LiPo batteries and FPS inconsistency

Shamusodoofus · February 23rd, 2015, 12:29

So I seem to be experiencing an interesting issue. I'm getting inconsistent FPS while running a LiPo, but the issue goes away when I switch back to a 9.6V NiMH.

I just recently switched from a 1600 mAh 9.6V NiMH to a 11.1V LiPo 20-25C. My FPS prior to the switch was +/- 1 at the most, after the switch my FPS is now +/- 6. I have taken all the necessary precautions and have upgraded my gearbox where is needed to run a LiPo (gears shimmed perfectly, sorbo, Lonex gears, MOSFET (GATE MERF 3.2)) Now, my groupings aren't bad (within 1") at 25 ft. but the FPS inconsistency is annoying me. Anyone have any ideas what the issue could be?

It is to my understanding that all the LiPo should be doing for me is increasing the speed of the motor and hence better trigger response and higher ROF. Is there something I am missing here, or is this just the nature of LiPos?

lurkingknight · February 23rd, 2015, 12:40

maybe the speed in which the piston is being pulled back is upsetting the piston o-ring somehow making it take longer to seat when it comes back forward. When you do a compression test on the piston/cylinder assembly is it leaking at all? does it seal immediately or only seal when the piston comes forward at a specific speed?

That's really the only thing I can think of that would be happening.

DeWee · February 23rd, 2015, 13:01

Sector gear may be releasing the piston prematurely

Spike · February 23rd, 2015, 13:08

Tappet plate timing?

Paging pestobanana

L473ncy · February 23rd, 2015, 13:11

It is literally impossible for a battery alone to do that. The battery is just a power source, power is power (current, voltage, etc.) doesn't matter if it comes from a battery or a solar panel or a hydro turbine or your wall or a nuke plant or whatever. Like others have said it's likely to do with how the motor is spinning and releasing the piston. My guess is premature engagement or over spinning or something affecting where the gears end up and messing with the airseal somehow. Possibly even something as stupid as how the sector gear interacts with the tappet plate and air nozzle (my best guess). Then again I have no idea.

Azathoth · February 23rd, 2015, 13:14

LIPO battery is spinning gears too quickly. Piston is traveling forward and is re-engaged by the sector gear, resulting incomplete compression.

Zfurlong · February 23rd, 2015, 13:33

Quote:

Originally Posted by Azathoth

LIPO battery is spinning gears too quickly. Piston is traveling forward and is re-engaged by the sector gear, resulting incomplete compression.

This would be my guess as well. The piston Oring shouldn't be the issue if it goes back to normal when you go back to the 9.6, I don't think it would be the seating either.

ThunderCactus · February 23rd, 2015, 13:37

I'd also go with tappet plate on this one, but 6fps is really not a whole heck of a lot. I mean you'd have to be off on the forward stroke completion by just a few milliseconds to get JUST a 6fps leak.
Could be as simple as a small pinhole leak between the air nozzle and cylinder head.

Shamusodoofus · February 23rd, 2015, 14:13

Thanks for the all the replies guys, especially from the gun docs. I understand 6 FPS isn't a huge difference, but I'm trying to get this rifle to be as accurate as possible, so every tiny bit counts. If in the end there is no solution it wouldn't be the end of the world, just trying to figure out why my AEG is behaving differently on different batteries.

I'll have a look into the tappet plate and swap it with a few others I have and see if it makes a difference. For what it's worth I'm using the stock Lonex tappet plate that comes with their gearbox.

Some of you mentioned pre engagement issues, is this still possible even with an active braking MOSFET? I have a MERF 3.2 installed and I have switched it out with a NanoAAB I have to eliminate faulty tuning on my part; both MOSFETS are still giving me the same result (+/- 6 FPS variance). They are both properly installed with the signal wires on the trigger contacts. I just double checked with my upper receiver removed and looking at the inspection port (V2 gearbox), the spring doesn't compress at all after the gun cycles in semi, which leads me to believe the MOSFET is doing its job.

pestobanana · February 23rd, 2015, 14:14

Spike read my mind, the issue is most likely tappet timing. If you have a sector delay clip, I'm almost 100% sure the issue is tappet timing.

Shamusodoofus · February 23rd, 2015, 14:18

Quote:

Originally Posted by pestobanana

Spike read my mind, the issue is most likely tappet timing. If you have a sector delay clip, I'm almost 100% sure the issue is tappet timing.

