Take a 'mage' whose magic takes the form of manipulating (non-magical!) energy and matter in an approximately 10m radius around them. Examples of this include high speed air currents around the mage that serve as protection or forcing oxygen away from a person to cause suffocation although they can't affect anything below electrons and neutrons etc. They also can't turn matter into energy or vice-verse.

Knowledge of science isn't required for them to perform magic- their mind 'magically' (haha!) works out how to make their spells happen, but they do have to obey any laws of physics magic doesn't directly ignore by its existence (meaning they can't create energy/matter etc). Their greatest weakness is that they can't make use of chemical energy, from themselves or batteries.

What could a mage like this-call her Anna- use as 'mana' batteries to store energy to power her spells? Ideally, the object in question should be:

  1. Light weight, so she can carry a few of them

  2. Inconspicuous, so she doesn't stick out like a sore thumb

  3. Not made of illegal substances- she should be able to acquire it through legal channels, although paperwork is fine.

  4. 'Rechargable' in her own home.

Magic in this universe is a legally accepted thing with compulsory magical education for mage-kids and various licenses for using magic in cosmetic surgery, construction etc.

  • 1
    $\begingroup$ Is it the same as green lantern power battery? $\endgroup$
    – user6760
    Commented Jul 5, 2015 at 13:16
  • $\begingroup$ I'll be honest, I understand none of that article $\endgroup$
    – Titanide
    Commented Jul 5, 2015 at 13:20
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    $\begingroup$ Why do mages need a battery if there are no rules to limit their magical capacity? $\endgroup$
    – Frostfyre
    Commented Jul 5, 2015 at 14:31
  • 1
    $\begingroup$ They use the energy in the environment around them, as the question states. They use batteries so they can cast spells without causing discomfort to people around them, and so they aren't limited to the heat/light in the immediate area. $\endgroup$
    – Titanide
    Commented Jul 5, 2015 at 14:37
  • 2
    $\begingroup$ Isn't what you're describing a staff/wand? $\endgroup$ Commented Jul 6, 2015 at 15:44

11 Answers 11


An interesting idea for this ( which shows up in one form in the Fionnavar Tapestry books ) is that the ability to carry magic is a talent a little like the ability to shape it, so the unobtrusive magical battery is another person. No extra weight to carry, not something obtrusive or obvious, but also a potentially challenging relationship with all kinds of intriguing ramifications:

  • Perhaps two people have to be attuned to be able to work together.
  • Perhaps the power can come through anyone, but it is dangerous to take it from someone untrained.
  • Perhaps only a very few people have either talent and seeking them out is a major endeavour for magical colleges.
  • $\begingroup$ I really like this. You have a symbiotic relationship. $\endgroup$
    – Josiah
    Commented Jul 6, 2015 at 15:41
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    $\begingroup$ @Josiah Reminds me of the magic system in Eragon/Inheritance cycle. Different people and different creatures have varying amounts of lifeforce, the conseqence for what happens when all lifeforce is used up in something is obviously death. Aswell as people for magic batteries, you should consider magical creatures (which should have more than other creatures), magicians having familiars is a common premise. Lifeforce is generally determined by the organisms; size, stength (mentally & physically) and aptitude to magic. Lifeforce would be eqivilant to Mana. $\endgroup$
    – Necessity
    Commented Jul 6, 2015 at 22:30

If I understand your magic rules correctly, the magic can convert/extract all the energy of matter in the 10m around to produce a magic spell.

There is nothing that would produce more energy than the binding energy of its constituants (atomic+nuclear scale). Even in a nuclear bomb, you release the binding energy of the Uranium in rapid succession, which makes the Big Boom. Your magic is more efficient.

The only interesting point you could consider is to add matter. Indeed, if you carry around more matter, you have more reserve of energy with you, that can be used to produce magic. You thus have an advantage compared to if you hadn't that matter. What to choose? Probably a high densitity material (to limit the bulkiness). Sticks of Osmium, Platinium or Mercury would be an idea.

The problem being: what prevents the opponent mage to use your sticks?

  • $\begingroup$ Not sure what OP thinks, but this could be considered converting mass to energy. $\endgroup$
    – Martin_xs6
    Commented Jul 6, 2015 at 16:26
  • 1
    $\begingroup$ I'm pretty sure that'd be outlawed, for health and safety if nothing else $\endgroup$
    – Titanide
    Commented Jul 6, 2015 at 19:41
  • $\begingroup$ @Martin_xs6 indeed, I read the question a bit too quickly it seems... $\endgroup$ Commented Jul 6, 2015 at 19:44
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    $\begingroup$ @Titanide considering that at this scale, matter and energy are essentially the same, could you clarify a bit your question, with, e.g. an example of what you mean "manipulating"? $\endgroup$ Commented Jul 6, 2015 at 19:46

How about having your magicians carry something with them that has a high specific heat capacity, and then store your energy as heat?

