Re: 1502 TDR Battery problems

Tom Gardner

In my experience the simple "fake batteries" are unreliable. Some work, some of the time, in some 1502s. Twiddling with the values increases the probability of them working.

I prefer to put new NiCd cells in; they cost ~£30/set, plus your time soldering the tags together.

On 10/06/20 22:01, Jeff Kruth via wrote:
Hello Folks!

Went to use my 1502 TDR, wouldnt light up. I had built a battery cable for a 12 Volt lead acid external battery, so I charged the 12 V battery up and got it working. I remembered the Battery Fooler mod and looked it up on the Tek site here: 2200 uF cap paralleled with 200 ohm 10 watt resistor. I built one of these in a kaput battery back, plugged it in, and it doesnt work! The little meter is pegged in the green, looks kinda normal.  Yes, I got the capacitor polarity right.  SO I plugged a power supply into the unit: 12V @ 275 mA or so and the unit operated fine. At 13.5 VDC about 200 mA or so.Am I missing something? The Battery Fooler seemed like a good thing.  Should I thinker the cap value? Why the 200 ohm resistor- is this needed to keep the SCR thingy working right? Should the value be increased?Any insight would be appreciated. TIANew info: Tried several caps and resistor values around ther original stated ones: No joy!Regards,Jeff Kruth
BTW Brooke Clarke's 1502 webpage is quite good.

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