Hindustan Scale Company · Est. 1955Wireless crane scales — safe-distance readout

The radio is cheap. Running it all night is not.

Asleep, a Bluetooth Low Energy radio draws about one microamp. Awake and listening, it draws tens of milliamps — roughly 10,000 to 30,000 times more, measured on commercial modules in published studies. Which of those two states a wireless scale spends the night in is a design decision, and it decides most of what crane scale battery life turns out to be in practice. This article covers what “hours per charge” must mean under the law, why searching for an accessory that is not fitted is the costliest thing a radio can do, how a good scale sleeps between lifts, and how to get more hours from every charge.

CRHRD10K – Electronic Crane Scale With Remote Display - the HSCo product this paper is about.
Awake for the lift, asleep between lifts: the scale that rests between loads is the one that still has a battery at the last lift of the second shift.

Forty hours of what? The number that matters is hours of correct weighing

The law is precise about what “hours per charge” must contain.

OIML R 76-1, the international recommendation India’s weighing rules are built on, says a battery-powered instrument must either keep functioning correctly or show no weight at all once its supply drops below the maker’s stated voltage; the minimum operating voltage is the point at which the instrument switches itself off. NIST Handbook 44 (2026 edition) agrees: a battery instrument “shall not indicate nor record values outside the applicable tolerance limits when battery power output is … deficient”. The Indian rules follow the same international text.

So a low-battery cut-off is a legal design requirement, not a nuisance, and it changes the question to ask a supplier. Not “how long does the display stay lit?” but “how many hours of correct weighing do I get, and what happens at the end of them?”

Hindustan Scale Company’s CRHBT5K Bluetooth crane scale runs on a 6 V, 6.5 Ah sealed rechargeable battery rated for up to 40 hours of backup per charge (indicative). Divide one by the other and the whole scale — display, electronics and radio — averages about 160 mA awake, as a rule of thumb.

What actually sets crane scale battery life on a wireless scale?

Not whether the scale has a radio. How often the radio wakes.

Bluetooth Low Energy was built to sleep. The Bluetooth SIG’s own primer says a device may advertise anywhere from once every 20 milliseconds to once every 10.24 seconds. Once connected, the link runs on an interval of 7.5 milliseconds to 4 seconds, and the scale end may skip up to 499 consecutive connection events without listening, according to a 2012 study in Sensors by Gomez, Oller and Paradells. Between those brief wake-ups the radio is off, drawing about a microamp — a 2014 energy model from the Technical University of Munich and a 2017 systematic review in Sensors both put that against tens of milliamps with the radio on.

That ratio is why Gomez and colleagues could show one 230 mAh coin cell lasting anywhere from 2.0 days to 14.1 years with nothing changed but the timing settings. Same radio, same battery. Only the timetable moved.

A crane scale is the ideal customer for that timetable. Between lifts the hook hangs empty — count your own shift and the empty minutes will outnumber the loaded ones. A scale that sleeps through every empty minute spends most of the day at the cheap end of the ratio.

Diagram of a crane-scale shift timeline: short awake bursts at each lift, long sleep stretches between, with the Bluetooth Low Energy timetable
Awake for the lift, asleep between lifts. The Bluetooth Low Energy timetable is what makes the sleep possible; the saving comes from resting the whole scale, not just the radio.

Searching is the most expensive thing a radio does

One Bluetooth state never sleeps: scanning.

To find another device, a radio must keep its receiver on for the whole scan window. The Munich study found “the energy consumption of the scanner is significantly higher than the energy consumption of the advertiser for all parameter values examined”. Google tells Android developers: “As soon as you find the desired device, stop scanning. Never scan on a loop, and always set a time limit on your scan.”

Now picture a crane scale whose firmware looks for an optional remote indicator or hand-held remote whenever it is on. If the accessory is not there, the scale searches all night for hardware it will never find.

As a rule of thumb, a radio held in scan at the 10–27 mA measured in those studies uses roughly 120–320 mAh over a 12-hour idle night. On a 6.5 Ah battery that is about 2–5 % per night — a tenth to a quarter of the battery over a five-night week. The same radio asleep uses roughly 0.01 mAh. Effectively nothing.

