The intelligent information age greatly increases electricity demand, which, in return, pressures people into seeking for green power generation due to the severe environmental pollution and energy consumption. Solar PV power generation is expected to alleviate the pressure. With government’s policy support and less cost of power generation, energy storage systems are brought in tens of thousands of households. For the entire household energy storage system, MORNSUN provides a complete power solution to simplify customer’s design and increase system’s reliability.

Structure and components of a household energy storage system

A household energy storage system is currently divided into two kinds, grid-connected and off-grid. A grid-connected household energy storage system is mixed-powered by solar and the energy storage system, including five parts:

  • 1.Solar array
  • 2.Grid-connected inverter
  • 3.BMS (battery management system)
  • 4.Battery pack
  • 5.AC load


Grid-connected solution

When the utility works normally, the solar grid-connected system and the utility together power the load. When the utility powers off, the energy storage system and the solar grid-connected system together power the load. The grid-connected household energy storage system is divided into three working modes.

  • provides energy storage and powers the utility.
  • provides energy storage and powers part of residential electricity.
  • only provides energy storage.


Grid-connected solution

Off-grid solution

An off-grid household energy storage system is independent, without any electrical connection to the grid. Therefore the whole system does not need grid-connected inverter except PV inverter. The off-grid household energy storage system is also divided into three working modes.

  • provides energy storage and powers residential electricity on sunny days
  • and energy storage battery power residential electricity in cloudy days
  • storage battery powers residential electricity at dusk and on rainy days



Off-grid solution


In summary, current demands for energy storage equipment mainly are BMS management system, PV grid-connected inverter and energy storage inverter. Combined the demands with the safety isolation requirement of the PV system’s unit circuits, MORNSUN puts forward a complete power solution of a control unit.


Power Solution for BMS management system

The battery is the core energy storage device of the system and needs to be monitored online status in real time, so the importance of BMS is self-evident. In the BMS management system, BCU real-time communicates with

  • 1.CAN bus and BMU to get monomer voltages, cabinet temperature, insulation resistance and others
  • 2.current sensor to collect charge and discharge current and dynamic calculation SOC
  • 3.touch screen to display relevant data

The BCU calculates and analyzes all the information of the battery pack and then intelligently manages the system, communicating with the independent CAN bus and achieving the secondary protection of charge and discharge through a relay. The latter ensures an effective isolation for strong electricity and weak electricity, meets customer’s demand for diverse security control and guarantees a stable and efficient operation of the system.

Power Solution for BMS management system

Practical example diagram 3:

Isolation voltage conversion is the main core of a power solution for BMS management system in the energy storage system. The main control unit is mainly based on a 24VDC system, and the power of the whole main control unit is less than 5W. Therefore, URB2405YMD-10WR3 offering 5VDC output voltage is recommended to power F0505XT-1WR2 and LDO. The LDO converts 5VDC into a 3.3V output voltage to power MCU. 6 pieces F0505XT-1WR2 in the system is used to power four CAN modules, voltage detection circuit, insulation detection circuit and a current detection circuit, and isolate power circuit, signal circuit and communication module at the same time to reduce interference and improve the stability and reliability. In addition, MORNSUN automotive-grade power supply CF0505XT-1WR2 is widely used in automotive BMS system.


Power Solution for solar PV inverter monitoring unit

Solar PV components converge energy and inverter converts DC into AC. The process of the inverter needs to be monitored, controlled and communicated so as to ensure its voltage to meet the requirement. This monitoring unit can directly get power from the utility.

As shown in Diagram 4, LH series directly gets power from the utility and converts it into 24V output voltage, which is converted into a 5VDC output voltage by non-isolated switching regulator K7805-500R3. B0503XT-2WR2 outputs 3.3V to power the MCU with isolation function. Isolated high-speed TD501D485H can inhibit electromagnetic interference and rise the ground loop’s resistance to protect the system circuit from an external network. In addition, MORNSUN developed an isolated driver QP12W08S-37 integrating DC/DC power supply, specialized for full-bridge IGBT, to simplify the design of the customer’s driven-control circuit and improve the reliability.

