@yamyam I typically see what the charger is capable to provide in terms of power.
Now you have 2 separate solar chargers (one with 3.5 watt output and other with 2 watt output).
Also looking at the EufyCam itself, in your stress test, the worst it did was 10 days before fully discharging.
It has 48 Watthour total power and its discharging in 10 days (give or take) so the batteries are discharging about 4-5 Watthour per day.
If the sun shines for 4-6 hours everyday the solar chargers can prevent the battery from discharging (if you begin with a fully charged EufyCam.
In my opinion you can do a permanent wiring for the solar chargers and it will keep your batteries in mostly charged state (with occasional drops in state of charge during night time or days without sun). That is good for the battery.
There is no concern for the overcharge (most modern devices have a protection against it).
3.5W @6V is a very low rate charging (about 580 mA total) and cannot damage the batteries.
+++ YAMYAM's detailed eufy cam SOLAR PANEL TEST & REVIEW +++
Yes, this fits my experiences in the past months with the 3,5 W solar panel (the first one). It powers my most in use cam with 200-300 videos daily and the battery is pretty stable between 3 to 4 out of 5 bars.
Sure, its summer currently and sun is shining a lot in the past weeks. I will see what happens in winter, when sun is not shining that much and snow may hide the panel too.
Yes, thought so. But with your knowledge about the eufy cam and its battery now, what would you say should be the paramaters of a solar panels at maximum?! (if looking for a new one or if the first one will fail too much in winter and i want to improve it)
5V at 2A would be 10W so i guess a 10W solar panel would be still ok or even more?
Thanks!
If I’m getting it correct the batteries inside EufyCam are possibly Panasonic NCR18650B (rated either 3350mAh or 3400mAh).
These can easily be charged with 0.5C or lower current (meaning about 1.5 Amp charging current).
Now there are 2 in parallel so this current will get split so you can use double the value (3A)
Solar chargers have variable output (that’s why there is a Vmp and Voc ratings) Vmp is max power and Voc is open circuit voltage (no load condition).
If you hook up a 5V 2A output solar panel it will be great. It can be upped till 3A (15 watt charger) comfortably. I wouldn’t recommend going over that.
Ecellent, thanks for the detailed answer! 
Last question:
I know that most, or even all solar panels, have variable output. Is that bad or disadvantageously for the battery or cam electronic? I have read also on some panel reviews that they have maesured some panels and can confirm a stable 5V output. So guess its a matter of quality and price of the panels.
Until yet, my first solar panel powered eufy cam still works and lives, even on heavy use and permanent recharging. As the eufy cam only exists since a couple of months, i am curious when the first customer will report the first total failure of an eufy cam 
Variable output is not a problem per se
Its just an inherent nature of solar panels. If the voltage drops too low then it may stop recharging but the voltage will not go high enough to damage anything since it has shutoff voltage limits.
I’m very skeptical of any claims where a solar panel is held responsible for a eufy cam failure 
another remark about high wattage charging - Li-ions like to get discharge/recharge to retain their capacity so it is best to not use high power charger since it will not let the battery get discharged enough.
OK, there will be anyway days or events or circumstance which will drain the battery in some week or day more or less or even to empty. But with 2W and 3,5W recharging i doubt my cams will get 100% full again ever … even with 6-8 h of direct sun on some days or even a whole week.
The only case is, right after i manuall charged the cams and then plug in the solar panel, the app bombs and spams me with messages that the cam is now fully charged! Dozens of notifications in just minutes. Just happened today:
@AnkerOfficial, @AnkerSupport, @AnkerTechnical, @ndalby, @TechnicallyWell
This is really really annoying! I know this notification has just been added in one of the latest updates and in general its good! I like it … you do not need to check the cam if the charging LED turned off, the app notifys you. Great! … BUT: In case someone is chargung by solar panels, like me, he will get massively spamed by notifications right after a fully charged cam is solar pluged. Sure:
- 100% manually charged
- 99,9% (because of couple of records in short time)
- solar panel recharges to 100% - notification is sent that cam is fully loaded
- 100% again
- 99,9% (because of some records or a short live streaming)
- BAM … solar panel recharging again, 100% - notifcation is sent again.
