Powering a Shark cordless vacuum cleaner

[FredWils0n]

Hello, I have bought a Shark cleaner from this xxxxxx, which has a 230volt ac to 25.1volt dc charger.
i plan to buy a 24 volt variable DC output converter.
I can get constant voltage or constant current.
I'll use this to charge it from our 24 volt battery bank.
They have these on AliExpress: 1PC DC 300W 20A CC CV Constant Current Adjustable Step-Down Converter Voltage Buck Z09 .
Should I get constant volt or constant current?
Thanks

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[Sunking]

It takes both. How stupid do you think we are?

Have a nice day.