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Home Electrical Upgrade Battery Testing For Robotic Purposes | Check & Measurement

Battery Testing For Robotic Purposes | Check & Measurement

In right this moment’s world, robots are used to carry out a number of sorts of duties that had been earlier carried out by people. As a result of batteries are the facility supply of robots, it is crucial to not take them with no consideration and recurrently monitor and precisely check their well being. Testing and measurement can present info on whether or not batteries are absolutely charged, their present efficiency, security upkeep, and rather more.

Robots at a battery charging station (Credit: www.theatlantic.com)
Robots at a battery charging station (Credit score: www.theatlantic.com)

In right this moment’s world, robots are used to carry out a number of sorts of duties that had been earlier carried out by people. From factories to workplaces, automation of those duties, which had been repetitive and consumed a number of time, has resulted in improved productiveness. Based on numerous latest market studies, the robotics market measurement goes to develop much more sooner or later.

As a result of batteries are the facility supply of robots, it is very important recurrently monitor and precisely check their well being for the dependable working of those purposes. Testing and measurement can present info on whether or not batteries are absolutely charged, their present efficiency, the quantity of cost left within the battery, security upkeep, and rather more.

What do battery rankings imply?

The chosen battery’s specs ought to be capable of meet the facility consumption necessities of various parts in a robotic. Energy limits fluctuate relying on the nation. In India, the facility supply is 230 volts, 50Hz alternating present. Power density is the quantity of vitality saved in a given system or area per unit quantity.

All batteries listing a voltage and a capability score. Generally, a discharge present score or burst present score can be talked about. Balaji Viswanathan, CEO, Invento Robotics, says, “Alternative of the battery is dependent upon vitality density and security. We try to run batteries for ten to 12 hours for our robots. We inform the customers to cost when the cost reaches 25 per cent, and we’re additionally engaged on an automatic docking station to cost at that stage.”

Voltage score

The utmost terminal voltage {that a} battery can ship to digital parts beneath ambient situations is what the voltage score talked about on a battery means. Though 9V batteries are often chosen for electronics, in a robotic these can’t be used for the complete system. These can be utilized just for powering parts like microcontrollers and sensors.

If a motor driver IC is getting used, then additionally 9V provide for the logic aspect is adequate. Motors draw rather more energy, so batteries rated AA, AAA, C, D, or battery packs go well with the aim. AAA, AA, C, and D batteries are every rated at 1.5V however fluctuate in measurement, and the quantity of present these can provide will increase in ascending order.

Present or capability score

The quantity of present per hour deliverable by a battery earlier than getting absolutely discharged is called its present or capability score. It’s typically given in amp-hour or milli-Ah (mAh) based mostly on the utmost output present. If a battery has a capability of xy amp-hours at a present of y ampere, it merely implies that y amperes will be offered to a load constantly for x hours.

Capability helps in figuring out battery life. Motors want batteries with a excessive present output for correct functioning. The present score must be greater than the sum of the present necessities of particular person motors.

C- and E-rates

C- and E-rates for describing batteries will be complicated for a newbie. The discharge present is generally expressed as a C-rate to normalise in opposition to battery capability. A C-rate measures the speed at which a battery will get discharged relative to its most capability. A 1C charge would indicate that the complete battery will take one hour to discharge.

Likewise, an E-rate is a measure of discharge energy. A 1E charge is the discharge energy wanted to utterly discharge a battery in a single hour.

Different types of batteries based on chemistries (Credit: https://components101.com)
Various kinds of batteries based mostly on chemistries (Credit score: https://components101.com)

Battery choice for robots

The elements mentioned within the earlier part fluctuate in response to battery chemistry. There may be at all times a trade-off between energy and vitality. Just one will be excessive, not each.

With so many sorts of robots available in the market, deciding on batteries will be complicated for a selected utility. There must be a proper steadiness between the burden of the robotic, battery, and selection of motors. Listed subsequent are some generally used varieties.

Lead-acid batteries

Lead-acid or sealed lead-acid (SLA) batteries are helpful for giant initiatives the place a considerable amount of present is required for longer durations of time. These are low-cost and don’t require a lot upkeep. Their voltages are increments of 6V. Nonetheless, these have low energy density, lose capability when idle, and can’t be used for light-weight cellular robots attributable to their heavy weight.

Nickel-metal hydride (NiMH)

These rechargeable batteries have been a preferred selection on the economical aspect as these can fulfill capacitance and present output for a lot of purposes. The voltage score of 1 cell is 1.2V, with a variety from 600mAh to 3300mAh.

Additionally, these are safer than Ni-Cad batteries since these don’t include cadmium, which is a poisonous aspect. Nonetheless, these lose cost when idle and are getting changed by lithium polymer batteries these days.

Lithium polymer (Li-Po)

These light-weight batteries are sometimes present in digital objects today. Together with excessive discharge charges, these are able to delivering giant quantities of energy which are many occasions their capacitance. These batteries can be found in a large voltage vary for numerous wants, in increments of three.7V. S and P suffixes in rankings are used for collection and parallel cells, respectively. Nonetheless, these batteries must be dealt with fastidiously and require a wise charger.

