This project goes into the build of a 1.72kwh emergency backup battery system out of old and used laptop batteries and an old military surplus ammo box. The materials you need to build this project are lithium ion 18650 batteries from old laptops, 4X5,3X5 cell holders, ammo can, 40 Amp BMS or Battery management system, spot welder, fused nickel strip, heat shrink, kapton tape.
First we determine how many batteries that we can pack inside the ammo box. In our case, we have 2 packs of 91 18650 cells , a total of 182 cells. We take the 4 X5 and 3 X 5 cell holders and connect them to make a couple of 7 x 13 cell holders.
To make this 24V lithium ion battery , we need a 7S ( 7 cells in series connection) combination . A single lithium ion cell has a nominal voltage of 3.7V . To make a single long 7S configuration battery , we connect 7 groups of 26 cells in series to get the 25V nominal voltage.
The cells used in the build are Samsung ICR18650 – 28A with a capacity of 2800Mah .The cells are rewrapped with heat shrink and added an insulator disk at the positive side of the cell for safety. The cells are installed on the holder in such a way that the first 26 cells are in a same polarity and are connected in parallel. Next 26 cells are installed with opposite polarity and is the connected in series with the first 26 cells . The rest of the cells are connected in the similar way to make a final 7S 2P ( 7 series and 2 Parallel ) configuration with max capacity of 26 X 2.8mah or 72.8 amp hours.
A four wide fused nickel strip is used to connect the batteries in series. The nickel strip is placed over the first 4 cells and spot welded in place using the sunkko spot welder. Each cell is individually fused in case there is short circuit or malfunction. The nickel strip connects the first two rows in parallel and then connects the next two rows in series .
Similarly, to complete the series connections, the nickel strips are placed and welded on the opposite side of the pack in such a way that it wont short out the connection by coming in contact with the most negative side of the battery.
We take 0.15mm standard nickel strips to connect the positive ends of the whole pack together. The last 2 rows of most positive end are connected together using the nickel strip . Small pieces of nickel strips are placed across these two rows to connect them in parallel . The pieces are bent so that it can be connected to a separate copper busbar.
The separate 2 battery pack of 7 X 13 cells are connected together by the nickel fuse strip in such a way that one of the pack is flipped on top of the other. The nickel strip that connects the first 3 connection on the 1st pack is bent to connect the 4th connection on the other pack. A 90 degree bent on the last row of the 4p fused nickel strip is welded on to the first battery pack.
A piece of kapton tape is placed over the nickel strip to insulate it and hold it together.
The bent nickel strip on the first pack is placed on the other pack is such a way that the fuses are perfectly aligned . Then it is welded using a spot welder. A one sixteenth inch ABS plastic is placed in between the two packs. The second pack is now slowly folded over the top of the first pack. The whole pack is then wrapped around with the kapton tape so that it doesn’t move around.
The last three unconnected terminals on one side of the battery pack is connected to the single row of unconnected terminal on the other side with help of four nickel strips. The 4p fused nickel strip is cut to connect the 3 sides and the other side.
To connect the main negative and the positive tabs , we attach a THHN copper wire across the both the terminal ends. The extended nickel connections are folded across the wire to hold it into place and soldered . The terminal wires are then connected together with XT90 connector.
Next step is to connect the BMS or Battery management system to the pack . This is a small circuit board which is used to protect each cells of the battery pack from overcharging and becoming unbalanced and getting damaged. It stop the over draining when the cells are fully charged. The BMS used here is a 7S 24V with charge current of 20A and discharge current of 40A. It has two negative leads, one connecting the battery and the other for charging and discharging.
The BMS also has 8 sense or balancing wires which are connected to each series connections on the battery. The black wire is connected to the most negative terminal of the battery. The first red wire is connected to the first series connected group of cells, the second red wire is connected to the second series connected cells and so on. The last red wire is connected to the main positive terminal of the battery. A heat shrink is wrapped around the whole battery pack for added safety .
Before inserting the battery pack into the ammo box, a hole is drilled on the back side of the ammo can to allow the cables from the battery to pass through. Also a small piece of one sixteenth inch ABS plastic is placed at the bottom of the ammo box as a support and insulation.
The battery is slowly dropped into the box . The BMS is placed on the top and is connected to the XT90 connector and the balance wires from the battery. The B- terminal on the BMS is connected to the XT90 connector on the battery. The black wire on the BMS is the charge and discharge lead. To provide extra insulation between the battery pack and the the ammo box ,we attach two pieces of the insulting ABS sheet on either side of the box.
The lid is put back on the box and the battery build is complete.
