Hello all this is my first post and going to be my first project .
Please can you advise if its possible to get a 12 - 14.5 battery measurement and send the voltage reading over wifi . As i want to send the reading over an area of 30 feet.
Please let me know if this is achievable.
thanks
Yes it is acheaviable.
Yes.
How do you plan on receiving the voltage? e.g., as a socket connection to a server, using a web browser, etc.?
Hello there i would like to send the signal over bluetooth sorry if i can confused things .
to another voltmeter placed in an room
Yes, Bluetooth/BLE has nothing at all to do with Wi-Fi.
So let's start over.
You want to send signal A to receiver B using BLE. How is the Voltmeter reading the wireless message?
Can you post the data sheet and links to the voltmeter that is BT compatible with a Arduino type MCU?
Hello again this is what i am trying to achieve but with a reading from an alternator voltage at the battery which is 12.7 to 14.9 maximum. just want to make sure that this will work on the voltage for my project.
The project has, what I consider, a serious flaw that brings me doubt the project linked to will work.
The flaw is
But from the vast project spec given in post 1 and the words of the linked to project it should work. What did you get when your tried the project?
Hello i did not actually start it yet but its something i must do .
So thats why i asked if you think its achievable , so i dont waste any time or anyone else time .
Any suggestions would be appreciated. Thanks
It can be done.
Explain what you need if you want suggestions. No clear situation & requirements = no clear advice.
I am trying to read my battery voltage on my boat battery and send the voltage reading to my
cabin so i can keep an eye on my battery levels.
So if the voltage monitor was in your boat house thingy and it has a MCU hooked to it the MCU could send the data to a MQTT Broker running in the house. Using Node-Red a graphical plug and play thingy, the MQTT Broker info can be read and displayed onto a thingy of your choosing.
In this code running on a ESP32 sitting in my backyard running off a battery it transmits the battery reading to my MQTT Broker for further processing.
/*
Chappie Weather upgrade/addition
process wind speed direction and rain fall.
*/
#include "esp32/ulp.h"
//#include "ulptool.h"
#include "driver/rtc_io.h"
#include <WiFi.h>
#include <PubSubClient.h>
#include "certs.h"
#include "sdkconfig.h"
#include "esp_system.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/timers.h"
#include "freertos/event_groups.h"
#include "driver/pcnt.h"
#include <driver/adc.h>
#include <SimpleKalmanFilter.h>
#include <ESP32Time.h>
////
ESP32Time rtc;
WiFiClient wifiClient;
PubSubClient MQTTclient(mqtt_server, mqtt_port, wifiClient);
////
float CalculatedVoltage = 0.0f;
float kph = 0.0f;
float rain = 0.0f;
/*
PCNT PCNT_UNIT_0, PCNT_CHANNEL_0 GPIO_NUM_15 = pulse input pin
PCNT PCNT_UNIT_1, PCNT_CHANNEL_0 GPIO_NUM_4 = pulse input pin
*/
pcnt_unit_t pcnt_unit00 = PCNT_UNIT_0; //pcnt unit 0 channel 0
pcnt_unit_t pcnt_unit10 = PCNT_UNIT_1; //pcnt unit 1 channel 0
//
//
hw_timer_t * timer = NULL;
//
#define evtAnemometer ( 1 << 0 )
#define evtRainFall ( 1 << 1 )
#define evtParseMQTT ( 1 << 2 )
EventGroupHandle_t eg;
#define OneMinuteGroup ( evtAnemometer | evtRainFall )
////
QueueHandle_t xQ_Message; // payload and topic queue of MQTT payload and topic
const int payloadSize = 100;
struct stu_message
{
char payload [payloadSize] = {'\0'};
String topic ;
} x_message;
////
SemaphoreHandle_t sema_MQTT_KeepAlive; // used to stop all other MQTT thing do's
SemaphoreHandle_t sema_mqttOK; // protect the mqttOK variable.
SemaphoreHandle_t sema_CalculatedVoltage; // protects the CalculatedVoltage variable.
////
int mqttOK = 0; // stores a count value that is used to cause an esp reset
volatile bool TimeSet = false;
////
/*
Topic topicOK has been subscribed to, the mqtt broker sends out "OK" messages if the client receives an OK message the mqttOK value is set back to zero.
If the mqttOK count reaches a set point the ESP32 will reset.
