Key things make sure the safety of lithium ion battery2020-03-24T13:57:11+00:00
battery safty
lithium battery safty

Diaphragm 135 degrees C automatic shutdown protection, using the international advanced Celgars2300PE-PP-PE three-layer composite Membrane. In the case of the battery heating up to 120 degrees C, the membrane holes on both sides of the PE composite film are closed and the intra-battery resistance increases
large, the battery internal heating slows down. When the battery heats up to 135 degrees C, the PP membrane hole is closed and the inside of the battery is broken. The battery no longer heats up to ensure that the battery is safe and reliable.

Add an additive to the electrolyte under the condition that the battery voltage is higher than 4.2V
Agent and other substances in the electrolyte polymerization, the intra-battery resistance increased significantly, the battery internal formation of a large area of broken,
The battery no longer heats up.

Battery cover composite structure Battery cover using nick explosion-proof ball structure, battery heating, battery internal activation process
The resulting part of the gas expansion, the battery pressure increased, the pressure reached a certain degree of nick rupture, release.

Various environmental abuse tests conducted abuse experiments, such as external short circuits, overfilling, needles, shocks, incineration
and so on, to examine the safety performance of the battery. At the same time, the temperature shock experiment and vibration, drop, shock and other forces of the battery
to examine the performance of the battery in the actual use of the environment.

What are the possible reasons why the battery and battery pack are not charged?2020-03-24T12:19:03+00:00

What would cause a battery or battery pack not to take a charge?

  • Zero voltage battery or zero voltage battery in the battery pack;

Lithium ion battery like polymer or 18650 li ion. They are very sensitive on low voltage. Normally, the battery or battery pack come with BMS, it has the function prevent over discharge. However, the bms circuit could be damaged for some reason. And battery cell fully discharged to 0. In this situation. The battery cell could be damaged permanently.

  • Battery pack connection error, internal electronic components, protection circuit abnormal;
  • Charging equipment failure, no output current;
  • External factors cause charging efficiency to be too low (e.g. very low or very high temperature).
battery pack are not charged

What to do when the battery pack does not charge

7.4v icr 18650 lithium ion battery packs

Step 1. Check the connections.
It may seem improbable, but the stability of any power connection is limited by its weakest link. Check the contacts and terminals for dirt, oils, corrosion, excessive wear or anything that can hamper a good, stable connection. This includes the battery contacts with application, in the charger, and on the battery itself.

Step 2. Reseat the battery in the devices.
It seems unlikely, but it happens. Some application require a tight fit with the battery and may seem attached when they are not fully locked in place. Make sure the battery is seated properly and the battery pack locks firmly in place when attaching it.

Step 3. Verify you are using the correct battery charger.
Using the wrong charger can not only prevent your  battery from charging properly, it could damage your equipment. It can also be potentially dangerous.

Step 4. Check to be sure the charger is plugged in and turned on.
Sound silly, doesn’t it? Well, it isn’t really, because it does happen. It’s one of the easiest mistakes to make when charging a fleet of batteries and one of the simplest to resolve.

Step 5. Reseat the  battery in the charger.
Battery seems like it’s connected to the charger when it’s not making contact at all. If it is a drop-in or desktop charger with a pocket or tray, the radio and/or battery may be able to sit in the tray without actually touching the contacts. If it is a plug-in type of charger, the plug may not be fully inserted. Be sure the radio/battery is properly seated or fully connected and the charging indicator light is on.

Step 6. Charge another battery of the same make and model in the charger.
Determine if the issue is really with the battery pack.

Step 7. Swap out the charger.
Sometimes a dead battery is the result of a dead charger.

Step 8. Charge the battery again.
Just to be sure, give it another chance.

Every battery has a limited life span determined by a number of different factors, including but not limited to how and where it is used, how much it is used and under what conditions. There is no set time table before a battery “kicks the bucket”. If your battery has reached its End of Life, it’s time to purchase a new one.

What are the main factors affecting battery cycle life ?2020-03-24T08:05:39+00:00

What are the main factors affecting battery life? 3 things you must know.

There are different reason affecting battery cycle life. Here we peak up some Main reasons to explain. So you can have a better understanding and how to take care of your batteries.

cycle life

Charge the battery:

When selecting a charger, it is best to use a charger with the correct termination charging device (e.g. anti-overcharge, negative voltage differential (-dV) cut-off charging and anti-overheating sensing) to prevent the battery shorten circle-life due to overcharge. In general, slow charging extends battery life more than faster charging. So, we suggest charging a battery with small current go gain longer life cycles.


