Re: Eton E-10 Up In Smoke



--
Say no to institutionalized interference.
Just say NO to HD/IBOC!
"JayBS" <john@xxxxxxxxxxxx> wrote in message
news:1154616101.832039.117950@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Now, cummon guys: you've had some really good advice on this which says
(in a nutshell) that

- charging cells outside the radio with the proper charger is fine
- reverse-charging might be a culprit, but most likely
- the smokin' was just a coincidence

I'm not an international expert on NiCAD v NiMH but I've worked with
these batteries for a couple of decades: they are very similar in many
respects, not least cell voltage which is nominally 1.2v but does rise
to 1.4v+ on charge, and may be c. 1.35 v when you first pop them into
the radio. There is no fundamental difference between a charger for
NiCd v NiMH cells, bar for fact that IN GENERAL you get more mAH
capacity from the latter (assuming same phyical size), so the charger
is usually programmed to wack out more current on it's NiMH setting.
Simple /cheap chargers still rely on a constant current regime which
should not exceed c. 1/10th of the cell's capacity, i.e for 1100mAh,
110mA. Charging at this rate indefinitely should not damage good
quality cells, but they do get warm. Nominal re-charge time will be
12hrs.
More intelligent chargers use higher charge rates to shorten charge
times, but essentially terminate or throttle back charge current when a
certain voltage is reached. There is more opportunity for cell damage
under this regime, but again, as cell voltages are similar, in general
it's OK.


Well... I got this radio in yesterday's mail, and got to playing with it.
First thing I noticed was that it would still work using the AC adapter..
verrrrry in ter est ing.. Next, I looked inside the battery compartment and
saw that the positive end of the three battery holder had been very hot and
melted the surrounding plastic. I installed a set of batteries, and, sure
enough, it got very hot and began to melt.. in the same place! This was
interesting. So I opened the thing up and started poking around.

First thing I noticed was that the battery connection that had gotten hot
was not on the actual positive end of the battery supply, but was connected
up to the negative end of the single battery holder. This holder was
completely undamaged, as was the negative end of the three cell holder, and
all the wires leading to the battery compartment. Curiouser and curiouser.

In fact, other than the melted plastic on that one connection, I didn't see
ANY damage at all. I next checked the polarity protection diodes. Both
seemed fine, so I cleaned up the melted plastic on the battery connection in
question, and reinstalled a set of batteries (held in with Scotch tape,
since the chassis was out of the case, so nothing to hold the batteries into
their holders). This time, no heat, no smoke. I hit the power button, and
voila... it was a radio.

Removing all other factors by process of elimination, the only thing I can
figure is that there must have been a poor connection to that battery
connector that was causing it to heat up. This really doesn't make sense,
though, since I doubt the whole radio when it is turned on draws enough
current to heat that connection up. Makes me wonder if there was some sort
of foreign matter between that connection and the B- bus.. that fell out
when I disassembled the radio. At any rate, the radio is now working on both
batteries and AC.. but I won't be using rechargables in it, nor turning on
the internal charger.. why push my luck.

BTW.. this is a nice sounding radio with pretty good performance.. but why
didn't they put a BFO on it???

Oh well.. the price was right for sure. Thanks, Jim. :)



.

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