Even at a low technology level, the magician could heat up 5kg of water (about 10 lbs) heated 50 or so above room temperature (25C) for a stored energy of about 1 MJ. They could use even more of that energy if you allow the water to go below the ambient temperature.

1 MJ of energy is a lot. It's the equivalent energy of about 210 AA batteries, or enough to lift a 100kg mass 1000 meters!

  • $\begingroup$ So, mages carry arround bags of thermos-flasks? $\endgroup$ Commented Apr 4, 2017 at 13:38
  • $\begingroup$ This reminds me kingskiller chronicles. The guy uses heat from various sources in order to have some effect. Even heat from his own body. $\endgroup$
    – Hanilucas
    Commented Nov 28, 2017 at 0:01

Idea: the 'battery' takes the form of a metal ingot or bar. To 'discharge' the battery, the user magically induces atoms in the bar to transmute, releasing energy. To charge the battery, one can reverse the transmutation (magically, of course), drawing on an external power source to provide the necessary energy.

We can divide such batteries into two types based on the type of reaction they employ:

  • Primary (non-reversible): These batteries use nuclear reactions which emit particles (e.g. neutron/proton emission or alpha decay). Since these emitted particles are lost, these batteries cannot be charged without a particle source to 'reseed' them.

  • Secondary (reversible): These batteries utilize transmutations between isotopes of the same mass number (e.g. electron capture or emission). Since the total number of nucleons is unchanged, the transmutation can be easily reversed in order to 'recharge' the battery. A second advantage is that a secondary battery emits no radiation when it's discharged.

There are a couple restrictions that we can make on candidate reactions:

  • Both the reactant and product isotopes should be stable, with half-lives longer than a hundred years or so.

  • The host metal should have acceptable mechanical properties and should be safe to handle.

Note that the isotopes need not be naturally occurring, since large-scale magical nucleosynthesis should be possible.

I'll just consider the case of a secondary battery (it turns out that primary batteries using alpha decay are only energy-dense for heavy, radioactive nuclides, and proton or neutron emission are almost never energetically favorable). Looking at a table of nuclides, we want two stable isotopes on a diagonal from each other (i.e. with the same mass number). Considering only elements that are found alloyed with various metals, this leaves us just a few possibilities:

$$ {}^{14}\text{C}\leftrightharpoons{}^{14}\text{N}\\ {}^{26}\text{Mg}\leftrightharpoons{}^{26}\text{Al}\\ {}^{32}\text{Si}\leftrightharpoons{}^{32}\text{S}\\ {}^{50}\text{Ti}\leftrightharpoons{}^{50}\text{V}\leftrightharpoons{}^{50}\text{Cr}\\ {}^{53}\text{Cr}\leftrightharpoons{}^{53}\text{Mn}\\ {}^{54}\text{Cr}\leftrightharpoons{}^{54}\text{Fe}\\ {}^{58}\text{Fe}\leftrightharpoons{}^{58}\text{Ni}\\ {}^{59}\text{Co}\leftrightharpoons{}^{59}\text{Ni}\\ {}^{60}\text{Fe}\leftrightharpoons{}^{60}\text{Ni}\\ {}^{63}\text{Ni}\leftrightharpoons{}^{63}\text{Cu}\\ {}^{64}\text{Ni}\leftrightharpoons{}^{64}\text{Zn}\\ {}^{92}\text{Zr}\leftrightharpoons{}^{92}\text{Mo}\\ {}^{93}\text{Zr}\leftrightharpoons{}^{93}\text{Mo}\\ {}^{94}\text{Zr}\leftrightharpoons{}^{94}\text{Mo}\\ {}^{96}\text{Zr}\leftrightharpoons{}^{96}\text{Mo}\\ $$

Let's go over the more plausible ones:

  • Carbon and Nitrogen: This reaction would be possible using iron as the host metal. The charged state would be high-carbon steel, and the discharged state would be a through-hardened nitrogen steel. Nitriding is usually only applied to the surface in a case-hardening process, since it causes the steel to become brittle (although hard and wear-resistant). The energy capacity of this reaction is on the order of $15~\text{kWh}/\text{g}$, since nitrogen typically only makes up around 5% of nitrided steel. Note that, unless nitriding processes are available in your world, these batteries would be produced by magically controlled neutron bombardment of regular carbon steel to result in 14C steel.

  • Magnesium and Aluminium: Magnesium is commonly alloyed with aluminum: in alloys like 5456 and 5356, the Mg content can be as high as 5.5%. Higher magnesium content leads to a brittle and less corrosion-resistant metal. The energy capacity is an impressive $230~\text{kWh}/\text{g}$, with low-Mg aluminum as the charged state. This would also require magical production, as 26Mg typically makes up just 11% of typical magnesium, and 26Al is slightly radioactive, and thus not naturally occurring.

