Batteries - NiMH Vs. LiPo - Which is better?
NiMH Vs LiPo Batteries - Which is better?
LiPo (Lithium Polymer, or more accurately, Lithium-Ion Polymer) and NiMH (Nickel-Metal Hydride) are the two primary battery types used in the hobby market. A NiMH battery is probably included with an RTR (Ready To Run) RC (Radio Controlled) car since they are safer, more dependable, and reasonably priced than LiPo batteries.
After becoming accustomed to using a NiMH battery to power their RC car or buggy, most individuals will eventually switch to LiPo.
LiPo batteries offer more incredible speed, more "punch" off the line, and more steady power throughout the run than NiMH batteries.
List of RC Battery abbreviations
LiPo - Lithium-ion Polymer (type of battery)
NiMH - Nickel-Metal Hydride (type of battery)
NiCD - Nickel-Cadmium (type of battery)
Mah - Milliampere-hour (measurement of current over time) 1000Mah = 1Ah
Ah - Ampere hour (measurement of current over time) 1Ah = 1000Mah
A – Ampere (unit of electrical current)
ESC - Electric Speed Control (connects between the battery and motor)
S - Series (commonly used in LiPos, e.g., 3S, meaning three cells wired in series)
V - Voltage (electrical potential)
C - Capacity rating (also known as discharge rating, higher the better)
NiMH Battery Pros & Cons
Pros
- Secure
- Dependable
- Smaller increases in voltage
- Simple to keep up
Cons
- hefty
- Heavy
- Reduced density of energy
- Inefficient
LiPo Battery Pros Cons
Pros
- High energy density
- Flat cell design
- High discharge rate
Cons
- It can be dangerous if mishandled.
- Require an ESC with LiPo Cut-off
- Require a balance charger.
What Battery Do I Have?
First and foremost, each battery needs to be labeled with the battery's chemistry (NiMH or LiPo), capacity (Mah, which stands for milliampere hours; this is the high number), and voltage (which is a multiple of 1.2 for NiMH and 3.7 for LiPo).
What Does a NiMH Battery Look Like?
Round cells called NiMH batteries come in various form factors to fit your needs.
The pictures below show that most NiMH batteries that power RC cars comprise several Sub-C-sized batteries.
Unsurprisingly, the well-known, widely used rechargeable AA batteries are just one NiMH cell.
Note: NiCD (nickel-cadmium) and NiMH batteries appear nearly identical from the outside, but they differ significantly on the inside and require distinct handling. I won't discuss NiCD batteries because they are no longer suitable for the hobby market. NiMH batteries have a far longer "run time" and are less susceptible to the "memory effect" than NiCDs. As a result, practically all electric RC cars use NiMH batteries rather than NiCDs.
What Does a LiPo Battery Look Like?
A balance lead is a feature of a LiPo battery with two or more cells connected in series; this does not prove that the battery is LiPo, but it does prove that it is a Lithium battery. A balancing lead is not necessary for NiMH batteries.
Although many RC cars are made to fit a 6-cell NiMH battery, typically 137x45x234 mm, give or take a few millimeters, this is commonly called the "standard size." A LiPo battery cell is flat and rectangular; there is no "standard" physical size for a LiPo cell.
Additionally, some cars have a rounded mount that nicely fits a 6-cell NiMH; in this case, you can obtain a rounded hard case LiPo battery.
Because LiPos vary significantly in width, height, and length, choosing a battery that will fit your RC car or any other use you may have in mind is easy.
As we discovered from studying the link between voltage and cells in NiMH batteries, LiPos are the same; however, because a single LiPo cell has a voltage of 3.7 volts (as opposed to 1.2 volts for NiMH batteries), the available voltages are lower.
The two most popular voltages for RC cars are 7.4 volts (2S) and 11.1 volts (3S).
Pictures
- With its "Hard case" design, the HPI 11.1v (3S) 3200Mah 35C battery is more resilient and less prone to punctures.
- Traxxas' LiPo batteries are depicted in a neat little diagram that is comparable to most others.
- A single-cell LiPo battery that comes from an Apple iPhone 3G.
- V8engineforsale strongly advises utilizing HPI's fireproof LiPo safe pouch for charging and storing any LiPo battery.
NiMH Batteries
The internet contains contradictory advice and information that can be highly confusing, particularly regarding the "Memory Effect," which only applies to NiCD batteries and not NiMH cells.
NiMH can suffer from "voltage depression," although it's controversial how obvious it is. Following the recommendations below will ensure your battery won't suffer from it.
Charging
Only chargers made especially for NiMH cells will charge NiMH batteries correctly.
NiCD-only chargers cannot correctly charge NiMH batteries.
"How fast can I charge a battery?" is frequently asked.
A 2000Mah battery can be charged at a maximum rate of 2000Mah or 2Amps because most batteries can be safely charged in an hour.
NiMH chargers come in two primary styles. The most popular (primarily due to its lower cost) is the "Trickle Charge," which is a low Mah output (at the proper voltage, of course) that doesn't cut off or stop when the battery is complete but doesn't have enough current to harm the battery because it's low output. However, we strongly advise disconnecting once the battery is charged. By dividing the charger's output Mah by the battery's Mah capacity, you can quickly determine how long it will take. For example, if the "Trickle Charger" produces 500Mah and the battery has 2000Mah, 2000/500 = 4 (4 hours for a full charge).
