diff --git a/GpsTracker/Config.cpp b/GpsTracker/Config.cpp
index 99811e2..b73ce02 100644
--- a/GpsTracker/Config.cpp
+++ b/GpsTracker/Config.cpp
@@ -7,7 +7,7 @@
 namespace config {
 	namespace main {
 
-		Config value;
+		Config_t value;
 
 		namespace details {
 
@@ -17,7 +17,6 @@ namespace config {
 				hardware::i2c::eeprom.readBlock(CONFIG_ADDR, value);
 				if (!String(CONFIG_SEED).equals(value.seed)) reset();
 				hardware::i2c::powerOff();
-
 			}
 
 			void write() {
@@ -29,21 +28,21 @@ namespace config {
 			}
 		}
 
-		Config get() {
+		Config_t get() {
 			if (value.seed[0] == '\0') details::read();
 
 			VERBOSE_FORMAT("get", "%s, %s, %s, %d, %d", value.seed, value.version, value.apn, value.firstEntry, value.lastEntry);
 			return value;
 		}
 
-		void set(const Config config) {
+		void set(const Config_t config) {
 			value = config;
 			details::write();
 		}
 
 		void reset() {
 			VERBOSE("reset");
-			Config config = {
+			Config_t config = {
 				CONFIG_SEED,
 				VERSION,
 				"Vodafone", //TODO : read from SD
diff --git a/GpsTracker/Config.h b/GpsTracker/Config.h
index ef03867..c9f8786 100644
--- a/GpsTracker/Config.h
+++ b/GpsTracker/Config.h
@@ -7,7 +7,7 @@ struct sleepTimings_t {
 	uint16_t seconds;
 };
 
-struct Config {
+struct Config_t {
 	char seed[5];
 	char version[5];
 	char apn[20];
@@ -38,8 +38,8 @@ namespace config {
 	};
 
 	namespace main {	
-		Config get();
-		void set(const Config config);
+		Config_t get();
+		void set(const Config_t config);
 
 		void reset();
 	}
diff --git a/GpsTracker/Positions.cpp b/GpsTracker/Positions.cpp
index 606a4aa..85b2030 100644
--- a/GpsTracker/Positions.cpp
+++ b/GpsTracker/Positions.cpp
@@ -70,7 +70,7 @@ namespace positions {
 		strlcpy(entry.position, gps::lastPosition, POSITION_SIZE);
 
 		hardware::i2c::powerOn();
-		Config config = config::main::get();
+		Config_t config = config::main::get();
 
 		config.lastEntry++;
 		if (config.lastEntry > details::maxEntryIndex) config.lastEntry = 0;
@@ -109,6 +109,13 @@ namespace positions {
 		return true;
 	}
 
+	uint16_t count(uint16_t fromIndex) {
+		Config_t config = config::main::get();
+		if (config.lastEntry < config.firstEntry) { config.lastEntry += details::maxEntryIndex; }
+
+		return config.lastEntry - fromIndex;
+	}
+
 	void doBackup() {
 		for (int i = 0; i < _backupLength; i++) {
 			_backups[i]->backup();
diff --git a/GpsTracker/Positions.h b/GpsTracker/Positions.h
index e91fb87..5cd9c80 100644
--- a/GpsTracker/Positions.h
+++ b/GpsTracker/Positions.h
@@ -26,6 +26,7 @@ namespace positions {
 
 	bool get(uint16_t index, PositionEntry &entry);
 	bool moveNext(uint16_t &index);
+	uint16_t count(uint16_t fromIndex);
 
 	void doBackup();
 }
\ No newline at end of file
diff --git a/GpsTracker/SdPositionsBackup.cpp b/GpsTracker/SdPositionsBackup.cpp
index d470e12..1ede67d 100644
--- a/GpsTracker/SdPositionsBackup.cpp
+++ b/GpsTracker/SdPositionsBackup.cpp
@@ -1,21 +1,57 @@
 #include "SdPositionsBackup.h"
 #include "SdPositionsConfig.h"
 #include "SdCard.h"
-
+#include "Hardware.h"
 #include "Config.h"
+#include "SdFat.h"
+#include "Positions.h"
 
 namespace positions {
 	namespace backup {
 		namespace sd {
 
+			namespace details {
+
+				bool isBackupNeeded(SdPositionConfig_t &sdConfig) {
+					Config_t referenceConfig = config::main::get();
+					sdConfig = config::backup::sd::get();
+
+					return sdConfig.lastSavedEntry == 0xFFFF ||
+						positions::count(sdConfig.lastSavedEntry) > sdConfig.saveThreshold;
+				}
+
+				void appendPositions(const File &file, SdPositionConfig_t &sdConfig) {
+					uint16_t currentEntryIndex = sdConfig.lastSavedEntry + 1;
+					PositionEntry currentEntry;
+
+					hardware::i2c::powerOn();
+					do {
+						if (!positions::get(currentEntryIndex, currentEntry)) break;
+
+						sdConfig.filePosition = file.position();
+					} while (true);
+					hardware::i2c::powerOff();
+
+				}
+			}
+
 			void SdPositionsBackup::setup() {
 				config::backup::sd::setup();
-				_config = new RawSdFile(&hardware::sdcard::filesystem, POSITIONS_CONFIG_FILENAME);
 			}
 