*/
////
void IRAM_ATTR mqttCallback(char* topic, byte * payload, unsigned int length)
{
memset( x_message.payload, '\0', payloadSize ); // clear payload char buffer
x_message.topic = ""; //clear topic string buffer
x_message.topic = topic; //store new topic
int i = 0; // extract payload
for ( i; i < length; i++)
{
x_message.payload[i] = (char)payload[i];
}
x_message.payload[i] = '\0';
xQueueOverwrite( xQ_Message, (void *) &x_message );// send data to queue
} // void mqttCallback(char* topic, byte* payload, unsigned int length)
////
// interrupt service routine for WiFi events put into IRAM
void IRAM_ATTR WiFiEvent(WiFiEvent_t event)
{
switch (event) {
case SYSTEM_EVENT_STA_CONNECTED:
break;
case SYSTEM_EVENT_STA_DISCONNECTED:
log_i("Disconnected from WiFi access point");
break;
case SYSTEM_EVENT_AP_STADISCONNECTED:
log_i("WiFi client disconnected");
break;
default: break;
}
} // void IRAM_ATTR WiFiEvent(WiFiEvent_t event)
////
void IRAM_ATTR onTimer()
{
BaseType_t xHigherPriorityTaskWoken;
xEventGroupSetBitsFromISR(eg, OneMinuteGroup, &xHigherPriorityTaskWoken);
} // void IRAM_ATTR onTimer()
////
void setup()
{
eg = xEventGroupCreate(); // get an event group handle
x_message.topic.reserve(100);
adc1_config_width(ADC_WIDTH_12Bit);
adc1_config_channel_atten(ADC1_CHANNEL_6, ADC_ATTEN_DB_11);// using GPIO 34 wind direction
adc1_config_channel_atten(ADC1_CHANNEL_3, ADC_ATTEN_DB_11);// using GPIO 39 current
adc1_config_channel_atten(ADC1_CHANNEL_0, ADC_ATTEN_DB_11);// using GPIO 36 battery volts
// hardware timer 4 set for one minute alarm
timer = timerBegin( 3, 80, true );
timerAttachInterrupt( timer, &onTimer, true );
timerAlarmWrite(timer, 60000000, true);
timerAlarmEnable(timer);
/* Initialize PCNT's counter */
int PCNT_H_LIM_VAL = 3000;
int PCNT_L_LIM_VAL = -10;
// 1st PCNT counter
pcnt_config_t pcnt_config = {};
pcnt_config.pulse_gpio_num = GPIO_NUM_15;// Set PCNT input signal and control GPIOs
pcnt_config.ctrl_gpio_num = PCNT_PIN_NOT_USED;
pcnt_config.channel = PCNT_CHANNEL_0;
pcnt_config.unit = PCNT_UNIT_0;
// What to do on the positive / negative edge of pulse input?
pcnt_config.pos_mode = PCNT_COUNT_INC; // Count up on the positive edge
pcnt_config.neg_mode = PCNT_COUNT_DIS; // Count down disable
// What to do when control input is low or high?
