Dual Wiring of a Mechox: IS IT POSSIBLE?

[venture]

I have been wondering if it is possible to "dual wire" a v2 mechbox to both front and back simultaneously? I believe the Mah would be doubled, but not the voltage?

What are the limitations? Is it even possible? Has it been done?

[Qlong]

Been done, just wire them in parallel.

[Styrak]

I've dual-wired a sliding stock MP5 so my buddy can use it with a mini battery and sliding stock, or large battery and fullstock.

I would highly recommend NOT using two batteries at the same time, even if they are the same type and voltage.

[The Chad]

Yes, only crappy part would be having two fuses and finding space for them.

[ShelledPants]

Originally Posted by LoveMyStubby

Yes, only crappy part would be having two fuses and finding space for them.

Don't use a fuse. :\ Also, both sections have space for a fuze + battery, by default. :\

[venture]

Good to know. I think I might try it with my upcoming high torque/ high fps setup. I may be able to use 2 batteries in parallel for a m140 spring with max torque gears.

[Cheesevillage]

Originally Posted by venture

Good to know. I think I might try it with my upcoming high torque/ high fps setup. I may be able to use 2 batteries in parallel for a m140 spring with max torque gears.

I would go lipo if you need a whole bunch of amps.

These lipos are apparently competitive with the high end:
http://www.hobbyking.com/hobbyking/s...2&v=&sortlist=
(I've used the flightmax 25c 4000mah in my RC car with great results)

Charger: http://www.hobbyking.com/hobbyking/s...w/_accessories

Make sure you read up on lipos and charging procedures before you buy anything. I am not suggesting you shouldn't double wire, but if you need the power of two batts, go lipo.

[Styrak]

Originally Posted by venture

Good to know. I think I might try it with my upcoming high torque/ high fps setup. I may be able to use 2 batteries in parallel for a m140 spring with max torque gears.

You won't need more than a good large for that.

[Rooster]

I can't seem to find the topic now But I've seen it done here. I think it was on an AK. One batt in the stock, and one in the top of the gun. Basically wired in parallel, so you're using both at the same time but they can last a lot more shots. Same voltage, but lots of extra Amps.

[CDN_Stalker]

I did that back in 2005 with my MP5, was just before I bought a large battery, I ran a pair of mini batteries in parallel for a few games. Worked well.

[coach]

Originally Posted by Styrak

I would highly recommend NOT using two batteries at the same time, even if they are the same type and voltage.

there is nothing wrong with it if they are properly wired in parallel. OP is correct that no increase in voltage is obtained with parallel wiring rather doubling of capacity (mAh)

using NiMH or NiCad batteries for this should fine. obviously matching voltage would be required. matching mAh output is a good idea, but not critical.

[m102404]

A more competent battery guy can chime in to expand on this, but it is my understanding that running two batteries in parallel is not a good idea. Theoretically, if all the cells are perfectly matched and behave exactly the same, it should work just like that...but in practice they never are.

My understanding is such that if the cell(s) in one pack either discharge faster or are not at the same capacity as the other pack, when you run down the packs you run the risk of driving the "weaker" cell(s) down below their tolerance threshold. Once driven too low they may suffer permanent damage and "kill" that pack.

I suppose that you could hedge your bets by:
- buying two packs with the same matched lot of cells
- being very meticulous with the wiring/connections
- being cautious not to run the packs down too much
- charging them both up the same amount each time
- monitoring any differential in charge between the packs and adjust accordingly

...all in all doesn't seem worth it to me. Even in frenzied all day long firefights, I'm hard pressed to drain a good quality large battery pack if it was fully charged up the night before....and if a battery dies, just chuck in another one.

[venture]

Originally Posted by m102404

A more competent battery guy can chime in to expand on this, but it is my understanding that running two batteries in parallel is not a good idea. Theoretically, if all the cells are perfectly matched and behave exactly the same, it should work just like that...but in practice they never are.

My understanding is such that if the cell(s) in one pack either discharge faster or are not at the same capacity as the other pack, when you run down the packs you run the risk of driving the "weaker" cell(s) down below their tolerance threshold. Once driven too low they may suffer permanent damage and "kill" that pack.

I suppose that you could hedge your bets by:
- buying two packs with the same matched lot of cells
- being very meticulous with the wiring/connections
- being cautious not to run the packs down too much
- charging them both up the same amount each time
- monitoring any differential in charge between the packs and adjust accordingly

...all in all doesn't seem worth it to me. Even in frenzied all day long firefights, I'm hard pressed to drain a good quality large battery pack if it was fully charged up the night before....and if a battery dies, just chuck in another one.

Good points there. I will have to look into those, or maybe someone with electrical knowledge could chime in.

I think a mosfet can stop the gun when the voltage gets too low. Ah, but you would need one for each battery to check voltages.

Starting to be more disadvantages than advantages to this setup. The lipo solution looks more economical all the time. Plus way less weight.

[Kos-Mos]

A MOSFET unit will cut voltage, but when the overall voltage of the two packs is low enough.

That means that a cell in the pack can go lower than it is supposed without the FET cutting off.

If you need more power, you can use a large-sized LiPo. A 7.4v 5000mAh 30C will drive your setup without effort. It takes the size of a 8.4v large pack.

If you don't have the space, you should consider making it. I mean, if your setup requires that much power, you won't be able to find an in-between solution. Two small packs does not equal a large pack.

[coach]

Originally Posted by m102404

A more competent battery guy can chime in to expand on this, but it is my understanding that running two batteries in parallel is not a good idea. Theoretically, if all the cells are perfectly matched and behave exactly the same, it should work just like that...but in practice they never are.

My understanding is such that if the cell(s) in one pack either discharge faster or are not at the same capacity as the other pack, when you run down the packs you run the risk of driving the "weaker" cell(s) down below their tolerance threshold. Once driven too low they may suffer permanent damage and "kill" that pack.

I suppose that you could hedge your bets by:
- buying two packs with the same matched lot of cells
- being very meticulous with the wiring/connections
- being cautious not to run the packs down too much
- charging them both up the same amount each time
- monitoring any differential in charge between the packs and adjust accordingly

...all in all doesn't seem worth it to me. Even in frenzied all day long firefights, I'm hard pressed to drain a good quality large battery pack if it was fully charged up the night before....and if a battery dies, just chuck in another one.

you bring up some valid points of concern but I have been unable to find anything that says using 2 packs in parallel would be bad or dangerous. caveat here being that it's NiMH or NiCad packs we're talking about.

a weaker sell in the pack won't affect voltage but rather decrease run time. I am sort of agreeing that if one cell of one pack fails prematurely, that it will render the one pack useless but it would likely happen if it was used as a single pack. over driving any pack would probably cause eventual damage. I'll take back what I said earlier and suggest if anyone wants to do this, to match packs. brand, voltage and capacity. when charging packs independently, use a smart charger and not a wall wart. additionally, keep track of how long they charge for to ensure they receive identical charge times.

I'll have to think a bit more about this but I don't think it's a problem to do such.