Charging 6S 18650 battery with 19V, which charger should I use?

Question

Batteries

Hello
It is necessary to charge the battery from 18650 (6 cans, 25.2 volts at the peak). The essence of the problem is that it is necessary to charge from the PSU from the laptop (respectively, 19V). The charger itself should be as compact as possible (it will be inside the case). The charge speed is not important (although there is no more than 1.5 amps, so even the weakest charger can withstand it).
Battery with balancer board.
Can't find charger.
Step-down charger found https://ru.aliexpress.com/item/5A-Lithium-Charger-..., but there is no sense in it if I have only 19 volts. Is it just to divide the battery into 2 pieces of 3S, connected in series, and charge each unit with its own charger. But this is a collective farm. Or use a step-up, to which you can connect a step-down charger, but this is generally a collective farm.
Just a step-up converter with current and voltage regulation https://www.lacrossetechnology.ru/preobrazovatel-d... for example, if I understand correctly, this is not an option (to get a full-fledged charger, with charging turned off).
How (with what) to charge?

Answer 1

You can’t charge from 19 volts, you need to increase it, but you yourself know this. Dividing the battery into two halves is not a solution, because in this case you must connect another one for 3s instead of the standard BMS-6s.
Yes, you will have to do something boosting, or use a universal charger like the IMAX B6, which needs 11-16 volts, even to charge a 6s battery.
But in my opinion, the most correct thing is not to do needlework, but to order something like this device (29 volts, 2 A, the size of a laptop PSU), or find something simpler on Ali for less current and smaller dimensions. Well, wait a month until it arrives.

Answer 2

increase dcdc with a booster
and charge through the charger for your configuration
on Ali, there probably is

Answer 3

with a balancer, the boost converter works fine.

Answer 4

Ali is full of DC-DC boost converters with current regulation
At least this one
is searched for by step up dc-dc current constant
Set the maximum voltage and maximum current. as a result, the charging algorithm will withstand as it should. When the maximum is reached, it will not turn off. but nothing terrible will happen - the voltage will not rise. will simply infinitely compensate for self-discharge