I would say maybe 8 amps at most out of that 170 watt panel and a pwm controller, if it averages 7 amps that would be good. I used to use a 240 watt 36 volt panel and pwm controller and it maxed out at about 6.5 amps. I think they just wrote what the panel is capable of producing in the best conditions. If the panel is a 36 volt panel an mppt controller might actually get you 9 amps.
But if you got a full battery you will see 3 amps or less. Something to look at is voltage drop, check the voltage at your battery terminals and bounce that with what is on the pwm controller lcd screen. If the controller is reading 14.4 volts but your battery is only reading 13.8 volts that means you got voltage drop. That means the controller thinks the battery is full and is going into float too soon. The only way to fix that situation is to raise the bulk setting on the controller until the battery terminals actually reach 14.4 volts. Undercharging your battery will eventually cause it to lose capacity.
Example on my system that has voltage drop, I have to set the bulk setting to 15.5 volts to fully charge my lifepo4 battery (max charge 14.6 volts) if I set the bulk setting to 14.6 volts it only charges at about 4 amps, at 15.5 volts I get the full 12 amps the 240 watt panel can put out. I learned about voltage drop when charging lithium, with lithium you don't have to guess if the battery is full, when my lithium batteries weren't getting fully charged, I found the voltage drop was causing the controller to go to float too soon. With lead acid I always thought my batteries were full and later realized I was undercharging my batteries for years.
