What charging module to choose from? Diode needed with solar charging?

Hi all. I’m in the final part of my project where i will be monitoring the water level of a tank and send data over rf back home. This tank is to far away from mains power zo i’ll be powering the arduino with a little solar panel.

Now my question is wich of these two charging modules would be the best for charging a single Lithium 18650 battery?

First one i have is this one:
5pcs 5V Step-Up Power Module Lithium Battery Charging Protection Board Boost Converter LED Display USB For DIY Charger 134N3P

The second o have is this one:
5 pcs Micro USB 5V 1A 18650 TP4056 Lithium Battery Charger Module Charging Board With Protection Dual Functions 1A Li-ion

For powering the arduino i’ll use a separate module. I tried the first module to charge the batterij en power the arduino at the same time but it has a cut of function to avoid draining your battery if the power consumption is below a certain level and the arduino usage is below that.

Second question is, should i put a diode between the solar panel and the charge controller to avoid “frying” the solar panel? Not even sure f that is possible.

Chargin from a PV panel is different to charging from USB - PV panels are not voltage sources, they are more like highly variable current sources. A charger module designed for PV operation is needed, not a USB one.

A proper charger unit would have the reverse-blocking diode built in.

Thanks for taking your time to read my post and answering MarkT.

This solar panel comes from a small garden lamp with a 18650 battery build in. There was nothing like the charging modules i have in there. Like 5 components or so. Sadly i don't have the rest of it anymore so i have to look for a different module.

Maybe it's possible to create my own charging module you got any idea?

Best to use a charging module intended for small solar panels and LiPo cells, like this one or this one or this one.

Ive had some success with these devices. https://www.aliexpress.com/item/1-Cell-9V-12V-Lithium-Battery-Charging-3-7V-4-2V-CN3791-MPPT-Solar-Panel-Regulator/32837348257.html?spm=2114.search0104.3.61.19cf7fc3Cq5QCZ&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10344_10130_10068_10342_10547_10325_10343_10546_10340_10548_10341_10696_10084_10083_10618_10307_10131_10132_10133_10059_306_100031_10103_10624_10623_10622_10621_10620,searchweb201603_50,ppcSwitch_2&algo_expid=098ce05f-9ec5-4c7c-ad58-3aaf147d16dd-9&algo_pvid=098ce05f-9ec5-4c7c-ad58-3aaf147d16dd&priceBeautifyAB=0

They need a 9V panel or bigger though, and Ive only tried with 4 - 6 watt panels, but they work Ok. Designed to charge a 1S (3.7V) LIPO cell like a 18650. Sorry for the humungous URL.

Thanks all for the replies. I'll go ge on with it and just test both modules and see what will give best results since this is what i have at this point.

I'll be adding a big capacitor to smooth the input out a bit. If interested i might post some results.

Hello, did those modules manage to charge the battery while in the same time provide power to the load (i.e Arduino) ?

In the end i used this module for charging the 18650.

https://m.aliexpress.com/item/32934427176.html?spm=a2g0n.orderlist-amp.item.32934427176&aff_trace_key=&aff_platform=msite&m_page_id=2040amp-GLYckj1gxRLwAWO63aCoXg1563740590071

Then i used thecsecond board to protect the battery from overdischarging

https://m.aliexpress.com/item/32631718585.html?trace=wwwdetail2mobilesitedetail&productId=32631718585&productSubject=New-5Pcs-lot-5V-1A-Micro-USB-18650-Lithium-Battery-Charging-Board-Charger-Module-Protection-Dual

Bringamosa: In the end i used this module for charging the 18650.

https://m.aliexpress.com/item/32934427176.html?spm=a2g0n.orderlist-amp.item.32934427176&aff_trace_key=&aff_platform=msite&m_page_id=2040amp-GLYckj1gxRLwAWO63aCoXg1563740590071

Then i used thecsecond board to protect the battery from overdischarging

https://m.aliexpress.com/item/32631718585.html?trace=wwwdetail2mobilesitedetail&productId=32631718585&productSubject=New-5Pcs-lot-5V-1A-Micro-USB-18650-Lithium-Battery-Charging-Board-Charger-Module-Protection-Dual

So you have connected both modules ? Isn't the first one enough ?

