The shutoff voltage for your bike is the LVC listed on the controller itself. If it's programmable on the controller, then whatever it is set to. Normally this is 3v to 3.3v per series cell of the battery pack; for 13s that's 13 x 3v (or up to 3.3v). It's a lot easier on the pack to shut off at a higher voltage, and doesn't lose you access to very much pack capacity by doing this.
The battery will have a BMS that will act as an emergency shutoff to prevent pack damage if the controller doesn't shut off above the BMS LVC (but you shouldn't depend on that for everyday shutoffs; that's what the controller's LVC is for). If the battery doesn't state what that LVC is, you can guess that it will probably be about 2.8v x the number of series cells (13 for a 48v pack).
Personally I suspect this battery isn't as good as it claims, based on what we've seen for a lot of cheap batteries--the usual is that the cells aren't good enough to sustain the currents stated, or dont' have the capacity claimed, or both. (or worse, aren't even new cells) It's also unlikely that it would last 1500 cycles. Most likely they've "accidentally" shifted the decimal point over, or "accidentally" added the 1.
If you read the reviews, there are numerous problems reported with them, even in the positive reviews (such as the battery getting "warm" or "hot", which shouldn't happen when used within it's specified limits).
Specs from the linked page below
Product Description
Agomola 48V Battery 8AH 10AH 14Ah 15ah 20AH Lithium Battery for Ebike Electric Bicycle Bikes Scooter Motor with BMS Charger
Ebike Lithium ion Battery Specifics
Model: 48v 20ah lithium battery
Amp Hours: 20AH
Weight: 10.14lb
Size: 10.43x5.43x2.8inch
BMS: 30Amp
Maximum Continuous Discharge Current (A): 30A
Chemical Composition: Lithium ion (Li-Ion)
Service Life: 1500+ cycles
Cell Combination: 7-parallel 13-series(13S7P)
Cell Quantity: 91pcs
Ours 48 Volt lithium battery 20AH is(13S7P) 91pcs battery cell, different from others seller 48V 20AH lithium battery only 13S6P (78pcs batteries cells) only.
Charge Cutoff Voltage (V): 54.6v
Charger Type: Rechargerable
Charge Current: 5-8 hours
Charger: 54.6V 2A 5.5mm x 2.5mm DC Adapter with cooling fan
Manufacturer Warranty: 1 year
Packing List:
1x 48v 20ah lithium battery
1x Original Charger (built-in cooling fan)
1x T-line cable
1x XT-60 connecter/adapter
1x user manual
Model: 48v 10ah lithium battery
Amp Hours: 10AH
Weight: 6.8lb
Size: 10x 3.6x 2.8inch
Cell Combination: 13S4P
Cell Quantity: 52pcs
Manufacturer Warranty: 1 year
Battery Power support FOR: 200W/250W/300W/350W/450W/500Watt/750Watt/800W/1000Watt motor/sctooer/ebikes
