Hoping someone can help me with this battery problem. I am attempting to make a 5 led solar lamp.
I am using;
Arduino nano,
5 leds,
Five 220ohm resisters
One LDR
One 10k resister.
For power I have;
Four AAA rechargeable batteries--unloaded voltage 5v
Four 2 volt solar panels in series --unloaded voltage 8v
All works great, except the freshly charged batteries only last an hour or less.
My questions are. Is the amp draw of the nano board too much? Are the batteries the wrong size? Should I get a 9v or AA batteries? Any help would be appreciated.
Use your multimeter to measure the actual current draw from the batteries.
The batteries should last longer than one hour. Assuming 100 mA for the LEDs, and another 40 mA for the Nano, then a minimal NiMH AAA battery pack with 600 mAh capacity should last around four hours.
But feel free to provide more details -- you might even consider reading the "How to use this forum" post.
Firstly only trust batteries of good brand with datasheet available. You can measure the current drain yourself
to check its what you expect.
The datasheet capacity of a battery is always greater than the real-word capacity:
Datasheet always assumes freshly fully charged cells (or even overcharged!)
Datasheet tests are at a fairly optimum rate, usually 10 or 20 hour rate. Most uses of batteries in the real world are not in the optimum range
Datasheet value is for brand new battery, at a suitable temperature for good performance. The real world doesn't give you those advantages often.
As a rechargable battery ages and is used its capacity inexorable falls.
So if you want X Ah capacity in the real world, get something more like a 2X Ah battery so its still useful after many cycles and when cold or hot or been stored for a few weeks...
A circuit diagram would be a good idea. E.g. what is the connection between the solar panels and the battery/Arduino. If that's wrong it may be the panels that are draining the power.
BTW unless you're in the Arizona desert at high noon solar panels will rarely deliver anything like their notional output.
jremington:
You STILL haven't read the "How to use this forum" post.
Yes I did. Three other people had no problem helping me. You don't have to answer. But don't you worry. I'll get my info elsewhere in the future. Maybe switch to Raspberry.
Hi,
Can you post a schematic please?
Have you got a blocking diode on the PV cells to stop the battery draining back through the cells when their output voltage is lower than the battery potential?
TomGeorge:
Hi,
Can you post a schematic please?
Have you got a blocking diode on the PV cells to stop the battery draining back through the cells when their output voltage is lower than the battery potential?
Thanks.. Tom..
Tom; I can post a schematic in a few days. I absolutely hate Fritzing so I will in another program. Check back in a while
Hi,
Thanks for the circuit, frizty doesn't do much for most of us here either.
I hope you have the negative of the battery connected to gnd of the Nano? :o
TomGeorge:
Hi,
Thanks for the circuit, frizty doesn't do much for most of us here either.
I hope you have the negative of the battery connected to gnd of the Nano? :o
I would suggest you also test the solar panels and batteries unconnected to any of the other components. Then you can check what actual voltages you're getting in the light levels you're working with and if there is any chance of charging the battery.
slipstick:
I would suggest you also test the solar panels and batteries unconnected to any of the other components. Then you can check what actual voltages you're getting in the light levels you're working with and if there is any chance of charging the battery.
Steve
I did, thanks. panels are all 1.9v Battery is 6.29v
Running the Nano and LEDs for 2 hours hardly decreases the voltage on the battery by .02v or .03v
I thought the problem was that the system ran for less than an hour before the batteries were depleted? That sounds like it would run for much longer so is there still a problem?
Except that 6.29V from 4 AAA batteries doesn't sound like any rechargeable batteries that I know.
