overcharging

[jaacee44]

have seen several threads on equilizing (overcharging) does it actually do any good? i understand the concept of the scrubbing bubbles but do they really do enough to make it worthwhile?? just thinkin and stinkin

[scottyb]

I almost didn't read this because the title suggests another charger gone bad thread.
But Equalization is a very important part of a proper lead acid battery maintenance program. If you're not doing it regularly, you're batteries are not as healthy as they could be. Lets take a single 12v battery for example

In a normal three stage charging algorithm, the max charging voltage is 14.4 - 14.6 volts
 A 12 volt lead-acid battery is comprised of six 2 volt cells connected in series
 There is always an inherent slight imbalance in voltage between the six cells
 It is possible one cell will not reach the targeted 2.4 volts / cell because of this imbalance
 Increasing the charging voltage to 15.2 volts assures that every cell will reach at least 2.5
volts to remove sulphation
 Equalization, when done properly at a low controlled current, generates slight heating of
the electrolyte and forces current through plate areas that may be mildly sulphated
 The resulting effect removes any remaining sulphation and completely restores the plates
 Equalization must be time limited. Some cells can experience excessive overvoltage and
cause permanent battery damage
 The equalization process only works on lightly sulphated plates. It will not work for heavily
sulphated plates

[scottyb]

Sulphation of the positive and negative plates is a normal occurrence during the
discharging of a battery
 Equalization can be used to desulphate a mildly sulphated battery if the recharging
process failed to complete the reversal
 Equalization is not required after every recharge cycle
 Battery recharging should be performed in a timely manner to convert the lead
sulphate PBO4 in the plates back to lead Pb and lead dioxide PBO2 quickly
 The battery should be recharged as quickly as possible after discharge to prevent
excessive and permanent sulphation
 The degree of sulphation is determined by the length of time the battery remains in a
discharged state
 A desulphation device is required when the sulphation has become excessive,
preventing the battery from conducting electric current and accepting charge

[JohnnieB]

Originally Posted by jaacee44

have seen several threads on equilizing (overcharging) does it actually do any good? i understand the concept of the scrubbing bubbles but do they really do enough to make it worthwhile?? just thinkin and stinkin

Scotty covered the need for equalization, but there may be a misconception about gassing (scrubbing bubbles?).

The bubbles are a byproduct of DC amps passing through the diluted sulfuric acid electrolyte. The water in the electrolyte decomposes into hydrogen and Oxygen gasses (aka Electrolysis), which rise to the surface as bubbles. Other than de-stratifying the electrolyte if the battery has been sitting still for more than a few hours, the bubbles serve no purpose. Charging and/or equalization occurs whether the bubbles occur or not.

Battery aging (sulfation of the plates) is inevitable. Recharging after each use and equalizing occasionally, slows the aging process, so it is worthwhile.

[mutant]

thanks for sharing and supporting this community and educating our minds...this board is just SO cool!

[scottyb]

I agree There is more battery info on my website.

[jaacee44]

thx for info, some sites say don,t waste money on desulf,, machines then others say to just overcharge for a period. most chargers won,t charge long enough to help, even if you use 12 volt chger and do 2 batt,s at a time most newer ones will shut down after a certain voltage is reached. but at any rate you fellows know your stuff

[Perry007]

On this same line of thought....

How much different is the three stage charging algorithm compared to the DPI?

Should all batteries have a Equalization charge no matter what charger is being used?
(or are there chargers that have the same concept build into their charging stages?)

[JohnnieB]

Originally Posted by Perry007

On this same line of thought....

1. How much different is the three stage charging algorithm compared to the DPI?

2. Should all batteries have a Equalization charge no matter what charger is being used?

3. (or are there chargers that have the same concept build into their charging stages?)

1. It depends on what is considered a charging stage. DPI's Pre-qualification stage and Float Charge stage aren't true charging stages, so it is basically a 3-stage charger rather than a 5-stage charger.

More correctly, DPI's Pre-qualification stage, is a low power charging stage that checks if it is safe to charge the battery pack at full power. Some chargers will not turn on unless the battery pack is above some predetermined voltage, but the DPI attempts to charge a severely discharged pack with a constant current of about 5A and if the battery pack climbs to over 1.75VPC (Volts per Cell) within 5 hours, the charger progress to the Bulk-Charge (Constant Current)stage , then to the Absorption-Charge (Constant Voltage) stage and then to the Finish-Charge (Constant Current with dV/dT cutoff) and finally it goes into the Float-Charge stage. In addition, after being in the Float-Charge stage for 28 days, a new charge cycle is initiated.

2. Yes. About once a month, or whenever the At-Rest voltage varies by 0.1V or more between individual batteries.

3. By initiating a charge cycle after being in the Float-Charge stage for 28 Days, the DPI charger effectively equalizes the battery pack automatically when in extended storage. Other chargers may have similar features.