Question about car battery chargers

Reptile · 2 Feb 2023

Dumb question maybe but how do battery chargees workd,i dont mean how to hook it up,more like how does the needle work,does it go from right to left when charging?If so,this makes no sense for me cuz everything we do we go from left to right.Btw,it's an Einhell battery charger,german product.I'm trying to charge my car battery,its a 12v battery,first time i plugged it in it was around 6 v but what irritates me is that the needle goes from right to left,now it sits around 3v,i turned it off once and connected it again at it was at around 9 volt then it started going down from 9 and now it is around 3 as i already said.Does it show how much volt the battery is after you plug it in and then it starts charging it from right to left,is that the case here?I dont know much about this stuff and i saw old car charger batteries going from right to left,what about the newer one?

Reptile · 2 Feb 2023

From left to right(upper numbers) it has numbers 0,2,4,6,8 and then again from left to right but down 0,3,6,9,12.So,what am i looking at here,can someone explain a little?

jj4091 · 2 Feb 2023

Throw out your old charger & buy a new smart charger.

Avocet · 3 Feb 2023

It is normal for a lead-acid battery that has gone flat, to charge at a high current and then the charging current gradually drops. However, the charger you describe is old technology. As jj4091 says, modern "smart" chargers are much better. They are faster and better for the battery. Having said that, if your battery was as low as 6V to start with, then it is probably irretrievable.

Harry Bloomfield · 3 Feb 2023

Reptile said:
first time i plugged it in it was around 6 v but what irritates me is that the needle goes from right to left,now it sits around 3v,i turned it off once and connected it again at it was at around 9 volt then it started going down from 9 and now it is around 3 as i already said.Does it show how much volt the battery is after you plug it in and then it starts charging it from right to left,is that the case here?

I think you have maybe confused volts, with amps. Old fashioned chargers, usually had a meter, which showed charge current - amps. Low to high, left to right. A near flat battery, would take a high current initially, until the battery voltage came up, then the charge current would reduce to a lower level.

Really, modern chargers are much better and safer for the battery, than the old ones.

Justin Passing · 3 Feb 2023

Is it one of these?

It's reading amps (amperes is the long name for the same thing) ( current) not volts.
It'll charge at high current to begin with, then the current drops as the battery charges up.

If it sits at a couple of amps over night it won't do any harm. Don't leave it on forever.

Reptile · 3 Feb 2023

Justin Passing said:
Is it one of these?

It's reading amps (amperes is the long name for the same thing) ( current) not volts.
It'll charge at high current to begin with, then the current drops as the battery charges up.

If it sits at a couple of amps over night it won't do any harm. Don't leave it on forever.

Yes,that's the one, just 10 ampere it says.What i just wanted to know does this one when it charges a car battery (the needle) go from right to left instead of what is common in most stuff from left to right.Anyways,it charged my car battery because today i could turn on my car but im still confused on how this works.Explanation in lame terms please,does it charge from right to left(needle going from right/empty to left/full)

Stivino · 3 Feb 2023

In layman's terms, it goes from the high number to the low number.

flameport · 3 Feb 2023

Reptile said:
Explanation in lame terms please,does it charge from right to left(needle going from right/empty to left/full)

It shows the current going into the battery.

It's NOT a gauge to indicate how charged the battery is.
That type of charger doesn't have any indication of battery status.

Harry Bloomfield · 4 Feb 2023

flameport said:
It's NOT a gauge to indicate how charged the battery is.
That type of charger doesn't have any indication of battery status.

The indicated charge rate will decline, as the battery nears fully charged, but other than that, nothing. The idea was to check the battery with a hydrometer, to determine the state of charge. but that cannot be done on modern, sealed batteries.

Reptile · 4 Feb 2023

Ty for all the explanations guys but the most important thing is that i could charge the battery and it works now