Solar PV components converge energy

Power Solution for solar PV grid-connected inverter monitoring unit

Een aan het net geconnecteerde zonnepaneel omvormer (ook Bi-directionele omvormer genoemd) bestaat uit een AC/DC unit, DC/DC unit, controle unit en transfer relais unit. Deze energieopslag omvormer wordt vanuit twee soorten voedingsapparatuur gevoed. De ene is het elektriciteitsnet en de andere de zonnepanelen.

Power Solution for solar PV

Practical example diagram 5:

As shown in Diagram 5, the power selection of AC/DC Converter should mainly take the power of the main control board and fan into account. The equipment power in the above system is 15KW. AC/DC Converter LH40-10B24 offering 24V output voltage is recommended to power the fan and the main control board. For the main control board, it’s recommended to use R3 DC/DC Converters URB2415YMD-10WR3 to power IGBT driver and URB2405YMD-6WR3 to power MCU and communication module. URB_YMD-6/10WR3 series apply fully automated production process, greatly reducing the labour costs. With superior performance ahead of the peer level and highly cost-effective, they fully meet the overall cost demand of solar PV industry.

Energy storage battery

Would you like to speak to one of our engineers concerning this subject :




A standardized battery fits into any compatible compartment – after all, that’s why standards are defined. Depending on the application, however, button cells and cylindrical batteries reach their limits.


A Smartwatch, for example, has a significantly higher energy consumption than an ordinary wristwatch. A simple button cell is therefore far from sufficient to cover the device’s power requirements. However, the case of the watch is far too small for a powerful lithium-ion battery. Only a lithium polymer battery is capable of meeting the specific requirements of a Smartwatch.


Flexible product design

Lithium polymer technology is a match to lithium ion batteries in terms of performance, but is much more flexible in terms of design and size. The reason for this is the absence of a solid metal housing, as is common with lithium-ion batteries. Instead, the cells are merely enclosed by a thin layer of plastic-laminated aluminum foil. Thanks to the sandwich-like structure of the battery cells, even curved or ultra-flat designs with a thickness of less than one millimeter are conceivable.


For product developers and designers, the great flexibility of Lithium-Polymer batteries is a blessing. Conversely, the new design freedom can also lead to uncertainty. It is therefore advisable to take battery developers such as Jauch Quartz GmbH on board at an early stage for new developments.


The following six parameters must be defined at an early stage if design-in is to be successful.


1) Voltage

The average single cell voltage for lithium polymer cells is 3.6 volts as standard. The switch-off voltage is 3.0 volts and the maximum charging voltage is 4.2 volts. If a higher voltage is required, several cells can be connected in series. A parallel connection of several cells also makes it possible to increase the capacity.


2) Currents

In addition to the voltage, the current requirement of the application must also be defined. The average continuous currents must be specified as well as the maximum pulse currents and pulse lengths. The inrush currents and their lengths must also be taken into account.


3) Temperature

In connection with the current power load profiles of the application, the temperatures at which they are used must also be taken into consideration. By default, lithium polymer cells are designed for a temperature range between -20 and 60 degrees Celsius. Temperatures between 0 and 45 degrees Celsius should prevail when charging the cells.


Special cells are available for use under extreme temperature conditions above or below this range.


4) Dimensions of the Battery Compartment

Of course, the dimensions of the battery compartment must also be defined in advance. It is important to remember that lithium polymer cells expand over time. This “swelling” phenomenon is responsible for the cells to become up to 10% thicker over time. Accordingly, the battery compartment should be generously dimensioned. In addition, sharp edges or the like in the immediate vicinity of the battery compartment must be avoided at all costs so that the battery is not damaged.


5) Capacity

The capacity of a battery indicates the amount of electrical charge that a battery can store or release. Capacity is determined by voltage, current consumption, temperature and the available space in the battery compartment.


