If I were to double the exact same battery of a particular device (noted below), could/would that effectively ~double the device's usage time (more or less)?
For reference --
There's a motorized wheelchair I'd like to increase usage time of before needing to recharge. I'm curious if doubling the exact same batteries in parallel could be an option for roughly doubling the wheelchair's use time -- perhaps enabled by custom circuitry for cell/charge balancing/monitoring.
The wheelchair uses lead-acid 12-volt/70 Amp-hour batteries (sealed).
If doubling batteries is not feasible (particularly in this case), how might one go about increasing the usage time of a device, without neutering/trimming already present functions/features of such device?
(Note -- I'm asking this question in the feasibility of such approach, and not in a "I'm about to do this willy-nilly and I'm waiting for either thumbs-up or thumbs-downs". I understand that, if feasible, such a route would likely require more than simply "stacking" batteries in parallel.)