" I checked amperage draw of the motor and it was pulling about 1.1v. "
That doesn't make sense.
A 12v battery not on charge and supplying a load is not going to produce 17v.
You have a meter problem or you are doing something wrong.
Normally even cheap meters are fairly close but some of the very cheap ones do strange things when the battery is flat. Better ones shut down or show a battery error and still give sensible answers.
The 15.5v when on the charger is perfectly normal but off charge it will soon drop to about 12.8v.
You can get some errors with prodding batteries with acid on the connections if the prods are of dissimilar metals ( additional cells) but this is never going to give you an extra 4 volts.
Try your car battery, about 12v with lights on or near 14v with engine running and alternator charging. If these figures are way out then yes you have meter problems.
Flux