My exact one is an EL1901 however seems they are no longer sold as far as I can tell. Getting a tad old. As i bought it in 2017. It has 18x 2400mAh cells in it. Has balancing. Trickle charging and electrically is built to be really hard to kill
I plan to eventually replace the cells as 2 have failed short during 2 years without charging it. But the balancer is smart enough to now only charge up to that new max voltage. Derates the charge current for weaker cells. and atleast on 16V is running fine on that lower max voltage
What I have found that heavily borrows from that design is this. However I cannot speak for its internals. atleast seeing as the dimensions and exterior look similar, I would guess its 18x 2900mAh cells.
https://www.bixpower.com/Bat-BP160-p/bat-bp160.htm