pcnt_config.lctrl_mode = PCNT_MODE_KEEP; // Keep the primary counter mode if low
pcnt_config.hctrl_mode = PCNT_MODE_KEEP; // Keep the primary counter mode if high
// Set the maximum and minimum limit values to watch
pcnt_config.counter_h_lim = PCNT_H_LIM_VAL;
pcnt_config.counter_l_lim = PCNT_L_LIM_VAL;
pcnt_unit_config(&pcnt_config); // Initialize PCNT unit
pcnt_set_filter_value( PCNT_UNIT_0, 1); //Configure and enable the input filter
pcnt_filter_enable( PCNT_UNIT_0 );
pcnt_counter_pause( PCNT_UNIT_0 );
pcnt_counter_clear( PCNT_UNIT_0 );
pcnt_counter_resume( PCNT_UNIT_0); // start the show
// setup 2nd PCNT
pcnt_config = {};
pcnt_config.pulse_gpio_num = GPIO_NUM_4;
pcnt_config.ctrl_gpio_num = PCNT_PIN_NOT_USED;
pcnt_config.channel = PCNT_CHANNEL_0;
pcnt_config.unit = PCNT_UNIT_1;
pcnt_config.pos_mode = PCNT_COUNT_INC;
pcnt_config.neg_mode = PCNT_COUNT_DIS;
pcnt_config.lctrl_mode = PCNT_MODE_KEEP;
pcnt_config.hctrl_mode = PCNT_MODE_KEEP;
pcnt_config.counter_h_lim = PCNT_H_LIM_VAL;
pcnt_config.counter_l_lim = PCNT_L_LIM_VAL;
pcnt_unit_config(&pcnt_config);
//pcnt_set_filter_value( PCNT_UNIT_1, 1 );
//pcnt_filter_enable ( PCNT_UNIT_1 );
pcnt_counter_pause ( PCNT_UNIT_1 );
pcnt_counter_clear ( PCNT_UNIT_1 );
pcnt_counter_resume ( PCNT_UNIT_1 );
//
xQ_Message = xQueueCreate( 1, sizeof(stu_message) );
//
sema_CalculatedVoltage = xSemaphoreCreateBinary();
xSemaphoreGive( sema_CalculatedVoltage );
sema_mqttOK = xSemaphoreCreateBinary();
xSemaphoreGive( sema_mqttOK );
sema_MQTT_KeepAlive = xSemaphoreCreateBinary();
///
xTaskCreatePinnedToCore( MQTTkeepalive, "MQTTkeepalive", 15000, NULL, 5, NULL, 1 );
xTaskCreatePinnedToCore( fparseMQTT, "fparseMQTT", 10000, NULL, 5, NULL, 1 ); // assign all to core 1, WiFi in use.
xTaskCreatePinnedToCore( fReadBattery, "fReadBattery", 4000, NULL, 3, NULL, 1 );
xTaskCreatePinnedToCore( fReadCurrent, "fReadCurrent", 4000, NULL, 3, NULL, 1 );
xTaskCreatePinnedToCore( fWindDirection, "fWindDirection", 10000, NULL, 4, NULL, 1 );
xTaskCreatePinnedToCore( fAnemometer, "fAnemometer", 10000, NULL, 4, NULL, 1 );
xTaskCreatePinnedToCore( fRainFall, "fRainFall", 10000, NULL, 4, NULL, 1 );
xTaskCreatePinnedToCore( fmqttWatchDog, "fmqttWatchDog", 3000, NULL, 3, NULL, 1 ); // assign all to core 1
} //void setup()
static void init_ulp_program()
{
// not sharing this code.
}
////
void fWindDirection( void *pvParameters )
// read the wind direction sensor, return heading in degrees
{
float adcValue = 0.0f;
uint64_t TimePastKalman = esp_timer_get_time();
SimpleKalmanFilter KF_ADC( 1.0f, 1.0f, .01f );
float high = 0.0f;
float low = 2000.0f;
float ADscale = 3.3f / 4096.0f;
TickType_t xLastWakeTime = xTaskGetTickCount();
const TickType_t xFrequency = 100; //delay for mS
int count = 0;
String windDirection;
windDirection.reserve(20);
String MQTTinfo = "";
MQTTinfo.reserve( 150 );
while ( !MQTTclient.connected() )
{
vTaskDelay( 250 );
}
for (;;)
{
windDirection = "";
adcValue = float( adc1_get_raw(ADC1_CHANNEL_6) ); //take a raw ADC reading
KF_ADC.setProcessNoise( (esp_timer_get_time() - TimePastKalman) / 1000000.0f ); //get time, in microsecods, since last readings
adcValue = KF_ADC.updateEstimate( adcValue ); // apply simple Kalman filter
TimePastKalman = esp_timer_get_time(); // time of update complete
adcValue = adcValue * ADscale;
if ( (adcValue >= 0.0f) & (adcValue <= .25f ) )
{
// log_i( " n" );
windDirection.concat( "N" );
}
if ( (adcValue > .25f) & (adcValue <= .6f ) )
{
// log_i( " e" );
windDirection.concat( "E" );
}
if ( (adcValue > 2.0f) & ( adcValue < 3.3f) )
{
// log_i( " s" );
windDirection.concat( "S");
}
if ( (adcValue >= 1.7f) & (adcValue < 2.0f ) )
{
// log_i( " w" );
windDirection.concat( "W" );
