when a battery goes bad, does it smell like sour ***?
a 7 I'm working on, smelled like crap when I was test driving it. my friend said that its the battery, and that when they go bad they smell like that. so I disconnected the battery and the smell went away.
I've never heard of this, is it true?

 

That was especially true of batteries before they became maintenance free. They would eventually lose all their water, and give off a distinct strong sulfer smell. It stands to reason, since sulfer is the "S" in H2SO4, i.e., battery acid.

You don't smell it too much any more, because maintenance free batteries tend not to go dry. But, it can happen.

Edit: If your battery is dead, and you smell sulfer, see if you can get the cover off the cells, and add water before charging it back up.

 

Ummm... This information is not entirely correct. The sulfer smell is indicative of a POTENTIALLY HAZARDOUS problem. Dont take my word for it:

 

That would be distilled water you add to batteries. Not filtered or deionized water. Minerals in regular water will slowly neutralize the acid...

 

^
It was correct in stating it was a dried out battery... it just didn't go far enough. I agree with you about the voltage regulator, and should have said that.

I treated the symptom; you treated the cause!

 

I just dont want them blowing themselves up... Thats a dangerous condition. Hence the reason I use Optimas... I hate lead/acid batteries.

 

Optima = PbA

And a poor quality one at that...Most of the EV racers are abandoning them for better built units like the Exide Orbitals, Deka Intimidator, etc.

 

Yep.. You = correct. I should have been more specific and said that I hate CONVENTIONAL lead acid batteries. The chances of an Optima or any GEL or AGM battery outgassing is pretty low to non-existant..


Some good reading:

Flooded or Wet Cells are the most common lead-acid battery-type in use today. They offer the most size and design options and are built for many different uses. In the marine business, they usually are not sealed so the user can replenish any electrolyte the battery vented while charging the battery. Typically, the cells can be access via small ~1/2" holes in the top casing of the battery.

The plastic container used for flooded cells will have one or more cells molded into it. Each cell will feature a grid of lead plates along with an electrolyte based on sulphuric acid. Since the grid is not supported except at the edges, flooded lead-acid batteries are mechanically the weakest batteries.

Since the container is not sealed, great care has to be taken to ensure that the electrolyte does not come into contact with you (burns!) or seawater (chlorine gas!). The water needs of flooded cells can be reduced via the use of Hydrocaps, which facilitate the recombination of Oxygen and Hydrogen during the charging process.

Gel Cells use a thickening agent like fumed silica to immobilize the electrolyte. Thus, if the battery container cracks or is breached, the cell will continue to function. Furthermore, the thickening agent prevents stratification by preventing the movement of electrolyte.

As Gel cells are sealed and cannot be re-filled with electrolyte, controlling the rate of charge is very important or the battery will be ruined in short order. Furthermore, gel cells use slightly lower charging voltages than flooded cells and thus the set-points for charging equipment have to be adjusted.

Absorbed Glass Mat (AGM) batteries are the latest step in the evolution of lead-acid batteries. Instead of using a gel, an AGM uses a fiberglass like separator to hold the electrolyte in place. The physical bond between the separator fibers, the lead plates, and the container make AGMs spill-proof and the most vibration and impact resistant lead-acid batteries available today. Even better, AGMs use almost the same voltage set-points as flooded cells and thus can be used as drop-in replacements for flooded cells.

Virtually no gassing under normal operating conditions: Unlike flooded cells, gel cells and AGMs are hermetically sealed and operate under pressure to recombine the oxygen and hydrogen produced during the charge process back into water. You find VRLAs in the bilges of high end yachts such as Hinckley, Hans Christian, Island Packet, etc.. Every boat benefits from a low center of gravity over the keel (good for righting purposes) and the minimal venting requirements make it possible.

 

its a maintenance free battery, and it is still green in the little window. but there is something wrong with the electoral system

 

<snip>


I like the "under normal operating conditions". The people I hang with use them in drag EVs that will pull 3000+ amps during a 1/4 mile run. They can sag a 336V pack down to 250V and below. This current will cause almost any battery to gas, sputter and/or blow up. Lately they have noticed that the Optimas are being made with very weak intercell connections. They quickly overheat and then blow up. The Exide Orbitals can apparently push these currents without breaking a sweat, as can the Deka batteries. Not really relevant for day to day use, but interesting information nonetheless.

Personally, I've had bad luck with the Optima. I killed a RT after only a few accidental cycles (less then 5). The RT is not deep cycle, but even the cheap Autozone/Canadian Tire/NAPA batteries handle abuse better then that. The replacement Optima had a bad cell from the factory.

 

well, I dont drag EVs, so I cant speak intelligently on the merits of the Optima vs others, but in the Tucson heat, the Gel Cel batteries seem to vastly outlast conventional. Either way, I have seen what happens when a battery explodes. I dont want to risk (or at least lower the risk) of those gasses excaping into the engine bay.