After the First Life: State of Health, Second-Life Storage and India's Battery Waste Rules

A battery pack retired from an electric scooter at 80% state of health is not waste. It is a pack with four-fifths of its original energy that no longer meets the requirements of a demanding application. What happens next is partly an engineering question, partly a commercial one, and — since 2022 — substantially a legal one.

What state of health actually measures

State of health is usually quoted as remaining capacity against original rated capacity. 80% SoH means the pack now delivers 80% of what it did when new. This is the most common definition and the most common end-of-first-life threshold for mobility applications.

Capacity is not the whole picture. Internal resistance growth matters at least as much, and often more. A pack at 85% capacity but with double its original internal resistance will sag heavily under load, run hot, and deliver a poor experience even though its capacity number looks acceptable. Any serious health assessment measures both.

The third dimension is cell divergence. As a pack ages, cells diverge, and the spread between the strongest and the weakest widens. Once that spread exceeds what the BMS can balance, usable capacity collapses much faster than average cell capacity does. A growing cell delta is the earliest reliable warning that a pack is approaching the end of its useful first life.

When to retire a pack

For a 2W fleet, the practical trigger is usually when range no longer supports the duty cycle — often somewhere in the 70–80% SoH band, depending on how much margin the original sizing carried. For a drone, retirement should be earlier and driven by voltage sag under peak load rather than by capacity, since sag is what actually ends missions. For an ESS, the threshold is economic: retire when the capacity available no longer supports the contracted or required service, which in a well-designed system is often addressed by augmentation — adding capacity — rather than by wholesale replacement.

Retire early on evidence of abnormality regardless of these numbers: swelling, repeated protection trips, an unusual temperature rise, or a cell delta that is growing quickly.

Second life

A pack unsuitable for a vehicle can be entirely suitable for a stationary application where weight is free and the duty cycle is gentler. Telecom tower backup, solar street lighting, small commercial UPS and behind-the-meter storage are the usual destinations.

The economics work only when three conditions are met. The packs must arrive in reasonably consistent condition, because a second-life system built from wildly mismatched packs performs to its worst member. The testing and regrading cost must be low enough to leave a margin against falling new-cell prices — and with

LFP packs now averaging around $81/kWh globally, that margin is thinner every year. And the packs must have been designed to be opened, tested and reconfigured, which most were not.

The conclusion for a manufacturer is that second life is created at design time. A pack with accessible modules, a documented BMS interface and a lifetime data record is a second-life candidate. A sealed, potted pack with no data history is a recycling input.

Recycling, and what the law requires

India's Battery Waste Management Rules 2022 place responsibility for end-of-life batteries on producers, under an Extended Producer Responsibility framework.

Producers must register, meet collection targets against the quantity they placed on the market, ensure recycling through registered recyclers, meet mandated minimum recovery percentages, and — significantly — meet requirements for the use of recovered material in new batteries. Compliance operates through an EPR certificate system, and obligations are enforceable.

If you manufacture, import or brand-label battery packs in India, this applies to you. It is worth confirming your current obligations and targets directly, as the rules have been amended since notification.

The recycling process itself recovers lithium, cobalt, nickel, manganese, copper and aluminium through mechanical pre-processing followed by hydrometallurgical or pyrometallurgical extraction. India's recycling capacity has grown quickly, which is fortunate, because the volume arriving is about to grow much faster as the first large cohorts of EV packs reach retirement.

What this means for a buyer

When you choose a pack supplier, you are also choosing a partner in an obligation that outlives the sale. Ask whether they are registered under the BWMR, what their take-back arrangement is, whether the pack is designed for disassembly, and whether lifetime data will be available when the pack is retired. Those answers cost nothing to obtain now and are expensive to obtain later.