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?

  • 5
    $\begingroup$ 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" $\endgroup$
    – uhoh
    Nov 23, 2020 at 10:32
  • 1
    $\begingroup$ Thanks a lot for the links! Although they haven't really given me the battery mass, they hold a lot of useful info $\endgroup$
    – Ruben
    Dec 19, 2020 at 17:10

1 Answer 1


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.


  • $\begingroup$ The energy density of lithium polymer battery is no more than 1 MJ/kg. Given 1 MW power and 2.5 minute first stage burn time, the mass of a LiPol battery should be no more than 150 kg. It agrees with the 135 kg estimation. $\endgroup$
    – Mys_721tx
    Apr 15 at 19:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.