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Poor wording. Charging Lead-Acid batteries is all about controlling VOLTAGE(link); the current that flows into the battery is a function of the electrochemistry inside the battery. You need one voltage regulator connected to the battery; the two unregulated charging sources can be diode-ored into the input side of the regulator. That is how commercial "solar charging regulators" are made. These are readily available and cheap. Why build one?
Poor wording. Charging Lead-Acid batteries is all about controlling VOLTAGE(link); the current that flows into the battery is a function of the electrochemistry inside the battery. You need one voltage regulator connected to the battery; the two unregulated charging sources can be diode-ored into the input side of the regulator. That is how commercial "solar charging regulators" are made. These are readily available and cheap. Why build one?
I'm sure you understand, MikeMI, that by controlling the voltage level your are controlling the current. Perhaps you feel I took a bit too much for granted about the OP's level of understanding.
Don't yet understood why some members insist on editorializing ("poor wording") on another member's post. Had I been utterly incorrect, fine. Not in this case, however.
If your going to quote me, please refrain from commenting on my use of the English language. I don't believe that is your pervue on this forum.
Actually, I wasn't quibbling about your use of English, I was commenting on your post leaving the wrong impression about how to charge lead-acid batteries. Your post leaves the impression that you should use a constant-current source ("controlling current" ) to charge lead batteries. While that may be just fine for NiCd and other battery chemistries, it is the wrong thing to do for lead batteries. A lead battery charger is a constant-voltage source (voltage regulator).
Well, I would say you're both right, but each focused on only part of the issue.
For safe, reliable charging of lead acid batteries, you need to control, or at least limit, both the current and the voltage.
The current needs to be limited to the lower of either the safe charge rate of the battery, or the safe output power capacity of the charger.
The voltage needs to be limited to prevent overcharging of the battery. That level varies somewhat depending on usage and temperature. Here, Mike's link is a great source of info.
Please note: Both of these limits are mainly to prevent bad things from happening, to either the battery or the charger. The actual mechanism of charging a lead acid battery, is simply pushing properly polarized current through it. The voltage point is when to stop, or significantly reduce, the current.
The current does not need to be "constant", and many chargers aren't. See "Taper chargers" in Mikes link.
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