I've got a Sabertooth 2x32 motor controller from Dimension Engineering that I'm using to drive two wheelchair motors off of an old Pride Mobility Jazzy motor. When I was using the two original batteries (see attached PDF) I had no problem with the Sabertooth; I had the batteries wired in parallel without issue.
I had the wheelchair out in the garage this winter, and for whatever reason, my charger wasn't working right and so the batteries sat all winter discharged and are junk now.
I bought two new 12V 35AH SLAs to replace the original ones. They came in at 12.7V each; I wired them up in parallel like I had the old ones, but couldn't get the Sabertooth to drive the motors. I used the DEScribe software from Dimension Engineering to ensure that RC signal was being passed to the Sabertooth and it was, but the motors still won't function. I got the continuity tester out and checked connections and everything seemed good.
The status LEDs appear okay. Depending on the DIP switch configuration for battery protection it will either be solid green or blinking three times green. This was a little odd to me, the manual for the Sabertooth says in battery protect mode the LED blinks out the number of cells detected. I would think there should be four blinks if the batteries are in parallel, but maybe I'm mistaken.
I'm going to try to wire the batteries up in series tomorrow; the Sabertooth 2x32 says it can take a maximum of 33.6V so I don't see that being an issue. My only guess is that it is detecting an error with the battery charge and isn't running for that reason. Brakes have been removed from the motors, so that shouldn't be an issue.
Attached is a schematic of my build. Any ideas would be very welcome, I'm at my wits end with this.