For high load camera setups in which weight will be a priority, we would recommend using either the E-HL9 (www.idxtek.com/products/E-HL9) or E-HL9S (www.idxtek.com/products/E-HL9S) batteries. The E-HL9 & E-HL9S batteries are both 87wh batteries which will be able to handle 10A/120W loads while weighing in at only ~1.6lbs(each). These models are available and shipping now.
Another option we would recommend is using our upcoming E-HL10DS(www.idxtek.com/products/e-hl10ds) battery. The E-HL10DS will be an economical 95Wh high load battery with an onboard 50W D-tap(to power accessories) & will weigh approx. 1.76lbs(a little larger than the E-HL9/E-HL9S). The E-HL10DS will be available/ready for shipping by next month.
Please also note that the E-7S battery can only handle up to a 4.6A/50W without experiencing cell damage. Therefore, to prolong the life of the E-7S battery, we would not recommend using it battery to power high load cameras like the Alexa if possible. Please let me know if you have any other questions or concerns.