12V or 24V for a 2000W inverter with induction cooktop

filippomasoni

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Hello,
I'm designing the electrical system for a truck camper I'm going to build in the future and I'd like to order the 280ah cells since delivery time is about 3 months from China to Italy.

I need to decide between a 24V and 12V system.

Setup idea:
Solar 600W
Battery: 6720Wh 280ah 24V or 560ah 12V
Daily energy consumption: 2500Wh (worst-case scenario, I estimated 900Wh for cooking and 8h of computer use)

Since I would like to have an induction cooktop I was planning on having a big inverter and so I was decided on 24V, but I recently found a few models of cooktop that can set a maximum power draw of 1600W, 2000W, or 3600W and I'm certain 1600W will be enough for me for 2 zones. So I'll go for a smaller Giandel 2000W inverter.
At this point does it still make sense to have a 24V system or I could go with the simpler 12V?

The truck is 12V and sourcing 12V components will be easier around the world.
The cost will be a bit higher for the 12V, I'll spend more for the MPPT and a bit less for the DC-DC charger and inverter. How I planned the layout I'll have everything electrical close by with less than 1m of cables, except lights and fans, so the only longer cables are going to be for the panels and alternator.

What are your thoughts?

Also unrelated do you know where to source flexible solar panels in Europe? I was going to go with GWL but they recently discontinued their 300W version.
 

smoothJoey

mumble...
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560ah@12.8vdc = 7168 watt hours
7168 watt hours * .95 snoobler factor = 6809.6 watt hours
6809.6 watt hours * .8 depth of discharge = 5447.68 usable watt hours


The Giandel 12 volt inverter is 2200 watts.
2200 ac watts / .85 conversion factor / 12 volts low cutoff = 215.68627451 dc amps
215.68627451 dc amps / .8 fuse headroom = 269.607843137 fuse amps.

To service your inverter at 12 volts you need a 275 amp fuse and a wire that can handle 275 amps.
You will also need a bms with a continuous rating of ~220 amps.

Its my policy to size for the maximum continuous rating of the inverter.
 
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filippomasoni

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98
Thank you, that'll definitely be the way I'll do my calculations going forward.

The Giandel sold in Europe for AC 220V is 2000W both 12 and 24V versions. At least from what I see on amazon. Based on your calculation that'll put me at 196 dc amps, 245 fuse amps and probably a 200 amps bms is enough. Or for 24V a 100s bms.

The induction cooktop will be my only AC load, as everything else will be DC and with it limited to 1600W, my load will be 157 dc amp tops.

Based on that is it worth going to 24V? Using an Overkill Solar 8s BMS 100a or building a 12V battery with a 250A daly bms?
 

smoothJoey

mumble...
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Thank you, that'll definitely be the way I'll do my calculations going forward.

The Giandel sold in Europe for AC 220V is 2000W both 12 and 24V versions. At least from what I see on amazon. Based on your calculation that'll put me at 196 dc amps, 245 fuse amps and probably a 200 amps bms is enough. Or for 24V a 100s bms.

The induction cooktop will be my only AC load, as everything else will be DC and with it limited to 1600W, my load will be 157 dc amp tops.

Based on that is it worth going to 24V? Using an Overkill Solar 8s BMS 100a or building a 12V battery with a 250A daly bms?
Either will be fine.
What you save in wire size you spend on the 24->12 converter.
One of the often overlooked benefits of the converter is you get regulated 12 volts.
If you stay at 12 volts you can make 2x batteries each with its own 100amp bms and have a bit more fault tolerance.
 

filippomasoni

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Either will be fine.
What you save in wire size you spend on the 24->12 converter.
One of the often overlooked benefits of the converter is you get regulated 12 volts.
If you stay at 12 volts you can make 2x batteries each with its own 100amp bms and have a bit more fault tolerance.