The depth of discharge is the main factor affecting battery life cycles, and the higher the depth of discharge, the shorter the battery life. In other words, reducing the depth of discharge can significantly extend the battery life. Because

For this reason, we should avoid over-setting the battery to very low voltages.

  • When the battery is discharged at high temperatures, it shortens the life of the battery.
  • If the design of electronic equipment can not completely stop all current, if the equipment is put on hold for a long time, without removing the battery, its residual current will sometimes cause the battery to be excessively consumed, resulting in excessive discharge of the battery.
  • When a battery with different electrical capacity, chemical structure or different charging levels is mixed, and a battery of different ages and sizes, the battery will also discharge too much, and may even cause anti-polar charging.
LiFePo4 battery cell cycle life


If the battery is stored at high temperatures for a long time, it will attenuate its electrode activity and shorten its service life.

48 volt lithium ion battery pack
Can Lead-acid Batteries for Electric Vehicles Be Converted to Lithium Batteries2019-12-30T14:45:58+00:00

As we all know, after the issuance of the new national standards, there are strict regulations on the standards of electric vehicles. If lithium batteries are used instead of lead-acid batteries, it must also be considered that the voltage of the lithium batteries must be the same as that of the original lead-acid batteries. In addition, a special lithium charger must be replaced. Can lead-acid batteries for electric vehicles be replaced by lithium batteries? Listen to Chilong New Energy Engineer!

Lithium VS lead acid

First, the production cost of lithium batteries is high, the production equipment is expensive, the labor cost accounts for about 40% of the production cost, and the price is about three times that of lead-acid batteries. The triple price of lithium batteries brings about low cost performance, fairly smooth feeling, and it is difficult to recycle lithium batteries, and the utilization rate is not high. Due to the small size of lithium batteries, multiple lithium batteries are connected in series during the assembly process, which may lead to the disconnection or welding of a solder joint during transportation and use, which is a common problem in the connection of lithium batteries.

Secondly, the high current discharge characteristic of lithium ion power supply itself is short plate. Considering the frequent start-up of congested roads, the battery life will be greatly shortened. Lithium batteries have potential safety hazards of fire and explosion. Nobody wants to buy a “time bomb” and put it under his body. Especially when consumers do not know the fact that they have purchased some inferior lithium batteries online, the sealing condition of electric vehicles is not very good, and it is easy to cause unsafe contact due to dampness and other reasons. Some people may say that lithium battery technology is developing very fast, there will be no such problem, but no one can guarantee that this problem will not happen.

Thirdly, compared with lead-acid batteries, lithium batteries have the same weight and volume. The capacity of lithium batteries is generally about three times that of lead-acid batteries. However, for electric vehicles as alternative tools, the effect is actually limited, because many lead-acid batteries also greatly improve their endurance, which reduces the gap between lithium batteries and lead-acid batteries.

4. If lithium batteries are used instead of lead-acid batteries, it must also be considered that the voltage of lithium batteries must be the same as that of original lead-acid batteries. In addition, a special lithium charger must be replaced. Of course, there is another problem. If the lithium battery is improperly installed or has quality problems, the controller may burn out, which is one of the reasons why the installation is not recommended.

Fifth, coupled with the promulgation of the new national standards, speed limits of 25 km/h and other provisions, consumers will not be too harsh on the pursuit of electric vehicles, so that consumers spend several times the money to pay, I believe that not many people will be willing. The price of lithium batteries is several times higher than that of lead-acid batteries, reflecting the low price ratio of lithium batteries, which does not meet the standard for ordinary users to choose electric vehicles. Although lithium batteries have the characteristics of light weight, long life and long service life, the effect is not obvious in actual operation. To replace lead-acid batteries with lithium batteries, we must also consider the size of the battery bunker. Generally speaking, lead-acid batteries are larger and lithium batteries are smaller. If you want to replace them, you must take this into account. If the gap after installation is too large, it is easy to cause small shaking inside the battery and reduce its life.

6. Lithium batteries are more stable than lead-acid batteries. If they are exposed to water or improperly treated, they can easily explode. Therefore, this is an important reason why I do not recommend replacing lead-acid batteries with lithium batteries. Another point to note is that lithium batteries are multi-piece structure, as long as there are problems, it will affect the overall quality.

