Battery Charging

[Vev]

Why does my battery charger asks me if my battery is a Gel or Lead Acid? Whats the difference in charging these batteries?

 

Cheers

 

Vev

 

 

[Guest nunans]

• 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.
   
  Basically, an AGM can do anything a Gel-cell can, only better. However, since they are also sealed, charging has to be controlled carefully or they too can be ruined in short order.
   
   
  

 

 

 

 

[greybeard]

Here ya go http://batteryuniversity.com/learn/

 

 

[planedriver]

Quite well explained nunans. To some, a battery is just a battery.

 

I'm sure your explanation helped others understand some of the differences.

 

Some don't realise that if you charge certain batteries the wrong way, there is also a possibility of the K'boooom factor,

 

 

[Phil Perry]

Bit like power tool batteries really,. . . .

 

I've had a power dril that I purchased ten yars ago,. . .it has two battery packs, and these are Nicads. If you don't discharge them completely, they will not last very long. . . when I've had a bit of a day with the drill. . . I wrap a bit of masking tape around the trigger and allow the drill to discharge the battery to absolut zero. That way, they last longer. . . . I recently replaced them with Nickel Metal Hydride cells.

 

This way, the batteries will never produce the weird NiCcad battery problem often described as "Memory" wheich exhibits as the disability to discharge below a certian point, at which the machine fails to work any more, when you "Feel" that it ought to.

 

This is due to the build up of sodium hydroxide whiskers which build up between the terminals of the battery and discharge it to ground well before it's designed charge limit.

 

You can remove these "whiskers" by discharging a large volume electrolytic capacitor across the battery terminals,. as long as you have available a bomb proof suit,. . . ie the ones they used in Iraq when they were defusing I.E.D.s. . . .as . . .sometimes,. . . .for no apparent reason. . . .they go bang in your face.

 

The best alternative, is to go to a place which will exchange your drill batteries for Nickel Metal Hydride cells. . . ( At a few dollars fifty. . .).as these, are brilliant,. . .they have no Sodium Hydroxide generated "memory" and may be charged from any point in their discharge cycle without harm. . . .( these are the preferred batteries in your current mobile phone, Laptop, or Ipad, or whatever. . . ) I have not managed to make an explosion out of one of these batteries thus far, but give me time. . . . .

 

Stay safe. . . . . .

 

Blaster Perry.

 

 

[Sapphire]

I think I'll stick to basket weaving.

 

 

[facthunter]

The fact is the methods of charging and the voltages vary so many are not simply replaceable with another type. My son's Van has a big NO PB sign on the battery cover. Nev

 

 

[planedriver]

. My son's Van has a big NO PB sign on the battery cover. Nev

Presumeably indicating non-lead.

 

If the battery was then changed with the common lead acid type, the charging system would probably not be suitable.

 

Out of curiosity, what type of van Nev?

 

 

[facthunter]

2005 transit 6 speed TDiesel 350. Nev