Battery charging algorithm

Question

I have designed my MPPT battery charger to a state and I have been able to generate the 14.4V charging voltage, with the 40Ah battery charged upto 14.4V during bulk charging stage and absorption mode charging kicks in to maintain the battery voltage at 14.4V while the current tapers, the panel input is 200W, 12V, at maximum sunlight my Isc is about 7A, and the battery when discharged takes about 5.8A with MPPT.

At what point will I know to enter float charging? Since float charging needs the voltage maintained at 13.8V, will I generate another charging voltage that will give 13.8V?

Answer 1

My question now is this, at what point will i know to enter float charging,

After a certain time at 14.4 V. The battery data sheet ought to give you a limit of maximum time at this voltage before long term damage occurs. It's going to be somewhere between minutes and days. It's a compromise between obtaining the maximum run time following a charge (more time at 14.4 V), and obtaining the maximum number of charge cycles from the battery (less time).

... and since float charging needs the voltage maintained at 13.8V, will i generate another charging voltage that will give 13.8V?.

You could generate another voltage at 13.8 V and switch to it, if that's convenient. It is a very low current supply, so it has that in its favour. I think most people would simply change the set point of the main regulator from 14.4 V to 13.8 V.