Lithium ion (Li-ion)

These rechargeable batteries (akin to 18650 cells) are fairly just like Li-Po however differ in cell development. These batteries are simply obtainable, have steady voltage whereas draining and excessive capability. These are additionally light-weight and protected when used with a battery administration system. In contrast to Li-Po batteries, these are most popular for low present requiring parts like controllers and sensors.

Alkaline batteries

These non–rechargeable batteries often include 1.5V and 9V rankings. Duracell, Energizer, and Sanyo are among the in style manufacturers of alkaline batteries. These batteries are low-cost, have a excessive vitality density, and are available. However these discharge shortly and have excessive inner resistance.

Testing and measurement

Whereas designing batteries, high quality assurance and security testing are needed for approval from authorities organisations and security regulatory companies. All of the cell parameters a design engineer would want could not at all times be doable to quantify by direct measurement. Qualification testing, for instance, checking for electromagnetic compatibility (EMC) compliance, is finished earlier than it’s authorised to be used in a robotic.

To find out whether or not a battery can fulfil the facility demand when put to make use of in anticipated situations, load testing is finished. For figuring out the ambient situations for batteries, their behaviour beneath publicity to various warmth and temperature ranges, altitudes, humidity, and fireplace is studied. Mechanical checks embrace choices like vibration check, impression check, crush checks, shock check, nail penetration checks, drop check, amongst different comparable ones.

Safety from or tolerance to points akin to overcharge (time/voltage), over-discharge, brief circuit, misuse, or abuse is crucial to make sure the security of customers. In relation to measuring battery parameters for the robots, Viswanathan says, “We run batteries on a check bench with a continuing load, and we additionally run highway checks with extra energy drain.”

In an actual setting, the parameters could also be fairly totally different from these calculated utilizing assumptions. Testing is required to verify the precise parameters throughout sensible utilization.
There are quite a few units obtainable available in the market for analysing, recording, and monitoring a battery’s parameters. Devices and software program programs that may measure and handle the life cycle of particular person cells maintain the consumer knowledgeable and be sure that the robotic doesn’t cease working impulsively.

For example, SBS is a battery producer that gives totally different battery testing, monitoring, and upkeep options that fulfill trade requirements, apart from security applications. Calibration elements are constructed into any piece of check gear attributable to variations within the growing old profiles of the totally different battery chemistries.

Relying on the appliance, the machine chosen for testing may check the quantity of cost current and/or its voltage output, or it could do a extra complete testing that retains a tab on different parameters too. The most typical solution to measure a battery’s present state, usually seen in colleges and universities additionally, is utilizing a multimeter.

Whereas we could acquire info on the state of cost, we nonetheless can’t decide whether or not the required quantity of present might be delivered when demanded. Efficiency monitoring must be achieved on the consumer’s finish to confirm {that a} battery is performing as required when used within the utility for which it was chosen.

The outcome

There are a number of phrases whose values give an perception right into a battery’s current situation as soon as put to make use of. Whether or not or to not recharge or exchange batteries is dependent upon these values. A few of the parameters that totally different instruments measure are defined subsequent.

Increasing resistance/impedance with time and temperature (Credit: www.mpoweruk.com)
Rising resistance/impedance with time and temperature (Credit score: www.mpoweruk.com)

State of cost (SOC). It offers the current battery capability as a proportion of most capability. For a lot of robotic purposes, it is very important know the quantity of vitality left in a battery. It determines the change in battery capability over time and is a vital parameter in battery administration programs.

State of well being (SOH)

It’s a measure of a battery’s means to ship the required present when required. It’s helpful in understanding battery efficiency in actual time throughout utilization.
Depth of discharge (DOD). It’s a measure of the battery capability that has been discharged and is expressed as a proportion of most capability. A discharge higher than or equal to eighty per cent is termed as a deep discharge.

Terminal voltage

It’s the voltage between the battery terminals when the precise load is utilized. It is dependent upon SOC and discharge/cost present.

Open-circuit voltage (OCV)

It’s the voltage between the battery terminals when no load is utilized, that’s, when the circuit is open. It determines the flexibility to ship present however varies with SOC (immediately proportional). After a while, because the battery begins to age, its means to just accept and to carry cost decreases. Therefore, measuring inner resistance is critical to get a whole image of the state of affairs.

Battery impedance (Z)

A mix of inner resistance and reactance is called impedance. The resistance throughout the battery is called the inner resistance. It is dependent upon SOC and is often totally different for charging and discharging. The present generated by the battery interferes with direct measurement, therefore ohmmeter is just not used.

One methodology is to seek out the distinction between terminal voltage and OCV, which supplies IR voltage drop that corresponds to inner resistance. In one other methodology, a small AC voltage of recognized frequency and amplitude is utilized throughout the cells. Utilizing Ohm’s legislation, the worth of impedance is calculated. The upper the inner impedance, the decrease is the effectivity and the thermal stability, since extra of the charging vitality is transformed into warmth (I2R). This means the SOH and measures deterioration in battery efficiency from the unique.


 

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