- How to build a Super Efficient Portable Rocket Mass Heater from reclaimed and repurposed items and save up to 80% on your heating billsThis project goes over the build of a homemade efficient rocket mass heater which is portable ,uses less fuel and burns clean. This heater is made out of reclaimed and repurposed materials. The cool thing about a rocket mass heater is that it stays warm long long after the fire is out. The whole thing is powered by a rocket stove, which is a j shaped burn chamber. Fuel goes in the short side of the J, the fire burned sideways and the bottom of it. And then the draw is created by a tall vertical heat riser. The gases then come out of that chimney go all around the inside of the barrel, a lot of the heat is given off into the room right off of the barrel. That's your radiant heat source for the room. The barrel acts as that radiant heat source. The gases then go through a valve in the barrel down below and through a series of tubes that are encased in mass such as aircrete or cob .The gases are able to shed the heat into the cob. And the cob stores it as a thermal battery. The gases make its rounds through the tubes and goes out through the exhaust pipe. The rocket mass heater shown here is made of a burn chamber, heat riser, bench for containing the tubes , the exhaust pipe and an insulation refractory material like aircrete which is a high temperature cement mix. The burn chamber is made from an old sheet metal pressure tank and a stainless steel water heater tank. The pressure tank insulated with aerated concrete sits inside the water heater tank. The combustion or gasification chamber is connected to the heat riser chimney through a three inch pipe insulated inside a six inch pipe. This pipe is also insulated with a refractory mix. The vortex chamber is connected to this pipe. The vortex chamber is made from a saw blade and a left over piece of pressure tank material . It is insulated with the refractory material . Six glue stick 3/8th inch air holes are drilled at right angles around this refractory material that creates a vortex extra air suction effect .So as that heat comes up and creates a negative pressure up the riser, it swirls around the vortex chamber and enhances the burn. The initial combustion creates enough heat to release way more gases than it has oxygen to burn. By introducing a vortex air intake system, the burn output is amplified. For making the insulated heat riser, we are going to use an aerated concrete refractory material called aircrete . We make the mould for the four inch heater riser using a metal mesh fabric, sarnafil roofing material and a thin gauge wire. Then it is filled it clay sand up to to the top . We take this mould and put it inside the six inch stove pipe and pour aircete through the sides all the way up to the top and let them sit to cure. We pull the sand out of the center of the heat riser. And then eject the liner that went against the inner fabric webbing that acted as a mold for the aircrete. The Aircrete heat riser is installed on top of the vortex chamber .The heat riser is double insulated with a old water tank and an old 55 gal oil barrel. Also the water tank is insulated from the 55 gal barrel using some pea gravel .The insulated water tank has an outlet pipe at the bottom for extension into the mass bench . The exhaust pipe coming out the insulated heat riser has a two foot drop to a directional valve connecting two pipes ,one pipe acts as a flue chimney that goes out into the outdoors through the window, the other goes into the mass bench. The valve allows us to redirect the air to pass to the bench once the heat riser is all warm. The eight foot long wooden mass bench houses the six inch stove pipes coming out the exhaust of the heat riser. It has a mylar reflective insulation sheet on the floor. This helps prevent the heat escape through the floor .The mass bench is then insulated with pea gravel which absorbs the heat and holds it and slowly radiate out over a period of time. The pipe coming out of the bench goes out of the window through the valve. The flue chimney pipe that goes out through the window to the outdoors is made of double walled stove pipe. A five inch pipe is inserted inside a seven inch pipe. The space between them is insulated with a aerated concrete refractory material .All this insulated exhaust pipe is doing is taking and adding an element of acceleration up the chimney to negate the net negative you get from dropping two feet down into the bench from the heat riser. https://www.youtube.com/watch?v=o1ZKm7QZ-dY
- DIY Video:How To Turn Your Old Fan Into An Airconditioner AC for cheap.This project shows you how can take an old table fan and convert it into a simple ,cheap and easy to make homemade AC . The materials needed for the this project are a table fan, 75 gallon per hour fountain pump with valve to control the water flow, multi purpose zip ties ,two 3/8th inch transparent PVC Pipe tube, 15 foot quarter inch copper tube,two hose clamps. Unhook the locks if any and remove the screen of the fan. Take the copper coil and wind them across the rims of the fan .Secure them tight on the screen using multi purpose ties. Add the screen back to the fan body and then adjust the two ends of the copper coil by bending them to face the back of the fan and secure them using ties. Two 3/8 transparent vinyl PVC pipes are connected to the copper tube ends using hose clamps. We attach the fountain pump to the end of the vinyl PVC tube that goes straight into our cooler. The recirculated water coming from the other end of the tube goes straight back into the cooler bag. The cooler bag is filled with ice packs and water. The water pump is submerged into the bottom of the bag with ice and water over it. The water which is pumped with the help of the fountain pump gets recycled through the vinyl and the copper pipe and moves back into the bag, so you dont need to add more water .Both the pump and fan can be connected to solar generator in case if you want to make the system portable . https://www.youtube.com/watch?v=5NuvzWaBulw
- How to convert an Old Ceiling Fan Motor into a 70W Efficient Single Phase Alternator GeneratorThis project goes over the conversion of an old ceiling fan motor into an single phase alternator .You can't take your standard AC electric motor and spin it and get an electrical current out of it unless you modify it. The ceiling fan motor used here will produce about 70 volts at one amp which is roughly 70 watts. Through a bridge rectifier we can get about 70 watts of power out of it. We start by pulling the cover of the fan. Inside we have a squirrel cage rotor in the middle and 6 coil windings around it. The coil windings are placed in clockwise and anti-clock wise directions inside the stator. Next we remove the circular rotor from the threaded shaft which is attached to it with help of a vice. We attach the shaft with the rotor through it within a vice. With the help of an extra piece of pipe to give leverage, we press them against the rotor and push it away from the rod and pop it off. We are replacing the rotor that we have detached from the shaft with a two inch hex steel bar . It has six sides that matches with the six coils from the stator. With the help of one eighth inch drill bit we cut a hole in the center of our hex bar. We put the hex bar through the shaft and fit them snugly around the threaded area. We take six one half inch neodymium or rare earth magnets and place them along the the 6 sides of the hex bar. We place them in such a manner that the poles of the magnets are opposing each other. For permanent usage, wrap this with a little bit of tape or glue so that they are held in place securely. We place our modified rotor in the middle of the stator and align them such that they fit in tightly. The outer screen is bolted back onto the motor. We can also add second set of magnets to increase the magnetic field of the rotor .This will also bring it closer to the coils on the outside and increase the overall voltage. To convert the alternating current generated by our ceiling fan alternator to direct current, we use a bridge rectifier. It has 4 poles, 2 for connecting our alternating current, the other plus and negative for DC power. https://www.youtube.com/watch?v=k-4IbLOZwnA