Gauge Wire, 2 or 4 wires, deans?

[ecsinc]

I was thinking about wiring because a tab broke off the motor on my gun yesterday. I was thinking about voltage drop because the connectors for my battery get hot when I fire the gun. I'm running a M140 spring on a stock motor with infinite torque up gears. I've got a 9.6v battery 1500mAh and a 8.4V 1500mAh battery as well. The 8.4v battery says 30amp discharge. Using a multimeter I read a still voltage of at least 1 or 2 volts above what the battery are rated for, kinda werid I think.

Here's my questions:
Since the wire is like 18gauge wire, the voltage drop is around .192V. So the 11v that I read coming outta the battery is really only 10.8V, creating alot of voltage drop and resistance. Were talking almost 2% voltage drop. I herd anything over 2 is bad on a DC system, specially when I've got semi auto only. I'm wondering if I can add 2 more wires to where my battery connects to the trigger in the mechbox, then just run 2 wires to the motor. This way I'd have 2 hots and 2 neutrals going to the switch in the box, then just 1 each running to the motor. This would in turn cut the voltage drop in half. Also I could add capacitors, probably like 4 of them. This way I'd have stored up energy to combat the voltage drop once I press the trigger. I also herd that I need deans connectors. Since I'm running such a high spring the motor need as much volts and amps as possible. I've got a local hobbyshop and radioshack close by so I could probably pick those up if I need to. I'm wondering how much am I going to spend on the deans?

i'm also not sure what capacitors to get???
Something like this: http://www.radioshack.com/product/in...entPage=search


My trigger responce is really slow with the motor. I'm not sure if its bad because the motor is bad or just because of the infinite torque up gears... It seems like the motor is fine pulling the spring back...

Thanks guys!

[CDN_Stalker]

Your biggest problem is both your batteries are 1500mAh each. A minimum mAh battery for your set up would be 3000mAh at least, higher is better. Deans will allow more current to flow to your motor to help it do the work you are expecting it to do. Stop focusing on voltage and wires, focus on the current rating of your batteries first. #18AWG is totally fine for what you are doing, is all I use and never have a problem with it (Belden #18AWG Mil-Spec Teflon insulated wire).

Overall you are starving your motor when it's trying to work. Everything will improve drastically if you try at least a 8.4V 3300mAh battery.

[Kos-Mos]

You have a VERY big problem if you get a voltage drop that big.

Usually wires are considered nul voltage drop. Unless you have over 100 meters of wire in your gun.


There is something else.

And battery ARE supposed to be higer voltage than rated. Rating is nominal voltage under load. Plug your volt-meter in parrallel to your system (ie at the motor) and shoot full auto for as long as you need to get a good reading. The voltage will be a bit higher than rated. If not, then your batteries are either dead or not allowing enought current to feed the motor.

If you have "mini" type batteries, they are NOT 30A. They are 10A, 15A at best (talking about matched, TQ grade cells, about 80$ a pack).

[ecsinc]

I could rewire the gun to the back and have a magazine pouch as a battery holder on the adjustable stock... then you think I should go with 10.8V?

[m102404]

Not sure what type of rifle you have...so it's a bit of guessing.

Stalker's always got a good grasp of things, I'd mirror what he said with a few notes to add:
1. If you stick to a "regular" wiring setup, you can get up to 16AWG wire in your mechbox, but it may be an extremely tight fit with reinforced mechboxes.
2. Large batteries rule. A 8.4v 1400mah large (i.e. sub-c cell size) battery will blow a 8.4v 1400mah mini (i.e. 2/3A cell size) away. Large 9.6v 2000+mah batteries are plenty. NOTE: we usually top out at M120 springs around here (local field limits) so an M140 may have different results.
3. I'd try a Systema Magnum motor (I love 'em) but I hear really good things about the Guarder Infinite Torque Up motors (and they're cheaper than the magnums).
4. It's completely normal for a fully charged battery to read higher than the "common" rating of 1.2v per cell. My memory is fuzzy (should have wrote this stuff down), but a 8.4 will read up to 10v and a 9.6 up to 12v...I think...

Here's one of my setups:
M120 (shoots 430fps...have to tune it down for field play)
Systema Magnum motor
9.6v 3300mah large battery
DEANS ultra connector
18AEG wire
Version2 mechbox...6mm bushings, standard ratio gears, silent piston set, nothing too fancy
It fires great with good trigger response and around 900rpm.

I'm sure that with a M140 I'd have to go with torque up gears.

[ecsinc]

Ok, here's what I haven't told you.
I was running a M130 spring on stock gears, 18.whatever gear ratio, now I'm running infinite torque up, 45 ratio, but with only a M140. That's like a 240% increase in gear ratio but yet only a 140% increase or something close to that in FPS, so added torque load wouldn't be that much more, if it was proportional to the fps then I'd be loading 140% more torque onto 240% more ratio gears. So in turn, I should be working the motor less then what the M130 was doing on stock gears. It's just the trigger responce is poor, possibly due to the high, 45, gear ratio. That's my thinking. Correct me if I'm wrong but I would be getting more battery drain and more power consumption with that M130 then the M140 in infinite gears I have now. And I played in a game with the 2 1500mAh batteries without any battery issues.

