The chips on the batteries are the issue, I'm a big makita guy got everything running in the 3 and 4Ah battery system but I burn through them every 18 months on average. They were supposed to be fixed with the 4Ah but still got issues, the key is when you hit the first charge issue you don't retry, it's caused by one cell running flat as the chip powers off of one cell only, instead and a pain in the arse, charge on a non dedicated charger, only, however you try three times on a makita charger then something(?) rests on the charge controller so that they don't recharger on makita charger and I've yet to be able to reset them. A big issue personally as now I have almost £900 of batteries which won't charge cause of a chip