do the batt. have to be identical to use them in parrelel?
 

want a answer before i mess suttin up

They should be the same voltage and type if you're going to use them in parallel. The capacity (mAH) doesn't have to match but it's a good idea.

Mixing NiMH 1.2V 120mAH and NiCad 1.2V 120mAH would be bad.

Mixing NiMH 1.2V 100mAH and NiMH 1.2V 135mAH would be okay

Mixing NiMH 1.2V 120mAH and NiMH 2.4V 120mAH would be bad.

i have the 100mah that came with the zip and i have the 120mah that coms from quest for madness..seem ok??

yup, that's what I'm running... works fine.

If I hook two lithium batteries in serial and then hook the duo up to the stock zip battery in parallel could a diode be installed to prevent the charger from energizing the lithium batteries???

The problem is that the voltage would block the diode-org bat untill the potential of the lithium drop below the drop of the diode and the orginal battery voltage.

I was looking through Jameco and notice they have some nicad stack to get 3v or more. They are around 60maH but two of those would make sense.