So you've got a kna**ered battery and a wallwart that only outputs 6.6volts with a 150mA load current. I don't think you are going to get there.
If you want 2.3volts per cell ,then the open circuit of the power supply should be at least 7 volts. If you use an unstabilised unit then you don't want to go much above the 7volts because you're bound to forget to disconnect it when the battery is on charge.
General rule on charge rates should be somewhere around C/7 maximum (preferably a bit less) so for a 4.5AH battery I'd say around 500mA is more than enough. There's nothing wrong with 150mA - it'll just take longer to get a discharged amount back into the battery.