Re: 1502 TDR Battery problems

Tom Gardner

On 11/06/20 16:02, Mark Pilant wrote:
I tried for quite a while to get the "battery fooler" to work *reliably* in
the 1502 and 1503 I have.  I was never successful.

The zener concept isn't too bad, but there is the power dissipation in the enclosed volume.

I did try the Batteries Plus route and had them make up a replacement pack.
While it looked fine, it wouldn't fit.  The original Tek design used flat
top "C" cells, and pretty much all that is available are button top "C"
cells.  According to the specifications I could find, the "original" flat
top "C" cells were slightly shorter than the button top "C" cells; by the
height of the button.
I have found these acceptable

The diameter is slightly too small, but that is easily rectified with some closed-cell foam.

BTW, I did some checking, and these batteries will last about a month before
needing to be recharged when "sitting" in TDR that has been turned off.
Yes. There is an ~1mA (higher if the chart recorder is present) drain even with the front panel switch off. If the battery is left in then eventually one or more of the cells will be damaged by being reverse charged. That's the reason the manual specified the battery should be charged monthly.

Personally I just leave the battery pack out of the case. If I wanted to keep it in the case, e.g. for shipping or long-term storage, then I would remove the fuse in the battery pack.

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