Preventive Maintenance for Batteries

Dear Sir,

The Battery may explode if the same polarity is connectede. Or else the Sulphuric acid you have used may be highly concentrated.

Regards,

N.Suresh

tomhara:if it is a lead/acid battery it will generate hydrogen gas while charging, a spark may have caused the explosion. unplug or turn off the charger before removing clips, & ventilate room were batteries are. perry

The vapours of a breathing battery is hydrogen sulphide which is highly explosive,maybe in your case there was a spark/ cigarette smoke or a welding job nearby which might have ignited the explosion.

So far everyone has talked about lead acid batteries, with a brief mention of NiCds...

For a battery to explode (any variety) there must be more heat dissipated internally than the battery was designed for.

In the case of Lithium laptop batteries, the lithium has a natural reaction to air / water to explode/ burn.

This is why transporting lithium batteries by air is heavily regulated.

I have a personal experience that may more directly apply to your question, specifically about maintenance.

As mentioned above, the air space at the top of lead-acid batteries consists of a hydrogen/oxygen mix. This is because DC separates H₂O into it's gasses.

What the maintenance person must be aware of then are sparks. Usually sparks outside the containment of the battery don't cause trouble since, as mentioned, the gasses dissipate rapidly. (But it is certainly possible).

How then do maintenance procedures create sparks in the concentrated mixture inside the battery?

Batteries have terminals. When too much torque is applied in the tightening of terminal connections, eventually the internal end will break loose from it's connection creating a gap, and thereby a spark opportunity, in the concentrated gasses.

In the process of maintaining terminals, it is important to reduce the torque applied to the connections. As a comparison think of the methods used to reduce torque when tightening tubing connections etc.. Usually a second wrench is applied in the opposite direction to reduce stress on the tubing itself.

The other cases given in previous posts are all quite valid, but from my experience this is the most dangerous maintenance related cause since a person is often leaning over the battery while causing this spark, and the lead-acid mixture causes the primary damage, to vision etc.

Regards, CJ

Go to the web sites of the manufacturers and print off their safety leaflets.....

Hye guys

Thanks a lot for your generosity to throw some idea on the issue. Most of the causes from previous discussion are focused on the acidic battery which can produce Hydrogen (very explosive). That's why there are innovations on the battery itself whereby they equipped with regulated valve (VRLA) to vent the hydrogen out. Is there any possibility for alkaline type of battery (NiCd) to explode? Any incident related to the temperature&pressure?

Regards

Tom

Nicads should have a valve, that lets off water/steam if the battery gets too hot.

Due to this happening, it also loses capacity. Keep cool when charging, do not overcharge.

An old trick was to re-introduce a drop of distilled water to revive a battery, with a hypodermic, when they were relatively far more expensive of course!!!

What kind of batteries are you trying to maintain? Different types require different methods.

I can speak for lead acid batteries, but not NiCd or Li Ion. With lead acid batteries the positive plates tend to grow over time. Over charging will accelerate this growth rate. The battery cells start to short out as the positive plates grow beyong the seperators and sometimes all the way up to the straps. The battery also loses a lot of water over time especially from over charging. If a pos plate grows enough to short on a strap or the lug of a neg plate it will short out the cell. Normally the acid level is above the straps and this just kills the battery and often stinks like a ton of rotten eggs. If the acid level is low and the short occurs in the head space of the battery it will cause a spark and kaboom. Oddly often times this explosion like to occur right as you begin a heafty discharge which will scare the heck out of you. These explosions are not large fireballs, but they will spray acid around.

The prevention is to make sure your batteries are topped off with water. Check the owners manual for a watering schedule. Having worked in a battery lab I induced these types and many other types of explosions. This is the most common type. All other types are related to misuse (dead short) or defect (leaky battery and static shock).

Cheap chargers being used for too long are a good cause of all the problems you mentioned!!

That is exactly right. I have seen exploded batteries that were returned for claims where people were expecting to recover damages. Often a cheap charger is a constant current charger. These are ideal for quick charging because they are forcing the current into the battery. It is also good for a mix (helps mix the acid)charge at the end of a constant voltage charge, but we won't get into that. On a constant current charge once the battery is fully charged the current begins to cause electrolosis. Basically cooking off the water in the battery. These overcharges also accelerate the growth of the positive plates. When I used to work in a battery lab doing new product development one of the tests to compare variables was exactly this type of overchaging, but with twice weekly watering to prevent explosions. They just stink really bad when ones shorts out and they all short out eventually.

The best approach is to go through manual of the battery manufacturer and follow it.