I wouldn't use a jumpstart pack - too hard. I should have probably said "at least 10 Amps".
The conventional chargers are like the modern chargers build for different battery size(s). For our battery, the smallest charger will have the 10Amp setting, that's why I mentioned that. Also, there are conventional chargers that can go to 75Amps, which I think is too much and might do harm. Even the 40 Amps seems a tad on the hi-side...

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Stable: e92is, e46 M54B25, e83 N52, e53 N62 - sold, e39 M54B30 R.I.P.