Help with variable voltage Charger

[fesanand]

I've got a generic Chinese charger, customized for a 14S battery, final voltage 58.8V (14 x 4.2V)

My new battery is different, is a 15S battery.

I'm wondering if I can tune the final voltage (target 15s = 63V) adjusting the Variable Resistance (VR1 VR2 or VR3). Does anyone know what these 3 variable resistances adjust?

Thanks in advance!!

 

[mcintyretj]

Hi Fesanand,

Mine looks similar to yours. I just attached a voltmeter and rotated VR2 till it read 62.8 or so.





I did not touch anything else. It's been working fine for more than a year.

Tim

 

[dogman dan]

Correct, that's the pot you want to adjust. if it won't adjust all the way up for 4.2v per cell, it can still be used for a 90% charge or so.

One of the others will adjust wattage of the output (adjusts the amps actually). I'm not sure what the 3rd one does. With a watt meter attached and charging an empty battery, you can adjust the wattage by trying one, then the other, while making sure to put the one that is not wattage back were it was.

Increasing the voltage will mean more total wattage at the same amps, so you might want to turn the amps down a tad if you want the charger to run cooler.

 

[spinningmagnets]

Because of the sideways "S" shaped curve of lithium discharge voltage, charging to 4.1V per cell is highly recommended, and it actually doesn't lose you but maybe a minutes worth of riding. Due to manufacturing tolerances and the slightly variable resistances in each cell, the 4.2V per cell could be constantly putting a small amount of damage into the pack each time you charge.

When the digital meter reads 63V, is it really 63V? or maybe closer to 62V or 64V? And even if it truly is an accurate 63V for the whole pack, half the cells might be at 4.15V and the other half at 4.25V...which would still equal 63V. Try charging to 62V, and see if that gives you enough range to make your usual commute. If your battery is big enough to make the round trip between charges, then charging to (a presumed) 63V...it is a risk that can shorten the life of the battery unnecessarily.

 

[fesanand]

Thanks Tim.
VR2 made the trick.

Also thanks DogmanDan & SpinningMagnets. Now that I have a Variable charger I will play with voltages to max ratio lifespan/range 4.10-4.15V seems reasonable.

 

[Baron]

Hey sorry to resurrect an old thread, but how much were you able to adjust the final voltage? I am looking to buy a similar charger, based on the pictures you posted it's identical inside and out.

Say I wanted to charge both 12s and 16s lipo by adjusting VR2, would I be able to use a 12s labeled charger (50.4V) and adjust it up to the higher 16s (67.2V) voltage? Or is the adjustable range not that wide.

 

[999zip999]

I would like to know the limits as I turned up my kingpan (ping ) 48v 5a charger to 63v and worked great then to 72v and it worked for 3 weeks. I think it had 63v caps ( ? ) So replaced the caps with 100v ones and turned it up to 84v and it works. I only used it a couple times and Im a little scared of it. Should I be scared ?

 

[flippy]

If you replaced the caps you can usually go to about 90~95V no problem. But efficiency takes a dive. Lower the amps to keep the main transformer from melting and the diode from exploding.

Cut away the metal in front of the fan and rotate tje fan 180 degrees so it blows inwards.