Unable to cycle with 8.4v Battery

[Anthology]

I was working on shimming a version 3 mechbox today and became worried when I tried my configuration after reassembling the gearbox. My 8.4v batteries would not pull my new M110 spring. They might pull it half way then just get locked.

I thought it could have been my shimming but now it is together with a lighter spring and works just fine. It cycles with the M110 and a 9.6 volt battery, I had only tried it with 8.4's today. The motor became hot when trying with the 8.4's but it was only warm with the 9.6. This is a stock VFC motor from a number of years ago.

Does anyone have suggestions as to how to approach this? Should I just invest in more 9.6's/7.4 lipos or is my motor more of an issue?

Thanks.

[JerryMcGoulBerry]

The battery isn't strong enough. could be a motor issue. try a new motor out before buying one.

[Anthology]

For reference, the batteries I am using are all stick type batteries:
Intellect 9.6v 1600 mAh (New, Ni-HM, cycles well)
DBoys 8.4v 1100 mAh (old, Ni-HM, cycles at times)
Sanyo Cadnica Extra 8.4v 600 mAh (old, Ni-Cad, rarely cycles fully)

[JerryMcGoulBerry]

Originally Posted by Anthology

For reference, the batteries I am using are all stick type batteries:
Intellect 9.6v 1600 mAh (New, Ni-HM, cycles well)
DBoys 8.4v 1100 mAh (old, Ni-HM, cycles at times)
Sanyo Cadnica Extra 8.4v 600 mAh (old, Ni-Cad, rarely cycles fully)

In that case, I would put my money on the batterys. old batteries can be pretty weak. I recommend these batteries
http://www.hobbyking.com/hobbyking/s...y-Airsoft.html
look at that price tag! buy 5 of these and you'll be set
you can also try to clean your pinion gear
There are many things that can be a factor in this. I'm only telling you the most likely things.

[MaciekA]

Shot in the dark but here's something I run into V3 gearboxes all the time, and it produces the same symptom: Binding of mechanical parts.

Check to see that the part of your trigger that actually pushes the trigger's trolley doesn't rub against your sector gear. This is sometimes hard to debug since it sometimes only happens on certain positions in the rotation of the sector and/or the positions of the trigger's range of motion. Can be a hard problem to catch.

Another example of the same issue that I've seen in a few V3 gearboxes is binding of sector gear against the piston. My SHS gearsets tend to actually be somewhat oversized for some gearboxes I've tried them in (CYMA for example).

The tricky thing about the above problems is that sometimes, with enough torque, parts can move past each other and mask the true nature of the problem, that is until you starve the system of power.

[Anthology]

The trigger trolley I know for a fact clears the sector gear.

As for your second suggestion, why do the 8.4's work when a lighter spring is installed? Is it simply a matter less resistance from the spring translates into less resistance on the possible binding sector gear?

[MaciekA]

Originally Posted by Anthology

The trigger trolley I know for a fact clears the sector gear.

As for your second suggestion, why do the 8.4's work when a lighter spring is installed? Is it simply a matter less resistance from the spring translates into less resistance on the possible binding sector gear?

Could be. I'm just throwing stuff at the wall here to see what sticks.

Of course my solution to everything is to give it more power, like way way more. NiMH's?!? 8.4V?? Pure heresy!!

[Anthology]

Originally Posted by MaciekA

Could be. I'm just throwing stuff at the wall here to see what sticks.

Of course my solution to everything is to give it more power, like way way more. NiMH's?!? 8.4V?? Pure heresy!!

Haha, I've been looking into Lipos recently so this may be a worthwhile investment. I should see if I can find a brand new 8.4 to try... the 8.4's I have are rather old.

[R.I.T.Z]

older motor weaker motor + New Strong spring + weak battery
= no go

options
new motor
new batteries

preferably both, considering your motor was overheating under the stress of the new spring.

[Kos-Mos]

Both your 8.4v batteries cannot be called "close to reliable". You will probably have no issue with a good quality recent 8.4v.

[winterrises]

Originally Posted by macieka

could be. I'm just throwing stuff at the wall here to see what sticks.

Of course my solution to everything is to give it more power, like way way more. Nimh's?!? 8.4v?? Pure heresy!!

more power? Moar power!!!! :d

[Styrak]

Use a stronger battery.

You're also using mini cell (weaker) batteries, use large cell batteries. A large cell 8.4v can pull almost any reasonable spring.

[Anthology]

Originally Posted by Styrak

Use a stronger battery.

You're also using mini cell (weaker) batteries, use large cell batteries. A large cell 8.4v can pull almost any reasonable spring.

Problem is I have an AKS-74U, only room for sticks or lipos but I'll keep that in mind.

[p.phresh]

maybe get a hi-torque motor? You'll lose on rate of fire but it should be able to pull the spring back using a small battery. Either way... you should probably replace your old worn out batteries.

[bizkilter]

I've had similar issues with v2 gearbox's and the answer most times has been an upgrade to a better battery. the times when that hasn't been the issue it's been better motor + battery.