"How to" choose the right batteries for your calibrator

Most of our calibrators are designed to use standard replaceable Alkaline batteries. You know, the ones you can buy at the corner store. That’s a good choice because of the relatively high power density and mostly flat discharge curve of these cells. They start out with a high terminal voltage (1.5 V  or more). A really strong point for these batteries is the long shelf life. If you don’t use your calibrator much, that would be a good reason to use Alkalines. New ones typically have a shelf life of 3 years or more.

On the flip side, if you are a heavy calibrator user, rechargeable batteries, especially very high energy density Nickel Metal Hydride batteries would be a good choice. What is meant by high energy density? Energy in the battery world is measured in Amp hours. For small batteries, it’s most commonly milliAmp hours.

AA Alkaline batteries are typically rated at 2000 mAH. They’re small so they have a high density. Even inexpensive Nickel Metal Hydride batteries now come with 2700 mAH ratings. They have another plus. Although the battery terminal voltage for NiMH batteries starts out at 1.2V, the discharge cycle is extremely flat and the internal resistance is lower. They work right up to the end, so to speak.

You may get as much as 40% more usage from the NiMHs than the Alkalines when they are fully charged. But, that’s the rub. The shelf like of rechargeable batteries is not good in 2 ways. One, they need to be charged regularly, and, two, they will lose their charge when not being used. Infrequent users may find their rechargeable batteries are dead just when they want to use their calibrators.

Here are the tips in short form.

  1. If you use your calibrator everyday and use it a lot, consider switching to rechargeable batteries. They are reliable and efficient and you’ll help save the planet. You will recharge your calibrator every night.
  2. If you have poor access to replaceable Alkaline batteries, also consider changing to rechargeable batteries. Just remember to keep them charged.
  3. If you don’t use your calibrator much, stick with the Alkaline batteries. They’ll be ready when you are unless you have situation 2 above. In this case, if you do use rechargeable batteries, just remember to charge them once a week or at least a couple of times a month.