http://dl.dropbox.com/u/11023364/20111215711.jpg

This is a battery terminal on one of these:

http://www.halfords.com/webapp/wcs/s...egoryId_255204

Pic shows the upper washer removed. The excessive sleeving held the
lower terminal surface off the stud face completely, and allowed what
appears to have been contact by arcing between the top terminal surface
and the washer. Oddly the stud thread did not contact the terminal,
although wiggling it would make it do so.

The unit worked perfectly through about ten charge/discharge cycles,
then when asked for power after a fortnight of no usage, failed. Each
time the light was turned on there would be a brief burst of power, then
nothing. The battery condition indicator was likewise. The compressor or
inverter did nothing.

The unit accepted a charge normally, except that the charge rate started
low (1A, quickly dropping to 150mA), as it would be with a fully-charged
battery that just needed 'refreshing'.

Of course when the unit was tested after the recharge it was no better.

I find it puzzling that any charge at all went into the battery. Is it
possible that the pitted surface of the terminal had a semiconductor
effect?

Bill

In article ,
Bill Wright wrote:
http://dl.dropbox.com/u/11023364/20111215711.jpg

This is a battery terminal on one of these:

http://www.halfords.com/webapp/wcs/s...egoryId_255204

Pic shows the upper washer removed. The excessive sleeving held the
lower terminal surface off the stud face completely, and allowed what
appears to have been contact by arcing between the top terminal surface
and the washer. Oddly the stud thread did not contact the terminal,
although wiggling it would make it do so.

I don't see how. The washer would have tilted and made contact. Not a
perfect contact, but probably ok if tightened enough. Unless the nut was
plastic. Which would be stupid.

Ages ago, I bought an identical jump start pack/compressor in Lidl that
Halford's also sold. Even the same brand name and part number. Lidl was
exactly half the price.

--
*A bicycle can't stand alone because it's two tyred.*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Bill Wright wrote:
http://dl.dropbox.com/u/11023364/20111215711.jpg

This is a battery terminal on one of these:

http://www.halfords.com/webapp/wcs/s...egoryId_255204

Pic shows the upper washer removed. The excessive sleeving held the
lower terminal surface off the stud face completely, and allowed what
appears to have been contact by arcing between the top terminal surface
and the washer. Oddly the stud thread did not contact the terminal,
although wiggling it would make it do so.

I don't see how. The washer would have tilted and made contact.
No, I mean when I had the nut and top washer off as shown in the pic I
could wiggle the terminal about and it would then make contact with the
threaded stud. But left alone there was no contact.

Regarding the tilting of the washer, this was obviously restrained
because the sleeving came right to washer's centre point. It obviously
did tilt, but not enough to make good contact. Hence the pitting.

Regarding price, I got the thing for £80 from Halfords (though it's gone
up now). I thought that was OK because the 20Ah battery would be
expensive. The device works well, and with an inverter, lamp, and air
pump seems like quite a good package. I've always found Halfords little
air pumps and so on to be quite good value. More reliable than similar
products with 'no-name' names. This goes against my general belief
system, but as you know I have an open mind on all matters.

Bill