[EVDL List]

That's correct what David said. Do not add pure H2SO4 which has a 1.800 SG
to a battery that has a mix electrolyte of 1.275 SG.

When I was working in a military battery shop back in 55, we recondition 2
volt battery jars, not call cells. Cells are separate compartments in a
larger battery case. These jars have removable tops where we can pull the
plates out. We then read what the electrolyte specific gravity is and
record that SG for that battery.

Lets say we remove a specific gravity of 1.200 from the battery and after we
recondition it, which normally includes washing the plates in a vat of
distill water and pushing in new separators while pushing out the others at
the same time.

We then mix a new electrolyte to a specific gravity of 1.200 to put back
into the battery. Always put in the same specific gravity electrolyte that
you take out. Lets say you put in 1.275 sg into a battery that was at 1.200
sg and you charge it, it will overcharge or if discharging, will under
charge.

Sometimes when you get a new battery and the electrolyte is not up to the
correct level which could be to the bottom of the fill neck or in some
cases, about 1/4 inch above a split cut neck which allows the fumes to be
release back into cells, you first take a specific gravity reading of the
specific gravity and add the same specific gravity electrolyte to the
correct height.

Now in a older battery that a person has been watering for some time, it is
possible that putting in too much water has diluted the electrolyte. If the
specific gravity reads low and electrolyte comes up higher than normal
during a equalization charging, then remove the electrolyte until it below
the fill neck. Continue to charge it and it may take a very long time for
it to get to 1.275 SG. If its gets to 1.275 SG and the level is still low,
then you can add 1.275 sg electrolyte to the correct height.

The 1.275 sg electrolyte is normally read at about 77 F. When mixing
distill water (H20) which has a specific gravity of 1.000 to sulfuric acid
(H2S04) which has a specific gravity of 1.800, you mix the two together by
only pouring the acid into the water. Not the other way around, or you will
have a violent explosive reaction.

The formula is 5 parts of water to 3 parts of acid which becomes:

1.0 + 1.0 + 1.0 + 1.0 + 1.0 + 1.8 + 1.8 + 1.8 = 10.4

The average of 8 parts is 10.4/8 = 1.300 specific gravity electrolyte at
over 100 F. We then let it cool down to 80 F which the electrolyte should
read 1.277 sg. At 70F it should read about 1.275 sg. Setting in a cool
storage room, I had read it as low as 1.265 sg.

Roland


----- Original Message -----
From: "EVDL Administrator" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, December 06, 2010 9:26 PM
Subject: Re: [EVDL] New charger: Wrong profile?

> On 6 Dec 2010 at 19:36, Steve Kobb wrote:
>
> > >> Do you do anything besides charging to try to keep the SGs near 1.275
> > >> fully charged?
> >
> > I ... bought a gallon of lab-grade sulfuric acid.
>
> Here's the wagging finger, and a couple of reasons you might not want to
> do
> this.
>
> There are two reasons for some or all cells reading low specific gravity.
> Either the battery is losing capacity, or some cells are undercharged and
> need to be equalized.
>
> First a little battery chemistry (disclaimer : I am not an electrochemist
> so
> if someone with a degree corrects anything below, listen to him and not
> me).
>
> When a battery discharges, some of its lead turns into lead sulfate. The
> sulfate ions for this reaction come from the acid in the electrolyte
> (another name for sulfuric acid is hydrogen sulfate, H2SO4).
>
> When you charge the battery, the sulfate ions leave the lead and return to
> the acid in the electrolyte.
>
> This is why a hydrometer can tell you the battery's state of charge - it
> measures how much H2SO4 is in the electrolyte.
>
> But as a battery ages, gradually some of that lead sulfate doesn't quite
> make it back into lead and sulfuric acid. It flakes off the plates and
> sinks to the bottom of the cell instead. This is one reason (there are
> others) that a battery's capacity declines with use.
>
> For an old battery, "full" just isn't as full as it used to be. The
> plates
> have lost some active material, and the electrolyte has lost some acid.
>
> You can "fix" the latter by reconcentrating the electrolyte (adding more
> acid). But you can't put the lead back into the plates so easily. Thus,
> when you pour more acid into an old battery, you upset the battery
> manufacturer's balance between plate capacity and acid capacity.
>
> Now, when you run the battery flat, its plates will over-discharge. This
> will make the battery wear out even faster.
>
> That said, what you did here may also stem from a slightly different
> problem. It may be that your SG differed from cell to cell because the
> battery wasn't properly equalized.
>
> The correct fix for this is an equalization charge. That's where you
> overcharge the fully charged cells in a carefully controlled way, in order
> to bring the lower cells up to a full charge. By adding acid, you hid the
> problem rather than solving it.
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
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[EVDL List]

