diff --git a/PowerEstimations.xlsx b/PowerEstimations.xlsx
index 4377ae8..99439ea 100644
Binary files a/PowerEstimations.xlsx and b/PowerEstimations.xlsx differ
diff --git a/README.md b/README.md
index 2fdb61f..b29f5ea 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,5 @@ MDDP - Subsea Cable Maintenance Ship
 ==========================
 
 Materials associated with post-grad MDDP (Multi-disciplinary design project). Designing a new ship capable of maintaining subsea fibre-optic cables.
+
+![Network layout](network/NetworkDiagram.png)
diff --git a/maths/battery.m b/maths/battery.m
new file mode 100644
index 0000000..880dfb0
--- /dev/null
+++ b/maths/battery.m
@@ -0,0 +1,126 @@
+%% battery.m
+%%
+%% Battery maths
+
+close all;clear all;clc;
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%              Flags
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+INTEGER_CELLS       = true;
+P_OUT_INCLUDES_P_IN = true; % subtract power in from power out
+% assumes that battery and generation coupled for connection to P out
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%           Parameters
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%% 18650 Cell
+cell_voltage    = 3.6;  % V
+cell_capacity   = 2850; % mAh
+cell_dis_c      = 1;    % 1/h
+cell_charge_c   = 0.5;  % 1/h
+
+cell_weight     = 48;   % g
+cell_dia        = 18.4; % mm
+cell_height     = 65;   % mm
+
+cell_price      = 6;    % £
+
+
+%%%%%%% P IN
+%V_IN            = 450;  % V
+%I_IN            = 10;   % A
+% above ignored if P_IN defined
+MAX_P_IN        = 8e6;  % W, max power from fuel cells
+P_IN_LOAD       = 0.8;  % most efficient load percent
+P_IN            = MAX_P_IN * P_IN_LOAD; % W
+
+
+%%%%%%% P OUT
+V_OUT           = 450;  % V
+I_OUT           = 10;   % A
+% above ignored if P_OUT defined
+PROP_P_OUT      = 8e6;  % W, propulsion max output power
+HOTEL_P_OUT     = 3e4;  % W, hotel average power usage
+P_OUT           = PROP_P_OUT + HOTEL_P_OUT; % W
+
+
+%%%%%%% unit conversions
+cell_capacity   = 1e-3 * cell_capacity; % mAh to Ah
+cell_dia        = 1e-3 * cell_dia;      % mm to m
+cell_height     = 1e-3 * cell_height;   % mm to m
+cell_weight     = 1e-3 * cell_weight;   % g to kg
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%          Series/Parallel
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+if exist('P_OUT') % SOLVE FOR CELLS USING POWER
+    
+    if P_OUT_INCLUDES_P_IN
+        solvable_power = P_OUT - P_IN;
+    else
+        solvable_power = P_OUT;
+    end
+    
+    total_cells = solvable_power / (cell_voltage * cell_dis_c * cell_capacity);
+    
+    series_length   = sqrt(total_cells);
+    parallel_length = series_length;
+    
+    if INTEGER_CELLS
+        series_length   = ceil(series_length);
+        parallel_length = ceil(parallel_length);
+        total_cells     = series_length * parallel_length;
+    end
+    
+    voltage_out = series_length * cell_voltage;
+    current_out = parallel_length * cell_dis_c * cell_capacity;
+    
+else % SOLVE FOR CELLS USING VOLTAGE AND CURRENT
+    series_length = V_OUT / cell_voltage;
+
+    % c-rate = current / capacity
+    required_capacity = I_OUT / cell_dis_c;
+    parallel_length   = required_capacity / cell_capacity;
+
+    if INTEGER_CELLS
+        series_length   = ceil(series_length);
+        parallel_length = ceil(parallel_length);
+    end
+
+    total_cells = series_length * parallel_length;
+    
+    voltage_out = V_OUT;
+    current_out = I_OUT;
+
+end
+
+max_power_out = voltage_out * current_out; % W
+total_capacity = parallel_length * cell_capacity; % Ah
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%          Physical Space
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+cell_volume  = (pi * (cell_dia/2)^2) * cell_height; % m^3
+
+total_volume = cell_volume * total_cells; % m^3
+total_weight = cell_weight * total_cells; % kg
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%             Output
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+printf('%d cells arranged %d x %d cells\n', total_cells, series_length, parallel_length);
+printf('%.2f m3, weighs %.2f kg\n', total_volume, total_weight);
+printf('£%.2fM\n\n', total_cells * cell_price / 1e6);
+
+printf('%.2f Ah\n', total_capacity);
+printf('%.2f V, %.2f A for %.2f MW\n', voltage_out, current_out, max_power_out / 1e6);
+if P_OUT_INCLUDES_P_IN
+    printf('Totals to %.2f MW including %.2f MW of coupled input power\n', P_OUT / 1e6, P_IN / 1e6);
+end