grumpyaz

We have a motorhome on a G 30 van 1995 with the 350 and automatic.
We filled up the other day and returned the motorhome to the storage. Today we picked up the vehicle to take home and charge the coach batteries and the speedometer worked when we parked it but wont work now. Strange but I know it worked to the lot because the miles were registered on the odometer but not any movement today in the speedometer needle. Any way it could be because the battery is to low? I am still working with the mentality of the speedo cable
Thanks for any help;
Grumpy