This project goes into the build of a DIY swivel top wind turbine generator that can generate off the grid electric power to run lights, radios, charge batteries. This durable, lightweight and portable wind turbine would be very useful in SHTF / Power outage / Emergency situations.
The materials you need to build this wind turbine are as follows. 3/4th inch PVC pipes including 5 90 degree couplers, 3 Tee couplers,4 Three and half inch pipe, Two 8 inch pipe, Two 3 inch pipe and long 11 inch pipe for the post. The propeller for the turbine is made from a 5 gallon bucket lid or you can buy them from your local hobby store, 3V 350ma DC hobby motor, wire from an old extension cord.
The base stand for the turbine is assembled using the PVC couplers and the tee’s. The 11 inch PVC post pipe is finally attached at the center of the support base. Use PVC pipe cement to strengthen the connection between the joints.
Next step is to make a hole at the bottom of the post for the electrical cord . A hole is drilled one inch from the end of the PVC pipe.
The wires from a broken extension cord is used for this project. The wires are soldered to the ends of the motor first for a good tight connection.
The wire is fed through the pipe and the motor is mounted at the top . A duct tape is wrapped around the motor multiple times so that it fits the entrance of the pipe opening. Before encasing the motor, the blade is put on .
To build the swivel assembly ,we need a PVC union, an adapter, 3 inch pipe. The adapter is screwed on to the union, the 3 inch pipe is then connected to the adapter.
The tail fins are made from an old waste basket. The fins are screwed on the post using machine screws.
To stop the post from rotating 180 degree in both directions, we put couple of screws on either direction on the side of the post in such a way that it prevents the post from rotating 180 degree .
Not only you can charge your batteries using this set , but this can be connected to an inverter to run AC powered appliances.
This project goes into the build of an outdoor wood boiler for heating your garage using an old barrel and a car radiator. The first step is to make a wood burning stove out of an old barrel . Here we are converting the barrel into a stove using a vogelzang stove kit.
We start by cutting a hole for the door using the the door accessory from the kit as a guide. Place the door on the side of the barrel and mark the four corners. Start cutting the hole using a grinder, reciprocating saw or a plasma torch.
Align the door with the hole and drill holes for the screws. The door is now secured in place .
Next step is to install the legs that came with the kit. Place the barrel on the the legs and align them so that everything is level. The spots are marked , holes drilled and the legs are bolted in place.
To control the air flow and how hot the stove burns, we install the flange and the damper within the chimney area. Center the flange that comes with the kit near the edge and make a circle for cutting the hole. Also mark holes for the bolts using the flange as a guide. The flange along with the damper is then screwed down securely.
The next step is to convert this barrel stove into a hot water heater. Begin by drilling two holes across both sides of the barrel and inserting couple of three eighth inch threaded rod across the sides. This creates a base where a 30ft coiled copper tubes are placed to circulate the warm water.
A 30ft half inch copper coil with the input and output straight end is placed inside the barrel on top of the two threaded 3/8th rod base which we have installed previously. Two holes are drilled at the back of the barrel so that the input and the output ends of the copper coil can be connected to a pipe or flexible hose.
The input end of copper coil coming out at the back of the barrel is further connected to another loop of copper coil outside the barrel . The coil is wound across the barrel so that incoming water is preheated using the outside coil before it goes into the barrel and gets further heated by the coils inside .
The ends of the coils are connected to two pipes, the outgoing and the return . These pipes are then insulated using half inch pipe insulation foam to prevent any leak. A small trench is dug and the insulated pipe is extended to the garage.
The water circulatory pipes are now connected to an old car radiator inside the garage. The incoming hot water pipe is connected at the top of the radiator and the return is connected at the bottom.
To circulate the water ,we use a cheap submersible pump. The pump is submerged in a bucket . The pump will pump cold water out through the heater, the hot water circulates through the radiator , cools down and collected at the bucket and it is again recirculated.
