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Discussion Starter #1
I recently found I needed to replace my Lead Acid battery after 2.5 years (the heat and poor quality of batteries here is not so great).

I borrowed a 7 Stage Automatic charger with MCU controlled & High frequency switchmode. Made in Japan so it seems a high quality unit.

I'd charged my old battery and it only got to charging(#3 bulk ) and then indicated DONE. Never got to the other 4 stages.

The 7 stages are:
1. Desulphation
2. Soft start (slow ramp up to 14.5v.
3. Bulk (ie charging) at 14.5 V
4. Absorption (ramp down)
5. Battery Test
6. Recondition. If battery test fails, a current of 16+ volts will be applied for 4 hours. Sometimes need for deeply discharged or deep cycle batteries.
7. Float to maintain charge with slow trickle.

My new battery went into #6 charging at 16v. and I stopped the process.

16v. Is this bad for the battery?

Thanks in advance,

Mark in Thailand
 

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Discussion Starter #3
w/o charger it drops back to about 13.5v. With charger it IS showing 16+v. Manual says it will and it does.
 

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Is the charger you are using intended for powersports batteries or car batteries? If it is intended for car batteries it may be reading a fully charged bike battery as a car battery that is not holding enough charge.

BTW: Depending on the battery, charging may not be necessary. Some lead acid batteries are shipped "dry charged", which means that the plates were immersed in appropriate electrolyte and charged, then removed, dried and assembled into batteries. When you pour in the appropriate electrolyte the battery is fully charged and ready to use.
Other batteries are shipped uncharged; The plates are assembled into the batteries without being charged and the electrolyte that comes with them is appropriate for that so they need to be charged right after filling (it may need to sit for a while to absorb the liquid first - see instructions).
 

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My AGM batteries came fully charged. I've had the first one for two winters, did not remove or trickle it and it started right up with the first try each spring. Bought them from Battery Sharks.
 

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The last time I bought a Pb-Acid battery, it came with a bottle of acid. I filled the battery, waited a couple hours, topped up the cells, installed in bike, started. I then took the bike out to run a few errands (stop-n-go), afterwards an hour cruise to just follow the front tire.

Battery was fully charged when I got home. No need to hook up a charger.

It was just a basic no-name battery from Autozone.
 

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That would be a dry charged battery (fully charged after filling and allowing to sit while the plates absorb the electrolyte).
As I said, not all batteries come that way (it would be nice if they did) so you need to read the instructions that come with the battery and do what they say.
 

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Interesting....... I wasn't aware that a Pb plate was absorbent.

I just thought it took a bit of time for the electrons to begin moving between the cathode an anode.

I misunderstood all these years.
 

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They dry them out to stop the chemical reaction during storage.When you add the electrolyte it takes a while to soak into the plates. That's why you need to top it up after it sits.
 

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In reality.....it does not soak into the Pb plates. Pb is not absorbent.

During the chemical reaction H2 gas is generated and leaves the acid solution. This is the cause of the volume reduction.

Yes, the electrolyte is removed for shipping and to halt the chemical reaction to generate the voltage.
 

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Solid lead is not absorbent. The plates are not solid lead but consist of lead grids packed with a paste of the appropriate compound for the positive or negative part of the reaction. The paste is wet when applied, then is cured so that it will not dissolve in the electrolyte. The plates need to absorb electrolyte in order for the chemical process to occur throughout the plate instead of just on the surface.
 

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Ok........ What prevents the "paste" from dissolving when immersed in the electrolyte??

lets say I'm skeptical about your assertion......

None of the battery centric companies that I have worked for used that type of construction.

But on the other hand, you are a Super Moderator with the last word on all subjects.

Have a good day.
 

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As I mentioned, the paste is cured so that it won't dissolve (this is the same principle as water no longer dissolving latex paint that has cured except that the chemicals involved are different).
I worked for Exide for a couple of years in my youth but that was long enough ago that I have forgotten a lot of the details so I always look up these things when I am not sure. There are lots of online sources that describe the construction of lead acid batteries and some go into great detail about what is in the paste and how it cures (if you are really interested Google is your friend).
You may find this video interesting
 

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Rather than absorption, what I believe is happening after adding electrolyte is the formation of an ionized layer on the surfaces of the lead plates, which is where all of the reaction takes place.
It is a form of "soaking", if you define the term broadly.

Randall
 

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When I worked at Exide they applied the past to the grids, cured them, assembled the cells and filled them. I am 99% sure that they had to let the filled cells sit for a time so the plates could soak up some of the (weak acid) electrolyte and top them up before charging them.

The plates in batteries are shipped dry would need to be as dry as those freshsly cured ones were (otherwise they would deteriorate in storage) so it would make sense for them to absorb liquid in the same way that the uncharged ones did.
 
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