Ive got lots of different battery tenders....from all manufacturers, including the HF one.
The major way its different is the status LED. The HF tender has one red led. It lights if the battery is plugged in correctly. Thats all it does. If you have it clipped on the battery correct, it lights up.....even if the tender isnt plugged into the wall. It indicated nothing and is pointless.
The status LED on the Battery Tender tells you many things:
NEITHER THE RED OR GREEN LIGHT TURN ON (Both models) – This
is an abnormal condition and most likely indicates that the charger is not
properly connected to the AC power.
RED LIGHT FLASHING (All models except 6V Junior) – The red light
flashing indicates that the battery charger has AC power available and that
the microprocessor is functioning properly. If the red light continues to
flash, then either the battery voltage is too low (less than 3 volts) or the
output alligator clips or accessory ring terminals are not connected
correctly.
RED LIGHT ON STEADY (Both models) – Whenever the red light is on
steady, a battery is connected properly and the charger is charging the
battery. The red light will remain on until the charger completes the
charging stage.
GREEN LIGHT FLASHING (1.25A only) - When the green light is
flashing, and the red light is on, the battery is greater than 80% charged
and may be removed from the charger and used if necessary. Whenever
possible, leave the battery on charge until the green light is solid.
GREEN LIGHT ON STEADY (Both models) - When the green light stops
flashing and burns steady, the charge is complete and the battery can be
returned to service if necessary.
ALTERNATING RED & GREEN LIGHTS FLASHING (PLUS) This is
abnormal and most likely indicates either that the battery is sulfated or that
there is a poor electrical connection between the charger DC output and
the battery posts.
The Battery Tender also says its for use on AGM and gel battaries......the general concensus on the HF charger is it should not be used with them (the manual is silent on this).