Two holes are drilled on the top of the bucket . One for the pipe coming out from the pump and another for the pipe coming back from the radiator. The inch and quarter radiator hose is adjusted to connect to the pex hose piping with the help of a PVC poly tube with a threaded end
The other side of the polytube with the threaded end is attached to a PVC adapter and a slip fitting with a bushing. This helps us to connect the pex pipe to the radiator . To prevent the water from boiling , an antifreeze solution is mixed .
A window fan is used as a back fan for the radiator. Placed right behind the radiator, this blows the hot air through it and into the garage.
This project goes into the build of an efficient portable ammo can wood stove that can warm your space, act as a cooking stove, baking oven and an alternative for ground fires at camp sites. This ammo stove is compact and doesn’t take up additional storage . All the basic components used in this stove are modular and can be stored inside the stove when not in use. These components are easily available in your local hardware store.
The basic components needed to build this stove are as follows. The ammo box called the “fat 50 “is purchased from an army surplus store for $30 , the titanium stove pipe for $100 , the metal for the control dial and the door is salvaged from old barbecues. Rest of the basic tools needed are grinder, blow torch, hack saw ,rivet gun and a drill press.
Not only you can use wood logs, paper, twigs but it also runs on wood pellets. The system has a gravity fed hopper that feeds the pellets intermittently for consistent heat over a longer period of time. For maximizing the burn, a divided combustion chamber is used. This forces the burn to go around a sealed baffle before it exits out the stove pipe providing less smoke and retaining more heat.
A thick steel plate is used as a cook top which is rescued from an old barbeque . This plate absorbs the heat for cooking and is removable thereby protecting the stove top. Additional feature is a baking oven underneath the stove.
The first step to build is simply removing the lid of the ammo can stove which just slides of the hinges. Remove the rubber gasket on the back side of the lid using a plier .
This rubber gasket is replaced using 3/8th inch stove rope. This provides heat resistant seal from smoke.
Remove the handle by drilling along the spot welds on the sides of the handle just enough to weaken them and pull it using a screwdriver .
Two holes of three inches are drilled at the top surface of the stove . These are done to fit in the titanium stove pipe and for the gravity fed hopper system. We use a three inch propane fuel cylinder tube to make a pipe collar as a guide to trace out the holes. These pipe collars acts as hopper support for gravity fed pellet mechanism and for securing the stove pipe. The hole for the first pipe is about five and half inches away from the door hinge and the second one , one and half inches away. The holes are then cut using a jigsaw.
The flanges in the stove pipe collars are made by securing them against a wooden fixture and bent them using a hammer. The edges are heated with a torch to anneal the metal for hardening.
Before inserting the stove collars into the lid, the metal sheet inside the lid was removed. Using fiber glass cloth, a smoke seal is made around the collars. The collars are then inserted and the metal sheet is reinstated with help of some stainless steel rivets.
A adjustable damper is installed inside one of the collars .These damper provide control to both burning speed and fire intensity. Also the damper in a closed state also acts a base for a steamer or a boiler. The damper is made using a thin steel cut out of a disc , the size of the inside pipe diameter. The shaft from a barbeque skewer is inserted along slots drilled in the disc holding them underneath the collar.
Inside the combustion chamber ,we have two dividers installed. One divides the combustion chamber and the bottom one separates the oven from the stove . The top divider acts as an inner wall . The combustion has to travel around the corner and then go outside through the stove pipe at the end. This collects more heat and has less smoke build up inside.
The side door openings are four inches high and three and three eighth inches wide. The door is made out of thick steel plate which was salvaged from an old barbeque. The door has three holes for the air intake and it is supported by a regular door hinge. A small circle metal piece at the front regulates the amount of flow that goes into the stove.
A secondary burn system is introduced inside the stove so that the air coming into the upper part of the combustion chamber where all the smokes ascends gets reignited . This drastically improves the efficiency of the stove. Here we use couple of half inch black iron pipe that is connected with 2 90 degree elbow and an end cap. Holes are drilled on the pipe so that the fresh air is introduced into the chamber. A hole at the side of the stove is made the air intake. The pipe is inserted into the chamber and secured in place using a coupling and a spacer.
