Rechargeable AA batteries for BG-E2 Grip

Hi,

I have the cassette which takes 6 AA batteries which totals 9V, as the normal battery is listed at 7.4V I assume that the camera is equipped to cope with this overvoltage. How does it cope with 6 NiMh rechargeable batteries which will total 7.2V?

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I am not so under the affluence of incahol as thinkle peep I am!