Replacement Battery for A2B Hybrid 2011 26" version

Hi there!

I recently acquired a 2011 A2B Hybrid with 26" wheels via a fantastic deal on craigslist. However, the battery is completely dead and I need a replacement. This bike is pretty old and I can't seem to find any dealers selling them online.

It's this one (not the more recent 24" hybrid):
http://www.evanscycles.com/products/ultra-motor/a2b-hybrid-26-wheel-2011-electric-bike-ec028933

This is the battery I'm looking for, but it's no longer in stock here: https://www.biketechshop.com/a2b-36v-external-battery-p-3266.html

Anyone have any ideas where I can get a replacement battery?

Also any current or previous owner: How did you like this bike? I'm excited to give it a spin, but it'll be my GF as the primary user with me on a normal roadbike.

Thank you in advance!
Eric

Also I just checked out this thread: http://endless-sphere.com/forums/viewtopic.php?f=6&t=50590

Would it be possible for me to replace the battery with an A123 battery instead? Also can anyone help me understand what "16s" and "5p" mean? Sorry for the newb questions.

A2B runs off a 36v battery. So basically any 36v battery pack would work for a replacement.

what have you done to test the battery? if it has a BMS then it will be hard to kill it. do you have a voltmeter?

Thanks dnmun. I can get my hands on a voltimeter. I'm not sure if it has BMS (google tells me this means battery management system). What would I be looking for with the voltimeter?

How easy, it is to physically remove the battery off an A2B Hybrid 26 ? My Battery is discharging faster than I would like and I need to find how to remove it for easier charging. I have unlocked the battery but is there anything else needed to slide it off ?

If you have disconnected the power cable to the bike, unlocked the battery, and lifted the retaining latch ( that the lock works with).. Then the battery should slide off the rear.
Im curious how you intend to charge it "easier" when its off the bike .?