 			void SdPositionsBackup::backup() {
-				Config referenceConfig = config::main::get();
+				SdPositionConfig_t sdConfig;
+
+				if (!details::isBackupNeeded(sdConfig)) return;
+
+				char *filename;
+				hardware::sdcard::filesystem.chdir("positions");
+				File file = hardware::sdcard::filesystem.open(filename, O_RDWR | O_CREAT);
+
+				file.seek(sdConfig.filePosition);
+				file.find('\n');
 
+				details::appendPositions(file, sdConfig);
 			}
 
 		}
diff --git a/GpsTracker/SdPositionsBackup.h b/GpsTracker/SdPositionsBackup.h
index 9e4d8f0..de5f5ac 100644
--- a/GpsTracker/SdPositionsBackup.h
+++ b/GpsTracker/SdPositionsBackup.h
@@ -3,8 +3,6 @@
 #include "PositionsBackup.h"
 #include "RawSdFile.h"
 
-#define POSITIONS_CONFIG_FILENAME "positions.config"
-
 using namespace sd;
 
 namespace positions {
@@ -13,7 +11,6 @@ namespace positions {
 
 			class SdPositionsBackup : public PositionsBackup {
 			private:
-				RawSdFile * _config;
 			public:
 				void setup();
 				void backup();
diff --git a/GpsTracker/SdPositionsConfig.cpp b/GpsTracker/SdPositionsConfig.cpp
index 3ab0add..de40a10 100644
--- a/GpsTracker/SdPositionsConfig.cpp
+++ b/GpsTracker/SdPositionsConfig.cpp
@@ -1,11 +1,71 @@
 #include "SdPositionsConfig.h"
+#include "SdCard.h"
+#include "RawSdFile.h"
+#include "Debug.h"
+
+using namespace sd;
+
+#define LOGGER_NAME "Config::backup::sd"
 
 namespace config {
 	namespace backup {
 		namespace sd {
 
-				void setup() {
+				SdPositionConfig_t value;
+				File configFile;
+
+				namespace details {
+
+					void ensureOpened() {
+						if (!configFile.isOpen()) {
+							hardware::sdcard::filesystem.chdir();
+							configFile.open(POSITIONS_CONFIG_FILENAME, O_RDWR | O_CREAT);
+						}
+
+						configFile.rewind();
+					}
+
+					void read() {
+						VERBOSE("read");
+						ensureOpened();
+						configFile.read((void*)&value, sizeof(value));
+						if (value.seed != POSITIONS_CONFIG_SEED) reset();
+					}
+
+					void write() {
+						VERBOSE("write");
+						ensureOpened();
+						configFile.write((void*)&value, sizeof(value));
+					}
+
+				}
+
+				void setup() { }
+
+				SdPositionConfig_t get() {
+					if (value.seed != POSITIONS_CONFIG_SEED) details::read();
+
+					return value;
+				}
+
+				void set(SdPositionConfig_t config) {
+					value = config;
+					details::write();
+				}
+
+				void reset() {
+					VERBOSE("reset");
+					SdPositionConfig_t config = {
+						POSITIONS_CONFIG_SEED,
+						POSITIONS_CONFIG_DeFAULT_SAVE_THRESHOLD,
+						0xFFFF,
+						0,
+						0,
+						0
+					};
 
+					value = config;
+					details::write();
 				}
 
 		}
diff --git a/GpsTracker/SdPositionsConfig.h b/GpsTracker/SdPositionsConfig.h
index 9922cd8..04b78d2 100644
--- a/GpsTracker/SdPositionsConfig.h
+++ b/GpsTracker/SdPositionsConfig.h
@@ -2,10 +2,17 @@
 
 #include <Arduino.h>
 
+#define POSITIONS_CONFIG_FILENAME "positions.config"
+#define POSITIONS_CONFIG_SEED 45
+#define POSITIONS_CONFIG_DeFAULT_SAVE_THRESHOLD 10
+
 struct SdPositionConfig_t {
+	uint8_t seed;
+	uint8_t saveThreshold;
+	uint16_t lastSavedEntry;
 	uint16_t fileIndex;
-	uint32_t position;
-	size_t size;
+	uint32_t filePosition;
+	size_t fileRecords;
 };
 
 namespace config {