我宿舍每天晚上会准时停电几个小时，然后早上再自动恢复供电。于是我想做一个提供无线网络信号的设备。并且我希望它会
自动充电断电，能保证我每次使用它都是可运行的状态。
那如何实现这个状态呢？
制作思路我准备拿常用的分立元件，构建一个带有自动充电、恒流充电、充满自停、欠压保护断开输出的UPS功能模块。
它的电路工作流程应该是：
1.DC停止供电的时候，切换继电器复位，变为电池供电模式。2.当DC恢复输入的时候，通过继电器从电池供电切换为DC供电。3.电路触发一个强制充电信号，电池开始充电。4.充电过程持续几个小时，当检测充电电流少于设定值时关断，真●充满自停。5.充满电的电池休息中，等待停电熬夜工作。6.以上五个过程周而复始。构思好，就开始画电路
电路原理说明如下[size=; font-size: 1.059em,1.059em]①电池供电模式（红色路线）
电池经过「欠压保护电路」流进「切换继电器」（原理图K4）。DC断电时触点自动复位，经由常闭端输出，或通过电压变换电路实现不同电压输出。
这部分因需而异无法统一，请自行添加。
[size=; font-size: 1.059em,1.059em]②DC供电模式（蓝色路线）电路说明
1.欠压保护当恢复DC供电时，启动切换继电器K4，断开电池供电，切换为DC供电。
为了延长电池使用寿命，充电不搞硬充（可以是一直充，在线充，浮充等）。
为了实现目的，复杂化了NE555电池保护电路（就是加了两个辅助部分）。
下面是由NE555构成的电池保护电路，简单介绍它的保护原理。
IC的2脚和6脚通过检测电压，执行保护和终止保护两个动作。
当2脚检测电压低于
2.55V时（5脚基准电压5.1V的一半，没基准是取三分之一VCC），3脚输出高电平启动继电器K1和K2。
K1负责断开输出，K2负责接通充电。
当6脚检测电压高于
5.1V时（没基准取三分之二VCC），3脚输出低电平，断开继电器。
假设电池续航不够到第二天，因为欠压保护会启动K1和K2，当DC恢复时，会自动执行充电。
但如果电池像喝了功能饮料一样能量十足，没有欠压自然就不会启动充电继电器，那样就算DC恢复也不会执行充电。
怎么办？
如果没有，那就让它自己制造一个充电信号！
2.触发充电（可选装部分）上面讲到NE555的2脚低于2.55V时3脚会输出高电平启动继电器。
简单的做法是断开检测电压，直接把2脚的电位
拉到0伏，符合触发条件。
下面是制造充电信号的电路。
刚上电的时候.
A点电压为二极管的压降值，大约0.6~0.7V。
B点因为电容刚开始充电接近0V，比较器同相比反相
电压高，输出高电平，所以继电器会启动。
因为这个继电器K3的常闭端与NE555的2脚的电压检测端串联，所以启动后会断开2脚的检测电压，从而使继电器K2启动执行充电。
当电容充电几秒后，B点电压高于A点，比较器输出低电平，继电器复位。
整过程的概括，就好比你按下开关几秒后松开。
继电器K3与NE555的2脚
通过排针+跳线帽（垂直方向）来连接，
原理图为了功能划分，H1和H2是呆在各自的部分，画PCB的时候要放置在一起。
PS:如果你是省材料执着户，此部分电路完全可以省略，排针H2改为连接一个复位开关（常闭型）。需要充电的时候自己手动按一下就行了。
3.恒流充电欠压保护电路接到一个伪欠压信号后启动继电器K2。
VCC兵分两路，其中一路负责充电。
充电电路由LM317构成，通过R17实现恒流控制，规格书上面有原理说明。
别的不说，只需要理解一个关键点，
恒流电流=1.25V / R17。需要多大的电流请代入计算，但电流再往上加，单靠散热片是行不通的啦。一般用2R或者2.2R的水泥电阻。
输出后加二极管或肖特基防倒灌，小电流可以考虑1N4007。
4.过充检测，充满自停原理大多数的NE555的防过充保护模块，6脚是连接电瓶，通过检测充电电压来截止。
12V电瓶的常规充电电压为
14.4V，实际上充电器从「恒流充电」转到「恒压充电」的时候（14.4V），充电电压已经满足了截止条件，模块产生动作结束充电过程，可能只充到80%的电量就结束了。
假设现在变换思路，不要检测充电电压，改为检测充电电流，少于设定电流值时才向6脚反馈高电平，截止充电。
K2启动后，VCC第二路负责检测充电电流用于反馈截止信号。
D8两端的电压约为
0.6~0.7V，再经R11和R13进一步分压（1：10+1分压），比较器2脚的电压约为0.06V。
U5是连接电瓶，负极回流先经过R15进行电流采样，再回到GND，两端产生的压降与2脚进行比较。
当充电电流少于
0.3A的时候(0.3A*0.2R=0.06V)，比较器U2.1同相比反相电压低，输出低电平0V。
比较器U2.2同相比反相电压高（0.06V>0V），输出高电平反馈到NE555的6脚，结束充电过程。
加电容是延长电压上升时间，防止刚上电就产生动作。
470uF充电到5.1V用时约三秒，数据仅作参考。
目标电流*R15 < R11与R13的分压点电压，就会停止充电，这都是可以自行更改的。
元件装配与实物调试（有顺序要求）①一定要先设置充电电压充电部分优先装上（或者全部提前装上也行），
但一定不能安装防倒灌二极管（要最后装）。
接上16V以上电压，扭动电位器R18设置空载输出电压约为14.4V。
②欠压保护部分再来装NE555欠压保护部分，先用跳线帽把靠近电位器的那个排针H2接上。
电池对应的输出端子接上可调电源，调整电压为欠压保护启动值11.5V。
然后扭动2脚对应的电位器，使IC的2脚电压在
2.55V左右，这样电池电压降至11.5V就会有保护动作。
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[backcolor=url("][backcolor=url("]
然后把电压调高一点，输入正极给电位器R9中间焊盘点一下就结束保护。
再次把电压降至
11.5V时，如果做出保护动作就证明设置成功，可以把剩下的元件都安装上去。
顺带一提，电位器R9本例可直接替换成一个
20K电阻。
在不需检测电流停止充电时，就要装上，连接排针那一端需要改为连接电池正极。
调整输入电压为14.4V，扭动电位器R9。
使IC的6脚电压为5.1V，这样当充电电压达到14.4V时停止充电。
最后把排针的方向改成这样，就可以进行测试了。
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<xg-icon class="xgplayer-time" data-index="2" style="box-sizing: border-box; margin: 0px 0px 0px 20px; padding: 0px; border: 0px; vertical-align: baseline; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: 0px; line-height: 40px; font-family: PingFangSC-Semibold; position: relative; height: 40px; cursor: pointer; color: rgb(255, 255, 255); fill: rgb(255, 255, 255); min-width: 40px; text-align: center; display: inline-block;">
