GreenBikeKit Charger Voltage

[Suggs]

I recently bought a 120W lithium battery charger from GreenBikeKit for my 48V 12Ah lithium battery pack. With it being 48V lithium I selected a voltage output of 54.6V to match the pack.

I've now bought some LiPo batteries from HK and hope to use the charger to bulk charge them. My LiPo pack (6 x 22.2V 5200Ah) will be 12S3P so 44.4V and 15,600Ah. Does anyone know if I can dial down the charger to 50.4V using either of the two potentiometers in the photos below?

Any help on if it's possible and how to do it would be very much appreciated.

 

[ccmdr]

Tbh the best way if your unsure is to mark the current position of both pots, connect a fluke and adjust, no voltage movement, reset postion move on . The EMC600 manufacturer set at 63V, could get down to 49V. So your most likely be able to drop it 3V.

Just make sure you have a steady hand if your adjusting it 'live', but if your not happy with electrical devices always isolate at the wall before adjusting anything :wink:.

 

[Suggs]

If I stick my DMM on the charge pins (without the battery connected) I get a reading of 54.4V. Could I just adjust the potentiometers 1 at a time until that goes down to 50.4V? I assume one potentiometer does voltage, the other current? Or.... do I need a battery pack/load connected to do it accurately?

I have a GT Power watt meter that could maybe be put between charger and battery pack to monitor voltage and current?

 

[Suggs]

I googled the reference code on top of the 14 pin amplifier in that last photo and found the following if it helps at all?!

The LM324N is a quadruple op amp (Operational Amplifier) in 14 pin DIP package. It consists of four independent high gain frequency compensated operational amplifiers. Designed specifically to operate from a single supply or split supply over a wide range of voltages. The LM324 features open loop differential voltage amplification of typically 100V/mV and internal frequency compensation.

•Single supply voltage range from 3V to 32V and dual supply voltage range from ±1.5V to ±16V
•Common mode rejection ratio (CMRR) is 80dB
•Slew rate at unity gain is 0.5V/µs
•1.2MHz unity gain bandwidth
•Low supply current is typically 0.8mA (independent of supply voltage)
•Common mode input voltage range includes ground, allowing direct sensing near ground
•Input offset voltage is typically 3mV
•Input offset current is typically 2nA
•Differential input voltage range of 32V equal to maximum rated supply voltage
•Operating temperature range 0°C to 70°C

 

[Suggs]

Any other thoughts/comments before I start fiddling this weekend?!

 

[ccmdr]

Don't quote me on this, but my EMC must have an auto sensing feature that chages the current output at various voltages as you can audibly 'hear' a contactor after every volts.

I'm no circuit designer, but one will change voltage the other won't. If the current isn't autosensed you would have to inline charge a battery and adjust. For the sake of a 3v change I doubt the current change would be worth the hastle.

To adjust the voltage, as you've done already just probe the output connector. You'll see a voltage change immediately with only a 1/4 turn. The whole process will take 3 minutes if that :wink:.