6) Safety

To protect lithium polymer batteries from overcharging, deep discharge or short circuits, they are equipped with individually programmable protection electronics. In order to optimally adapt this so-called “battery management system” to the respective application, individual switch-off values for the system are defined.


In addition, batteries must meet certain norms and safety standards to ensure that the applications are approved. Strict regulations apply here – understandably – especially in the field of medical technology.


Based on these six parameters, Jauch’s battery experts will find the right lithium polymer battery solution for every application. In order to guarantee optimum results, however, contact should be made as early as possible in the design-in phase. Otherwise, the desired battery solution may not be available or feasible.

SHENZHEN, China, March 29, 2020 /PRNewswire/ — Today, BYD officially announced the launch of the Blade Battery, a development set to mitigate concerns about battery safety in electric vehicles.


At an online launch event themed “The Blade Battery – Unsheathed to Safeguard the World”, Wang Chuanfu, BYD Chairman and President, said that the Blade Battery reflects BYD’s determination to resolve issues in battery safety while also redefining safety standards for the entire industry.


BYD highlighted a video of the Blade Battery successfully passing a nail penetration test, which is seen as the most rigorous way to test the thermal runaway of batteries due to its sheer difficulty. “In terms of battery safety and energy density, BYD’s Blade Battery has obvious advantages,” said Professor Ouyang Minggao, Member of the Chinese Academy of Sciences and Professor at Tsinghua University.


The Blade Battery has been developed by BYD over the past several years. The singular cells are arranged together in an array and then inserted into a battery pack. Due to its optimized battery pack structure, the space utilization of the battery pack is increased by over 50% compared to conventional lithium iron phosphate block batteries.


While undergoing nail penetration tests, the Blade Battery emitted neither smoke nor fire after being penetrated, and its surface temperature only reached 30 to 60°C. Under the same conditions, a ternary lithium battery exceeded 500°C and violently burned, and while a conventional lithium iron phosphate block battery did not openly emit flames or smoke, its surface temperature reached dangerous temperatures of 200 to 400°C. This implies that EVs equipped with the Blade Battery would be far less susceptible to catching fire – even when they are severely damaged.


The Blade Battery also passed other extreme test conditions, such as being crushed, bent, being heated in a furnace to 300°C and overcharged by 260%. None of these resulted in a fire or explosion.


He Long, Vice President of BYD and Chairman of FinDreams Battery Co., Ltd., covered four distinct advantages of the Blade Battery including a high starting temperature for exothermic reactions, slow heat release and low heat generation, as well as its ability to not release oxygen during breakdowns or easily catch fire.


In the past few years, many EV manufacturers have fallen into a competition for ever-greater cruising range. When the range becomes the prime factor to consider, this focus is then transferred to power battery makers, leading to unreasonable pursuits of “energy density” in the battery industry. It is due to this unpractical focus on “energy density” that safety has been sidelined from power battery development. BYD’s Blade Battery aims to bring battery safety back to the forefront, a redirection from the industry’s tenuous focus on this crucial aspect.


“Today, many vehicle brands are in discussion with us about partnerships based on the technology of the Blade Battery,” said He Long. He added that BYD will gladly share and work with global partners to achieve mutually beneficial outcomes for all industry players.


The Han EV, BYD’s flagship sedan model slated for launch this June, will come equipped with the Blade Battery. The new model will lead the brand’s Dynasty Family, boasting a cruising range of 605 kilometers and an acceleration of 0 to 100km/h in just 3.9 seconds.


Marine batteries are designed specifically for use on a boat, with heavier plates and robust construction designed to withstand the vibration and pounding that can occur onboard any powerboat. For this reason, marine batteries are usually more expensive than automobile batteries, which can tempt some boat owners to purchase an auto battery instead of a marine battery. Don’t make that poor decision. A marine battery will last longer and be more reliable than an auto battery in a boat.

