Solar charging for lithium battery
"I blinded him from what was" (c) Tanich M.
My good old friend is a water tourist. Once upon a time, back in the last century, as my son says, I gave a friend a solar battery to charge the camcorder batteries.
Then I bought five domestic-made solar cells in Chip and Dip, connected them in series, added a KD213 diode. It turned out the battery with a voltage of about 9 volts and a current of about 300 mA. Mechanically, the elements of the battery were connected by strips of blue electrical tape, the battery was made up of an accordion, my friend made a homemade case for it. About 15 years have passed since then, this battery has been on campaigns many times and with constant success has been charging various Ni-Cd batteries.
')
Now it is fashionable to use lithium power sources for both photo-video devices and LED lamps. Everything is cool, but lithium cells require careful handling - they must be carefully charged to a voltage of 4.2 volts, discharged to a certain voltage, otherwise you may irreversibly damage the battery or cause a fire.
On a trip, my friend takes a headlamp on 18650 batteries. There is no charging mechanism in such a lantern, so he asked me to figure out how to charge these elements in field conditions. Along the way, there is the task of recharging smartphone phones and other gadgets.
I studied the offers on Ebay.com, found a curious device - a battery with a capacity of 10,000 mache, in one case with a solar battery and electronics that controls the charge-discharge of the battery and provides 5 volts at two USB connectors at currents up to 2A. The price of 1000 r seemed adequate, the device was ordered. Instrument Name: Solar Panel Samsung Iphone5s HTC 10000mAh
I also found charging for the 18650, consisting of a great chassis holder and a charging controller built into the USB connector. It cost about 80 p. This item is called New USB 18650 Battery Function Charger.
The initial idea was that on a sunny day, the Power bank charged the internal battery, and then gave energy to 18,650 through charging.
Pretty soon both devices came from China and I began to study them. Charging for the 18650 did not bring any surprises - an excellent case, charges 18650 with a capacity of 2400 mAh from the USB port with a current of about 300 mA.
But PowerBank ended up with a marriage. I measured its capacity by the method of full discharge by a direct current of about 300 mA - it turned out 1200 mAh. When declared 10,000 mAh - cheating.
However, the case was made very soundly! Metal covers, everything is adjusted, in hands it is felt as a single whole. I decided to make out and see what's inside.
The inside turned out to be quite high-quality electronics - a lithium cell charging controller board combined with a 5 volt 2 A converter-stabilizer failed to establish all types of chips, but the impression was that the board was made for a multi-cell lithium battery with individual charge-discharge control for each cell. However, all this wealth remains unused, lithium cells are simply connected in parallel. By the way, the soldering of this battery fell apart literally from being touched by a soldering iron ... Then I saw the elements separately - IMHO is a frank marriage ...
A 5 volt converter is made on a modern microcircuit operating at a frequency of 500 kHz.
Along the way, I measured the maximum surrendered current - it turned out 1.6A. When declared 2A - is quite adequate.
The photo shows the discharge circuit. 33 ohm alternating wire resistor, two parallel-connected 2 ohm resistors (1 ohm total) to control the discharge current.
Since there is a 5 V stabilizer in PowerBank, it is enough to set the consumed current at the beginning of the experiment once.
The board also has an LED indicator for the battery charge level, which operates in both discharging mode and charging mode. As usual - bright blue "tear out the eyes" color.
In general, everything is good, except for the battery.
I signed with the seller, demanded to return part of the money for the defective battery. The seller tried to embarrass me with the allegedly incorrect method of measuring the capacity - they say I did not take into account the loss, but after my second letter, where I laid it all down, I returned some of the money.
Since I disassembled the PowerBank - I decided to try how it will work with the 18650 and the old solar battery. The results of the field experiment turned out to be quite encouraging: the controller worked perfectly perfectly with 18650, and the solar battery 15 years ago provided a charging current of about 370 mA. The measurement was carried out in Moscow on March 10th. I believe that the summer sun will give even greater charge current.
Measurement of charge-discharge current was carried out by installing a resistor of 0.1 ohm in series in the battery circuit. In my case, the 0.1 ohm resistor consisted of two 0.2 ohms connected in parallel. A multimeter measured the voltage drop across this resistor. The current was converted from millivolts to milliamperes by multiplying by 10.
I measured the current given by the native solar cell - it turned out to be significantly lower, however, quite expectedly - the surface area is much smaller.
Thus, the optimal design began to look like a holder for the 18650, a cut-off case with a board and a separately connected solar battery. On the 18650 holder there is a pin connector, I cut off the mating part from the USB connector and soldered it to the solar battery. From the holder 18650 leaves 4 wires - two from the actual battery and two from the solar cell. The tape at this time used in black, blue served for 20 years and is in excellent condition, let's see how black behaves.
A pair of watches with a dremel, a drill, and a pair of scissors gave me this design:
Fully assembled:
It turned out a system that can charge 18650 from a source of 5 volts (USB) and a solar battery, can give a stable 5 volts to charge various gadgets, the benefit of the PowerBank included several adapters. There was a glitch - if the device is long without a battery - it does not turn on from the button. It turned out that the glitch costs, if one or two times, remove and insert the battery.
Now this device will be tested in the next campaign in the Eastern or Western Sayan mountains or else in some exotic place of Russia.
