Spark when connecting Charger

I purchased a MEAN WELL USA Inc. / PB-360P-48 charger recently from Digi-Key. I have a 16S LifePo4 battery pack. I have connected a 16 awg wire from the positive terminal of the charger to the positive post of the battery. When I attempt to attach a 16 awg wire to the negative terminal, it sparks. This is prior to even plugging the charger into a receptacle or powering up the charger. The batteries are connected in series correctly and my BMS works properly.

Any idea of why this is happening or do you think I might have a faulty battery charger?

Thank you,

Mark Van Velsor

It’s possible that the battery itself is simply discharging enough to cause a spark. What is the total voltage of the battery bank? One possible way of avoiding this is bridging the battery terminals with a capacitor to get rid of any built up charge. If there is no power to the supply, then that won’t cause the sparking (in my mind anyway).

Kaleb, thanks for the quick response. I believe you are correct. Right now the voltage is at 51.7v. I got the spark when I was attempting to connect the battery charger wire, the BMS wire and and a wire from the battery together with a nut and bolt. The plan is to have them connected at all times. I will try your suggestion. Thanks again!

There are almost certainly a number of filter capacitors in the charger’s output that will be in a discharged state upon connection of a pack, and would approximate a short circuit for a small fraction of a second when the battery is connected, resulting in a spark. Not disconnecting/reconnecting often? Probably not a big deal. Otherwise, pre-charging those output caps by initially connecting the battery through a resistor of perhaps 10K ohm or so for ~15 seconds should reduce the surprise factor considerably.

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Thanks for the information Rick…I appreciate it.