[Elecraft] ECOM scare -- FW: Soldering lesson

[Don Wilhelm]

I was involved in product testing in my former career.
One large computing machine which I worked on had a backup battery 
consisting of 4 AA cells, which no-one thought would be a problem, but 
during environmental testing at shipping extremes, condensation formed 
and created leakage paths.  It was a hard sell to convince management 
and many engineers that AA cells could cause a problem.

The following action was to do extensive testing in the power systems 
lab in which several destructive tests were performed, which included 
shorting the battery pack terminals.

It is amazing how much current those "lowly" AA cells can produce in a 
shorted situation.  Under short conditions, they are just as powerful as 
any other battery, but the duration of the huge current discharge is 
shorter than for larger batteries.

Lesson I learned is to be careful with any battery.  High density 
battery chemistries make the short circuit discharge duration longer and 
can cause more damage.

73,
Don W3FPR

On 2/18/2017 6:25 PM, Rick WA6NHC wrote:

> Don't forget that some of the battery packs we commonly use now (LiFePo4
> is my example) are capable of tremendous current (mine are 'fused' by a
> BMS at 100 amps).