There is a second reason. Where Bluetooth and Wi-Fi share one aerial and the 2.4 GHz band, they take turns: a 2022 peer-reviewed study of combined Wi-Fi/Bluetooth radio chips describes the Wi-Fi side as “literally blocked” while Bluetooth holds its slot. HSCo’s CRHBT scales are Bluetooth-only, but the general lesson is HSCo’s design rule: a radio is never left searching for hardware that is not fitted. Accessories are talked to only when fitted; every search has a time limit.

Figure: one idle night with the radio searching costs 120-320 mAh, about 2-5 % of a 6.5 Ah crane scale battery; the same night asleep costs about 0.01 mAh
One idle night, as a rule of thumb: 120–320 mAh searching for an accessory that is not fitted, about 0.01 mAh asleep. Indicative — from published module currents, not an HSCo measurement.

Bluetooth or Wi-Fi on a battery crane scale?

Bluetooth. The numbers are not close.

A 2016 study in the International Journal of Wireless & Mobile Networks puts Bluetooth Low Energy transmit power at 1–10 mW against about 100 mW for Wi-Fi, and a 2019 paper in Sensors measured commercial modules at 7–11 mA against 100–150 mA. Wi-Fi is a mains-powered radio: it belongs on a platform scale plugged into the wall or on the crane’s indicator box in the cabin, not on a battery hanging from a hook.

What is drawing current Typical figure Source
Bluetooth Low Energy radio, asleep about 1 µA (0.001 mA) 2014 Munich model; 2017 Sensors review
Bluetooth Low Energy radio, advertising peaks near 11 mA, in short bursts 2017 Sensors review
Bluetooth Low Energy radio, receiving or scanning about 26 mA while the receiver is on 2014 Munich model
Wi-Fi module, transmit or receive 100–150 mA 2019 Sensors paper
Whole crane scale, awake about 160 mA (6.5 Ah ÷ 40 h) HSCo rating; rule of thumb

Radio figures are published measurements on commercial modules; your scale depends on its own module and firmware.

What this is not: the radio is not the biggest load — the awake scale is

A scanning radio adds 10–27 mA; an awake crane scale draws about 160 mA. The display and weighing electronics, not the radio, are the big consumers. So the honest version of the hook: the radio matters not for its own current but for what it keeps awake.

A radio that will not sleep is a scale that cannot sleep. The saving comes from putting everything to sleep between lifts — display, electronics and radio together — and from never letting the radio hold the rest awake. That is what auto power saving and sleep mode do on the CRHBT3K and its larger siblings, and why the display is a green LED chosen for longer battery life rather than a hungrier one.

Two more things this is not:

  • Not a reason to switch Bluetooth off. The phone readout is what lets the operator stand clear of a suspended load. Sleep it; do not lose it.
  • Not a bigger-battery problem. A scale that never sleeps drains a larger battery just as surely, and every kilogram on the hook is capacity you paid for.

How to extend crane scale battery life: the battery’s own rules

Most crane scale batteries are sealed lead-acid blocks, and most of their habits are about charging. The mechanism is agreed by a peer-reviewed Proceedings of the IEEE paper and industry references; the percentages are indicative rules of thumb.

