From 9914a005118001fb813281cdc21b06d6141b8272 Mon Sep 17 00:00:00 2001
From: Jens Ahrensfeld <jens@jayfield.org>
Date: Sun, 9 Mar 2025 19:13:49 +0100
Subject: [PATCH] add innenwiderstand.py

---
 innenwiderstand.py | 66 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/innenwiderstand.py b/innenwiderstand.py
index e69de29..51c890e 100644
--- a/innenwiderstand.py
+++ b/innenwiderstand.py
@@ -0,0 +1,66 @@
+from matplotlib import pyplot as plot
+import numpy as np
+
+class Params:
+	def __init__(self, alpha, beta):
+		self.alpha = alpha
+		self.beta = beta
+
+
+def bas(soc: float):
+	return 0.05, 25
+
+def model_r(temperature: float, soc: float, p: Params):
+	rb, tb = bas(soc)
+	tb = 25
+	tb2 = tb*tb
+
+	_t = temperature
+	t2 = temperature*temperature
+	return rb * np.exp(p.alpha*(t2 - tb2) + p.beta*(_t - tb))
+
+
+temps = [0, 5, 10, 20, 25, 40]
+pl = 10000
+il = 100
+ul = 100
+rl = ul/il
+p_ = np.linspace(0, 20000, 100)
+i_ = p_/ul
+
+bat_params = Params(alpha=0.0007545, beta=-0.07033)
+rt_ = []
+for t in temps:
+	rt_.append(model_r(t, 100, bat_params))
+
+plot.figure()
+plot.plot(temps, rt_)
+r, t = bas(100)
+plot.title(f"Ri vs temperature (Base R={r}@{t}°C)")
+plot.xlabel("Temperature [°C]")
+plot.ylabel("R [Ohm]")
+plot.grid()
+
+titles = [
+	"Battery power loss vs internal battery resistance (DCR)",
+	"Batter power consumption vs internal battery resistance (DCR)"
+]
+for sp, name, title in zip([0, 1], ["P_loss [kW]", "P_batt [kW]"], titles):
+	plot.figure()
+	legs = []
+	plot.grid()
+	for temp in temps:
+		ri = model_r(temp, 100, bat_params)
+		pi_ = (ri * i_ * i_) + sp*p_
+		x = p_/1000
+		y = pi_/1000
+		legs.append(f"temp={temp} °C")
+		plot.plot(x, y)
+		plot.xlabel("P_demand [kW]")
+
+	plot.title(title)
+	plot.legend(legs)
+	plot.ylabel(name)
+
+
+plot.show()