There are three basic types of marine batteries:

  • Marine Starting Batteries provide quick but powerful spurts of energy over short periods of time and are designed to start the engine and be rapidly recharged by the engine alternator. A starting battery should not be used for trolling motors or powering appliances.
  • Marine Deep Cycle Batteries are designed to discharge slowly over a long period of time and to withstand several hundred charging and discharging cycles. A deep cycle battery is a right choice for powering an electric trolling motor and other battery-powered accessories such as audio systems, a windlass, depth finders, fish locators, and appliances. Deep cycle batteries should not be substituted for starting batteries.
  • Marine Dual-Purpose Batteriescombine the performance of starting and deep cycle battery, and are a good choice on smaller when there’s no room for two batteries. While they’re able to perform the tasks of a starting battery and deep cycle battery, they’re not as efficient as separate batteries.

Boat Battery

Deep Cycle vs. Cranking

If you have an electric trolling motor, thruster, windlass, or other battery-powered accessories that draw larger amounts of current, you’ll want a separate deep cycle “house” battery for that purpose. A deep cycle battery is only meant to be used where high rates of discharging and re-charging occur often. A deep cycle battery is constructed differently than a cranking battery, with thicker, heavier plates. The longer, higher amperage requirements of trolling motors and windlasses, for example, would heat and distort the thinner plates of a normal cranking battery.

The cranking battery has more yet thinner plates to give a fast voltage spike to crank an engine but is not intended to maintain high power output for long periods. Yes, a deep cycle battery can be used to start your motor in a pinch, but a two- or three-battery system is highly recommended to separate the engine battery from the accessory (house) batteries.

The best way to be sure your battery is still good is to have it “load tested.” Most auto parts or battery specialty stores will load test your battery for free and tell you if it’s still serviceable. Just because it’s gone dead once or twice doesn’t necessarily mean it’s no good. The rest of your electrical and charging systems may need some attention as well, as something other than the battery itself may be the cause of the problem.

Replacing Your Boat’s Battery

Consult your boat owner’s manual or a marine dealer when replacing a marine battery, and be sure to buy a new battery that is a good match for your boat. Marine batteries are rated by their ampere hour rating, reverse capacity, and marine cranking amps. When shopping for a deep cycle battery, you’ll want to pay the most attention to the ampere hour rating and reserve capacity. For starting batteries, focus primarily on the marine cranking amps. Consult all three rankings when searching for a dual-purpose battery.

If you add electrical accessories to your boat, you may need to upgrade to a battery with a higher amp-hour rating, especially if you spend a lot of time trolling with the engine at a very low speed (which results in less charging power from the alternator) or you spend a lot of time beached or at anchor while using accessories like the audio system.

Charging a Marine Battery

Most of us understand that when we are buying a new or used boat, the batteries supplied may not necessarily be top-of-the-line. If they seem to do the job, we don’t think much about them. But in the warmer climates everyday heat is a major enemy of batteries and can shorten their life considerably. In areas of the country that force us to put boats in storage for the winter, how the battery is cared for during this period is also critical to increasing life expectancy.

It’s best to keep batteries on a regulated “trickle” charger to maintain charge while not in use. A battery that is not charged (and kept charged) can freeze in cold temperatures and a cracked case is the likely result.  A battery is like a lot of things in life—use it or lose it! A car battery will typically last longer than a boat battery because the car is used regularly and the battery stays charged. When it comes to boats, the old adage of a battery’s life being two years is pretty well on the mark. You’ll usually get a heads-up when it’s about to give up on you, with the warning being a “dead” battery one morning or a bit slower cranking speed than you’re used to. You plug in the charger, the battery miraculously comes to life, and you’re off on your trip. You may think the light was left on, or that the radio memory pulled the voltage down. The reality may be that the battery is sulfating, plates are warped, and it no longer takes or holds a charge like it once did.

