What Lipo for a realistic ROF

[Gazaam]

Hello

I'm in need of stuffing a battery inside an M4 RIS, and Lipo's are a possibility that probably won't require machining that part in order to fit.

I've read the lipo threads on the forum, but still haven't really found an answer for what I'm looking for: a small battery, capable of doing a realistic ROF (i.e. not in the 1300 rps mark). I'll be using a stock ICS M4 gearbox, as it's rather well put together, and we have a 350 fps limit that I don't have any intention of exceeding (I'm fine with anything between 300-350 fps)

I know Lipos will do this, but what would be the recommended specs (voltage, amperage, and discharge rate) I should be looking out for?

Also, I suppose a trigger master unit or something of sorts to prevent overdischarging should be considered. Any recommendations, in light of your battery suggestion?


Thanks

[ShelledPants]

7.4v Lipo 25C will do you just fine. Stock, the RPM will be too high, but since you're using a Trigger Master, you can program it to shoot at a more realistic RPM.

Problem solved.

[gvanzeggelaar]

ya if you have a trigger master you could even go with an 11.1v. Like shelledpants said if its too high you can just program the motor to go a bit slower.

[Gazaam]

And which of those would be more user friendly, form a charge/discharge risk point of view? Also, for a 11.1v should I also get a 25C Lipo?

[808]

I use 11.1V 1600mAH LiPos in my CA SCAR-H with the Trigger Master Mk.I/Mk.II. I tried to reduce the motor speed a bit, and it fires like any NiCd or NiMh battery.

But I'm all about power, so I hiked it back up.

[Gazaam]

I'm all about not changing internals after every couple of games, but thanks for the info!

[Kos-Mos]

You won't have to change internals at all if the job is done correcty.

TM AUG V3 mechbox
Metal bushings
Shim job
400 fps spring
EVERYTHING else stock.

I have yet to see any damage. I am running 11.1v LiPo for over a year now in my guns. (about 10 000 BB in the AUG)

For a stock gun, a 7.4v would be perfectly in the right range. You would get about the same ROF as using a 8.4v NiMh or NiCd.
Also, I ran a stock ICS on 11.1v LiPo no problem. As long as you stay above 350 fps, there will not be any issue (under that, semi double feed problems might appear).

[Gazaam]

Originally Posted by Kos-Mos

For a stock gun, a 7.4v would be perfectly in the right range. You would get about the same ROF as using a 8.4v NiMh or NiCd.
Also, I ran a stock ICS on 11.1v LiPo no problem. As long as you stay above 350 fps, there will not be any issue (under that, semi double feed problems might appear).

The issue is, as stated above, that I have to stay under 350 fps. It was running on an Intellect 9.6v 2000mAh V-shape battery, which gave it a reasonably accurate ROF.

[808]

My CA SCAR-H is completely stock.

Fires 345-355fps w/.2g BBs.

[Kos-Mos]

Read carfully.

If you use a 7.4v LiPo, it will give you about the same ROF as a 8.4v pack.

You should stay away from 11.1v unless you are 350+ fps.

[Dynamo]

you dont need to stay away from 11.1v.
i would use the 11.1v over the 7.4 as the low voltage of the 7.4 can trigger the low-voltage cutoff on the triggermaster board.

im running my VFC HK416 (PGC PRO-WIN 8mm gearbox) on a FireFox 11.1v 20C stick type LiPO on an ExtremeFire Cheatah board with ProjectWolfDragon's cell monitor board.
my gun is shooting around 350FPS with a fire rate of 16R/S with 30% motor speed reduction.

[Kos-Mos]

Change the spring to a 330 fps and try that.

He has to be UNDER 350.

It can be done, but it can cause problems because the gears cycle faster than the piston can move, so it causes 2-3 shots in semi and piston/sector gear failure.

That is the reason why.

7.4v packs cost less, are smaller (you can use that saved space to add capacity or rate (15c to 20c). And you don't need to use a CPU control unit.

[ShelledPants]

7.4v http://www.hobbycity.com/hobbycity/s...0mAh_2S1P_20C_

11.1v http://www.hobbycity.com/hobbycity/s...0mAh_3S1P_20C_

The price difference is minor.

[Gazaam]

So does a 7.4v pack not require a Trigger Master unit or anything else of such kind? Do you have any suggestions for preventing overdischarging it, apart from those units?

[Kos-Mos]

Yes. Look for hobby LiPo checkers.

Some are plugged between the servo and receiver (you don't want that kind)
Others simply have a flashing LED to indicate low battery.

Other than that, AS SOON as the gun start to drop ROF (it is quite noticeable, but you have to pay attention) stop using it. The pack will be at about 3.0v/cell.