# What is the mass of the Electron rocket's battery pack?

I am trying to estimate battery weights for electric pump fed rockets of various sizes and wanted to use the electron rocket as data to validate my calculations. However I was unable to find the mass of the battery pack that delivers the power for the 9 Rutherford engines in the Electron rocket.

Does anybody know where to find this data or know a reasonable estimate?

• Are the ejected first stage Electron rocket batteries really incinerated? links to Spaceflight 101's Electron The first “battery-powered” Rocket but at 1st glance no answer pops out though there are clues towards a minimum size: "Each of the small motors, about the size of a soda can, delivers 50 horsepower (37kW) when spinning at 40,000 RPM" & "A disadvantage of the design is the heavy battery required to drive the pumps" & "Each engine assembly, without battery, weighs approximately 20 Kilograms"
– uhoh
Nov 23, 2020 at 10:32
• Thanks a lot for the links! Although they haven't really given me the battery mass, they hold a lot of useful info Dec 19, 2020 at 17:10

## 1 Answer

Apparently the whole engine weighs 35kg so 35Kg-20Kg = 15kg. Though the battery is for all engines so 135Kg. Based on those numbers I'm sure it's not a standard rechargeable lithium cell. It would be a lithium primary cell. Much like what is used to power torpedo's and other kamikaze weapon systems. Remember the whole objective was to simplify the engine systems, not necessarily reuse them a million times.

The ideal would be a hydrolox engine kept simple by using a fuel cell to power the electric pumps. Unfortunately it's proving quite difficult to get a fuel cell with sufficient power density.

https://en.wikipedia.org/wiki/Rutherford_(rocket_engine)