Lead-Acid Versus Nickel-Cadmium Batteries

On the face of it, nickel-cadmium (NiCad) technology should beat lead-acid hands down. Among other things, NiCad’s provide almost consistent terminal voltage throughout their discharge cycle, which seems like a great start. We compare lead-acid versus nickel-cadmium batteries in this post, and reach a conclusion which may surprise some.

Comparing Nickel-Cadmium and Lead-Acid Performance

A NiCad battery pack comprises two or more individual cells. What follows in this post applies to each of these individually. Lining up lead-acid and nickel-cadmium we discover the following according to Technopedia:

Nickel-cadmium batteries have great energy density, are more compact, and recycle longer.
Both nickel-cadmium and deep-cycle lead-acid batteries can tolerate deep discharges.
But lead-acid self-discharges at a rate of 6% per month, compared to NiCad’s 20%.
Moreover, nickel-cadmium batteries require complete recharging to avoid ‘memory effect’.

Thus far the race seems fairly even, with advantages and disadvantages on both sides. However, the picture changes when we consider the two chemistries.

Differences in Battery Chemistry Matter

A number of recent incidents involving lithium-ion battery fires, have made us aware that batteries contain chemicals. And that some of these can harm the environment, not to mention us and the kids too.

NiCad batteries contain nickel-oxide-hydroxide in their cathodes, and use metallic cadmium anodes. Their electrolyte is a water-based, alkaline solution. Nickel-cadmium’s greatest disadvantage is the chemistry can overheat.

And potentially enter thermal run-away mode, and even self-destruct. For these reasons, NiCad battery packs should come equipped with internal thermal cut-offs to manage the situation.

Lead-acid batteries use lead derivatives for their electrodes, and a diluted solution of sulfuric acid for their electrolytes. Their chemistry takes place inside stout cases, and there are few incidents provided they are correctly handled.

NiCad batteries have largely fallen out of favor because cadmium and nickel are both toxic heavy metals that can cause health risks. Whereas sales of lead acid batteries continue to increase in real terms, because their solid dependability lives on.