Hi Kenneth,
I think you should be able to a little math to achieve this.
My Jinja sucks, but something like this might get you started, although I haven’t tested it.
sensor:
- platform: mqtt
name: "iSpindel Batteri Prosent"
state_topic: "brew/ferment/tilt/battery"
value_template: "{{ (states('sensor.ispindel_batterylevel' | float - 3.0 ) / (4.3 - 3.0) * 100) | round(0) }}"
unit_of_measurement: "%"
Good luck and happy brewing!
Cheers,
Michael.
Thank you for guiding me in a direction 
I found one bracket to much, but still it gives me wrong output. I get -231 % But my head does not manage to see the next step…
sensor:
- platform: mqtt
name: "iSpindel Batteri Prosent"
state_topic: "brew/ferment/tilt/battery"
value_template: "{{ (states('sensor.ispindel_batterylevel') | float - 3.0 / (4.3 - 3.0) * 100) | round(0) }}"
unit_of_measurement: "%"
value_template: >-
{% set full = 4.3 %}
{% set empty = 3.0 %}
{% set level = states('sensor.ispindel_batterylevel')|float %}
{{ [100, [0, (level - empty) * (100 / (full - empty))]|max]|min|int }}
Or you could do it hardcoded on one line:
value_template: "{{ [100, [0, (states('sensor.ispindel_batterylevel')|float - 3) * (100 / (4.3 - 3))]|max]|min|int }}"
This restricts it to 0% min, 100% max, so if the sensor does spike to 4.4V, it’ll still show 100%.
Also, add device_class: battery and you get an appropriately-charged battery icon for free.
Thank you Troon. This advanced code gives me 0%. The other gives me -227%. I dont get it
You need a range of 1.3V to cover 100%, starting at 3.0V. So you need to subtract 3.0 to get the offset and multiply by 100/1.3 to get the scaling.
The previous code fell victim to rules of order (BODMAS or various other acronyms). You had:
(x - 3.0 / (4.3 - 3.0) * 100)
The division operator is higher priority than the subtract, so you were getting:
(x - (3.0 / (4.3 - 3.0) * 100))
whereas you wanted:
((x - 3.0) / (4.3 - 3.0) * 100)
My template is equivalent to this corrected line, with just a little tweak to clamp it between 0 and 100%.
Thank you again. It was working after the next update from the webhook. Sorry for bother you more. 
Hi. Could you provide your code for this chart? Have you also one for gravity?
Sorry not replying!
Here’s my code - careful of cut/paste indents etc… this is obviously dependant on variable names too.
type: 'custom:apexcharts-card'
header:
show: true
title: iSpindel Temperature & Battery
apex_config:
chart:
zoom:
enabled: true
height: 450
yaxis:
- min: 18
max: 24
opposite: true
seriesName: Temp
decimalsInFloat: 1
name: Temp
title:
text: Temp
- min: 3.5
max: 4.3
opposite: false
seriesName: Battery
decimalsInFloat: 2
name: Battery
title:
text: Battery
- min: 1
max: 1.07
opposite: false
seriesName: Gravity
decimalsInFloat: 3
name: Gravity
title:
text: Gravity
- show: false
stroke:
width: 1
series:
- entity: sensor.ispindle_temp
name: Temp
group_by:
func: avg
duration: 8min
float_precision: 1
curve: smooth
- entity: sensor.ispindle_batterry
name: Battery
group_by:
func: avg
duration: 12min
float_precision: 1
curve: smooth
- entity: sensor.ispindle_gravity
name: Gravity
group_by:
func: avg
duration: 30min
float_precision: 3
curve: smooth
- entity: sensor.beer_template
type: area
curve: stepline
name: Heater
graph_span: 48h
y_axis_precision: 3
And here’s the code for the mqtt integration to pull the data into sensors from the mqtt server and also enable the chart to display the status of the heat pad.
A simple automation turns that smart switch on at 22C and off at 23C
sensor:
- platform: mqtt
name: "Ispindle Tilt"
state_topic: "ispindel/Batt_test/tilt"
unit_of_measurement: '°'
force_update: true
sensor 2:
- platform: mqtt
name: "Ispindle Temp"
state_topic: "ispindel/Batt_test/temperature"
unit_of_measurement: 'C'
force_update: true
sensor 3:
- platform: mqtt
name: "Ispindle Batterry"
state_topic: "ispindel/Batt_test/battery"
unit_of_measurement: 'V'
force_update: true
sensor 4:
- platform: mqtt
name: "Ispindle Gravity"
state_topic: "ispindel/Batt_test/gravity"
unit_of_measurement: ''
force_update: true
sensor 5:
- platform: mqtt
name: "Ispindle RSSI"
state_topic: "ispindel/Batt_test/RSSI"
unit_of_measurement: ''
force_update: true
sensor 7:
- platform: template
sensors:
beer_template:
friendly_name: "Beer Matt on/off"
value_template: >-
{% if is_state('switch.00655508840d8eb5a394', 'on') %}
1
{% else %}
0
{% endif %}
Hi,
I have to use 2 sensors to get battery %
- platform: mqtt
state_topic: "application/14/device/a84041f181830356/event/up"
name: Thyroxine Battery
value_template: '{{ value_json["object"]["BAT_V"] }}'
and then to covert to battery %
thyroxine_battery_percentage:
entity_id: sensor.battery
value_template: "{{ [100, [0, (states('sensor.thyroxine_battery')|float -2 ) * (100 / (3.6 - 2.4))]|max]|min|int }}"
device_class: battery
unit_of_measurement: "%"
The range of the batteries is 3.6V to around 2.4V
This gives me a battery % of 96%, however this is closer to around 55% in reality (current reading is 3.06V)
Can anyone spot anything awry in my calcs? Or any other optimisation tips tricks would be great too!
Many thanks!
At a glance, should that -2 actually be a -2.4, like this?
thyroxine_battery_percentage:
entity_id: sensor.battery
value_template: "{{ [100, [0, (states('sensor.thyroxine_battery')|float -2.4 ) * (100 / (3.6 - 2.4))]|max]|min|int }}"
device_class: battery
unit_of_measurement: "%"