[Samsung Galaxy S21 Ultra] nixnixnixnix4:
I can't stand batteries that die after 4 years.

As you may know: staying in the 30-80% range is ideal. Staying under 20% or staying at 100% will degrade/age your battery faster.

I try to keep it in the 37-65% range [28% DoD/Depth-of-Discharge] -- it lasts long without sacrificing usability for me.

I've read somewhere that Samsung limits us to <93% out of the box -- so, you never really charge to 100% and then degrade your battery faster.

What's your experience been with battery longevity?

Dialing *#0228# tells you the voltage and some battery health info.

I looked here: https://opensource.samsung.com/uploadSearch?searchValue=g998

I downloaded and unzipped: SM-G998U_NA_RR_Opensource.zip

I found this little tidbit:

battery {
battery,fgsrc_switch_name = "max77705-charger";
status = "okay";
compatible = "samsung,sec-battery";
battery,vendor = "Battery";
battery,charger_name = "sec-direct-charger";
battery,fuelgauge_name = "max77705-fuelgauge";
battery,technology = <0x2>;
battery,batt_data_version = <0x3>;
battery,temp_adc_type = <0x1>;
battery,adc_check_count = <0x5>;
battery,temp_check_type = <0x2>;
battery,usb_temp_check_type = <0x2>;
battery,chg_temp_check_type = <0x2>;
battery,wpc_temp_check_type = <0x2>;
battery,thermal_source = <0x2>;
battery,usb_thermal_source = <0x2>;
battery,chg_thermal_source = <0x2>;
battery,wpc_thermal_source = <0x2>;
battery,polling_time = <0xa 0x1e 0x1e 0x1e 0xe10>;
battery,cable_check_type = <0x4>;
battery,cable_source_type = <0x1>;
battery,polling_type = <0x1>;
battery,monitor_initial_count = <0x0>;
battery,battery_check_type = <0x0>;
battery,ovp_uvlo_check_type = <0x3>;
battery,temp_check_count = <0x1>;
battery,overheatlimit_threshold = <0x2bc>;
battery,overheatlimit_recovery = <0x2a8>;
battery,wire_warm_overheat_thresh = <0x1f4>;
battery,wire_normal_warm_thresh = <0x1a4>;
battery,wire_cool1_normal_thresh = <0xb4>;
battery,wire_cool2_cool1_thresh = <0x96>;
battery,wire_cool3_cool2_thresh = <0x32>;
battery,wire_cold_cool3_thresh = <0x0>;
battery,wireless_warm_overheat_thresh = <0x1c2>;
battery,wireless_normal_warm_thresh = <0x1a4>;
battery,wireless_cool1_normal_thresh = <0xb4>;
battery,wireless_cool2_cool1_thresh = <0x96>;
battery,wireless_cool3_cool2_thresh = <0x32>;
battery,wireless_cold_cool3_thresh = <0x0>;
battery,tx_high_threshold = <0x1c2>;
battery,tx_high_recovery = <0x190>;
battery,tx_low_threshold = <0x0>;
battery,tx_low_recovery = <0x32>;
battery,wire_warm_current = <0x625>;
battery,wire_cool1_current = <0xc4a>;
battery,wire_cool2_current = <0x418>;
battery,wire_cool3_current = <0x1b5>;
battery,wireless_warm_current = <0x418>;
battery,wireless_cool1_current = <0xc4a>;