No sector delay clip, I'm not looking at building a ROF build, just a DMR with great trigger response.

That being said should I look into a sector delay clip? I have one lying around that I decided against installing simply because when I tested the gun on burst the gun didn't have feeding issues.

ThunderCactus · February 23rd, 2015, 14:22

Might just need better lubrication to slide forward
If it was pre-engagement, you'd know it lol

pestobanana · February 23rd, 2015, 14:26

Quote:

Originally Posted by Shamusodoofus

No sector delay clip, I'm not looking at building a ROF build, just a DMR with great trigger response.

That being said should I look into a sector delay clip? I have one lying around that I decided against installing simply because when I tested the gun on burst the gun didn't have feeding issues.

I'd need more details on the gun. What's the base? What have you changed internally?

Normally sector delay clips improve feeding but cause tappet timing issues. They can pull the tappet too early, so the nozzle is retracting before the BB has left the barrel.

lurkingknight · February 23rd, 2015, 14:34

Quote:

Originally Posted by DeWee

Sector gear may be releasing the piston prematurely

Not possible. There are a set number of teeth on both. If the sector engages the piston early (PME) the piston will either take it and jam or the rack strips. There is only enough room for the piston to draw back when there's all 15 teeth present on sector and piston.

Quote:

Originally Posted by Azathoth

LIPO battery is spinning gears too quickly. Piston is traveling forward and is re-engaged by the sector gear, resulting incomplete compression.

Again, PME. If the sector is in mid cycle the piston will skip off if the rack takes it.. or it will strip.

This is why TC says you'll know if it's PME or not, it will sound like grinding or snap whirrrrrrrrrr.

Shamusodoofus · February 23rd, 2015, 14:44

I've experienced pre-engagement before in another high speed build and I'm certain that is not the issue here. The gun is a custom build with the following parts:

Internals:
Lonex 8mm bearing gearbox
Lonex tappet plate
Modify Trigger assembly
MERF 3.2 MOSFET
Lonex 16:1 high speed gears
Tienly GT-35000 Ultra Torque Motor
Modify M120 Spring
Guarder ball bearing spring guide
Modify full length cylinder
Stock OEM Marui Piston (I've tested with a Magic Box piston with Modify piston head, same issues occur)
Stock OEM Marui Cylinder head (with teflon tape mod and sorbo'd) AOE corrected

Barrel/Hop:
PDI 455mm 6.05
Lonex Hop unit
PDI W-Hold

I understand the PDI W-Hold has sealing issues. I actually have a second scrap barrel (a modify 455mm that I've modified to test FPS leak (I've glued the hop bucking and hop unit to ensure a perfect seal). I've tested it with this and my issue still arises.

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February 23rd, 2015, 12:29	#1
Shamusodoofus Trader rating Join Date: Feb 2008 Location: Toronto (GTA)	LiPo batteries and FPS inconsistency So I seem to be experiencing an interesting issue. I'm getting inconsistent FPS while running a LiPo, but the issue goes away when I switch back to a 9.6V NiMH. I just recently switched from a 1600 mAh 9.6V NiMH to a 11.1V LiPo 20-25C. My FPS prior to the switch was +/- 1 at the most, after the switch my FPS is now +/- 6. I have taken all the necessary precautions and have upgraded my gearbox where is needed to run a LiPo (gears shimmed perfectly, sorbo, Lonex gears, MOSFET (GATE MERF 3.2)) Now, my groupings aren't bad (within 1") at 25 ft. but the FPS inconsistency is annoying me. Anyone have any ideas what the issue could be? It is to my understanding that all the LiPo should be doing for me is increasing the speed of the motor and hence better trigger response and higher ROF. Is there something I am missing here, or is this just the nature of LiPos?

February 23rd, 2015, 12:40	#2
lurkingknight "bb bukakke" KING! Trader rating Join Date: Jul 2011 Location: Ottawa	maybe the speed in which the piston is being pulled back is upsetting the piston o-ring somehow making it take longer to seat when it comes back forward. When you do a compression test on the piston/cylinder assembly is it leaking at all? does it seal immediately or only seal when the piston comes forward at a specific speed? That's really the only thing I can think of that would be happening. __________________ I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.