- … and so on and so on … in just some minutes!
You should update this “feature” so only ONE “fully charged” notifcation per cam is sent and then “blocked” or restrained for a certain time, like 1 day for example, to prevent notification spam.
@kumar.sachin
May i ask if you know any serious micro-usb multimeter or tool which i could use to check the output of my solar panels?
Just for example:
It should do correct measurements as i know that a lot of those mini tools and multimeter are crap and showing wrong data. Do you know any by personal experience which is good and affordable? I rather buy one you can recommend that buying any random one where i do not know if its worth buying and using it and if the measurement is correct.
Thanks!
By the way … 1 year … ONE YEAR after anker released the eufy cam, there is still now own solar panel!
But tons of several new cams with irritating naming and features … wow!
Shame on you @AnkerOfficial , shame on you! 
@yamyam While we get you’re upset and disappointed with many aspects of the EufyCam product line & timeline…posts like these are not gonna improve the situation…
Who knows … maybe at least SOMEONE at eufy/anker does HAVE a certain?!
So hope dies last and maybe someone will, even after one year, listen to the community and customer wishes and starts fixing the issues and features and demands. You never know. Xmas is coming!
Hey yamyam, I plan to do something similar to your setup. But wanted to see if this solar panel from Reolink would work with the Eufy 2c?
REOLINK Solar Panel Power Supply Designed for Reolink Home Security Outdoor Rechargeable Battery Powered IP Camera Argus 2/Argus Eco/Go/Argus PT, Waterproof, Reliable and Long-Stop Charging https://www.amazon.com/dp/B07WL7FZR4/ref=cm_sw_r_cp_apa_i_sNJmEbVGRGDCM
Thank you
As it got a micro-usb plug, it will work, yes, as long as the ouput is quite stable at 5V!
Couldn’t find any infos about the voltage output. You may ask there and wait for an answer.
3,5-5W at 5V would be quite ok and you will not run out of battery power (at least in summer time and with lot of sunny days, in winter you may need to manuall charge from time to time)
Thanks man. I was looking into the solar panels that they make for the blink xt2. Which come with a battery within the panel. Not sure how that would work. But curious if the battery would also charge the internal battery of the eufy camera. I might test it in the near future.
Excellent, if you know more or wanna link it to me or make a review/test, tell and post it to me please. Thanks!
Hi Yamyam, really enjoyed reading your review and insights on using a solar panel with Eufy cameras. I purchased the Reolink and it has a maximum 6v output and max 3.5 W. I was excited when I connected it at night and pointed a very bright LED light at it and it showed the battery being charged in the app and the blue light came on showing it was charging. However, today, I took it outside in the sun and the app does not show it charging and the blue light doesn’t come on. I was checking the connections and noticed when I hold the solar panel right side down, it started to show it was charging. When I flipped it right side up, it stopped. Is it possible it has too much output in direct sunlight? Curious on your thoughts. Thanks in advance. Mark in Texas
Same for me
As far as i know, the voltage has to be exactly, or as most as, 5V!
6V seems to be too much. And sure, if the battery is full (100%) it won’t show any more charging.
Else, if the battery is not full and not showing any charhing, something is wrong.
Eufy told me to be sure the panel has 5V. Don’t know if 6V would make any difference, as the fast charging is on 9V … so normaly not. Suspicous. Maybe anker will help you here … but dont bet on it, we wait since 2 years to get updates and promised features.
Thanks, I went ahead and ordered the Wasserstein Solar Panel that said compatible with eufyCam E Wireless Security Camera for use with my eufy2’s. It seems to be working. It has been very cloudy here, but in 3 days it did charge 10%. Today was sunny and I had the solar panel in direct sunlight and it charged the battery approximately 10v in that time from 24 to 34v. Thank you again
Hello,
could I use the Wasserstein Solar Panel for the Eufycam C2, too?
Do you have a link to the right panel?