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How long will batteries last in the UM250 which is the 250mW beltpack transmitter?

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Here's the answer I posted on RAMPS about 9 Volt battery life:

Here's the last of the 9 Volt battery tests. This is a similar test to what we did in a previous post but with a high power transmitter. (See also FAQ How long will different types of 9 Volt batteries operate my transmitter?) For newer tests on the iPower LiPoly rechargeable 9 Volt (See FAQ How do the rechargeable 9 Volt iPower batteries compare to other batteries? How long will they operate my unit?) Here is what we did this time: we used a 250mW transmitter, a Lectro UM250 in the testing. This is a 250 mW UHF belt pack transmitter that eats 9 Volts like they were potato chips. This particular unit pulled 105 mA. We ran three different kinds of batteries to a final voltage of both 7.0 and 6.6 Volts. 7.0 Volts is where the LED is pretty dim and where two of our receivers with battery readouts start indicating low battery and 6.6 Volts is the very low battery indication. The transmitter is getting close to completely dying at 6.6 Volts but will usually run to 6.4 Volts or less. The LED goes out totally at 6.8 Volts. I'll list the type of battery and then the very dim LED point (7.0 Volts) and then the maximum use (6.6 Volts). Your mileage may vary.

  • Ultralife Lithium 5.5 hours and 6.6 hours
  • Duracell Ultra Alkaline 2.6 hours and 2.8 hours
  • Eveready Alkaline 1.8 hours and 3.2 hours (!)
  • Varta NiMh rechargeable 1.0 hours and 1.25 hours

These are interesting results. If you saw the earlier post with a similar table, you will notice that the Ultra alkaline has the same 50% advantage to 7 Volts but when run to 6.6 Volts, has instead, a 13% LOSS. This is not the same as for a 100 mW transmitter. There the Ultra was 50% ahead at either end point voltage. The Ultra fell like a rock when the voltage got to 6.6 Volts. In fairness to the battery manufacturer, these 1/4 watt units are very hard on batteries.   Same disclaimer as before: These were fresh, new batteries at room temperature. This was one test, performed on one transmitter.   And same anti-disclaimer: Most brands of alkaline batteries are about the same, alkalines and lithiums have a long shelf life, and our transmitters are pretty consistent. In any case, the ratios of battery life should be good numbers. You guys and gals know what kind of battery life you are getting now, and the ratios should be informative. We have found Eveready to be the most consistent general purpose alkaline.

On to other projects. I've seen enough battery strip charts for a while.

Posted 1 year agoby LectroAdmin
#42