}
if ( count >= 30 )
{
MQTTinfo.concat( String(kph, 2) );
MQTTinfo.concat( ",");
MQTTinfo.concat( windDirection );
MQTTinfo.concat( ",");
MQTTinfo.concat( String(rain, 2) );
xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY );
MQTTclient.publish( topicWSWDRF, MQTTinfo.c_str() );
xSemaphoreGive( sema_MQTT_KeepAlive );
count = 0;
}
count++;
MQTTinfo = "";
xLastWakeTime = xTaskGetTickCount();
vTaskDelayUntil( &xLastWakeTime, xFrequency );
}
vTaskDelete ( NULL );
}
// read rainfall
void fRainFall( void *pvParemeters )
{
int16_t click = 0; //count tipping bucket clicks
pcnt_counter_pause( PCNT_UNIT_1 );
pcnt_counter_clear( PCNT_UNIT_1 );
pcnt_counter_resume( PCNT_UNIT_1 );
for (;;)
{
xEventGroupWaitBits (eg, evtRainFall, pdTRUE, pdTRUE, portMAX_DELAY);
if ( (rtc.getHour(true) == 23) && (rtc.getMinute() == 59) )
{
pcnt_counter_pause( PCNT_UNIT_1 );
rain = 0.0f;
pcnt_counter_clear( PCNT_UNIT_1 );
pcnt_counter_resume( PCNT_UNIT_1 );
} else {
pcnt_counter_pause( PCNT_UNIT_1 );
pcnt_get_counter_value( PCNT_UNIT_1, &click );
if ( click != 0 )
{
rain = rain + (0.2794f * (float)click);// 0.2794mm of rain per click
pcnt_counter_clear( PCNT_UNIT_1 );
//log_i( "count %d, rain rain = %f mm", click, rain );
}
pcnt_counter_resume( PCNT_UNIT_1 );
click = 0;
}
}
vTaskDelete ( NULL );
}
////
void fAnemometer( void *pvParameters )
{
int16_t count = 0;
pcnt_counter_clear(PCNT_UNIT_0);
pcnt_counter_resume(PCNT_UNIT_0);
for (;;)
{
xEventGroupWaitBits (eg, evtAnemometer, pdTRUE, pdTRUE, portMAX_DELAY);
pcnt_counter_pause( PCNT_UNIT_0 );
pcnt_get_counter_value( PCNT_UNIT_0, &count);
kph = 2.4f * ((float)count / 60.0f);// A wind speed of 2.4km/h causes the switch to close once per second
pcnt_counter_clear( PCNT_UNIT_0 );
pcnt_counter_resume( PCNT_UNIT_0 );
}
vTaskDelete ( NULL );
}
//////
void fmqttWatchDog( void * paramater )
{
int UpdateImeTrigger = 86400; //seconds in a day
int UpdateTimeInterval = 86300; // 1st time update in 100 counts
int maxNonMQTTresponse = 60;
for (;;)
{
vTaskDelay( 1000 );
if ( mqttOK >= maxNonMQTTresponse )
{
ESP.restart();
}
xSemaphoreTake( sema_mqttOK, portMAX_DELAY );
mqttOK++;
xSemaphoreGive( sema_mqttOK );
UpdateTimeInterval++; // trigger new time get
if ( UpdateTimeInterval >= UpdateImeTrigger )
{
TimeSet = false; // sets doneTime to false to get an updated time after a days count of seconds
UpdateTimeInterval = 0;
}
}
vTaskDelete( NULL );
}
//////
void fparseMQTT( void *pvParameters )
{
struct stu_message px_message;
for (;;)
{
if ( xQueueReceive(xQ_Message, &px_message, portMAX_DELAY) == pdTRUE )
{
// parse the time from the OK message and update MCU time
if ( String(px_message.topic) == topicOK )
{
if ( !TimeSet)
{
String temp = "";
temp = px_message.payload[0];
temp += px_message.payload[1];
temp += px_message.payload[2];
temp += px_message.payload[3];
int year = temp.toInt();
temp = "";
temp = px_message.payload[5];
temp += px_message.payload[6];
int month = temp.toInt();
temp = "";
temp = px_message.payload[8];
temp += px_message.payload[9];
int day = temp.toInt();
temp = "";
temp = px_message.payload[11];
temp += px_message.payload[12];
int hour = temp.toInt();
temp = "";
temp = px_message.payload[14];
temp += px_message.payload[15];
int min = temp.toInt();
rtc.setTime( 0, min, hour, day, month, year );
log_i( "rtc %s ", rtc.getTime() );
TimeSet = true;
}
}
//
} //if ( xQueueReceive(xQ_Message, &px_message, portMAX_DELAY) == pdTRUE )
xSemaphoreTake( sema_mqttOK, portMAX_DELAY );
mqttOK = 0;
xSemaphoreGive( sema_mqttOK );
}
} // void fparseMQTT( void *pvParameters )#include <ESP32Time.h>
//////
void fReadCurrent( void * parameter )
{
const TickType_t xFrequency = 1000; //delay for mS
