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Calculating hold-up time for a 48V telecom site
Telecom backup is specified in hours at the real site load, not in amp hours, and the two are not interchangeable.
Start with the site load in watts, measured rather than assumed. Base station loads vary widely with configuration and traffic, and the nameplate rating of the equipment is usually well above what the site actually draws.
Convert to the required energy: load in watts multiplied by the hold-up hours your policy demands. Divide by the pack's usable energy, allowing for the fact that usable is not nominal, and you have the number of packs. Two packs with identical amp-hour ratings can give different hold-up times because the usable window differs.
Temperature then modifies everything. A cabinet in direct sun in a hot climate will run its cells warmer than a shaded equipment room, and that changes both usable capacity and cycle life. Tell us the cabinet environment as well as the load.
Specifications
| Specify in | Hours of hold-up at the measured site load |
|---|---|
| Not in | Amp hours, which do not translate directly |
| Also tell us | Cabinet environment and temperature range |
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Send us the application and the load
Tell us what the pack has to power, for how long, and which inverter or charger it works with. You will get a sized recommendation with capacity, dimensions, BMS rating and cycle life in writing.