Mex's Flash?

BFL13 wrote:
So, if you don't have enough charger/generator to get the batts to instant Vabs, can you apply this idea when there is a time while the battery rises to Vabs and then starts the absorption stage? I think I missed that info exactly.

So if I am doing my 50-90 and it gets to 75% when the battery reaches 14.8, I should lift the caps and start looking at bubbles. If it is only bubbling hardly any, I can keep going at 14.8 till it is bubbling "lightly" and then drop the voltage. So now I am at maybe 80% SOC, then do the 80-90 at the lower voltage? (but same amps into the battery so no time is lost?)

Or is it too late because it will already be bubbling "lightly" when it finally gets to 14.8?

Just experiment and take notes on when your battery starts bubbling, and how gentle to how vigorous your battery is bubbling, and add in a few specific gravity readings on the cells. By the time your SG is at 1.250, look at if it's bubbling. Keep reading SG until it's 1.260 and note the level of bubbling, Read the SG at 1.265 and look at how it bubbles, all at 14.8V. Somewhere in there, in that range, you'll know what point to shut off the 14.8V and charge at a lower voltage, say 13.8 to 14.0V, for absorption charging. Also note the time spent charging at 14.8 V when you do your SG readings. It should be clear from the above when the time spent charging at 14.8V is over.

You should very clearly notice a change in the level of, or how vigorous the cells are bubbling, at those states of Specific Gravity at 14.8V. Then compare it with how the battery bubbles at 14.8V with a Specific Gravity of 1.240.

If a SG of 1.210 is 50% charged and a SG of 1.275 to 1.280 is 100% charged, what would you estimate the SG to be at 80% SOC? 90% SOC. 80 to 90% is where the battery starts getting stubborn, showing resistance, and needing time at lower voltage instead of brute force voltage/amperage... the chemistry inside the battery is that it gets harder for sulfur on lead plates to find free hydrogen and oxygen in the electorlyte to bond to. Hence, bubbling is stirring up the electrolyte so that the free hydrogen and oxygen can find the sulfur on the lead plates, bond with it, and remove it. There's less sulfur to bond with, hence the charge rate and ability to take amps is reduced. Now it's a time issue, not voltage or amperage issue, to finish off charging the battery, it can't be rushed. The generator is inefficient at this point of the charge cycle.

That's the Dummy's version of how it works... MW could give you the full blown Calculus and derivative model of finding the area under the curve on that charge cycle... me, I just know that like most things in life, the closer you get to full, or 100% perfection, the harder it gets, the more expensive it gets, to get the least amount of percentage of gain. Just the way it is.

Batteries bubbling while recharging is a qualitative judgement... voltage, time, amps, and specific gravity readings are quantitative. Until you get a better feel for how all the quantitative readings mesh together, and some experience, it makes qualitative judgement difficult, just looking at bubbles.