Hey, its very simple, just rewind the coils with 19G, Its got 7 poles out of that 4 poles for lighting and 3 for battery charging. For halogen upgrade, u need to rewind the 4 poles only, if u need bit more battery charging rates to be upgraded, rewind them also. Ur electrician must've must've rewinded wrongly, ask him to rewind the whole thing as 4+3 and wire it as stock. U r done. No other changes required. How can he connect the bulb directly to the coils output? Its producing more than 90V? It should not be tested like that. Ask him to rewind it once again first pole in clock wise and next pole anticlock wise manner, like that all poles for lighting + 3 poles for battery charging. Ask him to ensure each pole should contain not less than 75-80 turns, else, the low rpm voltage will be low. I guess he must've winded and connected wrongly.