I've been using 8 rechargable AAA's in and they work great!
one think to note is most rechargable batts run at 1.2v when fully charged and a lower mah , where a normal AA when brand new is about 1.6-7 so running a extra rechargable just really ups the voltage and current up to fresh brand new normal bats!
I addded 2 extra and it runs A V35 great for a full day.