My good old friend is a water tourist. Once upon a time, back in the last century, as my son says, I gave a friend a solar battery to charge the camcorder batteries.
Then I bought five domestic-made solar cells in Chip and Dip, connected them in series, added a KD213 diode. It turned out the battery with a voltage of about 9 volts and a current of about 300 mA. Mechanically, the elements of the battery were connected by strips of blue electrical tape, the battery was made up of an accordion, my friend made a homemade case for it. About 15 years have passed since then, this battery has been on campaigns many times and with constant success has been charging various Ni-Cd batteries.
')
Now it is fashionable to use lithium power sources for both photo-video devices and LED lamps. Everything is cool, but lithium cells require careful handling - they must be carefully charged to a voltage of 4.2 volts, discharged to a certain voltage, otherwise you may irreversibly damage the battery or cause a fire.
On a trip, my friend takes a headlamp on 18650 batteries. There is no charging mechanism in such a lantern, so he asked me to figure out how to charge these elements in field conditions. Along the way, there is the task of recharging smartphone phones and other gadgets.
I studied the offers on Ebay.com, found a curious device - a battery with a capacity of 10,000 mache, in one case with a solar battery and electronics that controls the charge-discharge of the battery and provides 5 volts at two USB connectors at currents up to 2A. The price of 1000 r seemed adequate, the device was ordered. Instrument Name: Solar Panel Samsung Iphone5s HTC 10000mAh
I also found charging for the 18650, consisting of a great chassis holder and a charging controller built into the USB connector. It cost about 80 p. This item is called New USB 18650 Battery Function Charger.
The initial idea was that on a sunny day, the Power bank charged the internal battery, and then gave energy to 18,650 through charging.
Pretty soon both devices came from China and I began to study them. Charging for the 18650 did not bring any surprises - an excellent case, charges 18650 with a capacity of 2400 mAh from the USB port with a current of about 300 mA.
But PowerBank ended up with a marriage. I measured its capacity by the method of full discharge by a direct current of about 300 mA - it turned out 1200 mAh. When declared 10,000 mAh - cheating.
However, the case was made very soundly! Metal covers, everything is adjusted, in hands it is felt as a single whole. I decided to make out and see what's inside.
The inside turned out to be quite high-quality electronics - a lithium cell charging controller board combined with a 5 volt 2 A converter-stabilizer failed to establish all types of chips, but the impression was that the board was made for a multi-cell lithium battery with individual charge-discharge control for each cell. However, all this wealth remains unused, lithium cells are simply connected in parallel. By the way, the soldering of this battery fell apart literally from being touched by a soldering iron ... Then I saw the elements separately - IMHO is a frank marriage ...
A 5 volt converter is made on a modern microcircuit operating at a frequency of 500 kHz.
Along the way, I measured the maximum surrendered current - it turned out 1.6A. When declared 2A - is quite adequate.
The photo shows the discharge circuit. 33 ohm alternating wire resistor, two parallel-connected 2 ohm resistors (1 ohm total) to control the discharge current.
Since there is a 5 V stabilizer in PowerBank, it is enough to set the consumed current at the beginning of the experiment once.
The board also has an LED indicator for the battery charge level, which operates in both discharging mode and charging mode. As usual - bright blue "tear out the eyes" color.
In general, everything is good, except for the battery.
I signed with the seller, demanded to return part of the money for the defective battery. The seller tried to embarrass me with the allegedly incorrect method of measuring the capacity - they say I did not take into account the loss, but after my second letter, where I laid it all down, I returned some of the money.
Since I disassembled the PowerBank - I decided to try how it will work with the 18650 and the old solar battery. The results of the field experiment turned out to be quite encouraging: the controller worked perfectly perfectly with 18650, and the solar battery 15 years ago provided a charging current of about 370 mA. The measurement was carried out in Moscow on March 10th. I believe that the summer sun will give even greater charge current.
Measurement of charge-discharge current was carried out by installing a resistor of 0.1 ohm in series in the battery circuit. In my case, the 0.1 ohm resistor consisted of two 0.2 ohms connected in parallel. A multimeter measured the voltage drop across this resistor. The current was converted from millivolts to milliamperes by multiplying by 10.
I measured the current given by the native solar cell - it turned out to be significantly lower, however, quite expectedly - the surface area is much smaller.
Thus, the optimal design began to look like a holder for the 18650, a cut-off case with a board and a separately connected solar battery. On the 18650 holder there is a pin connector, I cut off the mating part from the USB connector and soldered it to the solar battery. From the holder 18650 leaves 4 wires - two from the actual battery and two from the solar cell. The tape at this time used in black, blue served for 20 years and is in excellent condition, let's see how black behaves.
A pair of watches with a dremel, a drill, and a pair of scissors gave me this design:
Fully assembled:
It turned out a system that can charge 18650 from a source of 5 volts (USB) and a solar battery, can give a stable 5 volts to charge various gadgets, the benefit of the PowerBank included several adapters. There was a glitch - if the device is long without a battery - it does not turn on from the button. It turned out that the glitch costs, if one or two times, remove and insert the battery.
Now this device will be tested in the next campaign in the Eastern or Western Sayan mountains or else in some exotic place of Russia.
Source: https://habr.com/ru/post/218747/
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