It probably has a BMS on the battery. You'd have to remove that and use a watt meter instead. It might be worth it, though. You'd have to just watch the battery on the watt meter. If the battery is lithium, you risk destroying it but it still might be worth it. You can't really destroy a lithium battery until it goes past about 90 % usage anyway. Actually, it'd probably be easier just to take that battery out, sell it, then replace it with a better one because that battery is such an unusal capacity size. When you add lithium, you usually want to match the capacity sizes so you don't kill your batteries so you'd have to buy another one of the same unless you just removed it and replaced it with a bigger pack.