  1. Charge it every night. A lead-acid battery deprived of a full charge grows lead-sulphate crystals — sulfation — which turns permanent after weeks or months and has no reliably verified cure. Industry references put the do-not-go-below line at about 60 % of charge. HSCo’s CRH crane scales charge without the battery being removed.
  2. Never store it flat. On the shelf a lead-acid battery loses about 5 % of its charge a month — roughly doubling for every 10 °C warmer. A scale put away flat in March is a sulfated scale in June.
  3. Keep it cool. The peer-reviewed data point: sealed lead-acid cells that gave about 4,000 cycles at 20 °C gave 2,100 at 40 °C; the rule of thumb is that every 8 °C above 25 °C halves the battery’s life. Park the scale and its charger out of the sun and away from the furnace wall.
  4. Mind the cold too. At about −20 °C a battery delivers roughly half its capacity (indicative), and the instrument itself is only required to hold accuracy between −10 °C and +40 °C unless the maker marks a wider range — the OIML R 76-1 and NIST Handbook 44 default.
  5. Use the sleep settings, and do not pair what you do not own. Auto power saving on, sleep mode on, nothing configured that is not fitted.
  6. Replace it on a schedule, not on a failure. Lead-acid batteries usually give fewer than 500 deep cycles (indicative). Section 29 of the Factories Act, 1948 already requires a competent person to thoroughly examine every lifting machine at least once every twelve months, with a register kept. Add the battery to that examination.
Worker connecting a crane scale to its wall charger at the end of the shift in a fabrication shop, charger lamp lit, scale display dark
Charge it every night, never store it flat, keep it cool: most of a lead-acid battery's life is decided at the charging point, not on the hook.

What changes on Monday morning — and a thirty-day battery log

On Monday the scale is ready at the first lift, not halfway through the morning, and the readout on the supervisor’s phone is still there at the last lift of the second shift. Nobody discovers a flat battery with a load in the air.

The thirty-day version:

  1. Week 1 — measure. For each crane scale, log hours on charge, hours in use and every low-battery event, and note how hot the overnight parking spot gets.
  2. Week 2 — settle the settings. Sleep mode and auto power saving on; no accessory configured that is not fitted. Ask your supplier the question that matters: at the end of its hours, does the scale cut off or keep showing a number?
  3. Week 3 — fix the charging. Nightly charging, charger at the parking point, out of the sun.
  4. Week 4 — compare and record. Hours of correct weighing per charge, before and after. Add the battery’s date and condition to the crane’s examination register.

Hindustan Scale Company has made weighing scales in Mumbai since 1955 and builds the crane scale, its radio firmware and the Android app itself, so one supplier answers for how the scale sleeps. The CRHBT range runs from 3 t to 50 t; the CRHBT3K lists at about ₹17,500 and the CRHBT5K at about ₹22,500, indicative and before GST. The family is on the crane scale range page; the crane scale buying guide covers capacity, hooks and safety.

Frequently asked questions

How long does a crane scale battery last on one charge?

It depends on the scale and how it is used. HSCo’s CRHBT Bluetooth crane scales are rated for up to 40 hours of backup on a 6 V, 6.5 Ah battery (indicative). That figure assumes the scale is allowed to sleep between lifts; a scale kept awake all night will not reach it.

Why does my wireless crane scale battery drain overnight?

Usually because something keeps the scale awake — most often a radio searching for a remote display, remote control or printer that is not fitted. Bluetooth scanning keeps the receiver on continuously and is the most battery-intensive thing the radio can do. Remove the absent accessory from the configuration and switch sleep mode on.

Does Bluetooth drain a crane scale battery?

Not by itself. A Bluetooth Low Energy radio draws about one microamp asleep and tens of milliamps only in short bursts, against roughly 160 mA for the whole scale when it is awake. What drains the battery is a scale that never sleeps — and a radio that will not sleep keeps the scale awake with it.

Can a crane scale show a wrong weight when the battery is low?

It is not allowed to. OIML R 76-1 and NIST Handbook 44 both require a battery instrument either to keep weighing correctly or to show no weight at all once the supply drops below the maker’s stated voltage, and the Indian rules follow the same text. A scale that drifts into a plausible-but-wrong reading as its battery dies is non-conforming.

Should I switch the crane scale off between lifts?

Let the scale do it. Auto power saving and sleep mode put the display, electronics and radio to sleep between lifts and wake them for the next one — the same saving without a worker climbing to the hook. Switch it off fully only at the end of the shift, when it goes on charge.

How should I charge and store a crane scale battery?

Charge it every night and never store it flat. A sealed lead-acid battery left below about 60 % charge for weeks grows permanent sulphate crystals, and it loses roughly 5 % a month on the shelf (indicative). Keep the scale and charger cool, and replace the battery at the crane’s twelve-month examination.