A 3 X 4 inch duct adapter is used as a funnel for the gravity fed hopper system. To make this efficient , we add a small cage made of door basket inside the chamber so that all the pellets wont drop suddenly to the bottom. The cage is made from the metal rods from the basket. The rods are spaced 8mm apart and put straps across both sides and secured it using rivets. To prevent the overflow of pellets inside the cage, a two and half inch tailpipe is placed at a specific distance below the hopper. This helps the pellet build up in the cage but not overflow. Now there is a sustained release of pellets at all time for a consistent burn.
Stainless steel tent stakes are placed at the bottom of the stove riveted to a metal plate. This prevents the bottom from burning out and also improves air flow. Also acts as ash collector.
To use this stove as a light source, we make a small window out of half mm natural mica glass. We use a fiberglass cloth to form a seal around window. It is held by green painters tape. After positioning the glass, spacers are added around the edge . These metal strips allow for the mica to expand and contract. Another metal frame is used to hold all these in place.
The portable stove pipe is made out of titanium rolls. The titanium prevents corrosion and also distributes the heat efficiently. To make a long cylinder without denting the foil, unroll the film across the ground, roll it small enough to get the clips on ,spacing them evenly along the length of the pipe.
This project goes into the build a simple Survival water purifier that can turn salt water /sea water into fresh drinkable water .This purifier is portable, easy to make and is very inexpensive. It works by the principle of desalination .When sea water/ salt water is heated to its boiling point, the water turns into steam which leaves the salt behind. Condensing the steam back into water ,it is purified.
The materials you need to build this desalination unit are a simple non insulated stainless steel bottle with a steel lid , copper tubing , stove or heating source, bottle for collecting the condensed water, soldering unit, right angle compression fiting. The condenser of this desalination unit is made from one quarter inch copper tubing.
Remove the lid and the gasket from the bottle . A hole is drilled using a drill press at the top of the lid to accommodate the quarter inch copper tubing . Before soldering the copper tubing , clean the surface of both copper and the stainless steel lid with the help of a sandpaper. The copper tubing is pushed through the hole just enough to stick half an inch from both side. It is then soldered securely in place. Once this is completed , the silicon gasket is then re-installed in the lid and lid is screwed back on to the bottle.
A right angle compression fitting is pressed into the lid at the copper tubing opening . The extension tube at the other end of the compression fitting is removed and replaced with a rubber gasket for better seal for the lock nut.
The copper coil for the re-condensing the steam when the water is boiling is made by wrapping the copper tube up tightly against the stainless bottle . Eight or nine turns of the tubing is ideal. The ends of the coil are bend outwards so that when one end is pressed into the fitting on the bottle, the other side will be sticking straight out.
The salt or sea water is added to the bottle and reattached to the lid which is hanging over a heat source such as a wood stove or camp fire. The other end of the coil is placed near a collection container to collect the distilled water.
To produce more condensed water out of the copper tubing ,we need to cool it down. Otherwise the production of steam will outweigh the production of the condensed water. To cool the copper tubing , wet put a wet piece of cloth soaked in cold water and wrap it around the coil or dip the whole bottom half of the copper coil into a vessel filled with cold water.
This project goes into the build of a passive solar thermal water heater using pex pipes and 4 X 8 plywood piece. The pex pipes are sturdy and tough , doesn’t easily leak. This passive solar heater can reach upto 120 – 150 F on a typical sunny day. Instead of pex pipes, you can use cheap irrigation pipe for this project. The pex pipes are more stronger and durable . The heater can be used for heating your domestic water, space or room heating or just heating a swimming pool.
The box that contains the pipes are made of 4 X 4 plywood . Four pieces of 2 X 4 pressure treated lumber are joined along the sides using screws to make the frame. We staple in some bubble insulation along the dimensions of the box . Since the insulation material is silver, it will reflect heat. To avoid this ,we coat it with a flat black paint to attract the solar heat.
Two holes are drilled on the sides of the frame for the inlet end of the pipe where the cold water comes in and outlet end where the hot water comes out. The inside and the outside of the heater is painted flat back using rust-oleum high heat paint to absorb maximum heat from the sun.
