Charging problem with after market battery on X41T

[gappleby]

Recently I have purchased a third party battery for my X41T and it appears to be defective. It starts charging then starts charging for 1 second, then not charging for 5 seconds, charging for 1 second, then not charging for 5 seconds, repeating. This results in it charging to 75 percent and no more. This is the second battery I have got from this supplier - same problem.

I though this might be a machine problem but the information about the battery is a little strange.

3rd party battery specs FRU 92P1083: Design Capacity 54.72 Wh , Full Charge Capacity 61.98 Wh, Remaining Capacity 46.42 Wh, Manufacturer SZBND.

Original IBM Battery specs FRU 92P1085: Design Capacity 64.80 Wh , Full Charge Capacity 37.11 Wh, Remaining Capacity 37.11 Wh, Manufacturer SANYO.

Notice the really strange parameters. How can the Design Capacity be lower than the full charge capacity?

Is there something I might try before I send this battery back again??

Please don't worry about the suggestions such as "bin it" - yet.

Another interesting quirk of this battery pack is its size. It appears to be about 5mm bigger than the original which I thought might be to accommodate a cheaper cell selection. You hardly notice it but it is a little impressive as everything else look like the original unit.