EGO Power Tools 7.5 AH Battery 56V for EGO Power Tools

Expensive but it is fantastic and that out weighs the cost

Bought an Ego mower with the 6ah battery (2017) but the battery degarded at the beginning of 2021 to <50%. However having watched a couple of utube videos, I took it apart and found that the top 7 cell triples measured 3.5v whilst the bottom 7 cell triples measured 4v. Hence only 52,5v instead of 56v. On the bench I managed to charge the top 7 cell triples back to 4v (mainly using a car battery charger). This has returned the battery to almost full capacity. The utube videos show that if you replace a cell (difficult) you must charge the new cell to the same voltage as existing cells. It appears that the charger stops charging when any of the 14 triple cells reaches charge, similarly the lawnmower is shown to have discharged (and stops) when any of the 14 triple cells reaches minimum charge. I suspect a design fault with some power only being drawn from the top half of the battery, eg to power the internal circuit board, over 3 years this becomes significant & degrades the capacity. However it can be recharged by manually charging the top 28v of the battery (in 4v, 8v or 12v increments if necessary). Don't throw it away!

they are powerful batteries but they always seem to fail just after warranty runs out. The trouble is you become invested in their platform. I think the BMS is designed to fail. To be honest I wouldn't have gone with Ego if I'd known the batteries were poor quality.