I've got a Vsrc of 14.97 crossing a LM317 current limiter ( 1.25V / 1.25R = 1A), and at the output of the LM317 I have 14.4V/1A. So far so good.
Next I use a BC239 NPN transistor to switch a P-channel IRF9630 MOSFET with a 4K7 pull-up. Source is wired to 14.4V positive terminal, and I plan to put a charging load on Drain.
My battery is a 12V/9Ah, so charging would be done at ~C/10, and elsewhere I use a zener diode to read the battery's voltage, and cut-off charging at 13.6V, also cut-off loads at
10.8V (that's done with a relay, it's not relevant to this question).
My question is probably simple to answer: What gotchas should I be aware of when charging a >100Wh battery?
Best Answer
Charging a Lead Acid battery is quite easy. You should first apply a constant current (CC) of max. 1C (in your case 9A) until the voltage reaches 14.4V. Hold this voltage for at least one hour, at most 10 house to balance the cells inside the battery. At the end of the constant (CV) period the current should be below 1/20 of C (in your case 450mA). Do not apply voltage above 14.4V, this will reduce the capacity of the battery over time because of water loss.