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Does your Schumacher charger also have the repair/desulfating feature when on 6v?"
I think it does, but not sure. While I was charging my battery I noticed that the battery voltage was up to 6.3 V (with charger leads disconnected), but the charger said it was only 60% done. It took another 10 hours for it to show 100% (pulsating green light). So it must have been desulfating during this time.
Also, read Stephen Throop's review on Amazon:
https://www.amazon.com/gp/product/B0...ustomerReviews
He has done some testing of this charging using oscilloscopes, etc.