  • Chromium and Manganese: Mangalloy is a steel with up to 15% manganese content that is abrasion- and impact-resistant, but hard to work. Stainless steels, such as the common 304 stainless, have similar chromium content (up to 20%). This makes a mangalloy/stainless steel battery possible, with mangalloy as the charged state and an energy density of $45~\text{kWh}/\text{g}$. Again, the 53Cr would need to be magically enriched from its normal concentration of around 9%.

  • Chromium and Iron: As mentioned before, chromium is alloyed in large fractions with iron to make stainless steel. With a typical carbon steel as the charged state, and stainless steel as the discharged state, such a battery could hold $50~\text{kWh}/\text{g}$. Unenriched steel has about 5% 54Fe, so this battery would be fairly easy to produce.

  • Iron and Nickel: There exist a large range of nickel-iron alloys, including Invar (36% Ni) and mu-metal (80% Ni). This makes a nickel bar an extremely powerful battery, storing an incredible $890~\text{kWh}/\text{g}$. Even with a naturally-occurring isotope fraction of only 68% 58Ni, you'd still get over $600~\text{kWh}/\text{g}$ when discharging to an Invar-like alloy.

The nickel/iron battery is probably the one you want to go with; not only does it have high energy density, but such batteries could literally be forged from fallen stars, giving them an additional magical flavor (if you're going for a "traditional fantasy" magic feel with hard-science backing).

Note that the amount of power contained in such a battery is enormous: a one-ounce coin of enriched nickel can release enough energy to:

  • launch a person out of the solar system (from rest at the Earth's surface)
  • vaporize two tons of rock or 41 tons of water
  • supply an average American household with electricity for two years
  • $\begingroup$ @Titanide, I'm interested in any feedback you have on my idea. $\endgroup$ Commented Jul 9, 2015 at 1:32

Why not chemical batteries? Rig them up so you can create a 'short-circuit' which sparks or otherwise releases the energy, and then tap that. Accidentally activating your battery could be dangerous, and in use it might be a little obvious, especially if the mage can't convert all of the electricity to magic. Maybe there's a brief flash of light before she starts channeling the energy->magic.


Just some loose ideas:

How about a genie bottle? Where you push magic inside and draw it out later?

If needed a genie bottle containing a magic cow? It will need to be fed but can be milked for magic at regular times.

Jewellery with magic storing gems would go at a premium, large ones being valued heirlooms in established magic families.

Less ethical and harder to control are apprentices that provide energy for teaching. Cannot be carried, have to hide in plain sight.

Magical potions that release energy on drinking have potential and can be traded as well.

Well-stored magical circles are SUCH a nuisance to fold up without spilling to carry around, after all.

  • $\begingroup$ He says it has to be storing normal energy (except for chemical energy), the question implies that magic energy doesn't work like that. $\endgroup$ Commented May 4, 2016 at 2:39

What you are essentially looking for is a system with a higher energy than another relaxed state but metastable. This is common but the magic just makes it easier to do something interesting. A good way to do this would be to transition highly ordered structure to disordered ones. Unlike reality, you don't have to design a safe mechanism to extract the energy so almost anything would work.


Crystals degrading into a tarnished state. A diamond to carbon black would be dramatic (despite being quite low energy). For less destructive situations, the formation opacifying defects and (possibly) oxidation on the surface would suffice. You can imagine her using water or forming crystals in a water bath to recharge it. Simple salt crystals could serve this purpose (and the water solubility could be an interesting tool for the story). Crystals hold alot more physical energy than most realise but the difficultly is in extracting it. Thematically, these are great for earth or water magic (again salt). Sugar crystals wouldn't fit well with earth but hold alot of energy too.

Pure metals are kind of like crystals but less conspicous. Braclets, buttons, swords, etc can corrode or homogenize upon activation. This is a showy version of how most batteries work. As the manufacture of this would best be done with electrolysis, this would be great for mechanical or electrical magic.

Organic polymers burn good if you get them hot enough. Everything from pockets of lint, bundles of paper, clothings, etc can be made of cellulose which burns well. Wax, hair, surrounding plantlife will work too. For a battery shape, compress the material and use magic to rend it apart and speed up the burning. Of course added sulphur, charcoal, and saltpeter will work amazingly (gunpowder). Obviously my hint here is that these would be useful for fire magic. It would be fine for air magic too if you focus on the oxygen element.

