How many 18650 do I need? Is it even possible?

I have a dream. I want to quit my job and make a food truck. I don't want to use a generator, instead I was thinking about using 18650 batteries like a PowerWall, but as cheap as possible. I was going to hit up all the computer repair shops in the city and see how many I could get.
My calculations are that I will need about 30,000 watts over an 8 hour period for my AC electricity needs. My back-of-the-napkin guess is about 4000 cells.
Is this stupid of me? I have a very limited budget, which is why I'm looking for every angle I can get to bootstrap this project.
Thank you for your input.

Possible yes, practical - perhaps not to produce that much power you'll need an expensive reliable inverter & my guess at least 8000-10000 cells if you want them to last any length of time. Probably cheaper and faster to go a good generator. Less space and a few bucks of fuel a day.

That's an odd way of calculating it. Are you saying that you need 3.75kW on average over a 8h day which means 30kWh? If so, then 4000 cells is about right if they have ~2Ah. That's roughly 14s286p and 82A at 51.8V, assuming 4250W DC to 3750W AC conversion at ~88% efficiency. The battery will be 200kg and also pretty big so you would need a big truck. I can't imagine having so much spare space in a vehicle that is essentially a moving kitchen. And I guess you haven't accounted for any reserves in battery capacity which you need if you want the battery to last as long as possible. So ~25% overhead at least and possibly even a bit more.

I think this might not be the most practical way as well. And this is not something that can be done easily on a budget. Since this is a commercial installation in a vehicle I think there are more strings attached as well which makes it more expensive. Red tape, certifications, fee, legal requirements and so on.

Since your future will be based on this I wouldn't do it. Qutting your job is already a risk you are taking as it is not easy to earn money with selling food. I wouldn't take avoidable risks on top of that.

If you put high wattage solar panels on the roof (and awning, perhaps) it could help to extend the battery charges. Also, depending on where you will be setting this up, you might even be able to setup a small vertical axis wind turbine as well, maybe.
You could also potentially pull a trailer that has all the power storage and collecting on the trailer and the only thing in the truck is the food/equipment. Or visa versa.

Interesting idea, intriguing idea. Practical, not sure. Depends on how much money you'd make from the food. Plus, you'd have to calculate the cost of fuel (which you'd still need a generator in case you need that extra umph for what ever reason; and as a backup) over the cost of the installation of the other equipment.

I think in the long run a generator is going to be your best bet. Depending on how big your truck is. Space is going to be a constraint. Weight certainly will be. Hauling around 200kg+ of batteries and associated electronics is probably not going to be particularly fuel efficient either.

You also have other factors too. Heat could be a potential issue. Lithium batteries are not going to like a hot environment found in a kitchen either.

A real nail in the coffin might be load spikes. If you have refrigeration equipment, you will also need to cater for load spikes when compressors start. (or soften the load using a motor soft start system)

Even adding to the system, using solar or wind to supplement your batteries, you are still adding weight. As Korishan stated, you will still need a generator as backup. If for whatever reason you overshoot your power budget.

I think the only possible practical solution would be large prismatic cells. But most of those are LiFePO4, and lower voltage than Li-Ion cells. I doubt second hand 18650s are going to work. You will need too many extra cells.

Have a look in the Cell Counter, this should give you an idea as far as how many second hand cells you will need for your project. Remember each cells weights on average 45g. You will also need to factor in the weight of bus bars and other battery interconnect.

The batteries are the least of your concern if your business is food service and your focus is rolling around in a mobile power station.

Making a setup like this is already challenging at home, in a mobile environment you have a new set of challenges for safety and road worthy durability. The amount of time it takes to use recycled cells is a deep investment, let alone the rest of the infrastructure doesnt come cheap. Embarking on a journey to become a small business owner and adding complexities for time you dont have right out of the gate isnt a good start.

Focus your time on a solid food product and business model, and keep the used batteries a hobby. If you build up a functional system you can always incorporate it down the road but a quality inverter generator like those Honda units are going to be your best bet to get your business up and running in a reliable and cost effective way.

If you really need power storage for an application like this you are better off using an Automatic charing relay and your trucks electrical system with LiFePO4 cells as laptop batteries dont fit well into a 12v system and making anything higher voltage requires DC-DC converters and just adds to the overall cost.

Really no need to complicate something that is critical to the operation and your revenue stream when you have off-the-shelf solutions that are proven.

mobile power requirements can be tackled by an inverter linked to the alternator of the motor.

a lot of servicetruck (amulances, firefighters,...) have these kind of installations.

Waeco Dometic has systems up to 5Kw, you will have to have the system fitted be specialists, they change the alternator, link it to the motormanagement, reprogram the ECU... and you have a fully working system. in theory.

maybe worth looking into

StefaanDeRidder said:

mobile power requirements can be tackled by an inverter linked to the alternator of the motor.

