Mackertop 5.25v 3a micro usb wall charger ac adapter for raspberry pi 3 with 1.2m (3.9 ft) power cord.
https://www.amazon.com/dp/B01HB44IE6/ref=cm_sw_r_cp_apa_i_JeT4CbMWE8VW3
I was facing that exact same issue, then I found this power supply on Amazon: https://www.amazon.com/Mackertop-Charger-Raspberry-HSTNN-LA43-PA-1150-22HA/dp/B01HB44IE6/ref=pd_lpo_vtph_147_tr_img_2?_encoding=UTF8&psc=1&refRID=12Z5711KZGXNBDY7VQPF
That low voltage warning never appeared again, look at the reviews.