Spud99

@RockyCaptain makes a really good point about depth of discharge. I'd add that the duration of the drive matters just as much.

Interesting thread this. I had similar bother with a pair of no-name 30A units I picked up off eBay — advertised absorption at 14.7V but my multimeter was consistently reading 14.4V at the battery...

Just to add to what @KeithWebb is getting at — the main thing with these cheap units isn't really the PWM technology itself, it's build quality.