I'd be quite willing to send Tim the batteries so that he could do the
necessary diagnostics.
Do I have a taker?
jh
----- Original Message -----
From: "Tim Hughes" <timhughes@xxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Saturday, April 26, 2008 7:10 PM
Subject: [OM] Re: rechargable lithium ion batteries
>
> Chuck,
> Actually most common Li ion batteries are not "rated" to give
> particularly high current,
> many are only rated 2C. There are some types rated for higher currents
> typically using a
> different electrode material, but they are not so common except for
> special uses radio control
> helicopter users and power drills. Most common Li-ion cells have built in
> internal curent
> limiting electronics, so you cannot draw too high a current, to prevent
> them self igniting! The
> NiMH are actually frequently rated for higher current and more
> importantly, don't have any built
> in protection electronics.
>
> In this particular case, of the so called "3V " lithium batteries these
> are frequently not
> Li-ion, but some other Li chemistry like Li-FePO4 (~3.3) with electronics
> or a diode to reduce the
> voltage a bit more. They reqiuire a special lower voltage charger too. I
> would not be surprised
> if their rated current was quite modest, like <2A.
> But this is a guess based on not seeing the batteries so, I can't say
> definitively, except the
> symptoms fit well with them having limited current capability.
>
> Tim Hughes
>
>
> --- Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>
>> But remember that these are supposedly rechargeable lithium ion
>> batteries and not elemental lithium. The thing that makes lithium ion
>> batteries potentially dangerous is that they are capable of delivering
>> far higher currents than alkaline or even NiMH batteries.
>>
>> So, I don't think your analysis can be correct if these are truly
>> lithium ion batteries. But maybe the problem is that they're not
>> lithium ion.
>>
>> Chuck Norcutt
>>
>>
>> Tim Hughes wrote:
>> > John,
>> > I am Making some big assumptions here, since I don't have enough
>> > info from what you have
>> > said, but I think this is what happens:
>> >
>> > When the flash capacitor is completely discharged at a cold start then
>> > initially the current
>> draw
>> > is greatest. As the capacitor charges up a little the current is
>> > somewhat reduced and then
>> > eventually drops off rapidly near full charge.
>> >
>> > It may be the particular Li batteries you have, can't supply the very
>> > high initial current of
>> a
>> > completely discharged flash capacitor and the internal electronics then
>> > stops the charging,
>> when
>> > the battery voltage drops too much at cold start. Once the capacitor
>> > is slightly charged
>> using
>> > the regular batteries, then the Li batteries can supply the lower
>> > current to continue charging
>> it
>> > up. The flash capacitor does not completely discharge even after a full
>> > dump, so once you have
>> > charged up the capacitor a little, with the regular batteries then it
>> > will operate fine
>> > thereafter, off the Li, until you switch it off and leave it to
>> > discharge completely.
>> >
>> > Tim Hughes
>> >
>> >
>> >
>> >
>> > --- om4t@xxxxxxxxxxx wrote:
>> >
>> >>
>> >> I normally use two rechargable 3 volt lithium ion battery packs in an
>> >> OM flash gun with my
>> E510.
>> >> The flash is a dedicated gun for the E series.
>> >>
>> >> When the flash has not been used for several days the battery packs do
>> >> not bring the flash
>> gun
>> >> to life. If I change over to four Ultra Duracell 1.5 volt batteries
>> >> the gun springs to life.
>> If
>> >> I then change yet again to the LI battery packs the flash springs to
>> >> life immediately. It is
>> >> almost as if the flash needs to be initially energized with the
>> >> Duracell batteries before the
>> LI
>> >> packs become operative.
>> >>
>> >> The LI packs are only a matter of a few weeks old, are fully charged
>> >> and the connector points
>> on
>> >> both packs and in the camera are clean.
>> >>
>> >> When I start off from "cold" with the LI packs installed in the flash
>> >> gun, the gun still
>> remains
>> >> inoperative even if I jiggle the packs slightly or apply a little
>> >> pressure to the slide mount
>> >> cover on the flash gun casing so as to effect a "better" contact
>> >> between the terminals on the
>> >> packs and in the camera.
>> >>
>> >> Does anyone have any idea about what might be ailing my flash gun and
>> >> / or LI battery packs?
>> >>
>> >> John Hudson
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
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