This was a big issue back in the day.. like 15 years ago with 1200mah & 1400mah SCR batteries. Mostly for runtime and off the line punch. Back then the batteries would barely make a 240second (4min) race geared for speed. We would have to set the car down on the line (not driving it at all) and wait for the tone! The old NiCads did have more punch from stepping on them hard while charging at 6 to 10amps.. Heat did not bother them like NiMh and LiPo.
A typical good matched pack like a 4200mah NiMh (EP Cell Pack) will have 60 to 100 seconds of "top charge" peak voltage (20amp typical stock motor at full speed). This is all but wasted these days with everybody driving practice laps before the race starts and driving the car to check in transponders..
This same 4200 NiMh also has about 600+ seconds (10min) of runtime on a stock motor at full speed! Now we all know that we don't run an offroad race except maybe for oval at full speed!
So in reality... are you really going to miss a top charge?
To see what I'm talking about look at the attached pdf.. It's a graph of a test I did on a 4200mah Slingshot Batteries NiMh pack. A 20 amp draw was placed on this pack and a computer attached meter took a reading every second until the pack reached 5.4v (6cell x .9v each).
The pack at 0 discharge time has 8.73v with no load.
At 120 sec in the pack starts to level off at 7.57v underload.
At 300 sec (5min race at full speed) the pack still is at 7.47v.
We have a whole lot of battery these days... nothing to worry about in racing...