Guessing that there was no clever end run around the 30v maximum I tried a DC to DC converter set to 15v then measured the voltage between the +38v and the +15v.
Instead of 23 v it jumped around all over the place then settled on 3.x v.
A cap between the terminals might not work either and may due to the fluctuating current short out the converter.
Whoops! It works, at least for an 8 amp converter with a .270 amp load.
The $3 volt meter reads a volt high, but once corrected the voltages add up only losing half a volt somewhere.
Just add 14.3v to get the voltage and remaining range of the ebike.
I will now try a 2 amp converter.
buy a better $3 voltmeter:
it may be possible to convert the one you already have to 3 wire operation.
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