Next step

Tell us which crane scale goes flat before the shift does, and we will check its sleep settings and charging routine with you and propose a thirty-day battery log.

Hindustan Scale Company (HSCo) · Mumbai · est. 1955 · www.hindustanscale.com · hsc@hindustanscale.com

Sources

  1. OIML R 76-1:2006 — Non-automatic weighing instruments, Part 1: Metrological and technical requirements — Tests (International Organization of Legal Metrology): clause 3.9.3 Power supply; clauses 3.9.2.1–3.9.2.3 Temperature; Annex A.5.4.
  2. NIST Handbook 44 (2026 edition) — Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices (US National Institute of Standards and Technology): Section 2.20 Scales, T.N.8.3.1(b), T.N.8.3.2, T.N.8.1.1–T.N.8.1.4.
  3. Bluetooth SIG — The Bluetooth LE Primer (M. Woolley), sections 7.8.2.2.2 Legacy advertising scheduling and 7.8.1.3 Peripheral latency.
  4. Gomez C., Oller J., Paradells J. — “Overview and Evaluation of Bluetooth Low Energy: An Emerging Low-Power Wireless Technology”, Sensors 12(9): 11734–11753 (2012).
  5. Kindt P. H., Yunge D., Diemer R., Chakraborty S. — Precise Energy Modeling for the Bluetooth Low Energy Protocol, Technische Universität München, arXiv:1403.2919 (2014), section 6.3.1 and Appendix A.
  6. Tosi J., Taffoni F., Santacatterina M., Sannino R., Formica D. — “Performance Evaluation of Bluetooth Low Energy: A Systematic Review”, Sensors 17(12): 2898 (2017), section 3.3.
  7. Cho K. et al. — “Analysis of Latency Performance of Bluetooth Low Energy (BLE) Networks”, Sensors 15(1): 59–78 (2015).
  8. Google — Android Developers, “Find BLE devices” (Bluetooth Low Energy guide), as read 14/09/2026; Apple — Core Bluetooth Programming Guide, “Best Practices for Interacting with a Remote Peripheral Device” (archived).
  9. Classen J., Gringoli F., Hermann M., Hollick M. — “Attacks on Wireless Coexistence”, IEEE Symposium on Security and Privacy 2022, arXiv:2112.05719 — shared antenna and time-slot arbitration between Wi-Fi and Bluetooth.
  10. Koulouras G., Katsoulis S., Zantalis F. — “Evolution of Bluetooth Technology: BLE in the IoT Ecosystem”, Sensors 25(4): 996 (2025); Song M., Shetty S., Gopalpet D. — “Coexistence of IEEE 802.11b and Bluetooth”, Mobile Networks and Applications (2008).
  11. Elkhodr M., Shahrestani S., Cheung H. — “Emerging Wireless Technologies in the Internet of Things: a Comparative Study”, International Journal of Wireless & Mobile Networks 8(5) (2016); Borza P. N., Machedon-Pisu M., Hamza-Lup F. — “Design of Wireless Sensors for IoT with Energy Storage and Communication Channel Heterogeneity”, Sensors 19(15): 3364 (2019).
  12. McKeon B. B., Furukawa J., Fenstermacher S. — “Advanced Lead-Acid Batteries and the Development of Grid-Scale Energy Storage Systems”, Proceedings of the IEEE 102(6): 951–963 (2014).
  13. Battery University (Cadex Electronics) — BU-802b, BU-804b, BU-806a, BU-502, BU-410, BU-808 (industry reference; percentages quoted as indicative); Wikipedia — “Lead-acid battery”, with its cited references.
  14. The Factories Act, 1948 (India), section 29 — lifting machines, chains, ropes and lifting tackles (India Code; Indian Kanoon doc 640593).
  15. Hindustan Scale Company — product pages: CRHBT5K and CRHBT3K Electronic Bluetooth Crane Scale; CRH Electronic Crane Scale (battery, backup and prices, indicative, before GST).