The battery questions buyers actually ask
Capacity gets the first question; battery gets the second, and it is the more practical one. The concerns split by battery type.
- Disposable: how long does a cell last? Is the battery easy to buy? Is it easy to replace?
- Rechargeable: how long does one charge last? How long does a charge take?
Disposable (non-rechargeable) batteries
A fresh disposable cell normally lasts about 18 months — roughly a year and a half of typical use.
Two sizes are used:
- 9V stacked battery — the same type used in a multimeter, available almost anywhere.
- CR123A lithium battery — Panasonic markets this size as a 'camera battery'; it is common in cameras.
Rechargeable batteries
New-generation readers have moved almost entirely to rechargeable cells, and the numbers buyers care about are consistent across them:
| Spec | Value |
|---|---|
| Cell | 3.6V, charged to 4.2V |
| Service life | About 5 years in customer use |
| Per charge | A month or more; under very heavy patrol density, never below 20 days |
| Full charge time | About 2 hours from empty |
| Emergency | 30 minutes from empty is enough to take it on patrol |
Heavy use — many checkpoints, high patrol frequency — drains faster, which is why the floor is stated as 20 days rather than a single number.
Which should you specify?
Both are valid. Disposable suits buyers who want a cell they can replace from any shop in minutes; rechargeable suits those who prefer no recurring battery purchase and a month-plus runtime per charge. The deciding factor is the buyer's own replacement workflow, not a capacity number.