In short, lithium batteries are not conducive to their promotion, regardless of safety or cost. As far as current technology is concerned, lead-acid batteries are still the main ones. Want to replace lead-acid electric cars with lithium batteries? In addition to safety, when implementing the new national standards, modifications may be defined as vehicles exceeding the standards. If you are really interested in lithium batteries, it is recommended to buy lithium trams that meet national standards.

Difference between Power Battery and Energy Storage Battery2019-12-30T14:20:45+00:00

The difference between power batteries and energy storage batteries

The internal resistance of battery power battery with the same capacity is less than that of energy storage battery.

The internal resistance of battery power battery with the same capacity is less than that of energy storage battery.

Power batteries are generally used in devices requiring high current discharge (3C-5C), and energy storage batteries are used in devices requiring low current discharge (generally 0.5-1C range).

Batteries of the same capacity will weigh heavier than energy storage batteries (different design processes).

DLG 18650 3200mah 3.7 volt
charge 1500mah LFP cell 18650

Different prices. The price of power batteries will be more than 1.5 times higher than that of energy storage (according to the different requirements of customers) power batteries and energy storage batteries are defined broadly, which kind do you refer to from the application point of view? Energy storage batteries generally have low current and belong to energy type. Power batteries generally need to discharge 3C. The discharge capacity, discharge curve and platforms can be compared by 3C discharge or 1.5C discharge. The price is expected to be 1.2 times higher than that of the latter for the same specifications.

lifepo4 applications
What is Ternary NCM Lithium Battery2019-12-30T14:10:22+00:00

About NCM ternary lithium battery

Most of the ternary materials are NCM. In general, the term “ternary lithium battery” refers to NCM. The representative manufacturers of NCM abroad are SDI and SKI. Tesla uses NCA18650, which has relatively strong stability and cyclic performance. However, in the manufacturing process, because Al is amphoteric metal, it is not easy to precipitate, so there is a threshold in the process. Because the content of aluminium in NCA is too small, it is often called binary material.

The NCM product model of ternary materials ranges from 111 ternary (N:C:M=1:1:1) to 433,532,622,811. With the increase of nickel content, the energy density of the battery was increased accordingly.

lithium polymer battery inside

Lithium batteries refer to a wide range of large categories, all used in lithium materials can be called lithium batteries. According to the scientific name, we usually say that lithium batteries should be called lithium ion batteries/lithium secondary batteries, with corresponding negative electrode materials.

The cathode materials of lithium ion batteries are mainly LiCoO 2, LiMnO 4, LiCox NiyMnzO 2, ternary materials and LiFePO4. The cathode uses ternary materials called ternary lithium batteries.

The main advantage of ternary lithium battery is that its energy density is higher than that of other materials.

The cathode materials of ternary lithium batteries are divided into NCA nickel cobalt aluminium and NCM nickel cobalt manganese.

lipo battery structure
How to match cells for a battery pack before assembling the pack2019-11-24T04:50:05+00:00

Coremax will do the following things before assembling the pack:

  •  Select capacity, same capacities cells for one pack
  •  Measure the voltage, same voltage cells for one pack(difference is under 0.02v per cell)
  •  Check and Measure the internal resistance, same IR cells for one pack (difference is under 1m Ohm)

All above steps are very strict to make sure the pack performance is perfect.

what is lithium iron phosphate battery2019-11-22T14:33:55+00:00

What is a lithium iron phosphate battery?

lithium iron phosphate battery is also a rechargeable type of battery but made with lithium iron phosphate (LiFePO4) as the cathode material.

While lithium-iron is a newer version in the lithium battery family, its anodes are also made up of carbon in batteries.

Phosphate based technology possesses superior thermal and chemical stability which provides better safety characteristics than those of Lithium-ion technology made with other cathode materials. Lithium phosphate cells are incombustible in the event of mishandling during charge or discharge, they are more stable under overcharge or short circuit conditions and they can withstand high temperatures without decomposing. When abuse does occur, the phosphate based cathode material will not burn and is not prone to thermal runaway. Phosphate chemistry also offers a longer cycle life.

byd lithium iron phosphate battery

lithium iron phosphate battery

The lithium-iron (LiFePo4) battery has a slight edge over the Li-ion (LiCoO2) battery for safety. This is important because a battery should not get overheated or catch fire in case of overcharging.

The lithium-iron battery has superior chemical and thermal stability. A Lithium-iron battery remains cool at room temperature while the Li-ion may suffer thermal runaway and heats up faster under similar charging conditions.

LiFePO4 is a nontoxic material, but LiCoO2 is hazardous in nature, so is not considered a safe material. Disposal of Li-ion battery is a big concern for the manufacturer and user. .

