Originally Posted by Polyian
Have you checked the electrolyte, it is possible for lead acid batteries to emit
Hydrogen Sulfide or some other form of malodorous sulfur gas when high charging a cell that has low electrolyte. Add distilled water to cover the plates and it should be OK.
X2. You probably need to add distilled water. Same thing happened to me because of the way I installed my EZ fill hardware. I ended up replacing my batteries because they couldn't hold much of a charge afterwards.
Since you have new batteries and you have checked electrolyte level it may be an over voltage issue. I doubt that you would be getting a smell unless your electrolytes are being cooked off.
Good luck. Keep us posted.