[Nexus 5X Themes and Apps] Tulsadiver:
For the QS backgrounds, check to see if you have a xml called qs_background_primary in your Systemui.xml drawable folder. That will change your QS background without anything else being affected.

The battery I changed via the array.xml in the Systemui.apk res/values folder. The original code looked like this:

<string-array name="battery_labels">
<item>0%</item>
<item>50%</item>
<item>100%</item>
</string-array>
<integer-array name="batterymeter_color_levels">
<item>15</item>
<item>100</item>
</integer-array>
<array name="batterymeter_color_values">
<item>@android:color/battery_saver_mode_color</item>
<item>#ffffffff</item>
</array>

I changed that to this:

<string-array name="battery_labels">
<item>0%</item>
<item>50%</item>
<item>100%</item>
</string-array>
<integer-array name="batterymeter_color_levels">
<item>1</item>
<item>2</item>
<item>3</item>
<item>4</item>
<item>5</item>
<item>6</item>
<item>7</item>
<item>8</item>
<item>9</item>
<item>10</item>
<item>11</item>
<item>12</item>
<item>13</item>
<item>14</item>
<item>15</item>
<item>16</item>
<item>17</item>
<item>18</item>
<item>19</item>
<item>20</item>
<item>21</item>
<item>22</item>
<item>23</item>
<item>24</item>
<item>25</item>
<item>26</item>
<item>27</item>
<item>28</item>
<item>29</item>
<item>30</item>
<item>31</item>
<item>32</item>
<item>33</item>
<item>34</item>
<item>35</item>
<item>36</item>
<item>37</item>
<item>38</item>
<item>39</item>
<item>40</item>
<item>41</item>
<item>42</item>
<item>43</item>
<item>44</item>
<item>45</item>
<item>46</item>
<item>47</item>
<item>48</item>
<item>49</item>
<item>50</item>
<item>51</item>
<item>52</item>
<item>53</item>
<item>54</item>
<item>55</item>
<item>56</item>
<item>57</item>
<item>58</item>
<item>59</item>
<item>60</item>
<item>61</item>
<item>62</item>
<item>63</item>
<item>64</item>
<item>65</item>
<item>66</item>
<item>67</item>
<item>68</item>
<item>69</item>
<item>70</item>
<item>71</item>
<item>72</item>
<item>73</item>
<item>74</item>
<item>75</item>
<item>76</item>
<item>77</item>
<item>78</item>
<item>79</item>
<item>80</item>
<item>81</item>
<item>82</item>
<item>83</item>
<item>84</item>
<item>85</item>
<item>86</item>
<item>87</item>
<item>88</item>
<item>89</item>
<item>90</item>
<item>91</item>
<item>92</item>
<item>93</item>
<item>94</item>
<item>95</item>
<item>96</item>
<item>97</item>
<item>98</item>
<item>99</item>
<item>100</item>
</integer-array>
<array name="batterymeter_color_values">
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@android:color/battery_saver_mode_color</item>
<item>@color/mybat1</item>
<item>@color/mybat2</item>
<item>@color/mybat3</item>
<item>@color/mybat4</item>
<item>@color/mybat5</item>
<item>@color/mybat6</item>
<item>@color/mybat7</item>
<item>@color/mybat8</item>
<item>@color/mybat9</item>
<item>@color/mybat10</item>
<item>@color/mybat11</item>
<item>@color/mybat12</item>
<item>@color/mybat13</item>
<item>@color/mybat14</item>
<item>@color/mybat15</item>
<item>@color/mybat16</item>
<item>@color/mybat17</item>
<item>@color/mybat18</item>
<item>@color/mybat19</item>
<item>@color/mybat20</item>
<item>@color/mybat1</item>
<item>@color/mybat2</item>
<item>@color/mybat3</item>
<item>@color/mybat4</item>
<item>@color/mybat5</item>
<item>@color/mybat6</item>
<item>@color/mybat7</item>
<item>@color/mybat8</item>
<item>@color/mybat9</item>
<item>@color/mybat10</item>
<item>@color/mybat11</item>
<item>@color/mybat12</item>
<item>@color/mybat13</item>
<item>@color/mybat14</item>
<item>@color/mybat15</item>
<item>@color/mybat16</item>
<item>@color/mybat17</item>
<item>@color/mybat18</item>
<item>@color/mybat19</item>
<item>@color/mybat20</item>
<item>@color/mybat1</item>
<item>@color/mybat2</item>
<item>@color/mybat3</item>
<item>@color/mybat4</item>
<item>@color/mybat5</item>
<item>@color/mybat6</item>
<item>@color/mybat7</item>
<item>@color/mybat8</item>
<item>@color/mybat9</item>
<item>@color/mybat10</item>
<item>@color/mybat11</item>
<item>@color/mybat12</item>
<item>@color/mybat13</item>
<item>@color/mybat14</item>
<item>@color/mybat15</item>
<item>@color/mybat16</item>
<item>@color/mybat17</item>
<item>@color/mybat18</item>
<item>@color/mybat19</item>
<item>@color/mybat20</item>
<item>@color/mybat1</item>
<item>@color/mybat2</item>
<item>@color/mybat3</item>
<item>@color/mybat4</item>
<item>@color/mybat5</item>
<item>@color/mybat6</item>
<item>@color/mybat7</item>
<item>@color/mybat8</item>
<item>@color/mybat9</item>
<item>@color/mybat10</item>
<item>@color/mybat11</item>
<item>@color/mybat12</item>
<item>@color/mybat13</item>
<item>@color/mybat14</item>
<item>@color/mybat15</item>
<item>@color/mybat16</item>
<item>@color/mybat17</item>
<item>@color/mybat18</item>
<item>@color/mybat19</item>
<item>@color/mybat20</item>
<item>@color/mybat1</item>
<item>@color/mybat2</item>
<item>@color/mybat3</item>
<item>@color/mybat4</item>
<item>@color/mybat5</item>
</array>

Those mybat* files are custom colors that I added to my colors.xml which is in that same values folder. Here are the hex code colors I used:

<color name="mycolor">#ffffffff</color>
<color name="mybg">#40ffffff</color>
<color name="mydim">#90ffffff</color>
<color name="mywhite">#ff000080</color>
<color name="mygone">#00000000</color>
<color name="mynote">#ffee0000</color>
<color name="mystroke">#ff000000</color>
<color name="mybat1">#ffffff00</color>
<color name="mybat2">#ffff0000</color>
<color name="mybat3">#ff0000ff</color>
<color name="mybat4">#ff00ffff</color>
<color name="mybat5">#ffb23aee</color>
<color name="mybat6">#ffffc125</color>
<color name="mybat7">#ff636363</color>
<color name="mybat8">#ff00ccff</color>
<color name="mybat9">#ff00cd00</color>
<color name="mybat10">#ffff6eb4</color>
<color name="mybat11">#ff20b2aa</color>
<color name="mybat12">#ffffffe0</color>
<color name="mybat13">#ffc71585</color>
<color name="mybat14">#ffffa500</color>
<color name="mybat15">#ffff4500</color>
<color name="mybat16">#ffee7ae9</color>
<color name="mybat17">#ff98fb98</color>
<color name="mybat18">#ffaeeeee</color>
<color name="mybat19">#ffa020ff</color>
<color name="mybat20">#ff4876ff</color>