Battery Energy Storage Appliances
I was reading today about a new induction stove that claims to be able to output over 10,000 Watts but uses a 120V, 15A supply. The way it does this is by having a battery on-board with enough capacity to provide short bursts of power, it’s analogous to the way a tank water heater can provide more hot water flow than a tankless one.
What’s interesting about this is that it would overcome one of the big obstacles to switching to induction, which is not having sufficient electrical capacity. Cooktops would seem particularly well-suited to this approach because they typically are used at high intensity for short periods.
While it’s an interesting idea, I’m not impressed by the actual product. You can see the specs here: https://www.channingcopper.com/products/pre-order
First, they’re selling an entire appliance with the battery technology. It seems to me that it would make more sense to sell a box that’s basically a 120V plug, a battery and a 220V receptacle, with the necessary electronics, that the consumer can install in a cabinet and then choose their own appliance to work with.
Second, the battery they’re including seems awfully small, 4000 wh. That’s good for about 30 minutes on full power, which seems a little light.
Third, their website has a bunch of pie-in-the-sky stuff about using appliances to power the grid. Let’s work on getting the kitchen working first.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Should let you use the biggest “burner” at max for around an hour, which is probably sufficient. It’ll still be plugged in so the smallest burners won’t need to tap the battery. Unclear about the oven specs however. I would also like to see a separate battery but it’s not much of a deal breaker - most ranges look the same anyway.
Deleted
First of all, don't most houses already have a 200 amp service, so adding a new 50 amp circuit shouldn't be very difficult or expensive.
This cooktop reflects the reality that batteries currently cost about $1000 per kw. So you'd be paying an extra $4000 or so to avoid the cost of running a new 50 amp/ 240 volt circuit.
Doesn't say how much this range weighs. Batteries are heavy. I'd guess the battery adds around 75 pounds. And the battery would be around 30" x 12" x 6", based on a comparison with a Tesla Power wall 2, which has about four times the capacity, weighs around 300 pounds and measures 30 x 6 x 45.
So where does the same extra space for the battery come from?
I’d need to see the citation for the 200 amp service :). Regardless, many homes don’t have that so this product can address that.
In older housing stock it's a huge issue. A lot of older houses still have 100A service. It's also a big issue for apartments and condos, where running a new 50A service to every unit isn't simple.
Thanks for posting. Totally agree with you -- not sure this specific product is so great for a variety of reasons, but I love the idea and that companies are trying to innovate in this area.
Nope.
The demand for a range, at least in our code is 6kW (25A). I've only run into services that won't support that once with a place that had a 120V/30A service. If your service is that old, you are replacing the wires anyways as they are well past their design life.
If you look at the cost of a 4kWh battery capable of 4C (high power) discharge plus say a 10kW grid tie inverter, running the proper wire would be fraction of that (very small fraction in case of an unfinished basement/crawl). Also a 4kWh battery+10kW grid tie inverter is not small.
Lets assume the cost can work. You are now putting a battery that doesn't like heat right under a hot oven that can run for many hours. Speaking of over running for many hours, where is the energy coming for that? Certainly not from a 120V/15A outlet.
At best, this is an idea that is half baked.
This has a very specific use case: removing an objection to people getting rid of gas stoves. The reason gas stoves are popular is that they can deliver a lot of heat in a hurry, much more than conventional electric stoves. Induction cooktops can deliver equivalent heat -- often more -- but there's no free lunch, they do that by drawing a lot of electricity. The cooktops I've seen are rated for 10,000 Watts, they draw 40 Amps full load and require a 50A circuit. This would be in addition to the circuit for an oven. In older housing the capacity isn't there, or it requires adding a new service panel or expensive interior work. In the older parts of DC it's common for houses to have 100A underground service, upgrading that is a major expense.
But how many minutes a day is the typical cooktop used at full power? Fifteen or twenty? So the average power used by a cooktop is miniscule.
I don't think this is good for ovens, which have a very different use profile.
