How long will a Li-Poly battery last?

[Vesper]

Battery size: 11.1V 1200mAh

Featuring:
M120 Spring
20 BPS

[D.Smitty]

Now, I've never tried this, but my physics students actually gave me the idea.  If you can put a multimeter in series with your gearbox and battery, then you can find the current that  your box is pulling from the battery when you fire.  After that, it's simple math to figure out how long your battery will last.

Everybody, feel free to tell me how wrong I am or how impossible this is w/o wire cutters.  It's just a thought.

[Inked]

Severed will chime in but I believe a magnum motor pulling a m140 spring is drawing close to 30 amps.

Vesper to answer that question it depends upon your shooting style, do you shoot semi, or spray and pray?

[Vesper]

Severed will chime in but I believe a magnum motor pulling a m140 spring is drawing close to 30 amps.

Vesper to answer that question it depends upon your shooting style, do you shoot semi, or spray and pray?

I shoot semi and bursts. I am never a spray and pray guy.

[SteevoLS]

If you stay on semi, that could very well last you all day. I ran a 2200mAh 20C lipo on the Thompson with a Systema M120 at a Newberry game all day on auto with no issues.

[GrimWulf]

Everybody, feel free to tell me how wrong I am or how impossible this is w/o wire cutters.  It's just a thought.

You are actually quite right Smitty. It is very possible to test FLA (Full Load Amps) without wire cutters. All you have to do is use a micro clamp-on Multimeter, like the one pictured below. Separate a section of your positive wire from the negative and clamp this sucker around the positive and pull the trigger. As long as your multimeter is set to amps, it will tell you how much current you motor is drawing. It is just that simple.

[img width=280 height=280]http://ecx.images-amazon.com/images/I/4 ... AA280_.jpg[/img]
BTW, a quality multimeter of this size will run about $45.

[Vanquish]

My 11.1 LiPo is 1800mAh, and it will generally last me all day with about two thirds of that being  semi auto fire.

[Gabe]

If you stay on semi, that could very well last you all day. I ran a 2200mAh 20C lipo on the Thompson with a Systema M120 at a Newberry game all day on auto with no issues.

In physics, it is generally easier to make an object in motion STAY in motion than it is to move an object from a standstill.  I'm not sure if this would be completely applicable to airsoft but I'd guess that you would get more shots out of shooting fully automatic than you would from a series of semi-automatic shots.
Now if you want the battery to last for a longer period of time, semi would be the way to go, but if you're counting the number of shots you'll be getting out of the deal, I would bet fully automatic fire would yield more total shots.
That said, I know from experience that firing in semi-automatic in quick succession is both less efficient for the battery and worse on the internals than firing fully automatic for the reason stated above.  By quick succession, I mean keeping the gun in semi and popping the trigger as quickly as you can.
Anyway, I realize I got a bit off topic, but hopefully someone will learn something from my ridiculous verbiage.

[SteevoLS]

I see what you're saying , Gabe. What I intended to convey was that your battery would last longer through the day on semi because you would probably be shooting a lot less than if you were running auto the entire time. That assumes you have good trigger control, of course.