Tips for Avoiding Battery Problems

  • Secure the marine battery with a good battery tray, which should have a base that is screwed or bolted to the boat and either a rigid bracket or a locking strap to hold it to the base. You don’t want the battery banging around in rough water.
  • Frequently check the battery terminal connections to make sure they are snug and free of corrosion. Replace the wing nuts often found on marine batteries with nylon locking nuts, which are much less likely to come loose.
  • If you use the boat infrequently, use a maintenance-type battery charger to keep the battery fully charged between outings.
  • Before off-season storage completely charge the batteries then disconnect the terminals so nothing can draw the battery down. If there’s power available at your storage site, keep the batteries on a battery maintainer/charger through the off-season to continually maintain your batteries. Otherwise, remove the batteries from the boat and store them where they can be connected to a maintenance charger.
  • Install a cover or “boot” over the top of the positive battery terminal, if one was not installed by the boat builder, even if the battery is in a covered box. The boot prevents sparks and arcing and possible explosion if, for instance, a tool is dropped on the terminal.

Bottom line? Keep your batteries charged, keep the terminals clean, and by all means get out in the boat and “exercise” your electrical system as often as you can!


12v 100ah lifepo4

Battery pole piece spot welding machine work principle:

12v 100ah lifepo4

Battery pole piece spot welder use of ultrasonic metal welding principle, ultrasonic metal welding should be classified as don’t need preheating welding. Oxidation surface is the great friction welding which division, and at the same time two parts are pressed together. This program let two materials to produce the atom so close to the action. Far below melting point relatively slight increase of temperature in the welding process is not important factors. At the same time, because the basic material not liquefied, so there is no microstructure changes, also will not damage to internal structure. Ultrasonic cell metal special welding machine is suitable for: aluminum + nickel, nickel and copper foil, aluminum + aluminum foil, multilayer copper foil, multi-layer aluminum foil, multilayer copper nets, multilayer aluminum mesh, aluminum plate + aluminum strip, aluminum nickel composite belt + aluminium plate, aluminum shell bottom + ni-clad-al strip double point welding; And with nickel and copper foil, nickel band and aluminum belt, aluminium strip and aluminum foil, aluminum band and aluminum cover, aluminum shell and ni-clad-al strip of the material such as the single point, multipoint, single, multi-layer, square, form and process of welding. Features suitable for battery, hardware, electrical appliances and motor industry.

Battery pole piece spot welder features:

  1.  due to the bench ultrasonic cell metal welding machine machine 80% use import parts and components, to ensure low failure rate and machine section structure design is reasonable;
  2.  ultrasonic lithium ion battery metal welding machine of welding mould can according to different application fast and convenient to change;
  3.  ultrasonic cell copper foil nickel sheet welding machine with German import piezoelectric ceramic transducer, stable and durable;
  4.  miniature ultrasonic power battery cover sheet welding machine operation easy, built-in electronic protection circuit, the use of safe,
  5. independent research and development, and the ultrasonic cell metal welding mould and welding head, reached the advanced world level, reduce the enterprise cost;
  6. ultrasonic nimh battery pole piece very ear welding machine used for the same kind of metal welding, to foreign non-ferrous metal implement single point or multipoint welding, especially copper aluminum nickel sheet, line, take welding.

Battery pole piece spot welder advantages:

The machine use desktop integration design, reasonable structure, beautiful appearance, Vertical motion, positioning accuracy is high, the welding effect is good; Welding head and the integral design of the mould can ensure the consistency of the welding effect, and extend the welding head life; New mould manufacture and maintenance cost is low, the welding of high efficiency; Advance to set the energy, time of welding parameters, constant welding parameter to ensure the welding quality. The operation is simple, convenient assembly, easy maintenance, can according to the customer the production needs of customized; Combined with quality control system for automatic process monitoring, without professional technician, on-site staff need to accept a day of training that will operate. Features suitable for wire and guide piece of the connections between, lithium nimh battery electric etc with nickel sheet alloy plate ni-clad-al strip connection, household electric parts and wire welding, all kinds of high or low conductivity metal and alloy, etc.

Elon Musk promised Tesla would soon have a million-mile battery, more than double what drivers can expect today. A new paper suggests he wasn’t exaggerating.


