So you’re saying even if the voltage from the battery is a bit low, the dcdc can raise it to put the right input into the battery?
I do not know which voltage you mean. If the charger voltage setting is not a fair bit higher than the battery "at rest" voltage, no effective charge current can flow.
On a 12V system, or a 24V one, that is just a nominal label, approx halfway through the SoC% working range.
So if 10.5V is 0%, dead flat actually harmful to longevity should never go there in normal cycling.
The **charging** voltage, AKA the Absorb / CV setpoint for FLA might be 14.8V, while with GEL you should not go over 14.2V. These setpoint specs vary depending on the battery make & model, and you need to buy a battery that matches your charger or v/v
Unless you future-proof by insisting on charge sources with user-custom adjustability, not just a limited set of canned profile choices.
After charging the **battery** voltage falls, without SoC% changing, until it reaches the 100% Full "isolated-at-rest" voltage, which again will vary by battery type
A Deka or Trojan FLA might be 12.85V, while GEL might be a bit over 13V.
> if there are two in parallel both trying to charge the battery, they both will put the precise charge profile without doubling it?
Voltage stays the same, amps current doubles - that is what "parallel" means.