precharge a battery charger like an inverter to avoid sparks?

[Helles]

I learned from Will's video that you should pre-charge an inverter before connecting to the Lithium battery bank, by bridging the negative cable from the inverter to the negative battery pole with a resistor for some seconds.
Do I have to do the same with a normal battery charger (fed by 220 V)? Because when connecting the charger, I sometimes get a spark, too.

 

[upnorthandpersonal]

Getting a small spark is normal - the spark you get (and inrush current in general) for an inverter is much much more than a typical charger due to the large input capacitors on the inverter. So, no, not needed for a charger and getting a small spark is normal and nothing to worry about.

 

[Frick]

i used a battery A-B-both-off switch (typical marine kind) and wired a 20ohm 100watt resister from A to B terminals. batteries are connected on B. so when i rotate from off to A i get the resister and watch the voltage come up. its fast to 12v , then a few seconds to 18, then twice that time again to 24. maybe 10 seconds total. then i click over to B and its going. i hope that makes sense, a pic is better but not possible right now. im super pleased with it, is simple and does what i wanted it to.

 

[Helles]

Getting a small spark is normal - the spark you get (and inrush current in general) for an inverter is much much more than a typical charger due to the large input capacitors on the inverter. So, no, not needed for a charger and getting a small spark is normal and nothing to worry about.

thanks a lot. Completely answered my concern.

 

[Helles]

i used a battery A-B-both-off switch (typical marine kind) and wired a 20ohm 100watt resister from A to B terminals. batteries are connected on B. so when i rotate from off to A i get the resister and watch the voltage come up. its fast to 12v , then a few seconds to 18, then twice that time again to 24. maybe 10 seconds total. then i click over to B and its going. i hope that makes sense, a pic is better but not possible right now. im super pleased with it, is simple and does what i wanted it to.

I like the idea! Thanks a lot!