Solar charger module results in slow gradual charging

So I have this solar charging module off the internet. I've placed it between a 5V solar panel and a couple of 18650 pair of batteries.

I measured the solar panel voltage at the terminals and it was 5v more or less. But when I put the voltmeter at the solar charging module terminals connected to the batteries, V sits at about 1.5V. So I thought there might be something wrong but I noticed voltage started to climb. About 2-3 minutes later it is up to 2.36V.


Is this normal? Because I know it won't charge the 3.7V batteries unless it reaches at least 4-4.5V right?


So I have this solar charging module off the internet

That's nice.

Lots of numbers in your post.
Not many facts.

Here is the data, sorry:

1a Li-ion lithium battery charging module charging board charger TP 4056 in the product image there are 2 similar items joint together, there will be only one item sold in this listing. Power: medium power brand name: Tp4056 usage: zenger diode structure: PNP special function: common point contact diode frequency: high frequency Type: power module construction: planar Type material: silicon install style: SMD function: power triode



If you measured 1.5 V across an 18650 battery, the battery is dead and will not charge.
An 18650 battery should never go below 2.8 V.

It has an under voltage protection. Your battery is to low on voltage so it will not charge it since that can be very dangerous with Lipo batteries.

Not recommended, but I have gotten life back into 18650 by boosting them. 5 volts directly to the battery for 2 seconds, measure the battery, as soon it reaches 3 volts it might charge again.

But, technically, your battery is dead and should be disposed of

OK I agree! I'll chuck en. Just found a bunch of 18650's in another charger and tested them at 4.20v so I'll use those :slight_smile: