I use this Battery Tender model. Works perfect with no issues. The battery is AGM.
Battery Tender (022-0186G-DL-WH) 12V 5 Amp Battery Charger
https://www.amazon.com/dp/B00EDFPN1O..._KYnSCb3AQJ9KA
But looks like they also have a 4 amp version that is switchable between AGM/Lithium
Battery Tender 022-0209-DL-WH 4A Selectable Charger is an AGM/Standard or GEL/Lithium Iron Switchable, 12v or 6v Switchable at 4a, Includes Rings & Clips. It Will Never Over Charge Your Battery
https://www.amazon.com/dp/B01K87YZ3C..._n.nSCbHMA5JY7
I’ve been using the Battery Tender brand for years on multiple vehicles/bikes with no complaints.