Two of our depots run frozen chambers for a food client, held at around minus twenty two degrees. Pickers in those chambers carry the same handheld scanners as everybody else, on the same batteries, charged on the same racks in the same offices.
Last winter the frozen teams began asking for spare scanners by mid morning. A battery that should have lasted a ten hour shift was flat by ten o'clock, and pickers were walking out of the chamber to swap devices, which costs time and lets warm air in every time the door opens. The service desk logged each case as a faulty scanner. We sent eleven back to the supplier in two months, and every one passed its tests.
The scanners were fine. The batteries were not, and the cold made the difference visible. A lithium ion battery delivers noticeably less of its capacity at minus twenty than at room temperature, and an old one delivers less again. Our batteries had never been tracked as anything. They were bought with the scanners in 2021 and treated as part of them, so nobody knew which were on their third year of daily charging. When we read the health figures the scanners report through our device management system, about forty percent of the batteries at those two depots were below the level the manufacturer recommends for replacement. In an ambient warehouse they still lasted most of a shift. In the freezer they did not come close.
There was a second problem. Batteries taken from the chamber were going straight onto chargers at room temperature, while cold and wet with condensation. Lithium batteries should not be charged until they are back above freezing, and the manufacturer's guidance said so, in a document nobody on the floor had seen.
Batteries now have their own records in the asset register, with health read from the devices every night. Any battery below eighty percent of its original capacity is replaced, and frozen chambers receive only batteries above ninety. Cold batteries rest in a warming cabinet for an hour before charging. The frozen teams use the manufacturer's extended batteries and insulated holsters.
Nobody has walked out of the chamber for a spare since February.
We had been counting scanners for years. The part that actually decides how long a shift lasts was the part we had never counted.
– Serguey Shinder
Top comments (1)
The last line is the whole story: you counted the scanners, and the shift is decided by the part nobody counted. I've seen the same pattern with field telemetry on batteries: the budget gets done with datasheet numbers and a new cell, and the field delivers neither. Two things that help from that side: log battery health and temperature next to the device's own data, so a "faulty device" ticket can be checked against the cell before anyone swaps hardware; and size for the coldest month and the oldest battery in service, not the average. Once only batteries above 90% went into the chambers, did the warming cabinet still matter, or was battery age most of the gap?