Your stator should be the same as mine. 150 w is a nominal power, the actual power is 55 on AC and 20-30 W on DC. Look at this
. Off road racing bikes are made like this because the AC-DC circuit is lighter and the less power draining.
LED lights need DC, so you only have 20-30 W available in the battery circuit. Note that in an ordinary circuit the generator current and the battery current are linked in parallel (all DC), so the energy comes directly from the generator and the battery gives energy only at the start or during short overloads. You're probably in my same condition, taking part of the power light from the battery, that normally should be avoided, unless the discharge is balanced with a charging period (lights off).
It is possible to convert the generator from the present two internal windings (one for untrasformed AC and one for rectified DC) to a single unified circuit, with some soldering and a new recitifier-regulator. Or to change the hole stator with a boosted one.