How “clean” should charge current be?

Was reading reviews of some of the power supplies sold here and some complaints the output was messy. I forget the terminology.

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How important is it?

A couple hundred mV of electrical noise shouldn’t affect anything but some supplies go over a few volts of noise at high voltage/current levels. That could be a problem.

The pack itself won’t care much as long as the spikes from the supply aren’t crazy high but a BMS might not like being forced over its voltage rating even if it’s just spikes/noise.

The hard part is finding out how bad any particular model of power supply really is.