Are you even reading my posts?
Instead of running the risk of trashing your LiPo batteries everytime you use them in a long game, spend 30$ on a PCB instead of a multimeter so your guaranteed that you NEVER overdischarge your batteries.

Trigger master FTW.

Mines acting wierd but im working on it. Either the gun is foobared or the lipo has dropped to low that my TM isnt even responding to it. I doubt that as I only used it once guess it's back to the drawing board. damn rifles. lol

The problem your having is you didn't do a factory reset before you plugged the LiPo in. I know because the same thing happens to me when i switch from a 9.6v batt to a 7.2v batt.
How it works, is the old TM's (the one you have), detect low batteries by a percentage of input voltage. The input voltage of a 7.2v lipo is actually 8.4v, 80% of that is 6.72v where the triggermaster will tell you your battery is low and stop the gun from firing. That's good since under 6v your LiPo is over-discharged.
NOW, one would ponder, well what happens if you plug in a NEAR DEAD LiPo? Say one at 7v? Wouldn't the cutoff be well under 6v? Well that why the TM has a memory. It remembers that you use 7.2v batteries with an input voltage of 8.4v, so it's naturally set cutoff voltage will be at 6.7v. This is specifically to prevent overdischarge from plugging in a half dead LiPo.

So YOUR issue is, because your used to using 9.6v batts, with an input voltage of around 10.5v, the TM's cutoff is 8.4v. Therefore as soon as you plug in your fully charged 7.2v LiPo the triggermaster thinks your battery is already dead!

So the solution is to do a factory reset, and use your 7.2v LiPo to setup the TM. Typically if you plug in a 9.6v battery afterwards, you have to do another factory reset to be able to use a 7.2v LiPo :)

I have been using Lipos for many years (not in airsoft but RC cars) and it baffles me that some company has not come out with really good cut off's yet.

Its good that we have what we have but if we could get the quality of the RC ESC's into airsoft many it would be deadly

Well most AEG manufacturers are, for lack of a better term, "Chinese businessmen". They will do anything and everything to get as much as your money as possible with no regard for screwing you big time in the long run.
Most AEG's I've seen that are "LiPo Ready" are actually fairly dangerous to run off LiPo batteries, especially those that take buffer tube batteries.
Some companies, and reliable individuals DO produce electronics for airsoft guns to make your gun 100% LiPo ready. This includes SW-comps, PCBs, and other such devices.
The only problem is it's HIGHLY doubtful that any manufacturer outside of Japan would ever put these electronics in as OEM parts, and if they did they'd likely be of such poor quality you'd have to replace them anyway!
Thus far the only airsoft gun I know of that comes stock with electronic components is the systema PTW line.

Marui did an electronic burst for their SIGs years ago. Apparently it burnt out fairly often.

TSI Tavor has a FCC, but apparently it's completely crap. Takes seconds to switch between firing modes.

The upcoming ICS MP5X and FNC both have an electronic burst.

Systema took years to work the bugs out of their PTW design, it'll be interesting to see how long it takes the increasing number of PTW clones to do the same, or if they will leap frog Systema's past problems.

Those are the ones off the top of my head.

yeah i agree u dont need one. airsoft may have been using lipos for short time but they've been out for RC helis and planes for donkeys... used to be big into them and ur safe as long as u switch batteries as soon as u notice a drop in ur ROF or if it starts fast and slows very quickly - the best way to protect ur LIPO is simply to drop the 150-200 bucks on a good multicharger with a battery diagnostics program and it'll monitor ur battery for signs of damage and let u know if it's safe to charge - never once had one go off on me and i've been using them in mu guns for over 3 years now :P 11.1's and 7.4's - tried a 14.8v once - lets just say i may as well have doused the gun in napalm and lit it whistling to the tune of "we'll meet again" ...

not saying a chip is a bad idea but unless u really run ur battery into the ground ur pretty safe

and on another note I'm using 7.4v 2600 mAh 35C batteries on my scar with a madbull 120 spring in it - standard 9.6v NiMh just wouldn't push it properly although the stock is interestingly big enough for 10.8v NiMh mini batteries - I know not many people use them but they give u a good ROF and last nice and long hehe. - LIPO's still last longer but if ur not comfortable then the 10.8v mini's are ur friend there - would give a stock scar an insanely crisp trigger response and more than capable of pushing an upgraded spring as well :)

Also just a quick warning - I installed my own gearbox in the SCAR the day i bought it but I've had a few who upgraded springs alone or used lipos on em stock in my workshop for gear replacements - the metal seems to be a little brittle I guess - although knowin my luck im just one unlucky sod lol

Alot of great advice and clarification. Ive done alot of research on these batteries and frankly the size difference, available power and cost is a great benefit when used correctly. And installing a PCB is a low cost way of ensuring that your battery will enjoy a long life.

Thank you to everyone that posted helpful information and first hand experience.