battery,wireless_cool2_current = <0x418>;
battery,wireless_cool3_current = <0x1b5>;
battery,full_check_type = <0x2>;
battery,full_check_type_2nd = <0x2>;
battery,full_check_count = <0x1>;
battery,chg_gpio_full_check = <0x0>;
battery,chg_polarity_full_check = <0x1>;
battery,chg_high_temp = <0x1d6>;
battery,chg_high_temp_recovery = <0x1c2>;
battery,chg_input_limit_current = <0x3e8>;
battery,chg_charging_limit_current = <0x76c>;
battery,dchg_high_temp = <0x21c>;
battery,dchg_high_temp_recovery = <0x190>;
battery,dchg_high_batt_temp = <0x190>;
battery,dchg_high_batt_temp_recovery = <0x17c>;
battery,dchg_input_limit_current = <0x3e8>;
battery,dchg_charging_limit_current = <0x7d0>;
battery,wpc_temp_control_source = <0x1>;
battery,wpc_high_temp = <0x172>;
battery,wpc_high_temp_recovery = <0x15e>;
battery,wpc_input_limit_current = <0x258>;
battery,wpc_charging_limit_current = <0x3e8>;
battery,wpc_temp_lcd_on_control_source = <0x1>;
battery,wpc_lcd_on_high_temp = <0x181>;
battery,wpc_lcd_on_high_temp_rec = <0x16d>;
battery,wpc_lcd_on_input_limit_current = <0x1c2>;
battery,wpc_store_high_temp = <0x168>;
battery,wpc_store_high_temp_recovery = <0x154>;
battery,wpc_store_charging_limit_current = <0x190>;
battery,wpc_store_lcd_on_high_temp = <0x168>;
battery,wpc_store_lcd_on_high_temp_rec = <0x12c>;
battery,wpc_store_lcd_on_charging_limit_current = <0x190>;
battery,charging_limit_by_tx_check = <0x1>;
battery,charging_limit_current_by_tx = <0x320>;
battery,sleep_mode_limit_current = <0x320>;
battery,wc_full_input_limit_current = <0x64>;
battery,ta_alert_wa;
battery,mix_high_temp = <0x1a4>;
battery,mix_high_chg_temp = <0x1f4>;
battery,mix_high_temp_recovery = <0x186>;
battery,full_condition_type = <0x9>;
battery,full_condition_soc = <0x5d>;
battery,full_condition_vcell = <0x10fe>;
battery,recharge_check_count = <0x1>;
battery,recharge_condition_type = <0x4>;
battery,recharge_condition_soc = <0x62>;
battery,recharge_condition_vcell = <0x10ea>;
battery,charging_total_time = <0x3840>;
battery,hv_charging_total_time = <0x2a30>;
battery,normal_charging_total_time = <0x4650>;
battery,usb_charging_total_time = <0x8ca0>;
battery,recharging_total_time = <0x1518>;
battery,charging_reset_time = <0x0>;
battery,chg_float_voltage = <0x1130>;
battery,pre_afc_work_delay = <0x7d0>;
battery,pre_wc_afc_work_delay = <0xfa0>;
battery,pre_afc_input_current = <0x1f4>;
battery,pre_wc_afc_input_current = <0x1f4>;
battery,prepare_ta_delay = <0x0>;
battery,swelling_high_rechg_voltage = <0xfd2>;
battery,swelling_low_rechg_voltage = <0x109a>;
battery,siop_icl = <0x4b0>;
battery,siop_fcc = <0x708>;
battery,siop_hv_icl = <0x2bc>;
battery,siop_hv_icl_2nd = <0x226>;
