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Ross49

Does a battery effect fps?

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Good morning all.

I'm now to airsoft and have just got a G&G gr25 sniper, (used.)l

I have tested the FPS and it's achieving a constant 230.

Would a more powerful battery increase the fps?

If not could anyone instruct me on where to start looking as to what could be a effecting the FPS.

The gun is stock

Thank you for taking the time to read

Ross

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The battery should not make any difference to fps, a stronger battery will just cycle the piston faster.

Your fps seems very low, out the box it should be around 350fps on 0.2g BBs.

First thing to check the hop and bucking for wear and clean the barrel (not with silicone) then I guess check the nozzle for damage. If the gun is old then the spring could have softened but losing 100fps is a big drop so could be the piston seal is crap.

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Are you chronoing with .2 ammo for a start?

 

If you've just got it and from a store; contact them before anything. Don't void your warranty.

 

*edit: just seen you said it was used.

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The battery will not increase FPS. 235 suggests something is severely wrong, that isn't just spring settling or the seal dried out its most likely a damage part. Gun needs to come apart and the hop, nozzle and then potentially the cylinder head/piston head all need checking for damage

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No. As you can see in the picture there's a cogwheel that is only half cogged. This pulls the piston back, and then when there's no more cogs, it lets go, and the spring pushes the piston forwards. So no matter how fast or slow it takes for the cogwheel to reach that point, the spring takes over there and piston travels with the same speed forward - so battery should not affect FPS.



Thou hypothetically.. if the motor was damn fast and you was firing it on auto the cogwheel could grip onto the piston before it travelled the whole way and it would get lower fps.. not sure if this is possible thou, or if theres a function to prevent this from happening (I'm no gerabox expert - I fiddle with them as little as I can!!)

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Thou hypothetically.. if the motor was damn fast and you was firing it on auto the cogwheel could grip onto the piston before it travelled the whole way and it would get lower fps.. not sure if this is possible thou, or if theres a function to prevent this from happening (I'm no gerabox expert - I fiddle with them as little as I can!!)

 

The tappet would engage early too.

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The tappet would engage early too.

to what effect?

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to what effect?

 

I have no idea tbh, looking at the diagram it would break the airseal an infinitesimal time before the spring's decompression was halted. Since some cylinders are vented, stopping the cylinder early as you said above is very bad.

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No. As you can see in the picture there's a cogwheel that is only half cogged. This pulls the piston back, and then when there's no more cogs, it lets go, and the spring pushes the piston forwards. So no matter how fast or slow it takes for the cogwheel to reach that point, the spring takes over there and piston travels with the same speed forward - so battery should not affect FPS.

 

Thou hypothetically.. if the motor was damn fast and you was firing it on auto the cogwheel could grip onto the piston before it travelled the whole way and it would get lower fps.. not sure if this is possible thou, or if theres a function to prevent this from happening (I'm no gerabox expert - I fiddle with them as little as I can!!)

 

The 'cogwheel' is the sector gear as only a 'sector' of it has teeth (the other gears are the pinion gear on the motor, the bevel gear touching the pinion gear and the spur gear in the middle of the bevel and sector. This is a little confusing as the whole set is a 'spur gear set' rather than a 'helical gear set' this gets nice and confusing when using helical gears and the same middle gear is still called a spur gear)

Spring pushes it forwards as mentioned, speed at which it travels backward has no effect. a larger spring (M120 instead of M100, for example) simply pushes it forwards faster. You can use this effect in 'short stroking' by removing teeth from the sector gear so the piston is only pulled back, say, 12 teeth, not the usual 16, using a larger spring to push the smaller volume of air faster.

 

If everything is 'damn fast' then the sector gear CAN engage into the piston rack before it's fully forwards. This is baaaad. This pre-engagement can damage both piston and sector gear to the point of breaking teeth off both.

The function to stop this from happening is simple: Don't use 11.1 LiPos in stuff not designed for it.

 

The tappet plate engaging early can be measured:

Chrono on semi auto

Chrono on full auto

 

If there is early engagement on the tappet, the auto chrono test will be lower, typically a 10-40fps loss and inconsistent results.

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Thank you for your reply.

I have now stripped the gearbox down and can see no damage to any of the seals but the one on the piston seems loose around the head of the piston is this normal?

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Get some photos of the interior up. Will make it easier for people to see anything that may be amiss.

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Yes, the piston seal needs to be loose as it expands on the forward stroke to seal the piston to the cylinder and expel the air. Have you tried putting a bit of silicon grease on the piston ring? If the seal is dry then it will not seal tightly enough to give full pressure. If you have the gearbox apart, try putting the piston into the cylinder with your finger over the end of the pipe coming out of the cylinder head, with the open end upwards. If the piston (and head) seal is good, then the piston should either drop very slowly, or not at all, even if you press down on it. If the piston drops straight down, or moves very easily under finger pressure then you have an air seal leak, either around the piston seal or the one sealing the head to the cylinder.

 

If the seal is good then the issue is probably either a weak spring has been put in the gearbox, or you have a sealing issue between the nozzle and the hop rubber, or the hop is turned too far on.

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quite a poor way (from what I understand you're doing?) to check compression as some P heads release pressure on the return stroke.

 

Finger over the pipe as before, then shove the piston assembly in as fast as you can. Should not move or reach a point where you can't compress the air further before it returns home at the front of the cylinder

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That video was a great help.

And thank you guys for the help I'll strip down the gearbox again and test all the things you have suggested.

Results will follow.

Thanks again for helping a noob

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some bigger batteries can actually lower your OWN fps I found....

 

c88fcf9fb87d16c280adc46dbd539d1e.jpg

 

lasted ages but was maybe a liitle to large & a right bitch to use as some cqb sites

(soz I'll get me coat)

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