5000mah solar battery pack
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Hi Guys
I saw these on ebay and thought I would give them a go for a shed based node.
the picture is actually bigger than lifesize its just 142mm tall.
only £4.95 delivered free. 5000mah with solar charging. states 200mA under full sunlight so a little daylight should keep a node going for ever.
Unfortunately they are no use straight out of the box as they must have a current drain circuit and a node is not enough to keep it outputting juice.
However I cracked it open and the battery is a 4v pack so I fitted a 5V step up module to the battery leads and disconnected one of the USB socket feeds and connected it to the 5V output.
I am feeding the nano based node straight into the usb connector and the pack is held against a window in the shed which lights the green led to tell you it's charging. Only been in a few days but so far the battery has swung up and down between 93% and 97% probably depending on the amount of light. which considering the window does not face the sun and its in Scotland with all of 7 hours of sunlight at the moment if were lucky, it's not doing too bad. The current case hack is very rough but if it seems to work OK I will probably print up a new box for everything.
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Well i would have to say no go on these, only lasted 3 days and with my hack you lose the battery protection cut off for the lipo. seems a huge drain for a nano node, maybe the 5v step up is really inefficient I will take some current measurements. So I think unless it's possible to get around the fact that it will not supply juice to the usb socket unless there is a significant current being pulled these are a no go. shame.
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I think these are a bit of a con. I charged an un-hacked one up to full, plugged it into my flat nexus 9 and it pulled 1.3A out for less than 21 minutes as that is when I looked round and it was off. smells a bit electrical as well if you know what I mean. I know it's been a while since I used my electrical engineering but I'm pretty sure a 5000mAh battery should supply 1A for 5 hours. Oh well, the carabiners are nice.
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The cheap batteries usually don't have the full capacity they are specified for, but you are measuring the capacity the wrong way.
"To obtain a reasonably good capacity reading, manufacturers commonly rate consumer alkaline and lead acid batteries at a very low 0.05C, or a 20-hour discharge" (from battery university)
You were discharging at 0.26C (1.3/5) so you are likely to get less than 5Ah. But probably not as low as you got. -
Probably a bad battery, unfortunately. If you have a better quality 4V battery pack, you may be able to upgrade it.
As for the drain issue, would adding a small resistor and capacitor give you the discharge you need for it to continuously supply current? The step up converter is probably taking a lot of juice from the pack as well.
