12 January 2007
All of last year, I was running stick pack NiMH batteries (consisting of sub-c Intellect Batteries 3800 cells) in the Tamiya Asia Cup qualifiers and I didn't know how to discharge the cells. Ideally, battery trays that discharged cells individually with individual cell voltage monitoring should be used but they don't work with stick packs since the cells are all sealed. Discharging the whole pack at a high amp rate accelerated the aging of the cells while discharging at a low amp rate made performance sluggish. The Battery Manager from Spintec claims to solve the problem by discharging at a 35 amp rate in pulses, so that the battery has time to rest between pulses and recover its voltage. I had to try it out.
During the discharge, you a very slight buzzing sound came from somewhere. Sometimes it seemed like it was coming from the Battery Manager unit and sometimes it seemed to be coming from the battery pack. The popular belief seems to be that it comes from the battery pack and that it is the sound of the chemicals inside decrystalizing. It takes several hours (seven or more hours if I remember correctly) to discharge a fully charged 3800mAh pack. When it is done, you get a readout for the battery capacity, runtime, average voltage and internal resistance. The one thing me and my friend who has been using one of these notice is that the internal resistance for some old packs seem to be reduced after a few cycles on the Spintec. Actual performance wise, I cannot really tell if the old batteries really are rejuvenated but according to the readings, they definitely are. What I've noticed is the pack doesn't even get warm during discharge, although the Battery Manager unit does get a bit warm (and even quite hot if you discharge a new battery pack with it).
Conclusion: Because of how long it takes to discharge one pack, the Spintec Battery Manager is not something that is particularly useful on race day. In fact, if you exclusively use saddle or inline (side-by-side) packs, you're better served by a quality individual cell charger (like the Novak Smart Tray, or the Team Much More CTX-D version 2). But if you run stick packs, the Spintec Battery Manager's ability to cycle your cells without heating them up is very useful indeeed.
