Those HF automatic chargers are the epitome of solid snot. I salvage what I can from them. Most folks on this forum aren't heavu duty techies so I'll try and make this simple.
They use a flat sheet of 11 gauge aluminum doe the button diode heatsink. Then they attempt to retain a pair of button diodes by scrap metal spring tension to hold the diodes against the aluminum. Won't work can't work the principle is absurd.
OK down to business...
The mickey mouse 39 cent circuit board "automatic charger" sees the ripple in any parallel charger and throws a hissy fit. I tried caps to smooooooooth out the ripple but the sensor circuit detects the new capacitor and limits the charge voltage as being high which throttles current way back..
Neat huh?