Battery reference
Lenovo E530 takes L11L6Y01 aka 45N1048 https://www.amazon.com/L11L6F01-L11L6R01-L11L6Y01-L11M6Y01-Battery/dp/B00N4MRS8I
Lenovo E520 takes 42T4751 https://www.amazon.com/compatible-Extended-7800mAh-Capacity-Replacement/dp/B00GDPODSQ
Lenovo SL510 takes 45N1001 https://www.amazon.com/HWG-Replacement-Battery-T530-Thinkpad/dp/B015R5RVU4