Now you have a project and you want to power it off of a rechargeable lithium polymer Battery, but so many different rechargeable lithium polymer Battery in the market. how do we get the best based on the project?
Part 1: Selection criteria and charger implementation
As more devices become mobile, efficient battery usage has become essential. Engineers tend to give utmost importance to the current consumption of the device. They devise numerous ways to reduce the power consumption because the longer the battery lasts, the greater perceived market value for the product. One important aspect to consider here is the battery itself.
Selecting an appropriate battery for a particular application is important because the battery determines the number of hours for which the device can work without the need for recharging, the amount of weight it adds to the system, and how much it adds to the BOM (bill of materials) cost. Along with the selection of battery, proper design of charging circuitry is also crucial because improper design can reduce the battery life or can even lead to battery failure (i.e., dangerous leakage or explosion). Failure leading to produce recall can cause massive losses and damage a manufacturer’s reputation.
This article discusses the following topics:
1. Different types of rechargeable batteries
2. Comparison and selection criteria of different types of batteries
3. CC-CV charging method (Part 2)
4. Implementation using a microcontroller (Part 2)
Types of rechargeable batteries:
Rechargeable batteries come in various shapes and sizes, ranging from a coin cell to a battery weighing on the order of tons. These batteries can be classified based on their chemical properties. Some of the most commonly used batteries are:
1. Nickel Cadmium (Ni-Cd) battery
2. Nickel-Metal Hydride battery (NiMH)
3. Lead Acid battery
4. Lithium Ion battery
Nickel Cadmium (Ni-Cd) battery:
Ni-Cd batteries are one of the oldest battery technologies on the market and have distinct advantages like low cost for low power applications, sturdiest for rough environments, and the ability to be recharged many times. These batteries pack nickel hydroxide (Ni(OH)2) electrode as the cathode (positive) and cadmium hydroxide (Cd(OH)2) as the anode (negative) in electrolytic solution comprising of potassium hydroxide (KOH).
One Ni-Cd cell gives 1.2V during discharge. These batteries have a flat discharge rate that falls rapidly at the end of the cycle as shown in Figure 1. Thus, it is difficult to estimate the amount of charge left. The advantage of this kind of battery is that it can withstand deep discharges without damaging the cell.
Along with the advantages mentioned, Ni-Cd comes with disadvantages as well, resulting in shrinking market share. Some of the major disadvantages include:
• Memory Effect: If the battery is repeatedly overcharged after partial discharging, it loses its capability to hold the maximum energy. This condition is referred as the memory effect. Thus, it is advised to either go for precisely controlled charging or regularly do a deep discharge such that the battery can recover its capacity. However, care must be taken since excessive deep discharge can permanently damage the cells.
• Cell Reversing: A battery consists of many cells connected together where each cell differs from the others slightly in terms of capacity. Thus, when one cell completely discharges before the other cells, the remaining cells will still force current through the discharged cell. This is known as cell reversing and results in undesirable and irreversible chemical reactions which permanently damage the cell.
• Over-Charging: When fully charged, the positive electrode (nickel) generates oxygen while the negative electrode (cadmium) generates hydrogen gas. These gases must be properly vented out from the system or operating conditions can become hazardous. To address this problem in sealed Ni-Cd batteries, the negative electrode (cadmium) is built with higher capacity. This causes the positive electrode to reach its fully charged state before negative electrode does. Thus, the oxygen released by positive electrode gets absorbed by the negative electrode and oxidizes.
lithium polymer battery 402030
The two easiest cases are the extremes:
- Is your project very power-hungry? Projectors, large sound systems, and motorized projects all draw on the order of amps of current! You’ll want to go with lantern cells (one-time use) or lead acid batteries (rechargable). If you are planning to be somewhat ‘abusive’ to the battery (heavy-usage, running it down all the way) you may want to look at “marine deep cycle” batteries.
- Is your project super-small, like an inch on each side? You’re going to have to go with a lithium coin cell (one time use) or little lithium-polymer cells like the ones used for tiny RC planes.
Here are some other very popular cases:
- Do you need to make a lot of these things? Go with inexpensive alkaline batteries in popular sizes.
- Need to be user-servicable? 9V or AA size batteries are universal!
