Makita 18v USB voltage goes from 5v to 3v in seconds with no load. OK w/ load

[ez24]

I got one of these

https://smile.amazon.com/Source-Makita-Li-ion-Battery-BL1815/dp/B0725LWR1L/ref=sr_1_1_sspa?ie=UTF8&qid=1517971745&sr=8-1-spons&keywords=adp05+makita&psc=1


I hooked it up to fully charged batteries and connected a voltmeter to the USB post and the voltage started at 5.2v and immediately started dropping and within a minute it was around 3 v when I stopped the reading.

At 50 ma it stays on and at 25ma it turns off.

I want to use this as a portable PS.  I also need 9v sometimes, so I will use a boost module from Aliexpress.  Also I want 3v (or is it 3.3v ?) so I will use a 317 module.

My guess this has something to do with a minimum current required by a buck but I expected Makita to design the circuit to stay at 5v regardless of current.

So I will have to put a 100 ohm resistor across the battery (5v).  Or 4 LEDs ?

Is there any simple way to turn off this 50ma waste when the real load reaches 50ma ?


thanks