On Saturday, November 26, 2016 at 3:47:29 PM UTC-8, AS wrote:
(and lithiums are not an option)

Tom

Why might that be? Just curious ....

Uli
AS

The DGs use 6 volt batteries - AFAIK there are no 6 V lithium batteries. You might be able to assemble a custom battery pack, but that isn't adviseable for safety reasons.

Tom