TE engines connected via conduits are energy state aware. If you use for example magmatic engines connected via conduits to charge the cell, and the cell fills up, the engines should throttle down to 10% load (that is the minimum).
I say "should" because that feature is only advertised to work with machines (pulverizer etc.) and not specifically with cells. I haven't tried it out though, since I tend to use Railcraft engines.