Hybrid Car Battery

LAST APRIL, ELON Musk promised that Tesla would soon be able to power its electric cars for more than 1 million miles over the course of their lifespan. At the time, the claim seemed a bit much. That’s more than double the mileage Tesla owners can expect to get out of their car’s current battery packs, which are already well beyond the operational range of most other EV batteries. It just didn’t seem real—except now it appears that it is.


Earlier this month, a group of battery researchers at Dalhousie University, which has an exclusive agreement with Tesla, published a paper in The Journal of the Electrochemical Society describing a lithium-ion battery that “should be able to power an electric vehicle for over 1 million miles” while losing less than 10 percent of its energy capacity during its lifetime.


Led by physicist Jeff Dahn, one of the world’s foremost lithium-ion researchers, the Dalhousie group showed that its battery significantly outperforms any similar lithium-ion battery previously reported. They noted their battery could be especially useful for self-driving robotaxis and long-haul electric trucks, two products Tesla is developing.


What’s interesting, though, is that the authors don’t herald the results as a breakthrough. Rather, they present it as a benchmark for other battery researchers. And they don’t skimp on the specifics.


“Full details of these cells including electrode compositions, electrode loadings, electrolyte compositions, additives used, etc. have been provided,” Dahn and his colleagues wrote in the paper. “This has been done so that others can recreate these cells and use them as benchmarks for their own R+D efforts.”


Within the EV industry, battery chemistries are a closely guarded secret. So why would Dahn’s research group, which signed its exclusive partnership with Tesla in 2016, give away the recipe for such a seemingly singular battery? According to a former member of Dahn’s team, the likely answer is that Tesla already has at least one proprietary battery chemistry that outperforms what’s described in the benchmark paper. Indeed, shortly after the paper came out, Tesla received a patent for a lithium-ion battery that is remarkably similar to the one described in the paper. Dahn, who declined to comment for this article, is listed as one of its inventors.


The lithium-ion batteries described in the paper use lithium nickel manganese cobalt oxide, or NMC, for the battery’s positive electrode (cathode) and artificial graphite for its negative electrode (anode). The electrolyte, which ferries lithium ions between the electrode terminals, consists of a lithium salt blended with other compounds.


NMC/graphite chemistries have long been known to increase the energy density and lifespan of lithium-ion batteries. (Almost all electric cars, including the Nissan Leaf and Chevy Bolt, use NMC chemistries in their batteries, but notably not Tesla.) The blend of electrolyte and additives is what ends up being the subject of trade secrets. But even those materials, as described in the paper, were well known in the industry. In other words, says Matt Lacey, a lithium-ion battery expert at the Scania Group who was not involved in the research, “there is nothing in the secret sauce that was secret!”


Instead, Dahn’s team achieved its huge performance boosts through lots and lots of optimizing of those familiar ingredients, and by tweaking the nanostructure of the battery’s cathode. Instead of using many smaller NMC crystals as the cathode, this battery relies on larger crystals. Lin Ma, a former PhD student in Dahn’s lab who was instrumental in developing the cathode design, says this “single-crystal” nanostructure is less likely to develop cracks when a battery is charging. Cracks in the cathode material cause a decrease in the lifetime and performance of the battery.

When people wanted something roomier than a station wagon but not as commercial-looking as a van, the auto industry gave us minivans. Then when people wanted something sportier than minivans but not as workmanlike as pickup…

Reports from the Energy Storage Research Program at DOE have found that “every year roughly one-million usable lithium-ion batteries are sent for recycling”. Knowing when to replace a battery is an ongoing concern and date-stamping serves as only a partial and imperfect solution. It is important to understand and acknowledge the fact that batteries do not fail suddenly, but rather they follow a predicted decline in capacity losing performance over time. Battery life is governed by usage, not time.


A new battery is rated at a nominal capacity of 100%. As the battery ages, the reserve capacity drops and the battery eventually needs replacing when the reserve capacity falls below a certain level to be defined depending on the application of a battery-powered medical device.

