The ESR Internal Resistance Meter Mark II will give you the internal resistance of each cell in a pack and the total IR of the pack measured through the power leads and connector.

You can select the mAh of the pack you want to test by using the preset mAh or use a custom mAh.

Once the mAh is selected you can then get the cells and pack internal resistance in milliohms and the safe amp rate the pack and cells can do.

When testing packs of the same mAh the lower the internal resistance the more power/voltage the pack will provide under load.