Typical induction cooktops use a 30A, 240V circuit (typical for a 30" cooktop), or 40A, 240V circuit (typical for a 36" cooktop). A 30A circuit like that is the same as you'd use for an electric dryer. These aren't "really big" circuits, and even a 100A residential service should be able to easily support such a load. "My service is only 100A" is not a reason for induction cooking to be out of reach. Also remember that loads don't all draw their max all the time, so it's not as if the cooktop is maxxing out that 30A or 40A circuit while it's on. Many people have overly high expectations for their home's average electric loads.
I do think the battery in the cooktop is a dumb idea. I also do NOT like the idea of using batteries in homes for load leveling on the larger grid. For one, batteries have a finite cycle life, so using them for grid scale load leveling will shorten their useful life from the perspective of the homeowner. It is much better to just intelligently schedule existing devices, such as shifting the operating time of large appliances (air conditioner, water heater) around a little to spread the loads out to reduce average load on the grid. This stuff can be easily done with a little electronic brain and a relay, no need for a big, expensive, battery pack.
Energy storage is really best done at the utility, where the grid itself can help to spread out loads. I'm not a fan of trying to do that at the micro-level in individual homes, and certainly not in unreleated appliances within those homes.
Bill
My induction cooktop has a 50 amp circuit. My electric oven has another 50 amp circuit. Obviously, not necessary, since an oven/ cooktop combination uses a single 50 amp circuit.
I have not seen an induction cooktop that needs more than a 40A circuit, although that doesn't mean they don't exist. The other question is always "does it NEED a 50A circuit"? Maybe you have a 50A circuit, but could run on a 40A circuit. Either way, the AVERAGE load on that 50A circuit is probably under 20A or so. The ONLY time you're going to push the limits of the circuit is when you are running ALL burners at full power, at the same time.
Most single ovens use a 30A circuit. My double oven uses a 40A circuit, but it wouldn't surprise me to see a double oven using a 50A circuit. A 50A circuit is good for about 12kw at 240v, or about 9.6kw when derated with teh 80% rule (which doesn't always apply here).
The point is, many, if not most, induction cooktops will use a 30A or 40A circuit, and either is easily supported even by a 100A service in most cases.
Bill
Circuit sizing and demand calculations can easily get mixed up.
There is a difference between circuit size (used for selecting wires, plugs and breakers) and demand size (use for sizing house service).
For appliances with low usage, the demand is much smaller than circuit size. Even a continuous load say on a 40A circuit (ie EV charge) has a 32A demand since you can't run any circuit at full power continuously.
In our code a 12kW range (40A circuit) has only a 6kW demand, or a 4.5kW water tank (30A) is only counted as a 1.1kW demand (10A).
These demand calculations are very conservative, peak load is much smaller for most homes. Actual peak load might never even go above 50A on an all electric place.
It is no problem to have a fully electric house with a 100A service. You can even squeeze in an EV charger (15A to 20A) in most cases.
This is the cooktop I have:
https://www.ajmadison.com/cgi-bin/ajmadison/KM6375.html
16,000 Watts rated capacity combined from the burners. Requires a 50A service, but since you couldn't draw more than 40A continuous it must have internal logic that limits it to 10kW or so. But it needs a 50A circuit, you know you can't size circuits based on average load.
Service, yes. But capacity limits are a limiting factor in moving people away from gas and oil. I once demoed a house where it turned out the dryer and HVAC compressor were on the same circuit, I'm sure it was just easier than adding capacity. I bet the owner always wondered why they couldn't do laundry when the air conditioner was running.
The spec says that unit is 11kW. So in our code, that 11kW range counts as a 6kW demand. Add a 6kW wall oven, needs to be on separate circuit, 17kW total now, the demand jumps up to 7500W or 31A. Still well within a 100A service.
Some houses do have panels that are too small, in that case you are looking at tandem breakers, a panel upgrade or a sub-panel. Adding a sub panel and new wiring just for a range is still well bellow the cost of a 4kWh battery+10kW inverter and it will not wear out in 5-10 years.