100ah lithium iron phosphate battery
How to make a 12 volt rechargeable lithium battery pack2019-11-20T06:31:35+00:00

Make a 12 volt rechargeable lithium battery pack

Rechargeable lithium batteries produce 3.7 or 3.2 volts, depending on the type of battery and the chemicals it uses. To make batteries with higher voltages, manufacturers link identical batteries in a series circuit. In this way the voltages of the individual batteries are added together, so three 3.7-volt battery cells become one 12-volt battery (3.7x 3 = 11.1 volt). You can use the same electrical technique to create your own battery packs at home. Doing so requires basic math and no electronic skills.

Select the type of batteries from which to create a 12 volt rechargeable lithium battery pack. You might consider their size, shape or amp/hour capacity to be important, or you may just choose the batteries readily available where you live. It is important to use identical batteries in your pack. They must all have the same voltage and current characteristics.

Calculate how many batteries you need by dividing 12 by the voltage of the batteries.

Link together the batteries, connecting the positive terminal of the first battery to the negative terminal of the second. Link all the batteries in the same way, always joining opposite polarity terminals. You can stack cylindrical batteries, such as the A, C and D series batteries, on top of each other in a plastic or cardboard tube, or wrap them together in sticking tape. When using larger batteries with spring terminals, such as rectangular 6-volt batteries, join them with short lengths of wire.

Run a wire from the unused terminals at each end of the line of batteries. The voltage between the two wires is 12 volts.

If you want DIY for fan, Welcome to discuss and get help from Coremax Technical team. If you are looking for a professional 12 volt rechargeable lithium battery pack, please send business inquiry to Coremax. We are glad to offer all in one solution for you.

custom li ion battery pack
IFR32650 solar light batteries
how to charge a 12 volt lithium battery2019-11-20T06:21:09+00:00

First check what kind of lithium battery you have. There are major 2 type of lithium battery in the market. 3.7v cell and 3.2v cell. And find out the full charge voltage. If the cell is 3.7v. Nomally full charge voltage is 12.6v( 3S lithium ion battery. when fully charged, each cell 4.2 volt). While if it is 3.2v cell. When it fully charged, the voltage is 3.65 volt. 12 volt lithium battery pack fully charged is 14.6 volt.( 4S 3.2 v cell). Make sure your charger voltage is compatable with the 12v lithium battery.

Please note that not all Li-ion batteries charge to the voltage threshold of 4.20V/cell. Lithium iron phosphate typically charges to the cut-off voltage of 3.65V/cell and lithium-titanate to 2.85V/cell. Some Energy Cells may accept 4.30V/cell and higher. It is important to observe these voltage limits.

Important to Lithium battery chargers

Lithium cells (18650, lipos, LiFePo4 etc.) which require the charging cycle CC-CV (constant current, constant voltage). The battery system may work for other types for batteries as well, as long as they wants to be charged with CCCV.

CC-CV varies the voltage to constantly deliver the current set by you. When the voltage reaches the battery’s maximum charge voltage, the current is gradually decreased so that the voltage does not exceed the set value.

3.2 volt solar batteries 16850

3.2v LiFePo4 cells

sony 21700

3.7v Lithium ion cells

Lithium battery Charger guide List

Nominal Voltage Battery type series Charging voltage
12v 3.7v lithium ion 3 12.6v
3.2v LiFePo4 4 14.6v
24v 3.7v lithium ion 7 29.4v
3.2v LiFePo4 8 29.2v
36v 3.7v lithium ion 10 42v
3.7v lithium ion 11 46.2v
3.2v LiFePo4 11 40.15v
3.2v LiFePo4 12 43.8v
48v 3.7v lithium ion 13 54.6v
3.7v lithium ion 14 58.8v
3.2v LiFePo4 15 54.8v
3.2v LiFePo4 16 58.4v
60v 3.7v lithium ion 17 71.4v
3.2v LiFePo4 20 73v
72v 3.7v lithium ion 20 84v
3.2v LiFePo4 24 87.6v


Our prismatic cells already pass UL, MSDS, UN38.3, CE. These certification are available without ask customer to pay additional certification cost.

Shipping of Lithium Batteries:

Since our battery cells all passes MSDS, UN38.3 . And also we We can hold shipping documents.Ship our batteries by Air flight or by sea all is acceptable.



We provide 8 years for our batteries cells. 5 years for our battery packs. The warranty is only available for professional customer’s. Custom who without lithium battery knowledge and abuse with the batteries will be limited on warranty period.