I can?t guide you exactly and wont advice you to try this as every UPS is different from another. Few UPS systems have an option in form of a switch from where you can change the charging amperes. Best is that you consult the local manufacturer and ask him how we adjust the charging rate on that specific UPS.
As far as DESI UPS systems are concerned, may they name them what so ever they like but they have three different wires near the transformers. Two wires are not connected to any thing whereas third wire is makes a connection with the transformer. Now if you take that wire out from its slot and exchange it with remaining one of the two wires then charging rate will change. They have designed it such as 5 Volts, 12 Volts and 19 Volts options. You just need to put the right wire in right slot by taking the original out. Like I said that ask local technician to do it for you first and later
once you have seen it then you can do it yourself. You can verify this by using AMP-Meter.
Let me show this on image as rough example which will give you a slight idea.
e.g: in below image you can see three slots whereas last two are vacant and yellow wire goes into slot no 1 so i can change the charging rate by taking it out and putting it in second or third slot.
you have to be sure what you are doing.
