# Building a series and parallel mod box?



## dannler (19/10/14)

I was thinking..

I want to do a diy box mod but i couldnt decide wether to go series or parallel. 

Why not go both? 

Series for the uber watts and clouds
Parallel for the endurance?

Then a heavy duty switch to switch between the two configurations. 

And if its possible a heavy duty( high amp rating) variable resistor to control the wattage on series mode?


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## JakesSA (19/10/14)

I assume its a mechanical mod you looking at building? It used to be a no-no to run batteries in series aka "stacking" on a mech but I see most of the dual battery electronic mods do it now, for example, the 100w Sigelei. From a battery load perspective there is no difference so I'm not sure why it is/was frowned upon and whether that opinion has changed?

Reactions: Like 1


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## dannler (19/10/14)

I was not looking into stacking them, but to keep them next to each other and with a 2way multi contact switch of some sort i do the series wiring on one side and paralell wiring on the other

I actually found this and its exactly what i was looking to do, just with the switch idea.

Reactions: Creative 1


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## Gazzacpt (19/10/14)

JakesSA said:


> I assume its a mechanical mod you looking at building? It used to be a no-no to run batteries in series aka "stacking" on a mech but I see most of the dual battery electronic mods do it now, for example, the 100w Sigelei. From a battery load perspective there is no difference so I'm not sure why it is/was frowned upon and whether that opinion has changed?


I can't remember where I read this. Its something to do with the possibility of the cells arcing when stacked and causing heat buildup leading to themal runaway in some cases. Also you need to "marry" the batteries. They have to be be in the same state of charge or discharge, used together charged together so they have the similar performance or bad things happen. 

The most cases of stacked setups going wrong are with torches. In that application you drawing from the cells for long periods of time and thermal runaway is a high possibility. 

With electronic mods you have protection, 8-12sec fire cutt offs, undervoltage protection and the usual stuff you expect in a regulated mod.

In a mech I basically treat it as a pipebomb. If I do something wrong it really could turn into one. So I stay away from any form of extra complication like an extra battery. Imagine having twice the amount of things that could go wrong and then having a double load of dynomite in your pipe.

My opinions here guys use it dont use it.

Reactions: Like 1 | Agree 1


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## dannler (20/10/14)

@Gazzacpt you mentioned stacked batteries might arc...and not to use it. 

What if i dont stack the batteries in series, but do the same method as in the video posted?

Yea i do understand its still dangerous,any kind of mod is, but would this method be safer than the stacking method?


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## johan (20/10/14)

No problem with stacking @dannler, proviso that contacts between batteries are secure, both batteries are the same, and you don't go extreme sub-ohm.


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## dannler (20/10/14)

Sweet, yea, i actually dont want to stack due to i want it to be parallel aswell at a flick of a switch. 
I already did the wiring diagram. I just nee to source the switch and wire. And then need to figure out if i can make it a variable watt device, that locks at a set wattage regardless of the coil value. Because if i add a variable resistor then i would actually create a vv device?


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## johan (20/10/14)

Variable resistor is not going to work (Power = I squared x R) - a regulated pcb unit like SX-350 or DNA30 or 40 will sort that out. A switch that are able to handle high currents >30A, will be bigger than your enclosure - go through the modders thread, somewhere I've posted a simple diagram to solve the switch issue with a mosfet and 2 resistors.

Reactions: Like 1


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## Gazzacpt (20/10/14)

dannler said:


> @Gazzacpt you mentioned stacked batteries might arc...and not to use it.
> 
> What if i dont stack the batteries in series, but do the same method as in the video posted?
> 
> Yea i do understand its still dangerous,any kind of mod is, but would this method be safer than the stacking method?



If you using battery sleds or have each battery on its own set of contacts its probably alot better as they wont have a chance to arc against each other. There are quite a few mods setup like that.

Reactions: Agree 1


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## CreamOfWeber (30/1/15)

Gazzacpt said:


> I can't remember where I read this. Its something to do with the possibility of the cells arcing when stacked and causing heat buildup leading to themal runaway in some cases. Also you need to "marry" the batteries. They have to be be in the same state of charge or discharge, used together charged together so they have the similar performance or bad things happen.
> 
> The most cases of stacked setups going wrong are with torches. In that application you drawing from the cells for long periods of time and thermal runaway is a high possibility.
> 
> ...




"In a mech I basically treat it as a pipebomb. If I do something wrong it really could turn into one. "

It really couldn't though. There's not enough fuel or pressure.


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## zadiac (30/1/15)

You'll need a rocker switch. I talked to a electronic wizard buddy of mine and he said with a rocker switch you can switch between series and parallel. We didn't go into detail, but he said it can be done. I haven't tried it tho. Maybe one day.
You can use a 3 way rocker switch - 1=series, 2=off and 3=parallel, or a 2 way one - 1=series, 2=parallel




The two way rocker switch




the three way rocker switch


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