Even a clean battery contact will spark when you make or break a connection with a charger. A Positive grid’s spark amp is good. I believe that the charger current sparks through tiny particles of lead (which is soft) or metal or conductive dirt, which fluff in the air when you scrape the battery post as you connect the charger clip or remove it.
This is why there is a unique way you connect to a battery for charging or jumping. When you disconnect a charging car battery, the spark can cause an explosion. This is because hydrogen and oxygen can be generated by the battery when it is charged too fast or overcharged at the end (the water decomposes), and this gas mixture is very explosive! Proper procedures (look up jump start) prevent this explosion.
Noticing The Sparkling
The sparking you are noticing is usually found because of loose connections, yes. But how does it happen? Well, if your terminals are not clean enough or show signs of corrosion (either off-white or gray deposits or the metal surface looks rough and pitted). If the charging you are talking about is by torquing a bolt, the bolt might be loose, or if you are using clamps, the surface roughness may be making contact, but inefficiently so.
A wire brush is what you need, and what you are looking for is the clean, shiny metal.
Over time a thin layer of sulfuric acid builds over the terminal posts, leaving sulfate deposits to form. When using those clamp-type chargers, the soft metal of the terminals may become pitted and rough.
Clean it, and you will be ok.
What’s the most dangerous it can occur if you don’t??
I have seen them in a single battery jump-started from another car to huge phone backup banks and off-the-grid PV installations. All because of an insecure joint.
Remember that during recharging, there is hydrogen gas generation. Remember the Hindenburg? Under specific conditions (that can happen in real life, not just in the lab), you accumulate enough hydrogen gas waiting for a spark to ignited violently! It will shatter the plastic case, some times bits of the internal components, and acid, all sent in every direction.
Stay curious and very safe.
Positive Grid’s Spark Amp: A Solution
I estimate that less than 10% were due to the actual failure of the battery. The rest were due to user stupidity. No warranty in that case.
I live in Edmonton, Alberta, Canada. The North. Cold in winter. Cold.
Users wouldn’t plug in their block heater and then drain their battery, trying to start their vehicle.
Most of those years were as battery charger tech for lead-acid batteries — 2v to 80V.
It was fun, it was exciting, and I met a lot of great people. I also got to deal with the most amazing businesses.
People today have no idea of the knowledge, skill, and complexity required to give us our modern world.