What's the difference between NiMH and LiPo batteries?

One of the most confusing aspects of RC cars is batteries, and a big part of it is figuring out the differences between the different types, sizes and plugs and finding out which is right for you and your car. In this article we will elaborate on the differences between NiMH and LiPo batteries, what they are and what the benefits and downsides of each are. 

So - What is the difference between NiMH and LiPo batteries?

Well, the short answer is that they are two different types of batteries. NiMH, or Nickel-Metal Hybrid, is an older technology of battery somewhat similar to your regular AA alkaline batteries, whereas LiPo batteries consists of pouches and is based on lithium-ion, much like your laptop or smartphone. To really understand it, we need to dig a bit deeper.

About NiMH batteries

NiMH batteries are cheaper compared to LiPo and is often the standard choice on entry-level RC cars or cars which are delivered with a battery in the box. NiMH RC batteries consists mostly of 6-8 cells cylinder shaped cells, wrapped in a soft plastic coating, making for a voltage generally around 7.2 - 8.4 volts.

The batteries are heavy and large, which limits how powerful a battery you can stick in your RC car. When driving on a NiMH battery, the car will get slower as the battery discharges - which you have probably noticed when driving on them.

They are easier to use than LiPo and can be charged on a simpler charger, as they don't require balancing. They should be stored fully charged.

Positives:

• Cheaper to buy.
• Easier to store and charge.

Negatives:

• Heavy.
• Looses power as they discharge.
• Big limitations on voltage and power. 

About LiPo batteries

LiPo batteries are required on all the larger or more powerful RC cars, as well as in racing, and is the battery type of choice for serious racers, bashers or enthusiasts. LiPo batteries come in a wider range of options than NiMH and are more expensive. They do however provide some significant benefits for RC enthusiasts, that more than compensates for the price and increased care needed.

First of all, LiPo's come in a variety of power levels (like 2S, 3S or 4S), where the S figure indicates how many 3.7 volt cells are connected in series inside. A 2S has two, making for 7.4 volts in total, compared to a 4S which has 14.8 volts. More volts means more power. This design means LiPo batteries can pack a lot more power in the same space as a NiMh, allowing for up to 14.8 volt batteries, compared to the standard 7.2V from a NiMH, and can be connected in series for the ridiculously fast 6S and 8S cars.

The Lithium-Ion technology also makes them a lot lighter compared to NiMH batteries, which is a huge performance benefit on an RC car as well. 

The batteries need to be charged using a balance charger and the batteries should be stored at 50% charge. LiPo batteries should always be charged and stored in a fire safe LiPo bag or pouch as there is a risk of the batteries igniting (although of course extremely small), so they shouldn't be left alone to charge either. 

Positives:

• Lighter than NiMH.
• Can pack a lot more power in less space.
• Flexibility in terms of battery designs and sizes. 

Negatives:

• More expensive to buy.
• Requires more care and maintenance.

 So which is right for me?

The right battery type for you is down to three things - how much you intend to use your car, your experience level and budget. 

If this is your first RC car and you just want to try it out before deciding if its for you, go with NiMH as it's cheaper and simpler. Similarly if you are just getting a car to use for fun a couple of times a year, NiMH batteries will offer plenty of punch without requiring too much from you between sessions. 

However, if you are experienced, if you drive often, are looking to take your RC hobby to the next level or is looking for some more speed, LiPo batteries is simply a must have. They cost more, but the benefits far outweigh the price.