Thanks to both David and Roland for your comments on specific gravity.

I'm actually reluctant to make a detailed response in this thread because I
really want to focus on my main issue, which is: Why does my new charger
stop at 180v while my batteries heat up?

But OK -- that stated, I'll respond (briefly):

Yes, I use a Schumacher 20amp manual charger to equalize my batteries on a
regular basis. I also have PowerPulse Desulfators on the entire pack.

Unfortunately, some cells have been highly resistant to change: The SG
doesn't want to move, according to the refractometer.

For me, the stand-out phrase in Roland's post was: "Continue to charge it
and it may take a very long time for it to get to 1.275 SG."

Well, that might be the problem right there: A couple of hours at 20amps
simply might not be enough time, especially if there is major corrosion or
"mini-stalagmites" on certain plates.

I also note Roland's first sentence in that same paragraph: "Now in a older
battery that a person has been watering for some time, it is possible that
putting in too much water has diluted the electrolyte."

I actually think this happened in a few of my batteries, which is why I
boosted the juice with a few ml of higher sg electrolyte.

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[EVDL List]

On 9 Dec 2010 at 5:11, Steve Kobb wrote:

> Why does my new charger stop at 180v while my batteries heat up?

All of the energy you put into a battery charges it, generating negligable
heat (at normal currents), until the battery reaches gassing voltage. This
means that if your batteries really are heating up, then at least some cells
in that battery are nearing or at full charge.

As I tried to explain (maybe not too well) before, "full charge" today
probably isn't what "full charge" was a year ago. Your batteries are in
middle age. They don't have the stamina they once had and they won't reach
as high a voltage while on charge. If you charge and charge but the SG and
on-charge voltage don't rise, then that's all you're going to get.

If you do think it's undercharged and/or unbalanced and you'd like to try
equalizing your pack, here is what I would do.

First, get rid of those "desulfators." I don't know what effect they'll
have on the charger's logic, but I'm pretty sure that they won't do anything
more for the batteries than a proper equalization will. I know desulfators
have some followers, but in my book they're a waste of money. I don't know
of any electrochemist who doesn't agree with that assessment. And as I say
I don't know how they might affect/confuse a normal charger.

Second, find a current-regulated charger that you can adjust (with luck you
can do this with your present charger, maybe by connecting it to a laptop).
Set it for 2% of the battery's amp-hour capacity expressed in amps (that is,
if it's a 220AH battery, set your charger for 4.4 amps; 4-5 amps is close
enough). Connect it and >leave it< until the voltage across your battery
stops rising, no matter how long that takes. It could take days. Don't let
the battery overheat; if the voltage starts to fall, shut down.

When the voltage is no longer rising, every cell is as charged as it's going
to get. Because you've tinkered with the electrolyte concentration,
however, they may not all be at the same SOC or SG reading. I suppose you
could try tweaking the SG some more at that point to make them all equal
(probably better to equalize downward by adding water), but I don't know
that it will gain you anything. Maybe some others here have thoughts on
that.

As for the way your charger is acting now, my guess is that the battery
simply isn't reaching the voltage that the charger expects. Most likely
that's because the battery is aging. You could even have a bum cell or two.

Once you know that the battery is as charged as it's going to get, it's time
to adjust the charger so that it recognizes that as "done." I mean adjust
the charger's threshold voltage downward. If the charger isn't adjustable
that way, maybe you should consider getting a different charger.