No the first one only charges the battery. If you put your load on there now and there would not be enough charge from your panel you can deplete the battery past its lowest alowable voltage. This will damafe your battery and is even dangerous since it can catch on fire.

The second board is connected to the battery and via that board I power my projects. That board has a low voltage cutoff sp it will stop providing power to my project and not damage my battery and my property.

There are better boards with all this,build into one board. Andreas Spies made a video about this just last week or so: https://youtu.be/KaiQDS9jObY

So, what is the solution if I want to power my Uno and a small servo with 18650 and solar panels? Since the load draws current and I want it to be portable ( recharged from the sun ), but in the same time not over-charging it?

Solution is, solar panel → chargecontroller (first link) → battery → undervoltage protection (second link) → your project.

Even better is one of the boards that is shown in the youtibe link above. I think there is a board with everything in it.

However servos tend to draw quite sone power when under load so not sure if something like that is feasible with solar.

You may need a step up converter to get to the desired voltage for your servo.

Keep in mind als these boards use power to. All the conversions are with loss, so this is far far from efficient

The servo needs to work for 3-4 second only once a day. I was thinking of implementing this circuit with the TP4056 and P-channel mosfet in order to create a power-path (load-sharing) ?

Bringamosa: Solution is, solar panel --> chargecontroller (first link) --> battery --> undervoltage protection (second link) --> your project.

Even better is one of the boards that is shown in the youtibe link above. I think there is a board with everything in it.

Okay, how you kept your charging module from frying when the VIN is possible to exceed its limits, due to open circuit voltage of the solar panel? ( assuming "no load scenario" when the battery is fully charged ). Let say it accepts 4-6 V to the input, you put 5V panel, but the open circuit voltage rise to more than 6V, hence destroying the board?

Not sure what board you think cpukd be fried. The chargecontroler i used?

Specs are: Solar panel input: 4.4-6V

Solarpanel i used was a "6v" panel. Running since installed, still running. In two diffrent setups.

Okay, how you kept your charging module from frying when the VIN is possible to exceed its limits, due to open circuit voltage of the solar panel? ( assuming “no load scenario” when the battery is fully charged ). Let say it accepts 4-6 V to the input, you put 5V panel, but the open circuit voltage rise to more than 6V, hence destroying the board?

@garabetov
Still not reading datasheets ?
TP4056 DATASHEET

What does it say page-1 under “ABSOLUTE MAXIMUM RATINGS” ?

ABSOLUTE MAXIMUM RATINGS
·Input Supply Voltage(VCC):-0.3V~8V

Maybe , instead of wasting everyone else’s time, you should read a datasheet for once.
It clearly says the maximum input voltage is 8V

(8V>6V)

raschemmel: @garabetov Still not reading datasheets ? TP4056 DATASHEET

What does it say page-1 under "ABSOLUTE MAXIMUM RATINGS" ?

Maybe , instead of wasting everyone else's time, you should read a datasheet for once. It clearly says the maximum input voltage is 8V

(8V>6V)

read reply #7 :) if you can't provide a possible solution, just don't bother replying. Clearly I have stated my concerns when the voltage exceeds the limits, and yes I read datasheets.

if you can't provide a possible solution, just don't bother replying

Solution to what ? The only "problem" in your other post (T4056) was you didn't read page 2 of the datasheet where it says the typical temperature was 145 degrees C (so there was no heating problem)

The only "problem" in this post is you didn't read page 1 of the same datasheet where it says the maximum input voltage is 8V (2V HIGHER than the maximum OUTPUT voltage of the solar panel, so again, there was no problem and thus no solution was required. We don't mind providing assistance but we can't hold the datasheet in front of your face. You have to make a little effort.

The datasheet shows that the IC can tolerate 8V, which is 2V higher than the solar panel maximum output voltage so there is no reason for concern. If you read the datasheet you would know that.

Specs are: Solar panel input: 4.4-6V

Solarpanel i used was a "6v" panel. Running since installed, still running. In two diffrent setups.

Hi, You need to remember that as the load on the solar cell decreases, that is the battery approaches full charge, the voltage from the solar cell will increase.

You need to check what the open circuit voltage of the solar cells is in sunlight. 6V rating will be a loaded voltage on the cell.

Tom... :)