Hi, I'm new here (and kinda new to electronics).
I want to take an ordinary solar panel, say, between 5 and 50 watts, and be able to charge an ordinary sla. However, I want to charge the LiFePO4 batteries as well (not li-ion). They need 3.65v, thus, four in series is 14.6v, almost a perfect match with what the lead acid needs.
Now, the panel should put out about 17v.
Can I "just" put a zener or an adjustable voltage regulator somehow in the (very simple) design to stop voltage from ever going past 14.6 volts?
I understand that at very small currents, this may not work, and that these may not be precise, but am not sure. Especially since when the batteries are almost charged completely, the current will be almost nothing, which may allow the voltage to creep up past 18v or so. Which is OK for the lead acid (as long as its capacity is more than ten times the amps of the panel), but is NOT OK for any lithium based battery.
I want to use the lifepo4 because of its superior thermal handling and its many thousands of cycles. I also want to use it because it is a perfect match for the load, the Cree XML.
Also, I wonder if I could use a switching regulator to step down the voltage to that perfect 3.65v (thus avoiding the expense of having to use 4 of "everything).
The light I'm building would still be bright enough using just one XML...
In the case of the lead acid, I would need a charge controller because the leds allow the voltage to drop just slightly below what it "likes". (And that is WAY expensive for a light!) However, another reason for the lifepo4 is the fact that the leds will never dim to such a point as to discharge the lifepo4 below 2.2v (per cell) perfectly safe and acceptable... Unless that switching or zener is a "phantom"...
Thanks
I want to take an ordinary solar panel, say, between 5 and 50 watts, and be able to charge an ordinary sla. However, I want to charge the LiFePO4 batteries as well (not li-ion). They need 3.65v, thus, four in series is 14.6v, almost a perfect match with what the lead acid needs.
Now, the panel should put out about 17v.
Can I "just" put a zener or an adjustable voltage regulator somehow in the (very simple) design to stop voltage from ever going past 14.6 volts?
I understand that at very small currents, this may not work, and that these may not be precise, but am not sure. Especially since when the batteries are almost charged completely, the current will be almost nothing, which may allow the voltage to creep up past 18v or so. Which is OK for the lead acid (as long as its capacity is more than ten times the amps of the panel), but is NOT OK for any lithium based battery.
I want to use the lifepo4 because of its superior thermal handling and its many thousands of cycles. I also want to use it because it is a perfect match for the load, the Cree XML.
Also, I wonder if I could use a switching regulator to step down the voltage to that perfect 3.65v (thus avoiding the expense of having to use 4 of "everything).
The light I'm building would still be bright enough using just one XML...
In the case of the lead acid, I would need a charge controller because the leds allow the voltage to drop just slightly below what it "likes". (And that is WAY expensive for a light!) However, another reason for the lifepo4 is the fact that the leds will never dim to such a point as to discharge the lifepo4 below 2.2v (per cell) perfectly safe and acceptable... Unless that switching or zener is a "phantom"...
Thanks