- ~5V input necessary? 3 Alkaline (4.5V) or 4 NiMH cells (4.8V) will get you pretty close – check your circuit to see if it’ll run at these slightly lower voltages
- Making a ‘rechargeable battery pack’? Use a battery holder from your local hobby/electronics/repair shop and stick with NiMH batteries, then recharge them with a high quality charger.
- Want to replace alkalines with rechargeables? Test to make sure that the lower voltage won’t make the device unhappy.
- Need to stack batteries? Remember to stack batteries only if they have matching C and Ah capability, if you stack a 9V and a AA to make 10.5V the 9V will drain in 1/10th the time leaving you with 1.5V.
- Want your rechargable batteries to last a long time? Use a high-quality charger that has sensors to maintain proper charging and trickle charging. A cheap charger will kill off your cells
Cylindrical LiFePo4 Battery Packs
How to choose the correct razor battery?
There are too many models of Razors on market , we can not tell you which battery is for which model. However, you can find a suitable battery from our website by yourselves following the procedure blow:
Get a ruler and voltage meter in hand
Determine your battery pack voltage — Account how many cell in your original battery pack. Each cell has 1.2V. For example, if there are two single cells in your pack, its voltage is 2.4V. You can double check battery voltage by voltage meter if battery is not dead.
Determine battery pack’s size ( length x width x Height)
Choose a battery pack from Razor battery with smaller size and same voltage
Please be advised as long as battery voltage is correct, and battery pack can put in your razor, you can use it to replace your original battery
Whatever NiCd battery or NiMH battery — NiMH battery is better
Whatever mAh rating, higher mAh always is better
Whatever shape same or not, as long as it can put in razor
Warning: Battery pack must be connected to razor with correct polarity, e,g positive to positive and negative to negative. Please double check polarity on the both of Razor and battery before using.
How to choose the battery packs for bike lights?
Before replacing a rechargeable battery for bike light, you must know following data
What kind of light do you have ? Halogen Light or HID light ?
If it is halogen light, what are Voltage and Wattage on your bike light? 6V or 12V? 5W or 15W?
If it is HID light, what are Voltage on your Light? 12V system or 14.8V regulated ?
Battery Packs for Halogen Bike Light
Halogen bike lights have two types: 6V or 12V. Please make sure light bulb voltage before choose battery, otherwise, light bulb may burn out immediately
Halogen light has much lower cost than HID, and drain more energy from battery. NiMH battery pack is suitable for all Halogen light.
In order to get better brightness and longer burn time, you can overdrive light up to 25% at voltage, for example
6V halogen light can use battery packs from 6V to 7.4V
12V Halogen light can use battery packs from 12V to 14.8V
However, overdriving may reduce bulb life at same percentage ( Halogen light bulb is inexpensive )
Li-Ion battery pack can be used on halogen bike light, but you have to make sure PCB on Li-Ion battery pack can pass through higher higher initial current ( 3 time higher than normal current)
Battery Packs for HID Bike Light.
HID light three times higher brightness than halogen light at same power wattage, but much more expensive.
HID light must be fired between 9V -13.8V. If battery voltage is higher than 13.8V , the bulb may burn out quickly. So usually HIH lighting system has voltage controller to regulate voltage at 11V – 13V.
If using 12V-13.2V NiMH battery pack or 11.1V Li-Ion battery pack to drive HID light, you can drive any HID bike light on the market without voltage controller
Please never drive HID light by 14.8V or higher voltage battery pack without voltage controller.\
Li-Ion battery is the most suitable for HID light because its less weight and higher energy
Usually, HID manufactures don’t list all data on their battery pack , and they want to earn your money on replacement battery. Doesn’t matter. you can email us your light’s brand name and P/N to sales@coremax-tech.com, our engineer will suggest you a right battery pack immediately at 50% or more less cost. Also, you can find battery data from below list.
How to Calculate burn time of battery pack for bike lights
ebike battery pack
Battery burn time is decided by battery capacity , e.g. mAh or Wh. Higher mAh or Wh will provide more burn time
The time can be estimated as the following:
Burn time ( Hours) = Battery Wattage Hours (Wh) / BLight bulb Wattage (W)
here , Wh = Battery voltage ( V) x Capacity (Ah), 1000mAh= 1Ah
for example, battery pack ( 14.8V , 4.8 Ah) has 72Wh energy, can burn 13W light for 5.46 hour
more Questions? please contact us by click here and send inquiry to Coremax.