On Friday, November 16, 2018 at 11:45:04 AM UTC-7, Dave Walsh wrote:
At 17:37 16 November 2018, Emir Sherbi wrote:
A plastic container with concrete?

Eh? What is wrong with just leaving the existing battery in the
tail? I've several "dead" lead acid batteries from the days I
owned a DG400: they're now nearly 20 years old, all are
perfect physically, no swelling, no leakage....

Yep - my Discus 2 tail battery sat unused in the Arizona heat for ten years and remained intact with no leaks. Using that weight is a lot easier than reducing the mass ahead of the CG!

Mike