February 23rd, 2015, 13:01	#3
DeWee Trader rating Join Date: Dec 2013 Location: Hamilton, Ontario	Sector gear may be releasing the piston prematurely __________________ VFC Scar MK 17 w/EGLM Wester Arms 1911

February 23rd, 2015, 13:08	#4
Spike Privateer Airsoft Trader rating Join Date: Dec 2008 Location: Beaverbank, NS	Tappet plate timing? Paging pestobanana __________________ I change primaries like other people change socks.

February 23rd, 2015, 13:11	#5
L473ncy Trader rating Join Date: Oct 2004 Location: 11-30-24-1W5	It is literally impossible for a battery alone to do that. The battery is just a power source, power is power (current, voltage, etc.) doesn't matter if it comes from a battery or a solar panel or a hydro turbine or your wall or a nuke plant or whatever. Like others have said it's likely to do with how the motor is spinning and releasing the piston. My guess is premature engagement or over spinning or something affecting where the gears end up and messing with the airseal somehow. Possibly even something as stupid as how the sector gear interacts with the tappet plate and air nozzle (my best guess). Then again I have no idea. __________________ ಠ_ಠLess QQ more Pew Pew READY TO >> RACE

February 23rd, 2015, 13:37	#8
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	I'd also go with tappet plate on this one, but 6fps is really not a whole heck of a lot. I mean you'd have to be off on the forward stroke completion by just a few milliseconds to get JUST a 6fps leak. Could be as simple as a small pinhole leak between the air nozzle and cylinder head.

February 23rd, 2015, 14:13	#9
Shamusodoofus Trader rating Join Date: Feb 2008 Location: Toronto (GTA)	Thanks for the all the replies guys, especially from the gun docs. I understand 6 FPS isn't a huge difference, but I'm trying to get this rifle to be as accurate as possible, so every tiny bit counts. If in the end there is no solution it wouldn't be the end of the world, just trying to figure out why my AEG is behaving differently on different batteries. I'll have a look into the tappet plate and swap it with a few others I have and see if it makes a difference. For what it's worth I'm using the stock Lonex tappet plate that comes with their gearbox. Some of you mentioned pre engagement issues, is this still possible even with an active braking MOSFET? I have a MERF 3.2 installed and I have switched it out with a NanoAAB I have to eliminate faulty tuning on my part; both MOSFETS are still giving me the same result (+/- 6 FPS variance). They are both properly installed with the signal wires on the trigger contacts. I just double checked with my upper receiver removed and looking at the inspection port (V2 gearbox), the spring doesn't compress at all after the gun cycles in semi, which leads me to believe the MOSFET is doing its job. Last edited by Shamusodoofus; February 23rd, 2015 at 14:15.. Reason: grammar

February 23rd, 2015, 14:14	#10
pestobanana Squid Porn Superstar, I love the tentacles! Trader rating Join Date: Nov 2008 Location: Richmond Hill and Waterloo, Ontario	Spike read my mind, the issue is most likely tappet timing. If you have a sector delay clip, I'm almost 100% sure the issue is tappet timing.

February 23rd, 2015, 14:22	#12
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	Might just need better lubrication to slide forward If it was pre-engagement, you'd know it lol

February 23rd, 2015, 14:44	#15
Shamusodoofus Trader rating Join Date: Feb 2008 Location: Toronto (GTA)	I've experienced pre-engagement before in another high speed build and I'm certain that is not the issue here. The gun is a custom build with the following parts: Internals: Lonex 8mm bearing gearbox Lonex tappet plate Modify Trigger assembly MERF 3.2 MOSFET Lonex 16:1 high speed gears Tienly GT-35000 Ultra Torque Motor Modify M120 Spring Guarder ball bearing spring guide Modify full length cylinder Stock OEM Marui Piston (I've tested with a Magic Box piston with Modify piston head, same issues occur) Stock OEM Marui Cylinder head (with teflon tape mod and sorbo'd) AOE corrected Barrel/Hop: PDI 455mm 6.05 Lonex Hop unit PDI W-Hold I understand the PDI W-Hold has sealing issues. I actually have a second scrap barrel (a modify 455mm that I've modified to test FPS leak (I've glued the hop bucking and hop unit to ensure a perfect seal). I've tested it with this and my issue still arises.

LiPo batteries and FPS inconsistency

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