How to avoid spark on when connecting my inverter to my batteries

[FrostyNugs]

Hi

I want to avoid the spark that happens when I connect my inverter to my batteries. I have seen some people say to use a resistor for a few seconds but I am not sure what wattage or ohm resistor to get.

My system is a Mecer 24v 1400watt Inverter + Two 12v 100 Amp/H Lead Acid batteries

 

[Crowz]

I'm sure someones going to say this is a bad idea but I'm planning on trying it the next time I need to hook up a battery to an inverter.

I watched a video someone linked in the forum here where they were running an inverter straight from solar with no grid or batteries but later on in the video they connected the battery bank and used a carpenters pencil between the battery terminal on the inverter and the cable coming from the battery. It made a tiny spark and then the connected the wires to the inverter with no more sparks.

Going to try it to see if it works at some point but maybe someone else will chime in if they do this or not.

 

[Supervstech]

Pretty much any resistor will work.
A pencil has a fairly low resistance, so spark reduction isn’t as good as with a 8 to 15ohm 100W resistor, or a light bulb for that matter…

 

[Crowz]

Here is a video I found googling it. Again I havent tried this myself.

 

[timselectric]

The graphite in the pencil works fine as a resistor.

 

[Crowz]

Here is the vid from Will covering what resistor to use.

 

[Supervstech]

Here is a video I found googling it. Again I havent tried this myself.

I find it odd that he doesn’t actually show it live reducing the spark… and shows a 12v inverter as an example… which doesn’t need the resistor…

 

[Crowz]

I find it odd that he doesn’t actually show it live reducing the spark… and shows a 12v inverter as an example… which doesn’t need the resistor…

Let me see if I can find the video thats on the forum here. The one I watched was a 6500 inverter I think and it was 48volts.

 

[timselectric]

The goal is to limit the flow of current. Long enough for the capacitors to charge.
Any resistance will work.
The amount of resistance determines how long it will take the capacitors to charge.

 

[Crowz]

Found it.

 

[Quattrohead]

Sparks are fun, they make you jump so you then create another one !!!!

 

[Crowz]

Its at the 11 minute mark in the video.

 

[v_green57]

Easy, no-cost solution:

Close your eyes when touching the cable lug to the battery post. Hold it there.

Open your eyes again to finish attaching the cable.

I've done this for years and it always, always works. ;-)

 

[Adam De Lay]

You can also do it fairly simply if you have a desktop power supply.

 

[timselectric]

Easy, no-cost solution:

Close your eyes when touching the cable lug to the battery post. Hold it there.

Open your eyes again to finish attaching the cable.

I've done this for years and it always, always works. ;-)

That's fine with led acid batteries.
But when you have a BMS, the surge can be enough to trip the discharge limits.

 

[Q-Dog]

Do you have a battery disconnect? (you should if you don't like sparks) A 24 volt inverter? I just hook everything up with the battery disconnects OFF ... then turn on the disconnects when I'm ready to power up the inverter. I think I've only powered off the inverter a couple of times when adding new stuff. Otherwise it never shuts down.

 

[v_green57]

You can also do it fairly simply if you have a desktop power supply.

But his inverter's not running yet...

 

[v_green57]

That's fine with led acid batteries.
But when you have a BMS, the surge can be enough to trip the discharge limits.

Truth.

But the OP did not indicate what battery tech he is running.

 

[FrostyNugs]

Truth.

But the OP did not indicate what battery tech he is running.

They are lead Acid batteries

 

[FrostyNugs]

Do you have a battery disconnect? (you should if you don't like sparks) A 24 volt inverter? I just hook everything up with the battery disconnects OFF ... then turn on the disconnects when I'm ready to power up the inverter. I think I've only powered off the inverter a couple of times when adding new stuff. Otherwise it never shuts down.

Even with the inverter not plugged in it makes sparks