Nickel-based batteries provide about three-years of service; Li-on five. Storage characteristics have also improved. However, under-usage in healthcare is more common than ever, and bio-medical technicians have discovered that many medical batteries that are recycled still have a capacity of above 90%, leading to millions of unchecked batteries being discarded every year.


The date-stamping approach to batteries has several serious flaws:

It does not detect a damaged or prematurely faded battery. Batteries that are used regularly may fade before the expiry date listed on the stamp.

Through this approach, it is also often neglected that even batteries held in storage and are not in use, lose capacity over time.

It is a costly procedure as it does not allow for full battery service life to be used, resulting in most batteries in this system being replaced after less than half of their useful life is still intact. Li-on batteries, for example, often last 2-3 times longer than the date stamp mandates, but also have higher purchase prices making premature disposal even more costly.


By replacing the arguably outdated approach to battery replacement, with a greener, more reliable approach, the future of battery management in healthcare will be increasingly optimized.

Batteries achieve the desired operating voltage by connecting several cells in series; each cell adds its voltage potential to derive at the total terminal voltage. Some packs may consist of a combination of series and parallel connections. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve a nominal voltage 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh. Such a configuration is called 4s2p, meaning four cells in series and two in parallel.


It is important to use the same battery type with equal voltage and capacity (Ah) and never to mix different makes and sizes. A weaker cell would cause an imbalance, as a battery is only as strong as the weakest link in the chain.


Single Cell Applications

The single-cell configuration is the simplest battery pack; the cell does not need matching and the protection circuit on a small Li-ion cell can be kept simple. Typical examples are mobile phones and tablets with one 3.60V Li-ion cell. Other uses of a single cell are wall clocks, which typically use a 1.5V alkaline cell, wristwatches and memory backup, most of which are very low power applications.


Series Connection

Portable equipment needing higher voltages use battery packs with two or more cells connected in series.

Figure 2: Series connection of four cells (4s).
Adding cells in a string increases the voltage; the capacity remains the same.


High voltage batteries keep the conductor size small. Cordless power tools run on 12V and 18V batteries; high-end models use 24V and 36V. Most e-bikes come with 36V Li-ion, some are 48V. The car industry wanted to increase the starter battery from 12V (14V) to 36V, better known as 42V, by placing 18 lead acid cells in series.

Some mild hybrid cars run on 48V Li-ion and use DC-DC conversion to 12V for the electrical system.



Parallel Connection

If higher currents are needed and larger cells are not available or do not fit the design constraint, one or more cells can be connected in parallel. Most battery chemistries allow parallel configurations with little side effect.

Figure 4: Parallel connection of four cells (4p).

With parallel cells, capacity in Ah and runtime increases while the voltage stays the same.


Series/parallel Connection

The series/parallel configuration shown in Figure 6 enables design flexibility and achieves the desired voltage and current ratings with a standard cell size. The total power is the product of voltage-times-current; four 3.6V (nominal) cells multiplied by 3,400mAh produce 12.24Wh. Four 18650 Energy Cells of 3,400mAh each can be connected in series and parallel as shown to get 7.2V nominal and 12.24Wh. The slim cell allows flexible pack design but a protection circuit is needed.

Figure 6: Series/ parallel connection of four cells (2s2p).

This configuration provides maximum design flexibility. Paralleling the cells helps in voltage management.


Safety devices in Series and Parallel Connection

Positive Temperature Coefficient Switches (PTC) and Charge Interrupt Devices (CID) protect the battery from overcurrent and excessive pressure. While recommended for safety in a smaller 2- or 3-cell pack with serial and parallel configuration, these protection devices are often being omitted in larger multi-cell batteries, such as those for power tool.


