[EVDL] New Optima pack

John G. Lussmyer wrote:

> Of the 4 I've done so far, 2 started a little hiss venting when they
> were down to about 1.5A charging, 1 didn't vent at all, and 1 started
> venting at 3A! These are all with the voltage being held at a steady
> 14.50v.

A few years back, Paul Compton posted about having "blueprinted" the
vents on his Optimas. As I recall, he found that they were venting too
easily due to some platsic flash on the vent pipes. If you pry out the
flame arrestor disc over the vent, you can then remove the rubber nipple
and inspect the vent tube to see if any plastic flash needs to be
removed. Reassemble after cleaning any flash with a sharp knife.

I have found that Optimas may vent a bit if they have been sitting for
some time. My hypothesis is that differing self-discharge rates between
the cells leads to relatively significant imbalance between the cells if
the battery if left sitting long enough. I've found that Optimas can
easily vent at <14V when in this condition.

My experience has been that placing an ordinary 100W 120V lightbulb in
series with each battery and connecting them to a ~15V power supply
allows them to gently come up to full charge with a minimum of venting.
The current to each battery is individually limited to about 100mA by
the bulb in series with each. Leave the batteries charging like this
for a few days to a week. After this you should be able to put the
batteries in service without any venting.

Good luck,

Roger.

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Jeff Shanab wrote:
> Did you say you stopped chargeing at 1.4Amps? Is this a regulated
> 14.5Volt supply?
> You may be obscureing your SOC.
>
Using a Lab Bench power supply, charge at 14.50V until current drops to
1.4A. This was to just get them all to close to the same SOC. This was
a BRAND NEW pack. NEVER used.
> I think you are chronically underchargeing and then sucking them to low,
> which lessens their capacity which makes the situation
>
Hard to be chronic since this was the first real charge cycle.
> worse....Batteries need to be woken up slowly, hitting them too hard to
> soon will cause venting and imbalance if they have sat for any time.
>
I'm trying short runs to break them in. But those 2 batteries seem to
be bad.

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> Jeff Shanab wrote:
> > Did you say you stopped chargeing at 1.4Amps? Is this a regulated
> > 14.5Volt supply?
> > You may be obscureing your SOC.
>
> Using a Lab Bench power supply, charge at 14.50V until current drops to
> 1.4A. This was to just get them all to close to the same SOC. This was
> a BRAND NEW pack. NEVER used.

John,

Did you follow the taper with a 2 amp constant current charge for an hour?
You need to completely disable the regulators during this phase, since the
battery voltageis will get quite high, maybe even up to 17 volts.

On the two batteries that are 'bad', try discharging them at 25 amps down
to 10.5v, then give them a proper charge (any current until 14.7v, hold
14.7v until the current drops below 1 amp, then do 2 amps for an hour with
no voltage limit). You might find that these batteries are just
undercharged.

Ralph

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Ralph Merwin wrote:
> On the two batteries that are 'bad', try discharging them at 25 amps down
> to 10.5v, then give them a proper charge (any current until 14.7v, hold
> 14.7v until the current drops below 1 amp, then do 2 amps for an hour with
> no voltage limit). You might find that these batteries are just
> undercharged.
Fun part is that I've discovered I haven't yet replaced all my "tools"
that were burned last year.
I don't have anything to do a controlled discharge with.
So yesterday, I went out to the bird, and use a single 20A charger on
various batteries. I checked several "good" ones with the charger, and
it said they were all at 100% charge.
#12 (weak) was at 90%, and the charger brought it up in about 10 minutes.
#6 (really weak) was at 12%. The charger worked on it for over an hour,
and brought it up to 86% - and held at that level.
So, I did another short drive, and checked the battery voltages
immediately afterward.
#12 was again at 11.23, (all the good batteries were about 12.23)
#6 dropped below 10V during the run again, and was at about 10.23v
afterward. It had also developed a hot spot at one end. You could feel
the case was hot down near one post. The rest of the battery top was at
a normal temp.
#6 is also "filled" first on charge with the PFC 40 charger. It's reg
started triggering pretty quick.
I've left everything sit overnight, now I'm going to go out and see what
the resting voltages are.

I'm pretty sure #6 has a bad cell, and #12 doesn't look real good either.

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John G. Lussmyer wrote:
> I've left everything sit overnight, now I'm going to go out and see what
> the resting voltages are.
>
> I'm pretty sure #6 has a bad cell, and #12 doesn't look real good either.
>
Okay, checked the voltages. All the "good" batteries are reading 12.80v
to 12.90v.
#12 was at 12.67, #6 was at 11.61.

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> John G. Lussmyer wrote:
> > I've left everything sit overnight, now I'm going to go out and see what
> > the resting voltages are.
> >
> > I'm pretty sure #6 has a bad cell, and #12 doesn't look real good either.
> >
> Okay, checked the voltages. All the "good" batteries are reading 12.80v
> to 12.90v.
> #12 was at 12.67, #6 was at 11.61.

