looking for electronics guy who can help me in. designing and in selection of right IC.

looking for electronics circuit design . we want to add like ion battery as backup to gps tracker and we need safety of battery and Gps tracker. below is compete requirement I have a circuitary which is working at 3.8V (2 Amp on load). This Circuitary is being powered up by automobile battery 12/24 V through buck converter LM2596 which is TI product. Now, I am looking for switch over battery charging IC which can fulfil the following requirements:-   IC should be smart enough to charge when the battery is discharged and stop charing the battery when the battery is fully charged, by itself.   When the main supply to the circuitary is not available, IC should be able switch over to the battery, so that the circuitary is powered up by the [login to view URL] the battery is discharged to 3 to 2.5 V, the IC should stop supplying any voltage to the circuitary. From main power we need to get 3.8V with on load 2Amp. let me know if you can help . I need some experience designer .