The first layer of half inch pex tubes or irrigation pipes are secured inside the solar heater box using half inch pex talon clamps. The clamps are installed on four sides of the box securing each loop of the pipe. The second or upper layer of pipes are secured in using zip ties. The total length of the pipe is 200ft.
The pipe comes in through the inlet hole and goes to the outside on the first layer , all the way around and work itself inside .It then goes through the top layer and all the way to the outside and then exit through the outlet hole.
The bottom layer pipes aren’t going to be exposed to the sun as much but they still will be warmed up because the whole box is covered with lexan polycarbonate sheet. The top layer with the pipe that goes outside through the outlet hole will have the highest thermal BTU.
A very inexpensive reed thermometer with a 4 inch stem is installed on the side of the heater using a half inch to three eighths bushing reducer .
A 4 X 8 Makrolon Polycarbonate Sheet is placed on top of the heater box and secured down in place using a No 8 One and one fourth sheet metal screws ,finishing washers and rubber grommets. Silicon adhesives are used to seal the gap formed between the sheet and the box frame.
The Solar thermal heater is placed at an angle of 20 degrees. This is done with the help of leg supports with dimensions 16 and 8 inches 2 X 4 pieces at both the sides. A 50 watt Renogy Solar Panel is also installed adjacent to the heater. This Solar Panel is for powering the bilge water pump.
A 500GPH 12V bilge pump is used to pump the cold water through the pipes into the heater . In order to control the flow of water through the pump , it is connected to an speed control electric circuit box which has a relay, a buck boost converter,a motor pump speed controller, potentiometer and a switch. The pump is powered by a 50W Solar Panel .The negative connection from the panel is connected to the relay, the positive goes to the switch.
The relay determines the voltage for the buck boost converter .It activates on a certain voltage we set and then powers the buck boost converter. The buck boost converter will keep a constant voltage no matter what the voltage the solar panel is putting out. It is then connected to a 15 amp motor pump speed controller and a potentiometer which is used to control the voltage of the bilge pump motor. The 12V 500GPH bilge pump is connected to the motor pump speed controller.
In order to test the unit, we place the heater near a pool to heat it. The bilge pump is submerged into the pool which is then connected to the heater with help of a PVC hose. The output pvc hose is returned with heated water back to the pool. The water reaches upto 140 F based on our test.
This project goes into the build of a homemade water fueled radiant Air heater / Air Cooler that can blow cold air or hot air into your room or space using a heat exchanger and an old car radiator fan . This system can pump out cold air at 1500 CFM with the temperature reaching 55F and heat output at almost 170 F. The entire system is powered by a 100W Solar Panel and costs around 60 to 70 dollars . The major advantage of using this cooler is that it doesnt add any humidity to the air.
The materials you need to build this Cooler/ Heater are as follows. Standard bilge water pump or aquarium pump or 12V DC fan for solar, seven inch 12V 80W car radiator fan, 10 X 12 piece of plywood, a couple of eleven inch 2 x4’s, 8 X 8 heat exchanger, one inch PVC tubing , a couple of hose barbs with coupler , a tub to hold the ice or hot water . A 12V DC heating element can also be used to warm up the water
The first step is building a frame to hold the heat exchanger and the car radiator fan together. This is done by a taking couple of 11 inch 2 X4 ‘s and mount them parallel to each other on a 10 X 12 inch piece of plywood. A hole is cut on the plywood to place the car radiator fan . The heat exchanger is attached on the back side of the fan just between those two eleven inch 2 X 4’s.The heat exchanger is rated for over 25k BTU’s and covers about 1000 sq ft that can heat or cool an entire living space.
A tub containing Ice cold water or hot water is used as a source of heat or cold . The Water pump submerged into the water source is connected to the inlet tubing . This pumps the cold or hot water into the input of the heat exchanger . The car radiator fan is powered on using the 100 W solar panel and the hot or cold air radiates into the room or space. The water returns back into the tub through the other tubing .
The solar panel is connected to a speed controller that is further connected to the radiator fan to adjust the air flow.
The 200gph water pump with the half inch pipe is connected to the inch pipe main tubing using half inch barbed to inch threaded and inch threaded to inch barbed and a threaded PVC coupler.