battery,siop_hv_fcc = <0x708>;
battery,siop_apdo_icl = <0x3e8>;
battery,siop_apdo_fcc = <0x7d0>;
battery,siop_wpc_icl = <0x258>;
battery,siop_wpc_fcc = <0x3e8 0x1f4 0x64>;
battery,siop_hv_wpc_icl = <0x2bc>;
battery,siop_hv_wpc_fcc = <0x3e8 0x1f4 0x64>;
battery,siop_store_hv_wpc_icl = <0x1c2>;
battery,store_mode_buckoff;
battery,rp_current_rp1 = <0x1f4>;
battery,rp_current_rp2 = <0x5dc>;
battery,rp_current_rp3 = <0xbb8>;
battery,rp_current_rdu_rp3 = <0x834>;
battery,rp_current_abnormal_rp3 = <0x708>;
battery,pd_charging_charge_power = <0x3a98>;
battery,max_charging_current = <0xc4e>;
battery,wireless_cc_cv = <0x55>;
battery,wireless_otg_input_current = <0x384>;
battery,age_data = <0x0 0x1130 0x10ea 0x10fe 0x5d 0x12c 0x111c 0x10d6 0x10ea 0x5c 0x190 0x1108 0x10c2 0x10d6 0x5b 0x2bc 0x10f4 0x10ae 0x10c2 0x5a 0x3e8 0x10c2 0x107c 0x1090 0x59>;
battery,max_input_voltage = <0x2328>;
battery,max_input_current = <0xbb8>;
battery,cisd_alg_index = <0x8>;
battery,cisd_max_voltage_thr = <0x1162>;
battery,ignore_cisd_index = <0x0 0x0>;
battery,ignore_cisd_index_d = <0x0 0x50>;
battery,expired_time = <0x23dc>;
battery,recharging_expired_time = <0x1518>;
battery,battery_full_capacity = <0x1388>;
battery,ttf_capacity = <0xfa0>;
battery,cv_data = <0xc9c 0x360 0x5fe 0xbfb 0x368 0x5d5 0xb50 0x371 0x5a2 0xa87 0x37c 0x564 0x9bc 0x386 0x50d 0x8d7 0x38e 0x4b5 0x837 0x398 0x454 0x777 0x3a2 0x3e8 0x6ba 0x3ae 0x367 0x5fc 0x3b6 0x2fb 0x53a 0x3c0 0x2ad 0x4bd 0x3c9 0x1e6 0x431 0x3d4 0x133 0x3a4 0x3de 0x73 0x2ce 0x3e8 0x0>;
io-channels = <0x1 0x14b 0x1 0x148 0x1 0x14b 0x1 0x145>;
io-channel-names = "adc-temp", "adc-chg-temp", "adc-wpc-temp", "adc-usb-temp", "n/a";
pinctrl-names = "default";
pinctrl-0 = <0x2 0x3 0x4 0x5>;
battery,wireless_charger_name = "mfc-charger";
battery,chip_vendor = "QCOM";
battery,dchg_temp_check_type = <0x2>;
battery,dchg_thermal_source = <0x3>;
battery,temp_table_adc = <0x12b22 0x16468 0x1a04e 0x1e3cd 0x233b7 0x2923f 0x2ffbb 0x38079 0x41321 0x4bb53 0x57517 0x64362 0x72459 0x80f5d 0x903c3 0x9f70e 0xae404 0xbc629 0xc91ab 0xd4b03 0xde824 0xe6b56 0xed8a6>;
battery,temp_table_data = <0x384 0x352 0x320 0x2ee 0x2bc 0x28a 0x258 0x226 0x1f4 0x1c2 0x190 0x15e 0x12c 0xfa 0xc8 0x96 0x64 0x32 0x0 0xffffffce 0xffffff9c 0xffffff6a 0xffffff38>;
battery,usb_temp_table_adc = <0x11d28 0x15214 0x18e0e 0x1d395 0x2270b 0x28807 0x2f5ee 0x3790b 0x40e91 0x4b921 0x5771e 0x64961 0x72c4a 0x81a9a 0x90f2a 0xa0602 0xaf643 0xbd228 0xc9c0f 0xd46df 0xde93d 0xe66b0 0xeda6d>;
battery,usb_temp_table_data = <0x384 0x352 0x320 0x2ee 0x2bc 0x28a 0x258 0x226 0x1f4 0x1c2 0x190 0x15e 0x12c 0xfa 0xc8 0x96 0x64 0x32 0x0 0xffffffce 0xffffff9c 0xffffff6a 0xffffff38>;
