mixing batteries for the mag85

I know people say not to mix different batteries. But still being new at hotwiring I have to throw something out there and get some feedback.

I want to power my WA1185 8-cell 2D mag with:
7AA NiMH Sony 2100mAH
A cell from a RCR-V3 Li-Ion ???mAh (3V AA rechargeable)

My hopes is that it will allow me to run 9-cell specs out of my 8-cell mag.

Is there a reason why this wont work as planned? Will this harm any of the batteries? How will the batteries know that the other battery is in there?

Is it ok for momentary WOW effect?

If I shouldn't try this because of harm to the flashlight, batteries or myself, then please let me know the technical reasoning behind it.

If you believe it will work fine or ok, gimme the thumbs up.

I respect many fellow CPF members and their knowledge. I may ask stupid or not-so-stupid questions so please bear with my quest for flashlight knowledge.

Thanks.

anyone?

I strongly advise against using different batteries.

If the Lithium AA had the same capacity (the same mAh) as the NiMh AAs, it can work without problems. But I'm sure that they don't have the same capacity.

So if you use them, the following will happen:

Let's say you Lithium AA has a capacity of 1000 mAh, which means that 1000 mAh can flow through it, before it is depleted. At the time 1000 mAh have flown through your Lithium cell (and through the others as well because you connected them in series) your NiMh will still have a capacity of 1100 mAh (initial capacity of 2100 mAh minus the flown 1000 mAh)

If you continue to use your light, your NiMh want to deliver the rest of their capacity because they aren't empty yet. But the only way to do this (because you connected them in series) is to force the current through the empty Liion cell, which will take heavy damage of that and be nearly instatly dead.

Beacuse you force more than it's own capacity through the Liion cell, you reverse charge it which is the worst thigh that can happen to a cell (especially Liion, NiMh can survive this action with minimal damage, but Liion will be instantly dead.)

I hope you understand what I mean and this explanation helps a bit...

Damn!

Parallel is bad enough, series is a recipe for disaster. Not to mention the differences in internal resistance from the different chemistries. That would really screw up the discharge rate, especially if you have the protection circuit from the Li-Ion pack in there somewhere.