const float mVperAmp = 185.0f;
float ADbits = 4096.0f;
float ref_voltage = 3.3f;
float mA = 0.0f;
float adcValue = 0.0f;
float Voltage = 0.0f;
float Power = 0.0f;
float offSET = 0.0f;
int printCount = 0;
uint64_t TimePastKalman = esp_timer_get_time(); // used by the Kalman filter UpdateProcessNoise, time since last kalman calculation
SimpleKalmanFilter KF_I( 1.0f, 1.0f, .01f );
/*
185mv/A = 5 AMP MODULE
100mv/A = 20 amp module
66mv/A = 30 amp module
*/
String powerInfo = "";
powerInfo.reserve( 150 );
while ( !MQTTclient.connected() )
{
vTaskDelay( 250 );
}
TickType_t xLastWakeTime = xTaskGetTickCount();
for (;;)
{
adc1_get_raw(ADC1_CHANNEL_3); // read once discard reading
adcValue = ( (float)adc1_get_raw(ADC1_CHANNEL_3) );
//log_i( "adcValue I = %f", adcValue );
Voltage = ( (adcValue * ref_voltage) / ADbits ) + offSET; // Gets you mV
mA = Voltage / mVperAmp; // get amps
KF_I.setProcessNoise( (esp_timer_get_time() - TimePastKalman) / 1000000.0f ); //get time, in microsecods, since last readings
mA = KF_I.updateEstimate( mA ); // apply simple Kalman filter
TimePastKalman = esp_timer_get_time(); // time of update complete
printCount++;
if ( printCount == 60 )
{
xSemaphoreTake( sema_CalculatedVoltage, portMAX_DELAY);
Power = CalculatedVoltage * mA;
//log_i( "Voltage=%f mA=%f Power=%f", CalculatedVoltage, mA, Power );
printCount = 0;
powerInfo.concat( String(CalculatedVoltage, 2) );
xSemaphoreGive( sema_CalculatedVoltage );
powerInfo.concat( ",");
powerInfo.concat( String(mA, 4) );
powerInfo.concat( ",");
powerInfo.concat( String(Power, 4) );
xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY );
MQTTclient.publish( topicPower, powerInfo.c_str() );
xSemaphoreGive( sema_MQTT_KeepAlive );
powerInfo = "";
}
xLastWakeTime = xTaskGetTickCount();
vTaskDelayUntil( &xLastWakeTime, xFrequency );
}
vTaskDelete( NULL );
} //void fReadCurrent( void * parameter )
////
void fReadBattery( void * parameter )
{
float adcValue = 0.0f;
const float r1 = 50500.0f; // R1 in ohm, 50K
const float r2 = 10000.0f; // R2 in ohm, 10k potentiometer
float Vbatt = 0.0f;
int printCount = 0;
float vRefScale = (3.3f / 4096.0f) * ((r1 + r2) / r2);
uint64_t TimePastKalman = esp_timer_get_time(); // used by the Kalman filter UpdateProcessNoise, time since last kalman calculation
SimpleKalmanFilter KF_ADC_b( 1.0f, 1.0f, .01f );
TickType_t xLastWakeTime = xTaskGetTickCount();
const TickType_t xFrequency = 1000; //delay for mS
for (;;)
{
adc1_get_raw(ADC1_CHANNEL_0); //read and discard
adcValue = float( adc1_get_raw(ADC1_CHANNEL_0) ); //take a raw ADC reading
KF_ADC_b.setProcessNoise( (esp_timer_get_time() - TimePastKalman) / 1000000.0f ); //get time, in microsecods, since last readings
adcValue = KF_ADC_b.updateEstimate( adcValue ); // apply simple Kalman filter
Vbatt = adcValue * vRefScale;
xSemaphoreTake( sema_CalculatedVoltage, portMAX_DELAY );
CalculatedVoltage = Vbatt;
xSemaphoreGive( sema_CalculatedVoltage );
printCount++;
if ( printCount == 3 )
{
log_i( "Vbatt %f", Vbatt );
printCount = 0;
}
TimePastKalman = esp_timer_get_time(); // time of update complete
xLastWakeTime = xTaskGetTickCount();
vTaskDelayUntil( &xLastWakeTime, xFrequency );
//log_i( "fReadBattery %d", uxTaskGetStackHighWaterMark( NULL ) );
}
vTaskDelete( NULL );
}
////
void MQTTkeepalive( void *pvParameters )
{
sema_MQTT_KeepAlive = xSemaphoreCreateBinary();
xSemaphoreGive( sema_MQTT_KeepAlive ); // found keep alive can mess with a publish, stop keep alive during publish
// setting must be set before a mqtt connection is made
MQTTclient.setKeepAlive( 90 ); // setting keep alive to 90 seconds makes for a very reliable connection, must be set before the 1st connection is made.
