Exactly what the title says.
I read somewhere that the proper charging setting for the 7.2V 3000 mAH batteries in use for competitions is Fast mode and that the Safe mode is meant for the old 2000 mAH batteries. Is this true? Is it safe to charge the batteries on fast with regards to the effect, if any, it may have on capacity?
It is always better to charge batteries of both kinds on safe mode. Using fast mode reduces the battery life and also poses concerns like making the battery explode, which has happened to me.
If needed you can charge a battery in fast mode though. I have used it but only when in a competition and we needed to charge a battery fast before the next match.
@Gabriel D Yes, you can charge a battery on fast if absolutely necessary, but when its not, its better to refrain because it permanently damages the battery and reduces its overall life and charge retention.