why does the battery measure 19v when I use a laptop brick to charge via circuit instead of 17v?

reason for my question,   my jump starter circuit board  which i think it takes 17v but I am using a 19v laptop PSu to power it, with a 12v sla but when I check the battery voltage it is showing 19+ volts, why didn't the charger circuit lowered the voltage and regulate to 13.7 or 14v?

reading 19+ probably not good for the test SLA ?

can i use multiple diodes in series  to lover my input 19v to exactly 17v dc will this make this charger circuit work properly, I have tested two different brand same reading.

what gives?
thanks
Al


Picture of  why does the battery measure 19v when I use a laptop brick to charge via circuit instead of 17v?
Jump boxes don't create a jolt to jump start a car. They have a nice little 12V battery with allot of amperage to run the starter motor on its own and get the car started.

Like frollard said your jump box should have no problem charging a pair of 6V SLA batteries in series.
frollard5 years ago
so long as its a 12v SLA, yes.