To make the hot water , we use a 150W DC Water heating element . The heat element is connected at the base of the tub or barrel . This unit is powered by a solar panel . You can use an AC powered immersion water heater if there is no option for solar.
A 100W Solar panel is powering the 80W Car radiator fan and 12V 350 GPH Bilge pump that is used to pump the water to the heat exchanger and back . It also powers Heating element if you plan to heat the water this way. Another way to heat the water is using a 50 ft copper tubing. The water is pumped through the copper tubing using a small pump and a 5W Solar panel and heat it up. The hot water is then passed through to heat exchanger .
This project goes into the build of an offgrid portable water pump and filtration system that can turn any water from your creek,lake,river into safe and clean drinking water . This 12V portable system can be powered by solar or from your car directly and is ideal for camping , RV or outdoor survival enthusiasts. This system enables them to pump water from a fresh water source, filter and then store or use in case of emergency survival situation.
The materials you need to build this portable filtration system are as follows. A tactix storage box to lodge the water pump,inlet and outlet hoses, an inline water filter or twin carbon 0.5micron filter, pex pipe, garden hose pipes, 12mill barb strainer,rocker switch ,12V Shurflo water pump with the flow rate of 11 litres per minute, 50 amp Anderson plug and 10m heavy duty wire ,basic tools such as wire cutters, long nose pliers, solder.
The first step is completing the wiring for the water pump inside the tactix tool box. The rocker switch , the Anderson plug and a 7.5 Amp inline fuse are wired. The 12V rocker toggle switch is mounted at the center of the box lid.
The power input plug or the Anderson plug is mounted to the left of the switch. This input plug connects to the car battery or a solar battery. The positive red wires from the switch is connected to the Anderson plug through an inline fuse .The negative black wire from the plug goes straight to the switch. The remaining wires from the switch is then connected to the water pump which will be installed later. The wires are covered with corrugated split tubing to ensure that it is protected and safe.
The filter strainer is installed on the inlet side of the pump using an elbow, thread tapes. The strainer will filter out any unwanted debris before it goes to the pump.
Couple of holes are drilled into to the side of the box where the inlet and the outlet hoses will connect the water pump. The male fitting are attached to the holes before the pump is installed.
The pump is placed inside the box and mounted securely in such a way that the elbows are facing towards the two holes for the exterior hoses that was just made at the side of the box. Once the pump is mounted ,we connect the red and black wires coming from the switch to the positive and negative connections of the pump. The wires are once again covered with corrugated split tubing for safety.
To connect the pump with the hose outlets , we measure the distance between the outlets and the pump and connect two pex pipes . Heat was applied to the pipe for bending and moulding them to connect the outlets.
The 10 metre 50 Amp Anderson plug extension heavy duty cable wire is connected to the power source .Here the power draw is from a car battery. The other end is connected the input anderson plug on the top side of the box.
The inlet hose with the strainer attached is placed sitting midway
into the water source .The other end of the hose is connected to the intake pipe coming from the pump inside the box. The
The other hose is connected to the outlet pipe coming from the water pump inside the box. At the end of the hose , we connect an inline water filter or a twin carbon filter . The carbon filter ensures that there is no sediments or debris inside the water and also helps to eliminate bacteria and other contaminants.
This project goes into the build of a homemade wood burning heater with a heat exchanger for your garage . This heater is build from a recycled old propane tank . The other materials you need to build this heater are 55 gallon drum, fan blower, quarter inch steel plates , eighteen 2 inch steel pipes for the heat exchanger, welding unit, plasma cutter.
Before cutting into the propane tank , make sure to clean the tank so that there is no residual gas left in it . Cut both ends of the tank using the plasma cutter. Now we cut a 30 inch length piece from the tank .This acts as a main body where the heat exchanger pipes are installed. The heat exchanger consists of 18 two inch pipes that run the length of the heater from front to back.
Two quarter inch steel plates are welded at the ends of the propane tank . Before doing that we make 18 holes at both the ends of the steel plate. This is done to install the heat exchanger pipes across the length of the tank.