John,

If these are resting voltages after sitting overnight after a full charge,
your batteries aren't fully charged. They should be closer to 13.0v or
13.1v. I have some that hold about 13.1v for several days...

Have you tried running the published spec on either of the two "bad" ones?

Ralph

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Ralph Merwin wrote:
> If these are resting voltages after sitting overnight after a full charge,
> your batteries aren't fully charged. They should be closer to 13.0v or
> 13.1v. I have some that hold about 13.1v for several days...
>
> Have you tried running the published spec on either of the two "bad" ones?
>
I'm running a 2A finish charge now. I've set the regs for equalize
mode, and if they start coming on I'll disconnect them.

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Ralph Merwin wrote:

> If these are resting voltages after sitting overnight
> after a full charge, your batteries aren't fully charged.

John, based on your observation of a hot spot on one of the cells of
battery #6, I would strongly suggest that you remove it from the vehicle
immediately. Even if you have good insurance, it can't be that much fun
searching for another Sparrow if this one goes up in flames. The hot
spot suggests an internal short; it may not be a dead short yet, but if
you're going to continue to experiment on this battery to see if you can
make it usable, better to have it somewhere on its own where it won't be
a crisis if it melts down.

There may still be hope for #12, but I'd try to get warranty on #6 (I
know you said they told you no warranty on batteries used in EVs, but if
you walk in with a single blue top and can point to a definite hotspot
on it as the defect, a sympathetic counterperson may still exchange it
for you). I'm pretty sure that Al Godfrey was able to get a warranty
replacement when one of the 26 blue tops in his 928 was identified as
substandard within the warranty period.

> They should be closer to 13.0v or 13.1v. I have some
> that hold about 13.1v for several days...

Some? FWIW, even your old blems in my car will hold 13.0-13.2V for days.

> Have you tried running the published spec on either of the
> two "bad" ones?

At the very least, do as Ralph suggests and run the Optima recommended
profile. Or, if you are willing to take it more slowly, float the
battery as I suggested in an earlier message; the slow and sure approach
does work.

Cheers,

Roger.


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Ralph Merwin wrote:
> I missed the comment about the hot spot. Ditto Roger's comment about
> removing that battery from the vehicle right now... It probably gets
> hot while driving too.
>
Actually, it only got hot during discharge. Cooled off during charge.
Still, it's definitely a bad battery.
> I should've said 'most'. I have one that won't. It also gets warmer
> than the others while charing.
>
Most things get hot while "charing"...

I let the batteries sit for a couple hours after an hour+ at a 2A charge
rate.
Now they are all in the 12.95 to 13.05 range - except #12 which is at
12.77, and #6 at 11.80.

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Jeff Shanab wrote:

> I don't think this is a good idea for optima's. Never go over
> 14V and never go over an amp once over 14.5V.
> Maybe this is a floodie technique? Optima's have a platinum
> pellet in the battery top that acts as a re-combiner to take
> the hydrogen that has gassed and recombine it back with the
> avail o2 into water. If you exceed this little pellet's
> capacity the pressure builds and you pop a vent. From what I
> am told thye can handle about 1 amp worth of gassing.

A healthy Optima (D34) is supposed to be able to take 4A "indefinitely",
though you don't really want to do this as it will vent some. What you
can do to an individual battery is also different from what you can do
to a string of batteries.

If the cells in an Optima are imbalanced it can vent with less than 1A
and less than 14V on it; bypass regs are no guarantee that you won't
vent your batteries on charge, though they are certainly better than
nothing.

> I just re-read the optima and the orbital chargeing spec. Maybe I am
> undercharging my pack.

Anytime you have under-performing batteries after a very low number of
cycles, suspect undercharging. Over-charging will also kill your
batteries, but unless it is extreme it will take longer before you
notice.

> How do I do an IUI charge with the typical PFC charger and
> regulator set up? Is this the best way? Every Charge ?

As Ralph notes, you need to disable the regs to do the final I step,
otherwise they kick in to clamp the voltage and prevent the battery from
getting the appropriate overcharge.

You also need to readjust your charger's voltage and current limits.
You need to open up the voltage limit so that the battery voltage can go
where it needs to. While the voltage on a module may hit 16-17V during
this step, they won't all do so, so you needn't open the voltage limit
up to 16-17V x the number of modules. Adjusting the charger settings
manually at the start of the final I step and back to normal afterwards
will probably get old real quick if you try doing it on every cycle.
Probably doing it once every few cycles, or perhaps just once a week may
be enough to keep the batteries from deteriorating.

As Ralph notes, Optima's recommendation of 1hr @ 2A is based on the
assumption of an 80-100%DOD discharge, so it is reasonable to scale back
the duration if you are doing shallower cycles.

Note that the Orbital recommendation is 2hrs @ 1.5A, and I would suggest
observing this as a starting point rather than Optima's recommendation
since you are using Orbitals.

Cheers,

Roger.

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