consumption to an inverter/charger and discrete MPPT.
Its Victron quality that makes the difference.

 

[Rocketman]

Since you are planning on the Victron Multiplus + mppt, look very closely at finishing the Victron stuff.

A Victron Smartshunt or BMV712 and a Cerbo (and a touch if you like to see it easily) with the needed cables makes the system easy to know where your system is.

 

[edlittle]

Yep, will definitely be completing the system with other Victron stuff. Also planning an Orion for B2B, although I've seen some people prefer Sterling Power for B2B but haven't seen enough to convince me off keeping it all in the same system.

 

[edlittle]

Based on what I've said, here's my Current Connected Cart. I'll be buying cables/lugs/terminals/fuses/heat shrink elsewhere, and will be getting a DC load block and AC fuse block elsewhere

 

[Vigo]

Looks like the start of a really nice system.

As a south texan it still feels odd to me that people intentionally choose to build anything with 'no a/c'. But i assume that means you will rely on the Transit's engine-powered AC system if the need arises?

I have a 12v system in my RV which will power my rooftop AC, but im not recommending that as a practical approach, the startup current is ~300a! But i do have a smaller 5000btu window unit i stuck in it that it will run comfortably all night, and that was basically the 'goal' of putting more batteries in my RV in the first place.

 

[KITROBASKIN]

I will leave it up to more experienced members regarding your list except for suggesting you to consider the difference in price getting a charge controller that can handle more power. This is in case you choose to create a bigger system at some point? Maybe a portable set as additional collection in cloudy weather? Other possibilities?

 

[12VoltInstalls]

still feels odd to me that people intentionally choose to build anything with 'no a/c'

Never been to texas but circa 1991 I lived in Greenville SC area. Air conditioning was not all that common in residences in my locale but growing.
So to me the ‘necessity’ of air conditioning “feels a little odd.” Not that I ‘enjoyed’ the clammy nights, nor misunderstand wanting A/C, but it was tolerable even for a northerner. Plus a lot of people sat inside their homes with A/C not turned down to 72 or whatever to avoid expensive electric bills- and it was close, stuffy, and stifling at the typical 80*F. I’d rather throw open some windows at 85 or 88*F than sit in stuffy rooms at 78. I am not really an inside person anyways.

 

[AmyG]

From a purely practical standpoint I prefer 24V to keep cable sizes down - in my experience wiring up the main components in a small space can be a real pain with large stiff cables. I run mostly DC loads, and while there are some (MaxxAir fan, cellular router) that require 12V, I found that many (Dometic fridge, LED lights, USB-C charging for laptop, phone) can take either 12V or 24V. A 20 amp buck converter supplying a small 12V fuse block works well for my 12V loads, and the MaxxAir fan is happy because it's getting a steady 12V with no spikes.

Looks like you'll have a sweet system with all the Victron components - I second the suggestion to include the shunt - makes it much easier to see what's going on with the system and helps with the learning process.

 

[KITROBASKIN]

Doesn´t edlittle need the Cerbo display for the Cerbo system controller? Will then edlittle still want the battery monitor?