[Naglfar]

You're better off increasing the mAh rating of the batteries, that will do more for you than increasing the number of cells.

Secondly, when doing any measurement of voltage the proper way to do it is while the system is running under full load. Same goes for current readings, only you should always be measuring a voltage drop, unplugging power and then measuring resistance and applying ohm's law.

[ecsinc]

but do you agree with my statement above?

Correct me if I'm wrong but I would be getting more battery drain and more power consumption with that M130 then the M140 in infinite gears I have now.

[ecsinc]

I added 2 capacitors like the electrical guide on asf said to to increase voltage (2 x 1000uF). Well I blew up 1 of them and made the gun smoke like crazy after only like 15 shots. Without the capacitors I don't even get enough power to pull back the M140 spring. Its kinda weird. I had no problem with the M130 but the jump to the M140 even with new ITU gears poses way to much of a problem for the motor and it will lock rotor right before it fires. Although I just remembered now that I have a few pastic spacers on the spring guide that might be the solution to the added torque...
The sorbothane should be here tomorrow so I'm happy to get that. The gun should sound quieter as stated....
I'm kinda bummed. I guess I'll only be able to run a M130 until I can get the Guarder Infinite torque up motor, which i herd is just as good as a magnum but 1/2 the price...

[Styrak]

I'LL JUST TRY TO DO OTHER THINGS, LIKE ELECTRICAL MODIFICATIONS I HAVE NO EXPERIENCE DOING AND BE BUMMED OUT ABOUT MY GUN NOT WORKING PROPERLY AND COMPLETELY IGNORE THE FACT MULTIPLE PEOPLE HAVE SAID I SHOULD GET A NEW BATTERY.

Seriously. Get a bigger battery.

[ecsinc]

I'LL JUST TRY TO DO OTHER THINGS, LIKE ELECTRICAL MODIFICATIONS I HAVE NO EXPERIENCE DOING AND BE BUMMED OUT ABOUT MY GUN NOT WORKING PROPERLY AND COMPLETELY IGNORE THE FACT MULTIPLE PEOPLE HAVE SAID I SHOULD GET A NEW BATTERY.

wow, that was helpful...

Thing is I can't really afford anything right now as it is. I'm just trying to get away with what I have. I wish I could have a magnum motor, 12v 4000mAh battery, you name it, but money is a issue. Specially how gas prices is $3.50/gal.

[Styrak]

Originally Posted by ecsinc

wow, that was helpful...

Thing is I can't really afford anything right now as it is. I'm just trying to get away with what I have. I wish I could have a magnum motor, 12v 4000mAh battery, you name it, but money is a issue. Specially how gas prices is $3.50/gal.

But you have the money to upgrade your gun and buy circuitry?

[ecsinc]

Ok i figured it out. For some weird odd reason i horribly overshimmed the gears...I defintally spun the gears with just the motor and no spring for like 30 seconds to "break-in" the gears but when I took the box appart just now and put the gears back in it was soo tight I couldn't turn the gears, without the screws in. So I took out like 5 shims from all the gears and got them spinning good now. I did a side-by-side spinning the gears, stock vs ITU, it took 6 rotations to revolve the spur gear once on standard ratio, it took 16.5 revolutions to turn the spur gear once with the ITU. So I think I'll stick with the M140 now that I realized that the gears were dang tight!

The capacitors were $1.60 a piece and I got 2...

If the motor problem was just with the gears, which I sure hope so, I'd easially pull the M140. I thought something was wrong going from stock ratio pulling a M130 spring then going to ITU and a M140 and not pulling that. With stock ratio I could get the M140 spring to lock back fully compressed but I couldn't decompress it, on stock ratio.
I gotta wait tho to get the Sorbothane. It should be here tomorrow then I can put it in the cylinderhead and test it out!

[Naglfar]

You need more capacitance, provided you are installing them in parallel. Assuming a rough current of 15A at 8.4V your resistance is about .56 ohms and the time constant then becomes 5.26ms meaning those capacitors charge in almost two hundredths of a second and are only holding .33 joules of energy.

Just get a better battery and shim the gears properly...I've never put more than 3 or 4 shims on a gear(total of both sides) and I'm sure an experienced gun doc will agree with that.


Edit:
I think the reason you're blowing your caps is the voltage rating isn't high enough, 35V might be ok but if you are using them in parallel they become a 17.5V max cap. the inductive feedback when releasing the trigger can easily top 30-40V or even higher on more powerful motors. I'd try to find bigger caps with a 120V rating if you really want to go that route but I personally think it's a waste of time, money and space.

[ecsinc]

Ok. I got the shims correct.
If I did go with a capacitor(s), how many microfrads would I need?
I'll defintally be able to pull the spring now that I know I screwed up the shim job.
You think I should just totally ditch the capacitor idea? I just want a faster trigger responce, no voltage drop that is, without buying a new motor or battery. Anything over $20 and I can't really do that. I can probably pick up 4 2200uF 35VDC or 50VDC axial capacitors. I'm not sure if I should get 35VDC or 50VDC, probably 35VDC, if its 35Volts and 50V then I'm defintally not going to exceede 35v. 8800uF total.