1236 How To Make A Plant Pot Battery - ZnBr

[Music] hi so we're going to make a sink bromine battery now i've made quite a few versions of this but i was asked to revisit it particularly patent number 312 802 by cs bradley now i like the idea of revisiting it because it shows you that there are just a ton of ways to make batteries depending on what you've got available and how you can create an inventive way of using it bearing in mind some very basic principles now the cs bradley battery looks like this we're going to recreate that from a plant pot and a glass now the plant pots important it is anglers terracotta which means it's porous so it's going to act as a separator and ion filter and it's got no hole in the bottom now if yours is a hole in the bottom well fill the hole just pour some resin in there and it'll fill the hole and the rest of the plant pot will do the job we're lucky ours doesn't have a hole and it fits rather nicely into there so there's our battery container all made so here we have a container that's going to separate the anode and the cathode with a porous membrane and that's what you're looking for now we did a very similar thing with an unglazed tile when we used the unglazed tile as a protein exchange membrane but it functions functions just fine and this plant pot will function as a porous membrane without an exchange which is really cool if you think about it but lots of things will do this job and we have done lots of things including just using gravity to separate it now gravity will form a part in this because the one electrode is going to go at the bottom the other electrode is going to go at the top and of course it's standing upright it's a liquid so the bromine is going to sink to the bottom which is great because it will help reform that function if you do it like that you don't need a porous membrane you'll get a quite high self discharge which can be fine it just discharges by diffusion this will slow down the discharge a little bit so it'll hold its energy a lot longer and it'll give you a lot more out so again we can use those principles to design what it has that we want based on the stuff we've got around us so if you don't have a plant pot or a separator you can just do away with it if you have one use it and this is what the bradley battery does now once we we've made our battery and that's hilarious isn't it just stick a plant button the glass and you made your battery once you've done that of course we need the two electrodes now the problem with bromine is it's pretty aggressive stuff so we've used high density polyethylene which the research papers say that in the battery condition over 10 000 cycles doesn't degrade i've been told that people have experienced degradation i suspect they're over voltaging it but you can also make different kinds of carbon-filled plastics as long as they're conductive and we've done videos on that now one thing we haven't done a video on is using this material i love this actually that is a lump of graphite and it comes out the ground like a rock just like that and it can be a little size like this or it can be as big as a car graphite comes from the ground dug out as a rock and it looks like a rock and if you want to make it into plates actually you saw it up pretty much like you saw a marble for a kitchen table top off or a fireplace these were sent to me by very good friend of mine he sent me some graphite plates and there you go that is just a bit of rock sawn up into a nice pretty square plate and you can buy them you can buy them at any size actually i don't actually know how much they cost because like i say i didn't buy these now that is going to become one of our electrodes but like that it's not too good because the bromine will settle on the top and have to spill over the sides and we want it really to settle at the bottom so what we do is drill a load of holes in it this is really soft stuff it drills really easily so drill a load of holes in it and then drill a hole in the corner and what you will get is that that is our bromine electrode it's going to sit in the glass like that now i've rounded the corners so it sits a little bit off the bottom so it's sitting off the bottom like that now when the chart cell is charged the bromine is going to sink to the bottom right there and because of the holes in that graphite plate now obviously we have to connect to the graphite plate so the hole in the corner which is a four millimeter hole has a bolt stuck through it and we're going to connect to that bolt so we're going to connect to it with a length of wire and a crimp now as again there's a whole load of ways you can do this if your bolt which is four millimeters long was made out of brass you could just solder the wire straight on you can use a crimp you can use a terminal block anyway that you can get that to actually fasten to that bit of bolt just there so there it is bolted up now we have electrical connection to our plate however the electrolyte will corrode this arm bolt so you need to protect it in some way and you can use again the whole source of things coated in resin coated in glue and i'm going to use this stuff which is called plasti-dip it's a rubber solution meant for coating tool handles but it's actually really good in aggressive environments so if i dip that a couple of times and let that plasti dip turn what i'll get is a very nice coating over there that'll protect it from the aggressive environment of the electrochemical cell and that's equally what you need to do when you're doing something like this just so that doesn't get attacked okay so that's my seal drive and like i said just got to seal it with something and then that pops in there like that bend the wire over our plant pot goes in the top like that and then we need a bit of zinc now any old thing called do and you can find zinc all over the place they use at the bottom of boats for instance is a sacrificial anode i've got a bit of zinc foil that i've bent over and that will go in there so now all we have to do is fill that with its electrolyte this electrolyte is zinc bromide zinc bromide is a commercial chemical so if you want to buy a pallet load of this stuff piece of cake just order it you won't pay that much for it but buying a couple of kilos actually can be a little bit challenging but you can make it really easily from something like sodium bromide and zinc sulfate you chuck them all into the water and you evaporate it off when you've operated off that salt you get will be sodium sulfate and the greenish liquid is the zinc bromide so evaporate it a bit pour off the zinc bromide and you'll have something bromine that's a great way of making a couple of kilos but if you're going to do 10 kilos or so you're better off just buying yourself for 25 kilos if you find that really easy to get china and india sell it anyway that's as in bromide solution it's a concentrated solution and we just pour it in here that's our battery done now we're going to put it on charge there's a little bit serving to soak through that porous pot and then charge this bad boy hook it up to a power supply and stick it on 1.8 volts now i quite frequently use something called constant voltage so i'll stick it on 1.8 volts and just put up with whatever amps flow through it until these battery cell equals 1.8 volts then it's charged but zinc bromide is actually plating stripping battery so it charges best by something called constant current now the current you need to apply somewhere between 30 and 50 milliamps per square centimeter of the graphite electrode there so whatever your area is and this is uh i think this one is five by six so it's 30 square centimeters what you do is bang the voltage up until you get the respective current flowing through and then it's going to charge much more quickly safest way constant voltage correct way constant current anyway i've banged that on at 1.8 volts so take a wall let's just leave it to charge so after a little bit of charging you'll see the bromine forming right there beneath the actual carbon plate you won't see the zinc because it's been put onto the zinc plate but the bromine is really obvious now constant current means maintaining the current at a constant value so you'll see the current go up and what you have to do is drop the voltage to keep the constant current hence the term the energy density is directly related to the amount of zinc bromine you've got in there now as it's pleating then obviously it's taking ions out of the solution and sometimes the support salt can help so you add another salt in there and that'll be the ion carrier or you just don't charge it fully and allow that to happen it will last as long as that color is there it'll discharge at 1.8 volts for absolutely edges now i've got a little motor here and we're just going to hook up the motor and give that a spin as a demonstration that there's some power in there to make sure it's not going to hit oops okay that's going bananas obviously it's really spinning at a rate of knots and it will continue to do that so you got a 1.8 volts and a high ampage discharge out of that anyway there's how to make a plant pot based zinc bromine battery but i think has an awful lot to commend it it's quite a good battery it's very cheap to make and it's really easy to make it's quite safe in the bromine stays down here and this will go a deep sort of purpley color anyway i was asked to revisit that i hope i was fully my explanation i hope you enjoyed the video thank you very much for watching and please remember to like and subscribe still going to go for ages

Channel: Robert Murray-Smith

Views: 8,875

Rating: 4.9920793 out of 5

Keywords: plant, pot, battery, zinc, bromine, bromide, robert, fwg

Id: -Xrf2mFeyJ4

Length: 10min 35sec (635 seconds)

Published: Wed Sep 01 2021