Many years ago I was pretty heavily involved with 10th scale electric buggies and used 7.2v and 8.4v NiCad packs. My primary charger had the ability to fully discharge, but in the heat of the battle, I needed to discharge several packs at once and I was using the charger to charge or top off a pack.
I soldered together about 10 single element tail light bulbs together with a battery connector. I made several of these and they were did a good job pulling the packs down evenly without overheating them. The talk at the time was this load was very similar to what the motors were pulling and it helped the battery packs stay matched. I don't remember how far I would discharge, but I would I would monitor with a voltmeter and pull them off at a certain point.
Seemed to work well enough and I was still using this method when I moved up to 8th scale gas.
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