What I linked is a US Government document titled "MEASUREMENT OF VOLTAGE NOISE IN CHEMICAL BATTERIES - Frequency Control Symposium, 1995. 49th., Proceedings of the 1995 IEEE International".
Link again: https://tf.nist.gov/general/pdf/1133.pdf
Link again: https://tf.nist.gov/general/pdf/1133.pdf
Gerhard kindly provided me with a link: http://www.hoffmann-hochfrequenz.de/downloads/NoiseMeasurementsOnChemicalBatteries.pdf
A couple of years ago Bottlehead had a battery powered preamp kit using the 3S4 tube using four nine volt and two D cell batteries.
Regarding cordless tool batteries, do they like to be run strictly deep cycle or are they OK with being kept topped up?
See if you can pick up a dynamotor on ebay or from an old ham. They ran in lead acid batteries and they turned out high voltage by running a 6, 12, or 24 volt motor to turn a generator. It's stupid simple, and they are built with all the quality of 1950s American made stuff!
Theres no reason you cant put a lithium battery in front of them instead of a lead battery. The filtering of the noise should be easy with modern film caps, and I the end will probably make less noise than switching packs in and out of your supply for charging.
Ive heard from those with experience that the dynamotors have a built in inertia cap. When the load sources current the armature has momentum to carry right through it...
Worth considering...
Theres no reason you cant put a lithium battery in front of them instead of a lead battery. The filtering of the noise should be easy with modern film caps, and I the end will probably make less noise than switching packs in and out of your supply for charging.
Ive heard from those with experience that the dynamotors have a built in inertia cap. When the load sources current the armature has momentum to carry right through it...
Worth considering...