12v battery voltage drop

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mohsen 2012

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Hello , I purchased a battery from long time and i don't use it .
today when i try to power a 12v car bulb with the battery, the bulb is lighting slowly and the voltage is drop to 6 volts under load !!!!
please help me .
thanks
 

i want to know if there is some solution , if the battery is fully damaged i will buy another one.
thanks
 

I try to recharge it with 14.2 volts from a variable power supply during 5 hours , but the problem don't solve , the voltage of the battery after charging is 11.33 volts and the bulb is slowly lighting!!
 

I think it can't reach 12V
Don't wast your time
 

Batteries tend to self-discharge if left to sit for a long enough time. They have a longer life if kept fully charged.

Is your 12V battery a lead-acid type? Sulfation is the common problem which they develop if left idle for a long time. It is not easy to determine if you have this problem. There are techniques for removing it, but it is not easy to make sure whether it is working.

There is a chance that you can get the battery to behave normally (or almost), by putting it through a few charge/discharge cycles.
 

BradtheRad said:
Batteries tend to self-discharge if left to sit for a long enough time. They have a longer life if kept fully charged.
Click to expand...

Moshen has not told us how long the battery was sitting idle;
Whether the battery was initially charged or new (not charged or discharged)- if it were new (never charged), there may be some hope left.


Best to take it to a car service fellow, they usually have facilities for a thorough testing.

There is a chance that you can get the battery to behave normally (or almost), by putting it through a few charge/discharge cycles.
Click to expand...

Sulfation can be partly recovered by supercharging. But the overall capacity will be considerably reduced.
 

I have never purchased a brand new lead-acid battery. How do they come? Of course they are not pre-charged. Do they have any electrolyte in them? Maybe this battery is still empty from when it was purchased.
 

The way I heard it, a store charges a lead-acid battery, then drains out the acid. The lead plates store the electrical potential within their chemical makeup.

When the store sells the battery, they fill it with acid. Thus it is ready to use with no need to charge.
 

I have bought several new lead acid car batteries, and they always come filled with acid and supposedly ready to go.

When I was on an Antarctic expedition, the new lead acid batteries arrived in packing crates dry, with the acid in plastic bottles.
I suppose that was because when transported in ships and aircraft there is no guarantee the crates containing the batteries will be loaded right side up.
 

If the voltage only reaches 11.33V after charging when measured off load then one cell at least has gone short circuit. Open up the top of the battery and check which cell it is - could be two. Cells going short circuit is due to over charging so the lead falls of the plates and bridges them or the plates buckle with the heat. This could be done by applying the full voltage to a 5 cell battery, cos' one is short circuit. If it was an expensive battery it could be drained and the problem sorted out. The low capacity is caused by a layer of lead sulphate growing over the surface of the plates. This is an insulator so it stops the plates acting as their full surface. It can be mitigated by using a high voltage high frequency pulse wave form. The high frequency tends to spread the current more over the plates and will peel the sulphate off.
Frank
 

Hi,

I try to recharge it with 14.2 volts from a variable power supply during 5 hours
Click to expand...
This says nothing.

A battery has a Ah rating. And a battery needs a dedicated chrging method according it´s chemistry.

For lead acid a constant charge current of 1/10 x Ah-rating is a good start.
Then charge it until it reaches 13.8V (continous charging) or 14.4V (one cycle charging).
After that you should decrease current and limit the voltage to the given values.

A complete charging cycle may take more than 10 hours.

****
Best is to look on the manufacturer´s internet sites for information.

Klaus
 

It is like a can of worms- once you open it you cannot put it back. I guess you need to get a new one. It has been welded around the rim and once you 'cut' it open you will need to handle lots of nasty acid- quite corrosive sulphuric acid that is a problem to dispose.
 

Hi,

I think this is what the word "sealed" printed on the battery means.

Klaus
 

Please explore whether the seller offers an exchange: you could get upto 20-30% from the price of the new one. I guess they recycle the lead which is also an environment issue.
 

May be your battery passed off. I sugest you to charge it for 1 day to see what happens. But when this type of battery lowers as to half, it is sure in bad form..
 

That little code on top suggests to me that it was manufactured in month 7 of 2014.
If it has been left flat since then you may be out of luck, put it through several charge\discharge cycles.

Or just buy another & next time take better care of it
 

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