Author Topic: best usb battery bank to use with solar charger?  (Read 2718 times)

ebina

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best usb battery bank to use with solar charger?
« on: July 15, 2016, 01:31:14 PM »
I found this site from the youtube video reviews of both usb battery banks and solar chargers.  In the solar charger review Martin suggests the pairing of a usb battery bank with solar charger as better than direct charging the phone because of solar's up and down fluctuations with clouds.  I see this same recommendation all over the web, but no where do I see anyone figuring out which usb batteries work best with solar chargers (they don't seem to have been designed for solar charging)

I have tried several, and here are the sort of problems I encounter:

1) Some usb batteries require me to push a button to put it in charging mode.  I really hate this, I want it to just start charging when I hook up power.

2) Some usb batteries stop charging when input power drops too low (solar panel obscured) and then won't restart once the sun is back unless I manually unplug and replug the charging cord!

3) Most usb batteries don't allow sumultaneous power  draw and charging.  Phones and computers etc. can be using power to run while also charging a battery.  I want a usb battery bank that can be providing power (say to my phone), and if there is enough solar input, also be charging the battery bank with the extra power at the same time.

Has someone already found the perfect usb battery to use with a solar charger?  If not, maybe Martin can try some combinations with all the devices he has tested. :-)

ebina

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Re: best usb battery bank to use with solar charger?
« Reply #1 on: July 15, 2016, 03:20:48 PM »
I see the video on power banks with integrated solar panels dealt with combinations a little as a "wild card".  But none of the problems I've had with this setup were addressed. 

I've since learned that the feature I want of charging the bank while it is in use is called "pass through charging" and is uncommon because it can damage the battery.  It would be nice to find out which battery banks have smart enough charge controllers to provide this feature.

ebina

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Re: best usb battery bank to use with solar charger?
« Reply #2 on: July 16, 2016, 01:41:08 PM »
Update:
My problem: I have a wireless camera that requires 5v 2a.  I want to place it in my yard where power cannot be easily provided.  I have a rav power 14W solar panel.  It runs the camera just fine in full sun.  In fact, since it has two outputs, if I put a USB bank on one and the camera on the other, it runs the camera while still slightly charging the solar bank.  But when a cloud comes by, the power drops and the camera dies.

I figure if I have a power bank with pass through charging, the power bank can be hooked to the solar panel, and the camera hooked to the power bank.  When the sun is out, the solar panel runs the camera and trickle charges the power bank, when a cloud comes by, the power bank keeps the camera running until it passes.

Unfortunately it doesn't work!  I bought a lime fuel power bank which advertises pass through charging.  But on testing, it won't run the camera on pass through.  I don't understand why, but it seems while the power bank is charging, it can only run 1amp pass through power on output.  If I try to fast charge my cellphone, that fails too.  But if I just slow charge the cellphone (so it is only drawing 1a) that works fine.

So even though the solar panel is providing plenty of power to the power bank input, it won't pass through the 2amps to run the camera.  Can anyone explain this to me?  Is there any reason to believe a different power bank which advertises pass through  (like Zendure) would do what I want?
 

SeanB

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Re: best usb battery bank to use with solar charger?
« Reply #3 on: July 17, 2016, 07:31:16 AM »
14W is not really going to be able to both charge the battery and power the camera at the same time. You probably want 24 hours of recording, so need at least 16 hours of battery life to give that, meaning you need around 160 Watt hours of battery to run it at a minimum. Assuming a 1S lithium pack it would have to be over 50Ah in capacity to have any chance to run the camera all night till the next day. Then it needs to charge up in under 8 hours ( typical usable sunlight time with a non tracking panel in summer) and thus needs a panel capable of delivering a minimum of 25W of power. In addition you need another 14W to power the camera.

Thus at a minimum a 50W panel ( to cater for loss of efficiency as the panel warms up, as the angle to the sun changes and you are likely in the USA thus a little north of the equator) and a charge controller that can handle a 50Ah lithium pack.

If you are not running the camera all the time you can get by with a lot less battery wise, just that it will only start up in the morning when the sun rises high enough to get the panel operating, then will run it on solar for the day and charge the battery so it will operate for a limited time after dark. Same size 50W panel though, you need enough solar power to both charge the battery and support the load irrespective. This kind of use really calls for a solar management system and separate battery pack, not a simple solar power bank not designed for providing permanent power.

DanielArn

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Re: best usb battery bank to use with solar charger?
« Reply #4 on: August 13, 2016, 10:28:20 AM »
Hi,...i am a new user here. As per my knowledge at a minimum a 50W panel and a charge controller that can handle a 50Ah lithium pack.If you are not running the camera all the time you can get by with a lot less battery wise, just that it will only start up in the morning when the sun rises high enough to get the panel operating, then will run it on solar for the day and charge the battery so it will operate for a limited time after dark.

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« Last Edit: September 13, 2016, 04:56:16 PM by DanielArn »