Re: How to tell bad NiMH AA batteries


Xiaoding wrote:
> Sounds like? What the hell is "sounds like"? I've DONE it, no "sounds
> like" about it!
>
> Xiaoding

Quick googling reveals this:

--snip--
Please,

Before you KILL yourself - I am NOT joking (even though you MAY be)

You CANNOT 'measure the amperage' of a battery. A battery, or ANY other
supply, including the domestic mains supply does NOT HAVE A MEASURABLE
'AMPERAGE'.

Instead, any supply will have a value of current which it is 'rated to
supply SAFELY'.

DO NOT TRY THE FOLLOWING :
Buy a clamp-on current meter and a 0.5 inch diameter length of steel
rod. Put the meter around the rod, and drop this across the terminals
of a brand new and fully charged vehicle battery. Just before the
battery explodes (and it will !!) you might be able to observe it
generating a short-circuit current of around 1000 (one-thousand !!!)
amps. The rod will probably glow red- or white-hot, and will certainly
weld itself to the terminals such that you would be unlikely to be able
to remove it - assuming you were crazy enough to go anywhere near it
again.

DO NOT TRY THE FOLLOWING EITHER:
Take your cheap multimeter, and repeat the above experiment, this time
replacing the steel rod with the leads connected to your meter. IF YOU
ARE LUCKY, the internal 10A fuse will blow. If not, then SOMETHING else
in the meter will try to pass the same 1000A current as was generated
in the first experiment. Go figure !!!

Basically you should ONLY EVER USE YOUR METER TO MEASURE CURRENT WHEN
THERE IS A 'NORMAL' LOAD IN THE CIRCUIT.

An example might be if you wanted to measure the current darwn by the
headlights of your vehicle. You could connect the leads in place of the
feed wire to the headlights (assuming you know what you are doing).
MEsuring the current drawn by a single 65W quartz-halogen headlight
bulb, connected to a typical 12V car battery, should give you a current
reading of around 5 AMPS. Do NOT do this for too long - the leads of
your meter, and the internal connections will NOT withstand this level
of current for very long !!!

When you were trying to measure the 'amperage' of the small 'torch'
battery, you were effectively performing the 'second' of the two
experiments I described above. You are VERY LUCKY to have survived
without a major, if not fatal, injury. I have PERSONALLY observed a
standard 1.5V alkaline 'D' cell explode like a hand-grenade when it was
being abused. Fortunately the container in which the battery was
mounted absorbed the shrapnel that was created by the explosion.

Finally, I would personally advise you to only ever connect standard
domestic apparatus to your household mains outlet sockets - with your
limited knowledge of things electrical, you stand a very high chance of
becoming a candidate for next years Darwinian Awards for a major
contribution to the gene pool of the human species !!!

Remember the simple adage :
"Volts jolt, but mils kill"

In other words, a reasonably high voltage (and 24V is enough) will
cause an electrical shock, that WILL hurt. However, if you arrange for
the current that flows through your body to become high enough (and the
'mils' refers to around 50 MILLI-amps , i.e. 0.05, or 50 THOUSANDTHS of
an amp) YOU WILL DIE - no ifs or buts.

Normally your natural body resitance is quite high, requiring a higher
voltage to cause a higher, and therefore more dangerous, current to
flow. Add normal domestic mains to a hot and sweaty body, and the
reduced resistance caused by the salty sweat will guarantee a slow and
painful death (unless you are lucky, where death will perhaps be swift
and pain-free)

YOU HAVE BEEN WARNED

--snip--

.

Relevant Pages

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