Li-Ion packs

[Verne Koester]

Thanks, Jerry. That's what I was looking for. I understand some of the
systems out there have no light at all leaving the user wondering what stage
of charge they're at. Sounds like this system is a dandy!

BTW, a 3" O-ring is perfect with the Hush clamp and your E.S. pipe with a
piece of 1/16" silicone isolating the pipe from the clamp.

Verne


----- Original Message -----
From: "Jerry Budd" <jbudd at QNET.COM>
To: <discussion at nsrca.org>
Sent: Wednesday, September 11, 2002 1:00 AM
Subject: Re: Li-Ion packs


> Hi Verne,
>
> There is an indicator light but it operates a bit differently than
> what most people are used to.
>
> It appears that the charger is a constant voltage charger, which
> means that the amount of current flow into the battery pack is
> proportional (but not linearly proportional) to the difference
> between the voltage level of the battery pack vs the set (more likely
> requlated) voltage put out by the charger.  The greater the voltage
> difference, the greater the current flow into the battery pack.
> Initially there is a relatively high current flowing into the battery
> which decreases as the voltage of the pack increases.  Eventually
> (about 2 hours for a fully discharged pack) the voltage of the pack
> (given the pack is healthy) rises to the same voltage output level of
> the charger, at which point there is ZERO current flow into the pack,
> and you are done.
>
> As far as how to tell when the pack is fully charged?  If you connect
> a pack that has had some amount of usage, the indicator light (really
> a diode) on the charger will glow red.  As the pack voltage comes up,
> the current flow tapers off somewhat, and the indicator light changes
> to a red-yellow hue, then to a yellow color, then to a yellow-green
> hue, and then finally it goes completely green (indicating no current
> is flowing and a fully charged battery pack).
>
> The only flaw in the system is that when the charger is connected to
> a 12v power source, the light glows green, whether a battery pack IS
> CONNECTED OR NOT!  Why?  There's no current flowing through the diode
> to make it change color.  Obviously this creates a concern as to how
> can you tell that you actually have a good connection between the
> charger and the battery pack.  What I do is make sure that I see the
> diode change color when I connect the charger to the charge jack.  If
> I don't see a color change, I either have a battery which is still
> fully charged (not likely - check it with a digital voltmeter with a
> 0.5 to 1 amp load), or I don't have a good connection.  If I see the
> diode change color as described above I know it's charging.
>
> Now, can you leave the charger hooked up to the battery pack
> indefinitely?  In theory, yes.  In practice, maybe (you still need to
> exercise the pack once in a while).  Bern suggests NOT to leave it
> hooked up.  I have left mine on for as much as a week or more with no
> effect (as far as I can tell).  Your mileage may vary.
>
> The cool part of all this is that the charger is essentually a fast
> charger in that it initially puts out a lot of current at the
> beginning, and then tapers off to a trickle, without any really fancy
> circuitry involved.  This is a good thing as simpler directly
> translates into increased reliability (assuming reasonably high
> quality components are used).  The drawback is that if you have a
> "bad" battery pack, the voltage of the battery pack MAY NOT come up,
> causing the current flow to remain high, and you could "cook" a set
> of batteries (and maybe an airplane).  I think this type of failure
> mode is extremely unlikely.  A more likely scenario is that the
> (compromised) pack never does quite reach peak voltage, the charger
> continues to put out a small amount of current (which probably
> doesn't cause much of anything to happen), and you (hopefully) notice
> that the charge light never quite reaches a full green color (which
> tells you something is not right).  You then check the pack voltage
> with that 1 amp load VOM I mentioned, and realize the pack is maybe
> not doing so well.  I think that's a pretty graceful failure mode,
> and it's certainly one I can live with.
>
> I know that the DuraLight folks are putting some circuitry into their
> battery packs to eliminate overcharging as an issue.  However, that
> extra circuitry introduces additional failure modes, which may be
> what we are starting to hear about on this (and other) lists.  I
> personally don't think it's really necessary, and in fact it may
> actually cause more problems than it solves.
>
> Jerry
>
>
> >Jerry,
> >Is his charger of the type that has a light that tells you when it's done
> >charging?
> >
> >Verne
> >
> >
> >----- Original Message -----
> >From: "Jerry Budd" <jbudd at QNET.COM>
> >To: <discussion at nsrca.org>
> >Sent: Friday, September 06, 2002 2:00 PM
> >Subject: RE: Li-Ion packs
> >
> >
> >>  >Thanks Jim.
> >>  >
> >>  >Ive been curious what a discharge curve looks like for
> >>  >these batteries, anyone seen one?
> >>
> >>  My experience is that it's pretty constant (but not level), similar
> >>  to a lead-acid battery (which makes it very predictable).  As far as
> >>  I can tell (and I've run my Li-ion packs from Bern Furgang at
> >>  http://www.superbatterypacks.com down to slightly less than 6.6v) it
> >>  stays pretty linear with no discernable change in slope.
> >>
> >>  I eMailed Bern about this and he replied with, "I would not go below
> >>  the 6V threshold as you could loose the pack.  7.2V is a very safe
> >>  low end.  If you are at 6.6V you are OK."
> >>
> >>  Before I purchased the Li-ion pack/charger I consulted with Jim
> >>  Oddino as he had some experience with them.  He indicated that he was
> >>  favorably impressed.  I purchased the bx & charger in late June, and
> >>  at this point, I am too.
> >>
> >>  Jerry
> >>
> >>  --
> >>  ___________
> >>  Jerry Budd
> >>  mailto:jbudd at qnet.com
> >>  =====================================
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> >>  #
> >>
> >>
> >
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>
> --
> ___________
> Jerry Budd
> mailto:jbudd at qnet.com
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