Paul Joppa
Moderator
I don't recommend it, especially at the stock 36v B+. The upper half of the filament is essentially cut off, giving increased output impedance and reduced linearity. To double the life, put two D cells in parallel as PB suggests.corndog71 said:Hold the phone! Has this been discussed before? I must've missed it. 2 D batteries in series will last longer? Does this call for any other changes?...
[edited to say PARALLEL - oops!]
There used to be larger industrial NiCd cells (larger than D cells) - I don't know if they still exist, or (most important) if they are available with the recent long-shelf-life feature. But the 1.2 volts of a NiCd is maintained through the discharge and should be close to ideal for a Quickie.