How to Recycle Old Used Laptop Batteries to make a DIY 24V 72AH Emergency Backup Battery System

    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 Powerful DIY Off-Grid Emergency Backup Generator .Fully Portable!!
      This project goes into the build of a portable and powerful off grid emergency solar generator with higher capacity than commercial units at a fraction of the cost. This system can keep a small fridge operating 24/7, charge your devices, power TV ,LED lights, Laptops. it is small enough to be stored away in your garage and portable enough to move where it was needed. The main components used to build this generator are as follows. 4 Renogy 100 Watt 12 Volt Monocrystalline Solar Panel Renogy Rover 40 Amp MPPT Solar Charge Controller Renogy Deep Cycle AGM Battery 12 Volt 100Ah Sug 2000W(Peak 4000W) Power Inverter Pure Sine Wave DC 12V to AC Renogy 20 Feet 10AWG Solar Extension Cable with MC4 Female and Male BLACK+DECKER BM3B 6V and 12V Automatic Battery Charger / Maintainer 6 Circuit Fuse Block W/Negative Bus Milwaukee Hand Truck with handle Control Panel with USB Charger,LED Voltmeter,12V Power Outlet, ON-OF Switch. To create a solar system that can truly meet your needs and cope with the variability of your environment, you really need to do some planning. This will help you avoid building a system that isn't up to the job and can save you considerable money by preventing the expense of replacing components later on. To calculate the number of batteries and solar panels you will need to create a system to provide power in all seasons through inclement weather and at your particular latitude, you need to determine the devices you intend to power, log their power consumption across a few days using a power meter. Then find the reserve days . This is how many non sunny days the system can tolerate while still powering your devices. Also find the recovery time by calculating how many days of sun that will be needed to fully recover when the batteries have run down due to lack of sun. You also need to know the usable charging hours in day and the actual battery round trip efficiency since batteries give back something less than the amount of power used to charge them. Here we use 4 100 Watt 12 Volt Monocrystalline Solar Panels to charge our 12 Volt Deep Cycle Battery. The panels are wired in series so that the voltages add together and you can get up to 80 volts from four panels. With this system there is enough voltage to begin charging as soon as there is any daylight at all. It also charges the batteries right up until dusk. Another advantage of the series wiring is that it is much better for long wire runs when the solar panels are not close to the generator and you can use less expensive smaller wire gauges for the solar panel runs. To use panels in series you must have an MPPT type charge controller. They are specially designed to accommodate the high voltage of panels wired in series up to the particular controllers voltage limit .MPPT controllers are much more efficient converting nearly all the energy coming from the panels into charging power for the battery. A 2000 watt pure sine wave inverter is used that can provide up to 4000 watts of surge power, and with enough battery support can run any conceivable device including those with motors. To store energy we use a 2 12V AGM marine batteries . These give plenty of reserved capacity that will last with reasonable care . They don't leak and can tolerate cheaper discharges and have very good round trip efficiency. Four 100 watt solar panels are connected through the 40 amp MPPT charge controller . The panels can deliver up to 2400 watts of solar power in the shortest days of winter. And the charge controller converts solar power to charging power very efficiently and also support serial panel configurations increasing the systems capability. A heavy duty hand truck is used for loading all the components . A frame made of angle iron is welded on to the platform to mount the batteries. Two angled straps are welded across the truck to provide more support for the battery frame. The various components are mounted on a back support made of five eighth inch plywood. I use a tapered punch to make starter holes for all the screws that hold the components. The hand cart is laid on its back and the plywood board is aligned in such a way it doesn't block the holes. While the cart was on its back I screw down all the components with stainless steel screws. For the project we use a thinner 18 gauge wire for the low current circuits, medium 14 gauge for the 12 volt port and heavy 10 gauge for the high current charging circuits. Red is always connected to the plus or positive connectors, black always to the minus or negative. The positives and the negative connection coming from the solar panels are connected to the solar charge controller with the help of a quick disconnect Wire Harness SAE Connector. The negative of the solar charge controller is directly connected to the negative connection of the battery while the positive goes through a fuse block before connecting the positive of the battery. The negative connections from switch, voltage display ,USB ports and battery charge meter is connected via a medium 14 gauge wire to the battery negative. The positives are connected to the battery through the fuse block. The 12 volt port is on its own fuse so it gets separate wires in the medium 14 gauge. The positive of the 12V Battery Charger is connected to the fuse while the negative is connected to the battery. The batteries are placed on platform of the cart facing opposite directions so that positive and the negative terminals are near the plywood backboard where the components are attached. The battery connection cables are cross connected to create a parallel 12 volt configuration careful to ensure the block cable connected only to minus terminals at both ends and the red cable connected only to plus terminals at both ends. Next step is the orientation of the solar panels. As you probably know the sun is lower in the sky in the winter higher in the summer. In the winter, the days are also shorter as you really want to optimize for winter to get as much energy as you can when the days are short. Since my panels are fixed, we want to point them due south and angle them for the winter sun. There are tables you can find online that can give you a pretty good idea of the right vertical angle for your geographical location. In the summer the sun is pretty much straight overhead, so the panels are optimal when laying flat. The angle panels are their most productive in the depth of the winter losing a little each day until the height of the summer as the sun is further off the winter angle. Meanwhile, the flat panels are less efficient in the winter because the sun is at a low angle but gaining each day as the sun gets higher in the sky.
    • How to build a Homemade Off grid Solar Powered Water fueled Air Heater and Air Cooler using an 8 X 8 heat exchanger and a car radiator fan
      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 .
    • DIY Video : How to build a Simple Woodgas generator for small electric RV generator
      This is the build of a simple Wood gas generator for small 5HP electric generator.This is made from simple materials that can be easily found around your home. The main generator here is a 20 gallon garbage can inside I have a wine cooler and inside there I have hung a small steel bowl. It's just connected up to this very long aluminum duck line to my filter and my filter has been filled with wood pellets to also serve as the fuel. . Then the outlet line goes over to an air inlet port.When you burn the gas you have to add air and this is the valve I've designed to allow that. It goes all the way to the RV Gas engine.You can cut off the fuel by using a wire to cut off the fuel pump. We use a 20 gallon garbage can as the filter.So first I use a quarter inch drill to put two holes in here and then I've enlarged it with a nibbler.Put a harbour wire down in the can where the filter medium is dumped. I use pine wood shavings as a filter medium.Use about 1/3 to fill up my 20 gallon. The reactor is basically constructed out of a stainless steel thermos, which is a central cylinder that is double walled and it has like a one inch opening at the bottom. And below that we've just hung a steel mixing bowl that we basically drilled a lot of holes into and then hung by these three chains that you have riveted in. And then we just connected it with a simple 20 foot ordinary dryer duct. The reactor is filled up some wood pellets ,we have stretched out the hose, this will cool the gas into the improved 20 gallon filter. And I'm going to be driving this with a small air mattress pump. And what I've done is I've rigged myself a dimmer control here so I can actually control the speed.