 Simple Guidelines for Using Household Primary Batteries

  • Keep the battery contacts clean. A four-cell configuration has eight contacts and each contact adds resistance (cell to holder and holder to next cell).
  • Never mix batteries; replace all cells when weak. The overall performance is only as good as the weakest link in the chain.
  • Observe polarity. A reversed cell subtracts rather than adds to the cell voltage.
  • Remove batteries from the equipment when no longer in use to prevent leakage and corrosion. This is especially important with zinc-carbon primary cells.
  • Do not store loose cells in a metal box. Place individual cells in small plastic bags to prevent an electrical short. Do not carry loose cells in your pockets.
  • Keep batteries away from small children. In addition to being a choking hazard, the current-flow of the battery can ulcerate the stomach wall if swallowed. The battery can also rupture and cause poisoning.
  • Do not recharge non-rechargeable batteries; hydrogen buildup can lead to an explosion. ·Perform experimental charging only under supervision.


Simple Guidelines for Using Secondary Batteries

  • Observe polarity when charging a secondary cell. Reversed polarity can cause an electrical short, leading to a hazardous condition.
  • Remove fully charged batteries from the charger. A consumer charger may not apply the correct trickle charge when fully charged and the cell can overheat.
  • Charge only at room temperature.

LiFePO4 chemistry lithium cells have become popular for a range of applications in recent years due to being one of the most robust and long-lasting battery chemistries available. They will last ten years or more if cared for correctly. Please take a moment to read these tips to ensure you get the longest service from your battery investment.


Tip 1: Never over charge/discharge a cell!

The most common causes for premature failure of LiFePO4 cells are overcharging and over-discharging. Even a single occurrence can cause permanent damage to the cell, and such misuse voids the warranty. A Battery protection System is required to ensure it is not possible for any cell in your pack to go outside its nominal operating voltage range,

In the case of LiFePO4 chemistry, the absolute maximum is 4.2V per cell, though it is recommended that you charge to 3.5-3.6V per cell, there is less than 1% extra capacity between 3.5V and 4.2V.

Over charging causes heating within a cell and prolonged or extreme overcharging has the potential to cause a fire. EV Works Takes no responsibility for any damages caused as a result of a battery fire.

Over charging may occur as a result of.

  • Lack of a suitable battery protection system
  • Faulty of infective battery protection system
  • incorrect installation of the battery protection system


At the other end of the scale, over-discharging can also cause cell damage. The BMS must disconnect the load if any cells are approaching empty (less than 2.5V). Cells may suffer mild damage below 2.0V, but are usually recoverable. However, cells which get driven to negative voltages are damaged beyond recovery.

On 12v batteries the use of a low voltage cutoff takes the place of the BMS by preventing the overall battery voltage going under 11.5v no cell damage should occur. On the other end charging to no more than 14.2v no cell should be overcharged.


Tip 2: Clean your terminals before installation

The terminals on top of the batteries are made from aluminium and copper, which over time builds up an oxide layer when exposed to air. Before installing your cell interconnectors and BMS modules, clean the battery terminals thoroughly with a wire brush to remove oxidation. If using bare copper cell interconnectors, these should be cleaned too. Removing the oxide layer will greatly improve conduction and reduce heat buildup at the terminal. (In extreme cases, heat buildup on terminals due to poor conduction has been known to melt the plastic around the terminals and damage BMS modules!)


Tip 3: Use the right terminal mounting hardware

Winston cells using M8 terminals (90Ah and up) should use 20mm long bolts. Cells with M6 terminals (60Ah and under) should use 15mm bolts. If in doubt, measure the thread depth in your cells and ensure that the bolts will get close to but not hit the bottom of the hole. From top to bottom you should have a spring washer, flat washer then the cell interconnector.


A week or so after installation, check that all your terminal bolts are still tight. Loose terminal bolts can cause high-resistance connections, robbing your EV of power and causing undue heat generation.


Tip 4: Charge frequently and shallower cycles

With lithium batteries, you will get longer cell life if you avoid very deep discharges. We recommend sticking to 70-80% DoD (Depth of Discharge) maximum except in emergencies.

Swollen Cells

Swelling will only occur if a cell has been over-discharged or in some cases overcharged. Swelling does not necessarily mean the cell is no longer usable though it will likely lose