BTW, it's not at all impossible that your dealer adjusted a 144v charger to
work with a 156v pack. If you tell us the brand and model, maybe someone
here will know whether that's possible with that particular charger.

Hope this helps!

David Roden - Akron, Ohio, USA
EVDL Administrator

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[EVDL List]

>> As I tried to explain (maybe not too well) before, "full charge" today
probably isn't what "full charge" was a year ago. Your batteries are in
middle age. They don't have the stamina they once had and they won't reach
as high a voltage while on charge. If you charge and charge but the SG and
on-charge voltage don't rise, then that's all you're going to get. <<

Well, that's clearly-stated, and I think your analysis is right-on: My pack
is getting old.


>> Second, find a current-regulated charger that you can adjust (with luck
>> you can do this with your present charger, maybe by connecting it to a
>> laptop). Set it for 2% of the battery's amp-hour capacity expressed in
>> amps (that is, if it's a 220AH battery, set your charger for 4.4 amps;
>> 4-5 amps is close
enough). Connect it and >leave it< until the voltage across your battery
stops rising, no matter how long that takes. It could take days. Don't let
the battery overheat; if the voltage starts to fall, shut down.

When the voltage is no longer rising, every cell is as charged as it's going
to get. <<


Dumb question: If every cell in an individual battery has taken in its
maximum charge, you would characterize that battery as "balanced" or
"equalized"... correct? Not at the pack level, but just among the cells that
make up that particular battery.

Just want to make sure I understand the terms. And thank you, by the way,
for the clear instructions on how to deliver this charge.



>> Once you know that the battery is as charged as it's going to get, it's
>> time to adjust the charger so that it recognizes that as "done." I mean
>> adjust the charger's threshold voltage downward. If the charger isn't
>> adjustable that way, maybe you should consider getting a different
>> charger.<<

My new charger is an Elcon PFC4000, which is not adjustable by the user...
to my knowledge.
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[EVDL List]

On 12 Dec 2010 at 20:15, Steve Kobb wrote:

> Dumb question: If every cell in an individual battery has taken in its
> maximum charge, you would characterize that battery as "balanced" or
> "equalized"... correct? Not at the pack level, but just among the
> cells that make up that particular battery.

If you equalize the way I described before, every battery will be equalized.
Also, the entire pack will be equalized.

This is where terminology can get confusing, though. You'd think that
balancing and equalizing would be the same thing, but at least as those
terms are used among hobbyists, they aren't.

There are lots of battery management systems that "balance" a pack by
forcing all the batteries in the pack to have the same >voltage<. But that
may not be a pack that's equalized in the sense that we're using the term
"equalized" here.

This is because even new batteries have slight manufacturing variations.
The fully charged voltage for one battery won't be exactly the same as the
fully charged voltage for another. Forcing them to have the same voltage
almost guarantees that they'll be at different states of charge. And as
those batteries get used, the variations usually become greater, not less.
So, balancing and equalizing are not the same things.

> My new charger is an Elcon PFC4000, which is not adjustable by the user.

I don't know anything about that particular charger; maybe someone else here
does. However, I've heard that the Zivan chargers sold by the company that
imports the Elcon chargers tended (at least in the past) to be set for very
aggressive charging.

A friend of mine scrapped with Electric Conversions for years because they
wouldn't reduce the voltages in his Zivan's profile to what he thought was
appropriate. In his view, the high voltages were shortening the life of his
batteries. He got nowhere with the dealer. The charger was configured
correctly, they said. Eventually my friend gave up and bought a different
charger.

This is not to denigrate or even question your choice, but if I were going
to buy a relatively inexpensive Chinese-made black box "plug and play"
charger, one I couldn't configure myself, I'd be more likely to get one of
Roger's Delta-Q chargers than a Zivan (possibly still made in Italy,
actually) or Elcon. Though I might have to get two of them, depending on
the pack voltage.

David Roden - Akron, Ohio, USA
EVDL Administrator

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