Got it, yes the redundancy of having two batteries is nice, and I was actually thinking of that since I'll have 8 cells anyway. If I have a bad cell or something happens when in the middle of nowhere I still have a working system with half capacity, even though I won't be able to cook 😅

I didn't think about the regulated 12V, that's a nice bonus, what are the appliances that can benefit from that?
I know the fridge I'm going to get works both 12 and 24V so I'm assuming it has a wide tolerance and I'm going to get a couple of USB PD modules that require 9-24V input. Lights and fans should also be very tolerant of voltage. Maybe a webasto/ebesparcher works better with regulated 12V? Although if I'm doing a 24V system I'll be getting a 24V unit.
 

smoothJoey

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I didn't think about the regulated 12V, that's a nice bonus, what are the appliances that can benefit from that?
I have not run across one personally.
Some automotive accessories expect 13.6 volts and the rumor around the campfire is that some of those conk out or work sub-optimally at 12 volts or lower.
 

filippomasoni

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I have not run across one personally.
Some automotive accessories expect 13.6 volts and the rumor around the campfire is that some of those conk out or work sub-optimally at 12 volts or lower.
Oh I thought a 24->12 converter would output precisely 12V
 

HarryN

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Jul 25, 2021
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I am too lazy to build higher power 12 volt systems, so I build 24 and 48 volt versions.

The marine world is heavily into 24 volt, so world wide, any marine electrician can fix a 24 volt system easily.

To me, the big advantage of 24 volt is component size.

Example:

For your 600 watt panels, in theory you should use a solar charge controller that can handle ( 600 watts) / (12 volts) ~ 50 amps

In 24 volt, it is (600 watts) / (24 volts) ~ 25 amps, so a lower cost, more compact charge controller can be used. Physically it is smaller, cheaper, etc.

Current is under 30 amps, so now it is size 10 wire, which is really convenient in general to make your own crimped wires.

30 amp / 32 volt rated fuse setups are very common, compact and low cost.

As far as inverter brands - perhaps read some of the less positive reviews on that brand. Literally all of the US made inverters are very good, especially for induction type loads. A GOOD 2000 watt inverter costs ~ $1500. An inverter that costs $300 is a re- labled 500 watt inverter that is being pushed very hard to get your money.
 

filippomasoni

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Yes, that's a very good point. Checking again I'll actually save 350 euros for the MPPT alone. Victron 150/45 for 12V or 100/20 for 24V. From the Victron MPPT calculator page it says a 20a in enough: calculator even for this 2 330w panels.
The 100/20 is also smaller and half the weight. In a camper, everything counts.

As far as the inverter I wanted to go with Victron for everything, but the inverters, are not only 4 times the price but also 4 times the weight and size. A Phoenix 2000VA with a Cont. output power at 25ºC of 1600W is probably not enough for my 1600W load of the induction, so I'll need the 3000VA model. The Giandel was recommended here: mobile-solarpower.com so I thought it was still a good option since I won't be using it maxed out, but only 1600W.

Also going back to the 24V battery. An 8s configuration with a 100a bms is probably best, but in case of an issue with a cell I'm out of power. What other options do I have to make two smaller batteries in parallel to have redundancy?
 

Zwy

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Thank you, that'll definitely be the way I'll do my calculations going forward.

The Giandel sold in Europe for AC 220V is 2000W both 12 and 24V versions. At least from what I see on amazon. Based on your calculation that'll put me at 196 dc amps, 245 fuse amps and probably a 200 amps bms is enough. Or for 24V a 100s bms.

The induction cooktop will be my only AC load, as everything else will be DC and with it limited to 1600W, my load will be 157 dc amp tops.

Based on that is it worth going to 24V? Using an Overkill Solar 8s BMS 100a or building a 12V battery with a 250A daly bms?
If you are in Europe, I'd opt for 24V.
 

filippomasoni

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If you are in Europe, I'd opt for 24V.
Based on what do you think that?

Yes, I'm in Europe right now (Italy to be precise) and I'll built the whole system here. But I plan on traveling around the world sooner or later. Definitely in the US and south America.

24V systems are common in big trucks in Europe, but a pickup like the Ford Ranger I'm waiting for delivery is 12V like regular cars. I know that in the US is not the case, even big truck have 12V systems from what I heard, so 24V stuff is probably harder to find.
 

Steve_S

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I also recommend 24V. The cost for Battery Wires and extra for Big 12V is crazy ! @ 250A draw, you will have to have 4/0 and it's not cheap !
It is generally advised NOT to exceed 250A draw off a battery system. 12V@250A=3000W, where 24V@250A=6000W (excluding surge capacity).

