Updated: Convert Makita 6012HD 9.6 Volt Nicad Makita to LIPO Battery

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I have had an old 9.6 volt Makita 6012HD drill since around 1989 or 1990. I bought it when I was an A&P. Since then I have replaced the batteries about 4 times. I recently bought an 18v Lithium ion Makita. I wanted to continue to use the old Makita but did not want to buy any more batteries as they are kind of pricey and do not last long. I have seen several videos on the internet on connecting RC LIPO batteries to the Makita and they work fine.... EXCEPT that none of the people who do this take any precautions to prevent over discharging the LIPO batteries. LIPO cells do not like to be discharged below 2.7 volts. If you do that you kill them. The good thing about them is that they are relatively cheap. You can pick them up for $15 to $20 for an 1800mah or 2200mah battery respectively. this is 200 to 500 mah more than the replacement batteries from Makita which are 1300mah to 2000mah.
the battery connector is wired to the original connector inside the drill and the alarm is wired across those.