The Background of Batteries in Scales
The advent of battery operation in electronic scales and balances has allowed equipment with a wide range of features and capabilities to be portable. Now, electronic weighing equipment with all its wonderful features no long needs to be permanently tethered to an AC power source.
The battery technology found most often in scales is Sealed Lead Acid (SLA), where lead plates are surrounded with a gelled acid electrolyte—sometimes known as a gel cell—or catalyst. The chemical reaction between the lead and the electrolyte generates and stores electricity. And discharging a battery reverses that chemical process. Your car battery works in the same way, except that it is sealed. It can be tipped over, turned upside down, and still works; as long as the case remains intact the acid will not leak.
Some may wonder why scales and balances use SLA batteries rather than the more cutting edge chemistry like nickel metal-hydride or lithium. These pack more electricity in a smaller space, so they could make weighing devices smaller and lighter. The answer is that they are much more expensive, and require a complex charging unit. Lithium batteries must be charged very carefully, because they can catch fire if charging it done incorrectly. SLA batteries, on the other hand, are much more tolerant of charging conditions, so designing and manufacturing a charging circuit is much simpler and less expensive. The also use very mature technology which is widely understood and safe to handle.
SLA batteries require virtually no maintenance; however there are a number of things to take into account to get the most out of them.
First, batteries need exercise just like people. When a device has an SLA battery, it should be used on a regular basis. If a device with a battery is left plugged in, and not going through discharge and recharge cycles, the SLA’s “memory” will learn that behavior and its capacity will be diminished.
Second, when the battery icon lights up, it needs to be recharged. Makes sense, right? If the battery drains too low, it may not recharge, and in some instances it may actually pull down the power in the scale or balance, preventing it from working even when plugged in.
The third thing to keep in mind it that a low battery can make a scale or balance act strangely or inaccurate. When troubleshooting, use a voltmeter to check the voltage: a well charged 6-volt battery will be at least 6.5 volts. Check the voltage with the unit off, then with the unit on. And remember that sometimes a problem doesn’t show up until the battery is under load. The voltage will drop a little when loaded, but should remain above 6 volts. The voltage measurement does not require great accuracy, so an inexpensive volt meter should serve you well.
Fourth, check the connections to the terminals! Make sure they are tight and not frayed or otherwise damaged. Loose connections can limit battery output.
Fifth, make sure there are no loose metal parts floating around inside which could short out the terminals. A batter has a lot of energy which can be very destructive if it all comes out at once.
And lastly, at the first sign of battery leakage, remove the battery and clean the affected area of the scale or balance. The electrolyte will corrode
almost anything it comes in contact with, such as a metal case, wires, electronic components, and so on. Avoid touching any electrolyte, and wash your hands afterwards. SLA’s are considered toxic or hazardous material, so dispose of the battery properly taking care to contain any leakage; and always recycle.
Things that are not well maintained seem to give out at the worst possible moment. If you take care of your battery, it will give you years of trusty service and not fail when you need it most.
Now, go check your batteries!