An absolutely safe way to charge any NiMh or NiCad is to charge them at 0.1C for 15 to 16 hours. You do not have to discharge them prior to charging either as, at this low rate, the internal temperatures will not rise to where they cause cell degredation. For your 3800mah battery, that would be charging at 380 milliamperes. Since this is not a standard value and you may not be able to adjust to that exact amount, try 250 milliamperes for about 18 to 20 hours or 500 milliamperes for 10 hours. If you charge at the higher value, keep a note of the temperature and as soon as you see the temperature of the pack rise about 10 degrees above ambient stop the charge. If your battery has been dormant for a month or more, it may take three cycles of charage/discharge to bring it up to full capacity. Discharge at a rate as close to 0.33C as you can set the discharge current and discharge down to 1 volt/cell between charges. If, after the last charge, you get at least 80% of the milliamperehour capacity, the cells will be safe to use.