Take take 24V to 12V, you would require a 30V to 12V Converter (not buck converter). Why 30V ? Because charging voltages for 24V LFP can be as high as 29.2V (3.650Vpc) otherwise you "cook" the converter.
I can comfortably recomend any of these frm Samlex (also available in EU)- BUT note the details & differences


1627389642185.png
SOURCE: https://www.victronenergy.com/upload/documents/AWG to Metric Conversion Chart.pdf
 

filippomasoni

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Thank you for all the info.

I know big loads on 12V are not ideal and I decided on 24V for that reason early on, but started to thinker about it more when I found out I actually only need 1600W from the induction and I will size for a 2000W inverter. I'll have the inverter mounted really close to the battery so wires won't be long, but still expensive and a pain to deal with for sure.

Overall I'll probably save more than 400 euro by going with 24V, so at this point, I'm back on that decision. I just liked the peace of mind of redundancy.
 

Zwy

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Based on what do you think that?

Yes, I'm in Europe right now (Italy to be precise) and I'll built the whole system here. But I plan on traveling around the world sooner or later. Definitely in the US and south America.

24V systems are common in big trucks in Europe, but a pickup like the Ford Ranger I'm waiting for delivery is 12V like regular cars. I know that in the US is not the case, even big truck have 12V systems from what I heard, so 24V stuff is probably harder to find.
But you can source 24V so much easier in Europe. As long as you buy quality, I don't see the problem.

Everything can handle more watts and the system will run easier, probably last longer due to less heat.
 

Zwy

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Messages
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I also recommend 24V. The cost for Battery Wires and extra for Big 12V is crazy ! @ 250A draw, you will have to have 4/0 and it's not cheap !
It is generally advised NOT to exceed 250A draw off a battery system. 12V@250A=3000W, where 24V@250A=6000W (excluding surge capacity).

Take take 24V to 12V, you would require a 30V to 12V Converter (not buck converter). Why 30V ? Because charging voltages for 24V LFP can be as high as 29.2V (3.650Vpc) otherwise you "cook" the converter.
I can comfortably recomend any of these frm Samlex (also available in EU)- BUT note the details & differences


View attachment 57852
SOURCE: https://www.victronenergy.com/upload/documents/AWG to Metric Conversion Chart.pdf
Are those 6w of standby consumption on the 30a model? My current buck takes roughly 30w.

Just checked mine and it draws 0.006a at 24v .Must of had something on before drawing the 36w, I think it was the inverter.
 
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bobdelso

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I went with a 24v system. Cheaper MPPT charge controller, cheaper wiring, cheaper BMS. Inverter cost is the same, and you do need to buy a 12v converter for lights and stuff.

24v @ 100 amps can put out 2400 watts. With a true copper core welding cable you can use 6 AWG for ~2-3 feet. On 12v you need #00 which is ridiculously expensive and hard to work with.
 

RCinFLA

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Not all induction cooktops are created equal. European models have power factor correcting power supplies, U.S. models generally do not.

Since U.S. residential grid usage has no regulations on power factor, many manufacturers cut costs by just using simple rectifier-filter cap to convert incoming single phase AC to DC to run induction drive inverter circuitry. For residential usage, U.S. grid charges are based on true power so there is no incentive to have good power factor appliances.

Same goes for variable compressor speed inverter-refrig's. My expensive variable speed compressor Samsung 28 cu-ft has very crappy power factor of 0.6. The European Samsung model does have PF correction.

Running poor PF loads on inverters degrades inverter efficiency so consumes more battery power. The lower the PF of load, the higher the peak inverter current. Inverter losses are proportional to current through MOSFET switches and transformer.

Since U.S. market for mini-split inverter-air conditioners is small, and Europe/other countries that do use most of mini-splits built have PF regulations, most of the mini-splits even in U.S., do have PF correcting power supplies.
 

sunshine

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Unable to refill LPG bottles in the EU?
Stay with gas and upgrade the 12v truck system you already have to power less energy hogging appliances.
 
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