for (;;)
{
//check for a is-connected and if the WiFi 'thinks' its connected, found checking on both is more realible than just a single check
if ( (wifiClient.connected()) && (WiFi.status() == WL_CONNECTED) )
{
xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY ); // whiles MQTTlient.loop() is running no other mqtt operations should be in process
MQTTclient.loop();
xSemaphoreGive( sema_MQTT_KeepAlive );
}
else {
log_i( "MQTT keep alive found MQTT status %s WiFi status %s", String(wifiClient.connected()), String(WiFi.status()) );
if ( !(wifiClient.connected()) || !(WiFi.status() == WL_CONNECTED) )
{
connectToWiFi();
}
connectToMQTT();
}
vTaskDelay( 250 ); //task runs approx every 250 mS
}
vTaskDelete ( NULL );
}
////
void connectToWiFi()
{
int TryCount = 0;
while ( WiFi.status() != WL_CONNECTED )
{
TryCount++;
WiFi.disconnect();
WiFi.begin( SSID, PASSWORD );
vTaskDelay( 4000 );
if ( TryCount == 10 )
{
ESP.restart();
}
}
WiFi.onEvent( WiFiEvent );
} // void connectToWiFi()
////
void connectToMQTT()
{
MQTTclient.setKeepAlive( 90 ); // needs be made before connecting
byte mac[5];
WiFi.macAddress(mac);
String clientID = String(mac[0]) + String(mac[4]) ; // use mac address to create clientID
while ( !MQTTclient.connected() )
{
// boolean connect(const char* id, const char* user, const char* pass, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage);
MQTTclient.connect( clientID.c_str(), mqtt_username, mqtt_password, NULL , 1, true, NULL );
vTaskDelay( 250 );
}
MQTTclient.setCallback( mqttCallback );
MQTTclient.subscribe( topicOK );
} // void connectToMQTT()
////
void loop() {}
Thanks for a great reply , much appreciated .
Would it be possible for you to send me some links to the products i need to do this project . or even a parts list i want the voltage reading sent to a voltage meter display.
Also because alternators charge 12volt batteries at voltage levels up to say 15.0 volts would your code still work for this.
thanks
Yes, I can do your research for you. My fee for doing your research is $250.00 an hour prepaid in non-refundable increments of 4 hours plus expenses. I, also require a $10,000.00USD non-refundable deposit of good faith.
To determine voltage divider resistance values use the following site:
Voltage Divider Calculator (ohmslawcalculator.com)
Use 10K for R2.
Would you like real dollars or disney land dollars
Disney Land dollars, please.
Thanks for you help anyway
Should be pretty easy to use an ESP32 to analogRead the battery and send the value/result with its Bluetooth, which could be read/seen with smartphone Bluetooth serial terminal app.
Thanks for your reply all i need to do now is learn to code it.
You can buy an ESP32 for under $10, not a huge investment, and, at least, determine basic feasibility:
Program it to send 'Hello World' on Bluetooth;
Place the ESP32 where the boat batteries are kept and then;
check your smartphone's reception of that up in the cabin.
At that point, if you're getting your 'Hello World' messages then you can go on with the rest of the project.