battery,chg_temp_table_adc = <0xea60 0x120fe 0x1605a 0x1a3c4 0x1f430 0x25070 0x2be43 0x33e6a 0x3d0bb 0x478ec 0x53461 0x60488 0x6e595 0x7d1b2 0x8ca3b 0x9c1aa 0xabf5a 0xba35c 0xc7078 0xd2515 0xdcc84 0xe57fd 0xec91b>;
battery,chg_temp_table_data = <0x384 0x352 0x320 0x2ee 0x2bc 0x28a 0x258 0x226 0x1f4 0x1c2 0x190 0x15e 0x12c 0xfa 0xc8 0x96 0x64 0x32 0x0 0xffffffce 0xffffff9c 0xffffff6a 0xffffff38>;
battery,wpc_temp_table_adc = <0x12b22 0x16468 0x1a04e 0x1e3cd 0x233b7 0x2923f 0x2ffbb 0x38079 0x41321 0x4bb53 0x57517 0x64362 0x72459 0x80f5d 0x903c3 0x9f70e 0xae404 0xbc629 0xc91ab 0xd4b03 0xde824 0xe6b56 0xed8a6>;
battery,wpc_temp_table_data = <0x384 0x352 0x320 0x2ee 0x2bc 0x28a 0x258 0x226 0x1f4 0x1c2 0x190 0x15e 0x12c 0xfa 0xc8 0x96 0x64 0x32 0x0 0xffffffce 0xffffff9c 0xffffff6a 0xffffff38>;
battery,dchg_temp_table_adc = <0x15f90 0x1dc88 0x24a80 0x2c1a2 0x34b18 0x3e6e2 0x49e2a 0x57a1a 0x67188 0x78d9e 0x8d786 0xa3cec 0xbbdd0 0xd5108 0xeffbe 0x10a54a 0x125400 0x13d4e4 0x154374 0x168432 0x17971e 0x187c38 0x193caa>;
battery,dchg_temp_table_data = <0x384 0x352 0x320 0x2ee 0x2bc 0x28a 0x258 0x226 0x1f4 0x1c2 0x190 0x15e 0x12c 0xfa 0xc8 0x96 0x64 0x32 0x0 0xffffffce 0xffffff9c 0xffffff6a 0xffffff38>;
battery,charging_limit_current_by_tx_gear = <0x320>;
battery,standard_curr = <0x119e>;
battery,max_charging_charge_power = <0x61a8>;
battery,high_temp_float = <0x1068>;
battery,low_temp_float = <0x1130>;
battery,chg_ocp_current = <0x0>;
battery,chg_ocp_dtc = <0x64>;
battery,wpc_step_limit_temp = <0x168 0x15e>;
battery,wpc_step_limit_fcc = <0xc4e 0xc4e>;
battery,wpc_step_limit_fcc_12w = <0xc4e 0xc4e>;
battery,wpc_step_limit_fcc_15w = <0x898 0xa28>;
battery,health_condition = <0x384 0x4b 0x4b0 0x41 0x5dc 0x37>;
battery,step_chg_type = <0x0>;
battery,dc_step_chg_type = <0xe9>;
battery,dc_step_chg_charge_power = <0x55f0>;
battery,dc_step_chg_step = <0x3>;
battery,dc_step_chg_cond_vol = <0x1036 0x10c2 0x1130>;
battery,dc_step_chg_val_vfloat = <0x1036 0x10c2 0x1130>;
battery,dc_step_chg_val_iout = <0x15a4 0x15a4 0x119e>;
battery,dc_step_chg_iin_check_cnt = <0x3>;
battery,dc_step_chg_cond_soc = <0x14 0x32 0x64 0x14 0x32 0x64 0x14 0x32 0x64 0x14 0x32 0x64 0x14 0x32 0x64>;
battery,dis_auto_shipmode_temp_ctrl;
battery,tx_stop_capacity = <0x1e>;
battery,tx_minduty_default = <0x14>;
battery,tx_minduty_5V = <0x32>;
battery,tx_uno_iout = <0x5dc>;
battery,tx_mfc_iout_gear = <0x5dc>;
battery,tx_mfc_iout_phone = <0x44c>;
battery,tx_mfc_iout_phone_5v = <0x12c>;
battery,tx_mfc_iout_lcd_on = <0x384>;
battery,tx_5v_disable;
battery,ttf_hv_charge_current = <0xad7>;
battery,ttf_hv_wireless_charge_current = <0x591>;
battery,ttf_wireless_charge_current = <0x366>;
battery,ttf_dc25_charge_current = <0x1324>;
phandle = <0xbb>;
};