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Battery float charger made battery spark

So after jumping my car and driving it around to charge it, I tried to hook up my harbor freight battery float charger, I followed the manual and hooked up the negative first, then when I when to hook up the positive it sparked, and the red dot on the charger was lit red even though it was not plugged in. I immediately removed the cables after the spark. What should I do next? I really need to use this float charger.

Well plug it in and hook it up.

Remove the negative battery cable, and then connect the battery charger.


Sparking can cause a battery explosion. Why would I hook it up the same way?

Call a wrecker and send it to a shop…

Make sure the polarity is correct, now in my mind I usually do the negative last to a body point so if there is a spark any combustive gasses from the battery will be out of play. Do not plug in the charger until after the connections are secure, or like my favorite bomb deactivation bud loves to note, in the manual, cut the red wire after first disconnecting the black wire. Read all instructions.

Why would it spark if it is not even plugged in?

So, the spark came from the charge in the battery. (“So after jumping my car and driving it around to charge it, …”)

I do not know why it would spark, most probable guess an open short in the system. Was the key in the off position, Perhaps you have more info on why you are at this point to begin with,

That might be your problem. I’ve used a Schumacher Battery Maintainer for years.

When all else fails READ THE INSTRUCTIONS comes to mind here.

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The key was in my pocket. I am not aware of any short, the electronics in the car all work fine. When I hooked up the positive terminal there was plastic on 3 sides of the round metal piece below the plastic cap, and I figured it would not conduct, so I put it on the bolt attached to the round piece, could this be the cause of it sparking?

If this is the vehicle that the OP needed help deciding where to get a battery for a few months ago the solution is get a new battery and quit wasting time.

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What model is your Schumacher Battery Maintainer? I might get that instead of the harbor freight one. I looked online and they come in 1.5, 2, and 3 amp. Which one should I get?

And to volvo I already replaced my battery a couple months ago.

I have the 1.5 amp.

Added: Mine doesn’t appear to be made any more, but the current one would be:

If it is not holding a charge then it needs to be checked or find the reason it is running down. I had a truck that sat unused for weeks at a time and it started OK without a jump.

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Can anyone confirm if it matters if you put the cable for the positive terminal on the round metal part or the bolt attached to it?

It doesn’t matter as long as the positive cable from the charger is connected to the battery positive terminal.

I will strongly suggest that if you get a charger working it might be a good idea to unplug the charger before you disconnect the clamps after charging it for a while.
I’ve seen a few batteries explode accidentally and it can be very dangerous.

If the new battery is not holding a charge then you need to check (or have it done) for a parasitic draw. Make sure the trunk light is actually going off… :wink:

I assume by round metal part you are referring to the part around the battery post & the bolt is what is tightened to clamp it tight . If so , either should be ok .

If the float charger has a capacitor in it – which it may have – when you connect the float charger to the battery even with the float charger not plugged into AC, the battery will still charge up that capacitor as you make the connection to the battery, and that initial current surge to charge the capacitor could be quite large & produce a spark as you made the connection. I’ll add however that when I connect my normal (not float) charger in the same way you describe, there’s no spark as long as it isn’t plugged into AC. That charger is a 2/6 amp version and may not have use a capacitor. I expect what you are observing is just the way that gadget of yours works. Good idea to wear eye protection tho, if sparks are produced anywhere near a battery.