RE: Does HV mean MAH?
Barber,
From the link you gave:
RC18 series and Losi Slider Lipo 1550HV 3S 11.1V Pack
1550mah Capacity
11.1 Volts
In this case it appears they are interchanging HV and mAh.
However, they are using the HV in their part number.
Just a littls confusing compared to others.
Good Luck,
KW_Counter