Foldable Solar Charger, Cloud-Restart Test - EasyAcc 28W (SP28W)

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Foldable Solar Charger, Cloud-Restart Test - EasyAcc 28W (SP28W)

I recently purchased too many of these fold-able type solar chargers.  Some of them have many reviews, and some have very few, but almost no reviews discuss how the panel deals with shady interruptions like clouds.

NOTE: This is only a test of one aspect of this charger, not a full review.

Charge Restart Feature


These solar chargers are marketed toward backpackers, campers, and/or emergency situations.  In my opinion it makes sense to charge a battery bank with one of these, and then charge your mobile phone with the battery bank later on (after dark?).  These chargers can also work directly with your mobile phones, but that is a tricky endeavor. 

Many mobile phones (and some battery banks) will not adapt to the changing power provided by a solar charger.  For example, current generation apple devices will start charging at full power, but if a cloud reduces the output temporarily, the apple device will not resume charging at full power. 

In response to this, some solar chargers have begun adding charge-restart features to their circuitry.  The theory is nice, the panel detects an interruption in solar energy, and briefly cuts power to the usb ports.  This should trigger an apple device to automatically resume charging at full power.


Depending on how the charge-restart feature is implemented, there could be some serious drawbacks.  Ideally the solar charger would reset the usb ports only once, after the cloud has passed.  That means the charger has to notice a sudden increase in sunlight, and reset the device.

Some solar chargers are taking the easy way out, and just cutting the ports off when the output voltage drops below a certain threshold, say 4.4v.  This method means that when a cloud obstructs the sun, power is cycled immediately.  But as soon as your device begins charging, the voltage will drop again, and power will be cycled again.  This will repeat until the obstacle passes.  This method could be very bad for your device.  This method also makes it impossible to trickle-charge your device.

In this test I will try to determine if these solar chargers have a 'charge restart' feature, and if so how well it works.


The EasyAcc 28W (SP28W, purchased on amazon, Oct 15, 2016)

Some Pictures




The Test

In my test, I tried to obscure the sun as much as possible without cutting power to the device being charged.  For this charger, I closed the third panel over the second panel, leaving only the first panel exposed to sunlight.  Then I used a semi-transparent piece of plastic over the last panel to further reduce the output.  I monitored the charge rate with a simple USB charging meter.

After the charge rate slowed to almost nothing, I removed the plastic and opened the panels back up.  Here are the results:

From what I can tell, the EasyAcc 28W (SP28W) has current monitoring charge restart technology.

This charger was different than all the others right off the bat.  It starts resetting the usb ports as soon as sun hits the panels.  It continues to reset the ports until something starts drawing power from the usb ports.  I dont have much testing equipment, but from what I can tell it requires about ~100ma before it stops resetting the ports.  I'm not really sure how this is useful.  It wont cause an iphone to switch back to fast charge unless the charge rate drops below ~100ma.

I can imagine this would be bad when your phone's battery reaches 100%.  The charge rate will drop below ~100ma, and the charger will start cycling the usb ports.  This will cause the phone to chime, and turn the screen on/off constantly.  So as soon as the phones battery is full, the charger will cause the phone to start using up its charge.

Also note, this charger has 4 USB ports, and I was able to draw more power from the 1A ports than the 2.4A ports.


The Specifics

Resting Voltage
3 panels exposed
Charging Tesa PB
3 panels exposed

Charging Tesa PB

1 panel exposed

Charging Tesa PB
1 Panel with Plastic Cloud

5.11v 4.75v/1.54a 4.35v/0.51a reset




In my opinion the charge reset technology in this panel is not very useful, resetting the usb ports any time the current draw drops below approx ~100ma. 

I always recommend you fully test your setup in varying conditions before you rely on it.



Edited by: netprince on 02/15/2019 - 12:41