ITTSB.EU Blog Forum
Significant information’s in favor of a professional Workshop => All about NiMH and Ni-CD chargers in European Union => Topic started by: Kiriakos GR on October 30, 2025, 12:02:44 AM
-
I was watching a video footage on YouTube about the Nitecore UM4 charger.
The testing was with NiMH cells, and I did note that this thing it does measure Internal Resistance with somewhat lesser error from the expected value.
Most chargers claiming that measure internal resistance they are toys.
Nitecore UM4 charger this has and a second feature, when measuring internal resistance, and this is battery health judgment.
Copy - paste from the user manual ...
When the UM4 is on and the battery is installed, it will automatically detect and display the Internal Resistance below
the “CHG. STATUS”.
When the Internal Resistance is below 250mΩ, it will show “Good” on the screen.
When it is above 250mΩ, it will show “Poor” on the screen to indicate that the battery should be replaced.
This general rule were applied from the product designers, for any type of cell, from NiMH to Li Ion.
I will simply accept the information, as information and not as a fact.
There is specific information per battery chemistry, and internal resistance limits, this be offered from reliable battery manufacturers.
From the other hand, Nitecore engineers worth to be congratulated.
In the past 20 years, we have seen several chargers with micro controller, when these reject an old battery, there is no reference at the user manual, the limit of internal resistance so a battery this to be classified as poor.
Nitecore UM4 charger, this is not a dream machine.
This has a poor program for handling NiMH, with very few options.
This is mostly a Li Ion charger.
This article using as example the Nitecore UM4 charger, this is here as plain educational material.