Finally, you can discuss the use of alchemy for the really potent masters. Of course Azoth (i don't mean mercury) and Arcanum are the ultimate stores of energy and this idea can easily be romaticized. There was an alchemist who claimed to keep Azoth in his sword hilt. You can pay special attention to the connections between planets and metals or zodiac signs and chemical sythesis techniques. While Azoth can be viewed as medicinal and good for healing magic, a laymen could just used extracted vials of cholophyll or blood (maybe the 4 humours). They don't need to know what they do to know the indicate health and energy. Imagine the sangine vial turn black or the green one brown. Yellow sulphur was also considered a vital element of life by alchemists and (in the right form) has alot of energy too.

  • $\begingroup$ The question specifically says no chemical batteries. $\endgroup$ Commented May 4, 2016 at 2:37

As an alternative to storing mana, consider the possibility of streaming it from a remote source. The mage would have an antenna of some sort, either hidden on their person (e.g., sewn into the lining of a jacket) or perhaps even used as a wand. The mage's allies would have a device that takes input energy (from whatever source you want to use) and broadcasts it in the mage's direction. The mage's antenna receives the energy, allowing the further use of magic. This is the same general principle behind wireless phone chargers, and some of Nikola Tesla's experiments. Instead of applying the principle to electromagnetism, you'd be applying it to mana (which you could potentially treat as a fifth fundamental force). The physics of mana and its transmission would be completely up to you, so you can define things like how far mana can be transmitted, whether it has to be broadcast or can be transmitted in a narrow beam, or what sort of antennas are necessary.

This approach solves your general problem of the mage needing more energy than is ambiently available in their immidiate vicinity. It also opens up logical explanations for story elements like shielding a room against an opponent's magic, intercepting/stealing mana, creating powerful spells by having several mages combine magic, relationships between a mage's power and the quality of their gear, government limitations on magic by "metering" mana, etc.


Why not use magical ink?

I mean, you say that the "energy" has to be stored somewhere, but there is no real limitation on what it is. Magical inks can be used to scribe incantations in a book, and as you use spells the ink evaporates (or disappears, because magic) and once all the ink in the book is gone, you're toast.

Everybody can carry a book, be it a journal, a recipe book, a law reference book, or something else, it doesn't stick out

You can write on the book back at home, so it's rechargeable.

The magical ink can be made of various substances and therefore have a variety of inks with different amount of energy stored in each, say, milliliter or something. The production and sale of this ink could be regulated by the Mages Guild or something.

A book is naturally lightweight and everybody can carry a few. The richest of the rich can buy the most powerful inks with a lot of energy stored in them, so they only need to carry a thin book instead of a few.

Example: Suppose that there are 3 tier inks: Standard, Premium, and Ridiculously Strong.

The standard of this tier is how many Fireballs one can expect to be cast.

The mechanism of magic is that you write the incantation on a paper and as you use the energy in it, the ink evaporates, causing the text to appear more and more translucent until it's gone. The incantation used for testing has a standard size, typeface and boldness.

The standard of energy used to count the Fireball is each Fireball should be able to burn a 200 grams raw beef into a medium steak in 1 blast, not medium-rare, not well-done, but precisely medium-rare. About 5% margin of error is acceptable.

So say that Standard ink can cook 3 beefs before the ink evaporates, Premium can do 6, Ridiculously Strong can go 12.

The entire energy can be spent in an instant of big blast or used very sparingly in a small flame that it lasts way longer.

Suppose that the incantation of Fireball is the word "fireball" written in lower caps, and a standard sized paper can hold the word "fireball" in 4 columns and 12 rows for a total of 48 standard fireball words, using a standard ink will allow you to cast 144 standard fireballs before you run out

The poor and inexperienced will need bigger and more books to hold all the inks in case their spells miss or they went overkill too many times, the experienced can go with fewer and smaller books


If I understand the premise correctly your mage can take energy from their surroundings and re-purpose it; like taking heat energy and turning it into kinetic energy, but they can't directly draw energy from chemical sources.

The simple work around seems to be to carry a battery (or chemical energy source) and a device that turns that energy into something usable, like heat.

The simplest thing I can imagine would be a lighter or something similar. Quite a lot of chemical energy stored in the lighter fluid which can quickly and easily be turned into heat, which your mage can then manipulate. Small, unobtrusive and cheap too.

If they can extract electrical energy then even something like a phone might work, or really any electrical device. Perhaps a taser if you want to increase the available power (and if you needed the electrical energy to be more accessible then running through a device).

If light is a possible energy source they could carry torches (though to be honest, if light is a usable source then the sun is a far better source of energy most of the time)


Based on the wind example, it sounds like kinetic energy is one of the forms of energy that a mage can harness. What about springs or flywheels as potential energy / kinetic energy storage devices?

You'd have a nice little "battery" that runs on angular momentum, or release a spring (with some kind of trigger) to get a quick burst of energy to work with. Maybe you could use the flywheel to generate mage-usable heat via controlled amounts of friction, and there might even a way to convert a spinning metal wheel into usable electrical energy as well.


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