00:04 / 00:30<xg-center-grid class="xg-center-grid" style="box-sizing: border-box; margin: 0px; padding: 5px 0px; border: 0px; vertical-align: baseline; font: inherit; display: block; position: absolute; left: 0px; right: 0px; outline: none; top: -17px; text-align: center;"><xg-progress class="xgplayer-progress" data-xg-target-type="progress" role="slider" tabindex="0" aria-label="播放进度条" aria-valuemin="0" aria-valuemax="30" data-index="0" max="30" aria-valuenow="4" aria-valuetext="13%" value="4" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; display: flex; align-items: center; position: relative; min-width: 100px; height: 20px; left: 0px; right: 0px; top: 0px; outline: none; flex: 1 1 0%; cursor: pointer;"><xg-outer class="xgplayer-progress-outer" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; position: relative; width: 644.003px; height: 3px; border-radius: 0px; cursor: pointer; transition: height 0.15s ease 0s !important;"><xg-inners class="progress-list" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; display: flex; height: 2.99107px; width: 644.003px; border-radius: inherit;"><xg-inner class=" xgplayer-progress-inner" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; position: relative; flex: 1 1 0%; height: 2.99107px; background: rgba(255, 255, 255, 0.24); transition: height 0.2s ease-in 0s, opacity 0.2s ease-out 0s; border-radius: inherit; pointer-events: none;"><xg-cache class="xgplayer-progress-cache" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; display: block; height: 2.99107px; width: 644.003px; position: absolute; top: 0px; left: 0px; border-radius: inherit; background: rgba(255, 255, 255, 0.3);"><xg-played class="xgplayer-progress-played" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; display: block; height: 2.99107px; width: 77.0536px; position: absolute; top: 0px; left: 0px; border-radius: inherit; background: rgb(255, 255, 255);"><xg-progress-btn class="xgplayer-progress-btn" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0.5px solid rgba(255, 94, 94, 0.055); vertical-align: baseline; font: inherit; background: none; box-shadow: none; width: 20px; height: 20px; border-radius: 30px; left: 77.0685px; position: absolute; z-index: 1; pointer-events: none; display: block; top: 1.4881px; transform: translate(-50%, -50%) scale(0); transition: transform 0.15s ease 0s, -webkit-transform 0.15s ease 0s, -moz-transform 0.15s ease 0s;"><xg-right-grid class="xg-right-grid" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; position: relative; display: flex; flex-flow: row-reverse wrap; flex-shrink: 1; height: 55.997px; z-index: 1; align-items: center;"><xg-icon class="xgplayer-fullscreen" aria-label="进入全屏" tabindex="0" role="button" data-index="0" style="box-sizing: border-box; margin: 0px 12px 0px 28px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; position: relative; height: 40px; cursor: pointer; color: rgba(255, 255, 255, 0.8); fill: rgb(255, 255, 255); opacity: 0.9;">
<xg-icon class="xgplayer-volume" data-state="normal" aria-label="静音" tabindex="0" role="button" data-index="1" style="box-sizing: border-box; margin: 0px 0px 0px 28px; padding: 0px; border: 0px; vertical-align: baseline; font: inherit; position: relative; height: 40px; cursor: pointer; color: rgba(255, 255, 255, 0.8); fill: rgb(255, 255, 255); opacity: 0.9;">
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