In addition to being better for your battery, this approach consumes more energy than the "Delta Peak" approach.
"Delta Peak" is the name of the other (better) kind of NiMH charger.
This technology allows the charger to charge a NiMH battery at a considerably higher rate without overcharging since it knows when it is complete and can stop charging.
In addition to being a significantly safer method of charging, this method conveniently alerts you when the battery is full.
Discharging
Driving causes the battery to discharge, though you can also use a smart charger. Discharging is another word for using your car.
As this may impair the life of the cells, it is essential to avoid regularly draining your NiMH battery to extend its lifespan if you want to get the most out of it.
Storage
A NiMH battery is best stored at normal temperature in a dry place.
Ensure they don't overheat because heat can shorten the life of your NiMH battery.
The NiMH cell self-discharges by around 1% daily, so leaving your battery uncharged for more than 4 months may irreparably damage it. It is advisable to charge your NiMH battery before storing it and to recharge it periodically (every 7 to 30 days or so).
This shouldn't be a significant concern if you have LSD (Low Self Discharge) batteries.
Disposal
Simple: NiMH batteries may be recycled, so ensure you do so.
Safety
Even while NiMH batteries are generally safer than LiPo cells, improper usage or handling can still result in significant harm. These "dos and don'ts" can help you maintain good mental health.
Use a high-quality smart charger if you can.
A battery charging should never be left alone.
Avoid using a charger that isn't NiMH.
Unless the manufacturer specifies otherwise, don't charge above 1C.
Don't consistently discharge entirely.
Because NiMH batteries are susceptible to shock, avoid dropping them.
LiPo Batteries
As previously noted, LiPo batteries require a little more maintenance than NiMH batteries. To get the most out of your LiPo battery, we'll go over the essentials.
Charging
After you get a LiPo battery, the first thing you'll need to do is charge it. Check whether the charger is compatible with your LiPo battery; this information should be included in the charger's manual, box, or other packaging.
After confirming that the charger is compatible with the battery you wish to charge, you must know the proper settings to ensure your charger is programmable.
The iMax B6AC V2 charger should be set to "LiPo CHARGE" with a charge rate of 3.2A and a voltage of 11.1V (3S) if we are attempting to charge the HPI LiPo 11.1v 3200Mah. This should be comparable to most other chargers (many digital chargers have similar software).
Let's review those options once more. Since you are attempting to charge a LiPo battery, "LiPo CHARGE" is very straightforward. Setting it to 11.1v (3S) makes sense because it's pretty straightforward, and the battery is also at 11.1v (3S).
Therefore, we should set the charging rate to 3.2A, as it will take an hour to fully charge the battery (3200Mah).
Generally speaking, this is the safest course of action for LiPo batteries.
The "1C rule" states that you can safely charge a LiPo battery at a rate equal to its capacity, which in this case is 3.2A (you could safely charge a 5200Mah battery up to 5.2A).
Discharge Rating or "C" Rating
Examine the LiPo's discharge "C" (capacity) rating to ensure the battery can manage your car's power needs. If your vehicle had an 80A ESC (Electric Speed Control), you would know that this battery can handle more than the ESC will deliver, making it a safe rating for the application. This rating is typically between 10 and 90C. For example, the 11.1v 3200mah 35C LiPo battery has a rating of 35x3200 = 112Amps ("C" Rating x Mah).
Storage
An essential component of maintaining the health of your LiPo is storage. The performance and lifespan of a LiPo battery can be significantly impacted if it is stored flat or fully charged for more than two weeks. What is the solution?
Every LiPo battery likes to be kept between 3.70 and 3.85 volts per cell or between 50 and 70 percent charged.
Put the battery on storage charge if your charger has a feature that will automatically charge (or drain) it to the proper storage voltage, and you won't be using it for more than a week.
If you do not have a charger capable of doing this, charge it for half the time it normally takes to charge the battery. This should bring it to the proper voltage, which is preferable to keeping it wholly charged or flat. Additionally, if you have a multimeter, you can check the cell voltage via the balancing lead.
Disposal
You must dispose of your LiPo battery if it is broken or no longer charges, making it unusable. Naturally, you can't just throw it in the trash because it might still be harmful.
A LiPo battery must be fully discharged before it can produce any more power. This makes it hazardous and prevents it from being disposed of properly.
The easiest way to accomplish this is to plug in a low-draw gadget (such as a lightbulb) until the battery is fully depleted. Depending on the battery's capacity and charge level, you will need to leave it attached for varying amounts of time, but usually, this should take a day or two.
Safety
We can't stress enough how important it is to use LiPo batteries as safely as possible. There have been numerous "horror stories" of LiPos smoking, puffing, and catching fire. While there are multiple reasons why a LiPo battery could exhibit these symptoms, the two most frequent ones are overcharging, which is more harmful, and over-discharging, which is the leading cause of LiPo battery mortality.
NEVER use an ESC without a LiPo cut-off; ALWAYS use a LiPo balance charger on the proper settings to minimize harm to your LiPo and everything nearby.
Always store it at the proper storage voltage and charge it in a LiPo-safe bag.
As battery use grows globally, batteries may be powered by nearly everything, including laptops, power tools, and phones. Nowadays, going an entire day without using a battery is uncommon.
Therefore, it's critical that everyone understands how to properly care for batteries, as things can go horribly wrong if they don't.
