question

I am not sure this is going to work out for you.

A typical 2 ring induction hob looks to be about 3kw. Thats over 12A at mains, 250A @12v and 125A at 24v.

That really pushes you to 24v. With lead acid, your capacity is going to be severly impeded by the size of current your drawing.

Say you have two of victrons largest 240AH AGMs, 24v to avoid crazy wiring thickness, then you are discharging at around 0.5C so the 240AH is more like 160AH. But you can only use half if you want to maintain a decent cycle life. So at those rates your looking at the 2x 240AH providing 80AH usable @24v (1.9kwh). So you can kill your batteries in 40mins cooking with no other loads.

If you are basically looking for a system that works just on hook up, with the ability to occasionally spin up the hob for a brew, then it could work for you.

Moving to lithiium is going to give you a lot more power as lithium don't mind the high discharge rate as much and don't have the 50% floor.

As you are also pulling so much current, battery voltage will drop a lot when the hob is on, which could lead to brown out issues.

I don't think I would consider doing this without going to lithium, a big battery bank and lots of solar (but then I would want to have at least 7 days off-grid, perhaps doesn't apply to you)

We have a single induction hob that works at full 2kw in bursts to maintain temperature. We leave that at home. I came across some model that you can limit the power in steps of 200w from 400w up. We only have a 1600va inverter in the van and manage quite ok with electric cooking, anything up to 1200w. The battery bank is 400ah @12v and 600wp solar. Most of the time we use large draw in combination with solar harvest. But with Pb batteries is a push for electric cooking. You must have enough solar to put back what you consumed. As for the 24v, unless you need over 3000w peak draw, the 12v will cope ok providing you wire and fuse accordingly, and have good professional crimps/ terminations.

I have a 12v battery that I run my induction single burner on and it's max 1800w but I never use it at full power with a 3k multi and 400ah of lifepo4 at 12v. 12v is fine, 24v would work too. Check your DC loads as some may only work at 12v (lights for example). Most DC fridges are 12/24v but check that too. Since you are using a DC-DC then charger from the alternator will work with 24v if you get the right DC-DC. If you have to use a 24-12v converter to power your DC loads, if it were me, I'd just stick to 12v and buy thicker cables ;).

I will keep the system 12V to keep everything straight forward, lights, pumps, fridges etc.

Because of that I won't go with a bigger than 1600VA inverter, just look for a induction cooker which will work on the size inverter.

Remember you can still go with 24, 36 or 48V solar panels, as long as you get the correct MPPT controller which can handle the voltage.

I would say the same as above: 12v is simpler if you get a mppt that can handle the panels and cables to power the loads to your inverter.

If you can afford lithium, fine but the real issue is the burner. I don't use one but have friends who do. I'd look at the specs on it and check boat/RV ones people post about on YouTube that they have found work.

12v is simpler in small spaces but way cheaper than 24v and lithium even with huge wiring.

24v will give you easier system with mppt and 12v batteries but you need 24v inverter which is less common and a separate DC-DC system for anything 12v that can't handle the 24-29v specs.

And if you plan on using a big fancy burner you really are designing everything around that cooktop. So is that the top and main priority for solar and lithium and power in your build?

If so, 24v and go the extra expense (and make sure your inverter will still provide power when lithium voltage drops).

If the stove is anything but the main concern than 12v for a balanced system after checking what burners and their specs others in your situation are using successfully via YouTube, etc.

I've seen both by the way but def' YouTube other similar builds.

Thank you for all your answers. I have come across a "camping" induction hob made by vango (https://camperessentials.co.uk/product/vango-sizzle-double-induction-hob/ ) with a peak draw of 800 watt per hob which should reduce the on/off load during operation assuming it heats in bursts.

All the equipment on board is either 12v or 24v already other than lighting that could be series wired in pairs to make the correct voltage, however, if there is going to be little efficiency gain in going to 24v it seams a needless faff to do so! As suggested i will oversize the primary cabling and keep it as short as possible!

Final equipment list as follows if interested/can see a mistake!

2 x 320watt solar panels (9.54 IMPP, 33.55 VMPP, 9.87 ISC, 40.65VOC)

1 x Victron smart solar 100/50 ( I would cable the array in parralel to stay within the max voltage)

1 x Victron Cyrix-ct Combiner

1 x Victron Smartshunt 500Amp

1 x Victron Phoenix 1600Va

1 x Victron blue Battery Charger 15amp (undersized for battery bank but the 12v consumption is relatively low (>500 watts per day)

3 x 110 ah AGM Batteries in parralel

(Any observations or criticism would be appreciated!)

With a 1.6kw max draw (although not possible through the inverter) at 12v being 135amps, shared across 3 batteies so 45 amps per battery, would this be too aggressive a rate of discharge and cause issues?

Cheers

Dom

I would go 12V for simplicity and just put up with having to run fat cables.

My current van is based on an all-electric setup, with the major applicances being 230V AC as well, as a 230V AC unit is invariably cheaper than a 12V DC one.

I have a 2000W Induction, although I rarely run it above 1000W as they are just so fast! I also have a 10L 2kW Water Heater - takes around 10 minutes to heat all the 10L to max temp and I run a 230V Compressor Fridge.

All the above are fed by a Multiplus 12/3000/120 and 645Ah of Lead Acid. I do have Lead Carbon batteries which can deliver high current better than standard Lead Acid.

By going 230V, I would have saved a lot more money than the battery bank cost me. And a Refillable gas bottle system and install would probably have cost more than the Multiplus

One reason why I went all electric is I wanted to be able to use mains power-tools from the van on occasions and as I would have that ability, I may as well make use of the big bank for other stuff. Charging is via the hookup, B2B or 460W of Solar.