At a certain point, the batteries just won't take a charge. Sitting for 6 years means they're probably done for.
If you're going to swap the pack anyways, a lithium upgrade is highly recommended. Get some leaf modules and a decent BMS and you'll get quite a bit more range for not that much more $.
If you're going to swap the pack anyways, a lithium upgrade is highly recommended. Get some leaf modules and a decent BMS and you'll get quite a bit more range for not that much more $.