170mA? That sounds like a Ni-Cad charger to me. Is that the case? Unless it says it's suitable for Ni-Cad and Nimh's, then I wouldn't use it to charge Nimhs.
I've got several chargers: starting at (for AA's) at 265mA (manual) to 6,500mA. I'd go for at least 700mA which is a compromise between charging speed and battery durability.
With these chargers 3-4 hours is sufficient to charge anything. The charge rate for AAA's tends to be much less. My Ansmann Powerline 4 (might find them second hand), charges AA's at 700mA, but AAA's at only 200mA. You can always charge overnight, but with a manual charger make sure the batteries are flat and don't overcharge them.
The highest charge rate (6.5A) listed above is fine, as these chargers are 'intelligent' ones, so can work out how full a battery is when you insert it and tailors the charge to that effect. Make sure you buy a decent quality one: an Energizer, Uniross or Ansmann charger, as I've found these are the best.
The trick is not to heat the battery too much whilst charging. The higher rating I've given above has a cooling fan and monitors the battery temperature whilst charging.Allow batteries to cool completely before inserting in your equipment.
Rechargables are very cheap compared to what they used to cost, so if they last for less charges that you thought, it's not a big deal. You are still saving vast amounts of money compared to those that still insist on buying disposable batteries.
As for the battery gauge, rechargables don't give a proper reading unlike alkalines.Doesn't mean they aren't fully charged, but the battery gauge works on the amount of current produced and this can vary depending on how power the equipment needs to draw.