Just ask. -for any of the millions and millions of smartphones discarded every year. 43 Million tons of e-waste was dumped in 2016 per UN University. Split a few hairs. Some of this waste you don't want? Maybe a few plasma panels mixed in in with the smartphones with perfectly good batteries? Throw a few million tons of e-Waste away - you'll still be left with tens of millions of tons of smartphones for you to test. The average smartphone 'life-span', is under two years - i.e. the smartphones life is the smartphones battery life. Electronics runs for decades if not bricked OTA or otherwise deliberately disabled. There are nearly 8 billion smartphones and subscriptions on the planet - more than there are people.
Given forecasts closely approaching FIVE BILLION mobile ~ cellular subscribers, and with artificially- short device lifetimes measured in single-digit years, the number of discarded, and the numbers of freshly manufactured, phones - has to equal the numbers of cellular subscribers.
So - there's your supply of dead phones to test - five billion of them, every year.
With per-device revenues climbing toward $1000 in the US, and maybe 1/10th that globally, averaging in the hundreds of dollar-equivalents per handset, the hardware churn foisted on the planet by the mobile device and battery industries, the carbon and GHG and e-Waste footprints of device manufacturing and disposal are enormous. Funny how diddling with a few percentages in millivolt thresholds for device power management translates directly into producing or not producing tens of millions of tons of e-wastes and at the same time produces or wipes out hundreds of billions of dollars in profits for these industries. Such delivered 'value' for consumers who are forced, on average, to fork over hundreds of dollars each and every year to replace devices only 'deemed' CHARGING.
About the only non-vanity reason to replace a smartphone, unless that it's gotten too 'phat', is after you drop it in the toilet. OR maybe to upgrade the radios from 3G to 4G or 5G, when older networks, like 2G are turned down and coverage starts disappearing. OR maybe when OLED displays start to fade.
Hard to predict how consumer control over handsets, also title transfer, will transition to a cleaner model based on rents over which stakeholders, they being every party involved except consumers, have total control over consumables and expendables, and on how users are locked in by controls over user and device profiles.
The battery industry almost seems complacent in abrogating significant revenue opportunities of multiple battery replacement cycles per handset to the handset manufacturers, but they really have no choice; Energizer and Duracell haven't yet done the obvious - which is to design their own 'brands' of smartphones ~ which would be a major push-up against APPL, GOOG, LG, ZTE, etc. all which have progressed towards deep!crypto -assured designs where each and every component, batteries inclusive, will have 'smarts' like the 'authentic' chip in HP toner cartridges that protects more than half of HP's revenue stream.
Maybe the glimmer of light at the end of the tunnel is that with such 'crypto' 'authentic' smarts, batteries might once again become replaceable; Only likely if the profit for replacing batteries over a device's lifespan can be set to exceed the profit margin in manufacturing new devices to replace old ones.
CHARGING
500 charge-discharge cycles for $500 to $1000... what a deal!
And I get to pay for airtime and data charges too?