Adjusting cut-off voltage of EMC-120 charger from bmsbattery

[quuxman]

I'd like to adjust the cut-off voltage of my charger so I can set it to charge my battery to 80% for optimum lifetime. I'm just never going to figure out the timing to unplug it around the right time, especially since I'll be charging from a random level of discharge. I opened up the charger and found 3 pots, but don't know which to adjust or how to know what I'm adjusting to. Can I simply attach a volt meter to the output with no load to measure what I'm setting it to? I'd rather not experiment with all three to see which adjusts the cut-off.

Also I'm thinking about removing the PCB, unsoldering the POT and either mounting the existing one in the case, or maybe mounting a plug where I can stick in specific resistors for the 2 - 4 values I might want.

 

[quuxman]

Or maybe even better, is there a 36-48 V ~120 W charger on the market anywhere that has an easily user adjustable cut-off voltage?

 

[Jon NCal]

It's the one called VR2, off by itself. Set the voltage level with a multimeter attached to the output.

I have mine set also for 80%, 4.05V per cell. I was thinking of drilling a hole in the cover and then gluing a small stick to the pot so it could be adjusted without opening. I also am planning on attaching a small voltmeter to the output wires for easy reference.

 

[quuxman]

Ah awesome. Thanks! I was thinking of unsoldering it and glueing it to the case, or maybe swapping it with an equivalent pot with a bigger shaft. I have a good volt meter for exactly this kind of thing sitting around:

https://www.amazon.com/Digital-Display-Voltmeter-Voltage-Detector/dp/B016JQ2P6U

Maybe I'll get one or two more, because I was planning on installing it on my bike with a computer display that doesn't show voltage for some dumb reason.

 

[bardbe]

Jumping in on this old thread as it covers my questions. I have a couple of these chargers I bought second hand with a motor kit. Both are 36V, but I run mainly 48V batteries. The box has tickmarks for 12-48V so I figured it might be a universal charger with adjustment of output V/I. I opened it up and found 3 pots,but didn't want to adjust randomly to see if I could up the voltage. Thanks to this thread I found out that VR2 adjusts the output and I can easily get it to 54.6, so that is great news, as it makes it possible to adjust it to anything up to 13S battery as well as % of full charge!

Now my question is; It says 36V/2.5A and 48V/2A. Since I just increased to 48V, the current limit is probably at 2.5A, which might overload the charger. Does anyone know what the 2 other pots, VR1 and VR3, does in terms of current limiting, and how to anjust them?