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Good point. A good reason to go with a diesel truck. You'd only need a 3 or 4 cylinder engine for this task. It won't change much between 1/2 and full load in rpms. Although, you would need to make sure it doesn't puff out any carbon at all. No one want's to get food from around a "smoke" stack.

Mhm, guys, have you ever been around during fire fighting operations or similar situations with big diesel engines running for hours?

I have on a regular basis and let me tell you, no, you don't want that for your customers while serving food. Yes, it is possible, but under the usual scheme of emergency operations this is a necessity. You don't do it because it's a nice and convenient solution, you do it because you have to. You will have exhaust fumes, noise and heat. And a lot of each. Especially during summer this is really nice. If you're blind and deaf you can still easily tell when you are near a truck because it is extremely hot in the immediate vicinity.

It's not that bad when it's only one truck, but still, I'd say this is a no-no. Imagine you're attending a street food festival of some sort and every food truck does this
It's also extremely wasteful to have the engine running just to make some electricity. To put it into perspective, even a small truck engine would easily be powerful enough for a generator in the range of 50kW output.

That's why you usually use a grid connection or, if this is not possible, use gas powered equipment or a small pertrol powered generator.

Running a car engine is great, but a very inefficient way of generating power unless you need to be driving anyway.

For a little more than the cost of a quality inverter, you can start looking at 2-3kw gens.

I paid 1k for a 2000 watt Yamaha pure sine inverter gen with a tri-fuel kit and I can run off NG, LP, or Gas.

Well, with DarkRavens response, I would agree overall. However, there are way to keep the exhaust from interfering with the customers purchase. But, there's also the option of using Propane generator or a propane based engine.

Overall, there are lots of options. All of them should be looked at and the pros/cons should be weighed for each.

One Way I could see it working is to get a couple tesla Batteries or Volt Packs and Run them with Multiple Inverters to split the high loads. But would be costly but doable. Setting up Grid tied Charging would be fairly easy and depending on how much was used etc to offset some of the charging by installing Solar on the roof.

I dont know exactly what you have to run but i would try to run heating from propane and rest from battery...

jdeadman said:

One Way I could see it working is to get a couple tesla Batteries or Volt Packs and Run them with Multiple Inverters to split the high loads. But would be costly but doable. Setting up Grid tied Charging would be fairly easy and depending on how much was used etc to offset some of the charging by installing Solar on the roof.

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Tesla batteries and "cheap as possible"generally don't go in the same sentence.

I dont know what type of cost constraints he is working with, but without more information about actual load requirements, or budget, its pretty difficult to recommend a direction.

30kWh of Tesla packs would cost $8400, 40kWh to allow for some overhead would be $11,200 @ $1400 per pack.

All I know is that most food trucks I have seen at a festival, party, or private catered event generally have something along the lines of a 3kw generator, and that assumes they are running gas/propane fryers or ranges.

Reallyfor $2000 he can just get one of these and be done with it, and focus on running his business.
https://powerequipment.honda.com/generators/models/eu3000is

CrimpDaddy said:

....Reallyfor $2000 he can just get one of these and be done with it, and focus on running his business.
https://powerequipment.honda.com/generators/models/eu3000is

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But .... batteries and solar are waaaay more fun ....

emmeyekayeee said:

I have a dream. I want to quit my job and make a food truck. I don't want to use a generator, instead I was thinking about using 18650 batteries like a PowerWall, but as cheap as possible. I was going to hit up all the computer repair shops in the city and see how many I could get.
My calculations are that I will need about 30,000 watts over an 8 hour period for my AC electricity needs. My back-of-the-napkin guess is about 4000 cells.
Is this stupid of me? I have a very limited budget, which is why I'm looking for every angle I can get to bootstrap this project.
Thank you for your input.

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Go for it buddy. Life is short. Are you going to use propane for cooking? Heating and cooking with electricity would kill your plan. That said, if you are cooking with gas then you just need a refrigerator and a freezer, and a microwave, and an electric water pump. Not much power required forLED lights and a blender for the margaritas (milkshakes/whatever) I think a30k kWh battery with as many solar panels as you could fit on the top of the truck, a 4kW off-grid inverter/charger,(and possiblysmall backup generator), couldbe a great business if the menuissimple the food isgreat. If you are running a propane grill and or deep fryer, with an exhaust hoodyou will probablyneed to add an inverter air conditioner and that will requireanother 10 or 15 kWh of batteries, a larger inverter and a backup generator for sure. It's a big investment but you should do what you love. Good Luck! Take lots of pictures of the build.

What exactly are you trying to power with electric on the truck? If you do just some lights and perhaps a fridge and your exaust fan I don't see why you couldn't be achieved. It all really depends on what you want to run. When assembling a kitchen, on wheels or in a building there are a lot of questions to be answered. Now if you plan to have any electric heat source you may be headed down the wrong path. A 3 foot electric flat top can easily consume over 7kw and that may even be 3 phase. You should try to do as much propane as possible and leave the cooking up to gas. Much more efficient that way.