Can I replace NiCd with NiMH in solar lights?

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Solar lights being portable source of light uses batteries like NiCd and NiMH to store electrical charge and provide electricity to lights.

Different solar powered lights use different types of rechargeable batteries. The two most common used rechargeable lights in solar lights are NiCd and NiMH rechargeable batteries.

Both types of batteries have their own benefit and drawbacks. If you are considering replacing your solar light batteries from NiCd to NiMH and seeking answer to can I replace NiCd with NiMH in solar lights? then this article is for you.

In this article, I have written a detailed post on changing rechargeable batteries in solar lights. So let’s read it.

Key Takeaway: Yes, you can replace NiCd with NiMH in solar lights.

What are NiCd batteries?

Nickel Cadmium or NiCd are rechargeable type of battery that uses nickel oxide hydroxide and metallic cadmium as electrodes. They comes in various sizes and capacity. Ni-Cd batteries have nominal voltage of 1.2 volts.

NiCd batteries can be used individually or can be assembled into battery packs. They are used in portable electronic devices like portable power tools, toys, flashlights, emergency lighting, solar powered lights, etc.

Advantages and disadvantages of NiCd rechargeable batteries?

After learning about NiCd batteries let’s talk about their advantages and disadvantages.

The biggest advantage of NiCd rechargeable batteries is their ability to charge fast and work in low temperatures whereas the most noteworthy disadvantage of NiCd batteries is that they are not environment friendly and contains heavy metal.

I have created a table describing all the pros and cons of NiCd batteries below.

NiCd Advantages	NiCd Disadvantages
Fast charging.	Low energy density^*.
High number of charge and discharge cycles.	More cells are required to achieve higher voltages.
Can recharge at low temperatures.	Suffers from memory effect^*.
High power delivery at high discharge rates.	Can self-discharge when not in use for long time.
Terminal voltage declines slowly on discharging.	High cost.
Can tolerate deep discharge for long period of time.	Exhibits high negative temperature coefficient.
Very good performance in rough weather conditions.	Contains highly toxic heavy metal Cadmium.

*Energy density – Energy density is the amount of energy that can be stored in a system per unit volume.

*Memory effect – Memory effect is a condition found in NiCd rechargeable batteries that causes them to lose their maximum charge holding capacity. It is caused by repeatedly charging the NiCd batteries only after a partial discharge. The battery remembers the point of discharge where recharging began leading in loss of capacity and lifespan.

What are NiMH batteries?

Nickel metal hydride or Ni-MH are also rechargeable batteries which uses nickel oxide hydroxide and hydrogen absorbing alloy as electrodes. They also have same nominal voltage of 1.2 volts. They are more powerful than NiCd rechargeable batteries.

Advantages and disadvantages of NiMH batteries?

Like NiCd rechargeable batteries, the NiMH type of batteries also have their fair share of pros and cons.

One of the biggest advantage of using NiMH rechargeable batteries is that they have two to three times more capacity than the NiCd batteries and their biggest drawback is they can’t stand very high temperatures.

All of the benefits and drawbacks of a NiMH rechargeable battery are listed in the table below.

NiMH Advantages	NiMH Disadvantages
High energy density.	Complete discharge can permanently damage them.
Less affected by memory effect.	High self discharge rates.
No toxic elements.	Less number of charge and discharge cycles.
Low internal resistance.	Generates more heat during charging.
Less prone to leaking.	Charge time double than NiCd batteries.
Bipolar design to avoid short-circuits.	Experience charge decay.
Have more power.	Performance decreases at higher temperatures.
High resistance to over-charging and over-discharging.	More expensive than NiCd.
Requires very low maintenance	Low energy density than NiCd.

NiCd or NiMH which is better for solar lights?

Selecting the best type of battery for your solar powered lights will depend upon various factors.

One of the key factor is looking at their advantages and disadvantages.

If you are living in such areas where temperature gets low or have shade nearby, and sun is available for less number of hours than NiCd will be a good fit for you.

On the other hand, if the sun rays are available throughout the day than you can go for NiMH rechargeable batteries.

Can I use NiMH batteries instead of NiCd in solar lights?

Yes, you can safely use NiMH batteries instead of NiCd batteries in solar lights. Having built on different material their performance is also different.

The major benefit you will get from replacing NiCd to NiMh batteries is its higher capacity than NiCd(two to three times more), easy to maintain , and environment friendly.

However, you should first check your solar light compatibility with NiMH battery. This is because the voltage in NiMH batteries is higher than NiCD batteries. Just make sure that your solar powered light is designed to work with NiMH batteries.

You can read my article I wrote on what kind of rechargeable batteries do solar lights use? to learn more about using the right battery in your solar light.

Also make sure not to mix both types of battery as it can damage the solar light.

Conclusion

With solar energy powered lights becoming a popular alternative to conventional lighting, powering them up with right kind of solar rechargeable batteries is important.

Having right kind of battery in your solar powered lights will ensure best output from them.

Both NiCd and NiMH have their benefits and disadvantages. If you are considering changing the battery from NiCd to NiMH you can safely do.

If your solar lights are getting old or doing a upgrade NiMH batteries with long battery life and low maintenance are a good choice for solar lights.