With the help of an eighth inch hardboard, we make a template for cutting the 18 holes out of the steel end plates. The hardboard acts a guide for the plasma cutter to cut the holes.
The pipes for the heat exchanger are cut 31 and half inches long. Half inch sticks out at both the ends of the heater. They are welded to the steel end plates at both ends.
The opening for the door at the end of the heater for the wood intake has a dimension of 16 inch X 12 inch . A similar template is placed on the end plate and the opening is cut using the plasma cutter.
A frame around the door is made using a three quarter inch by three sixteenths inch flat stock .This is used for the door opening and to give the door something to close up against. Hinges are welded near the door opening for attaching the door.
The locking mechanism for the door to hold it shut is made using a flat stock and couple of bolts . The bolts are welded onto the flat stock and attached inside the heater just beside the door . The handle made of a 90 degree round stock is welded to couple of washers and the door is sandwiched in between.
The end plates along with the door is welded onto the body of the heater at both the ends and a hole is made at the top of the propane tank body for installing the flue exhaust pipe.
A small hole is cut near the door and a damper in the form of a simple sliding door is attached to the hole that will control the airflow into the heater.
A section from old 55 gallon steel barrel is cut and welded onto the backside of the heater .An inexpensive fan blower is attached to this 55 gallon drum . This is installed to concentrate the air that is going through the heat exchanger pipes.
The flue pipe is welded onto the top of the heater so that the harmful smoke and gases escape through the exhaust . A grate is placed into the heater through the door opening , wood pieces are introduced and the we start firing the heater. After few minutes , the fire will heat the heat exchanger pipes . The fan blower is turned on and the hot air is blown through the pipes into the garage .
This project goes into the build of an off grid rocket mass heater for heating water without propane or electricity. This system also doubles as a cooktop. This rocket stove is really efficient and can create tremendous amount of free heat from little pieces of wood.
The materials you need to build this rocket mass heater are copper coil , PVC pipes to make mould, clay and sand mixture, a frame for support, storage tank or drum ,oil, wood as fuel.
The stove sits on a frame made from a wooden piece. Here an old chair is used as a base for support. The cob mixture made from clay, sand and water is poured on top of the frame as it is raised up.
The next step is make hole for the air intake at the base of the stove. Also another hole is made for fuel intake at an angle to the base. We use PVC pipes as mould to make these holes.
We lubricate the pipes with oil before covering them with mud so that they can be easily removed once the mould has been set and dry. A half cut lubricated PVC pipe is placed at the base of the support frame in front of another PVC which forms the body of the stove where the copper coil is wrapped.
We start covering the PVC pipes with clay and sand mixture around the junction where the pipes meet. Once the mud has been filled and raised up , another PVC pipe at an angle is placed for the fuel intake.
The copper coil is inserted into a well greased up PVC pipe . This section acts as the burn chamber where the coil gets heated up with the water inside. The coil is extended at the ends for the intake and the outlet .The bottom side of the coil is the intake of the cold water and the top for the hot water outlet.
Fully pack the area around the copper coil and sides of the PVC pipe with the clay mixture such that the copper coils are completely covered . Pack the clay till you reach five to six inches above at the end of the pipe . This is done so that the top can be used for cooking or boiling.
Once the clay and sand mixture is completely dried and set, we slowly take the PVC pipes out. Dig out the back end of both the holes so that all of them are connected to form a elbow shaped hole.
The intake and the outlet copper tube is then connected to a water storage barrel. The intake pipe is connected near the bottom of the barrel where the cold water settles and the upper end of the copper coil is connected at the top where the hot water is collected.
So the cold water that flows into the rocket stove, gets heated through the copper coil, and then due to the thermosiphon effect and natural convection ,the heated water is pumped through the other end of the coil on to the top of the barrel and this way the water is recirculated without the help of any external source. The cold water natural sinks down due to its higher density .The hot water becomes less dense once its heated , therefore it expands and rises up the coil to the water storage tank. Make sure that there is a height difference between the rocket stove and the water storage tank . The rocket stove always should be installed below the storage tank so that cold water naturally descends down into the stove and there is no backwards flow .
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.
