Forum Discussion

MEXICOWANDERER's avatar
MEXICOWANDERER
Explorer
Aug 21, 2014

CHARGING TERMS Bulk/Absorbsion/Float

Lots of confusion about these three terms. Let's simplify things a little.

We have a TWO STAGE CHARGER. The main charger and a float. Not a three stage, that's a bunch of marketing hooey.

The MAIN charger has a VOLTAGE LIMITED point. The voltage rises to this limit point in volts then stays there for god only knows how long before voltage is changed to a much lower maintenance value for maintaining the battery in hibernation.

Let's keep temperature compensation back behind the barricades on this one. This is a simple accurate explanation.

You connect the charger to the battery and turn it on.

As long as the battery is charging and the voltage is rising, slow or fast HAS NOT REACHED THAT AMBIGUOUS pre-determined and preset voltage set point IT IS CALLED BULK CHARGING.

The voltage keeps rising and bingo, it reaches the voltage set point whatever the hell the nut farm slide rule boys at the manufacturer has determined to be the maximum voltage charge point.

WE NOW CALL THE CHARGING PROCESS "ABSORBSION" and forget about the word BULK.

The voltage limit has been reached. How LONG the voltage stays steady and the battery is allowed to charge is anyone's guess - Groucho, Harpo, and Zeppo now have control of the charging process. WHEN, HOW LONG? I ask. How long does the battery stay at "absorbsion" voltage limit before dropping down into float?

The absorbsion VOLTAGE LIMIT (setting) and time spent at this voltage limit...

SHOULD HAVE THE ABILITY TO BE ADJUSTED BY A USER

But they don't have that ability. I would like to see one that does...

This is like a car that automatically goes 37 miles an hour. In bumper to bumper rush hour or across the wilds of West Texas.

But knowing what your SMART CHARGER

CANNOT POSSIBLY DO

Should be job one. Learn about the mess that is under your counter and the gyro gearloose smart chargers that are purported to be "better".

INTELLIGENT battery charging DEMANDS adjustable voltage set points and ADJUSTABLE time spent at absorbsion.

Good luck trying to find these features.

Press a button, take a pill, Don't Worry be Happy!
  • red31's avatar
    red31
    Explorer
    Aug 21, 2014
    Boost is what WFCO does, supplement, like a boost over the fence. If the fence ain't very high, 'it' doesn't help out with a boost.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 21, 2014
    To label something as process "normal" means there has to be something commonly found abnormal to compare it with.

    Boost means to supplement. A rocket booster, a boost over the fence, a wage boost.

    If a charger is not in "Boost" what's it supposed to be doing?

    "Hey Delbert, you know those EPROMS we ordered from India..."

    "Yeah?"

    "I just exercised one, and the voltage control has some sort of weird plateau"

    "Huh. Better call administration"

    (Later on - two floors up)

    "You mean to tell me this makes our charger different than anybody else's?"

    "New model charger! Improved! Make it happen!"
  • Salvo's avatar
    Salvo
    Explorer
    Aug 21, 2014
    Nice graph! The PD is actually in current limit. I don't recall seeing that before. Usually current decays from the start. What's different? AGM?

    BTW, your stage descriptions are not correct. The first phase is current limit, not voltage limit. When the current starts to decline (105 min) then the converter goes into voltage limit. It remains in voltage limit for the rest of the charging period.

    AH64ID wrote:


    I have also labeled the PD names for stages for reference.

  • AH64ID's avatar
    AH64ID
    Explorer
    Aug 21, 2014
    I have had several discussions on this, where one battery charger is labeled 2 stage and one is labeled 3 stage but they both charge the same way.


    Here is my chargers graph from 50% SOC. I have put some labels in here. The entire chart is the Main Charge, as I didn't monitor/graph all the way to a float.

    You can see where the voltage set point cannot be obtained, it's then obtained and help, and finally the voltage set point drops.. all part of the main charge.

    I have also labeled the PD names for stages for reference.

  • BFL13's avatar
    BFL13
    Explorer II
    Aug 21, 2014
    The so-called "three-stage" converters are to blame for the terminology confusion. With those each "stage" is just a different level of voltage but they name them as though they were charging profile "stages".

    Meanwhile the battery itself has the three "stages" in the profile Mex describes.

    You have to pay close attention to context when people use the terms so you don't get mixed up what they are talking about.

    Then you have Vector chargers like the VEC1093DBD, which are programmed to "trip" from constant amps as battery voltage passes through 13.9v. That is "Stage 1"

    Amps now taper but voltage continues to rise all the way through "Stage 2" while amps continue to taper. So max voltage is reached just before they shut themselves down and say FUL (they claim to have a "Stage 3" at the end but if you blink you will miss it)

    So they do not have a constant voltage for Absorption, but a controlled one from 13.9 to 14.8 while amps taper. This has the effect of slowing down the taper of the amps to a less steep curve and that keeps the time to get it done shorter.

    You might ask why not just let it go to 14.8 and hold that while amps taper from there? Power requirement. The Vector is at max power at that 13.9/40a point = 556W. when it "trips" Later amps are down to say 35a with voltage now up to 14.2. 14.2x35 = 497 and so on

    If it went to 14.8 before dropping from 40a, that would be 592w

    Poor Mex would go even more crazy seeing that, where it is not in Bulk with voltage rising it is in Absorption with tapering amps.
  • time2roll's avatar
    time2roll
    Nomad
    Aug 21, 2014
    MEXICOWANDERER wrote:
    "BOOST" Which idiot came up with that buzzword?
    I use this term constantly.

    Calling it "BULK" mode is not correct either IMO as battery can go through Bulk, Absorption, & Float at any normal voltage (13.1 to 15.2?).

    In fact many WFCO do all three stages at 13.6 volts due to poor voltage controls.

    Progressive Dynamics will usually do Bulk and at least part of Absorption at 14.4 volts.

    IOTA and Powermax drop voltage as soon as Bulk is complete. So Bulk, Absorption, Float description actually works for these.

    And others have a fixed voltage but still go through the three stages.

    Anyway I prefer Boost, Normal, Float to describe CONVERTER stages so as not to be confused too much with the stages of charging a BATTERY.

    Converters don't have equalization or finish charges so that can be reserved for other discussions.

    Cheers :)

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