Solar Panel Regulators
Charging li-on batteries with solar panel?
With Nicads and Nimh batteries, you can leave them charging indefinitely as long as the charge current is limited to no more than C/10. Would this same rule apply to li-ons? What if you were to limit the li-on charging current to C/20 just to be on the safe side?
Right now, I use a LM317T regulator to limit the charge current and it works just fine. I was thinking of getting higher capacity li-on batteries and using another regulator to limit it’s current. But I don’t kow is setting the current to C/20 or more would possibly lead to fire or explosion if I just leave them charging all day.
Thanks for your help!
“What happens if a battery is inadvertently overcharged? lithium-ion is designed to operate safely within their normal operating voltage but become unstable if charged to higher voltages. When charging above 4.30V, the cell causes plating of metallic lithium on the anode; the cathode material becomes an oxidizing agent, loses stability and releases oxygen. Overcharging causes the cell to heat up. If left unattended, the cell could vent with flame.”
Source:
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
According to this site, you would design a charging circuit that , as the full charge is reached, reduces the charging current & measures the cell voltage. The charging circuit would be designed to shut off when the full voltage is reached.
In the alternative, you could also set a timer, to prevent over-charge.
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Solar Workshop – Charging Regulators & Shunts
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Sunforce 7 Amp Charge Controller $17.41 The Sunforce 60012 7 Amp Charge Controller prevents overcharging of 12-volt batteries. It is intended for use with 12-volt solar panels, and can handle up to 7 amps of array current and up to 100 watts of solar power. The controller is easy to use with a charging light that indicates that your battery is charging, and a green light that indicates a fully charged battery. The 60012 measures 4 x 1 x… |