Lipo Para wiring??

[ED66677]

2x2600mAh 20C in parallel will give 2x(20x2.6)=104A that's it!

[Jeff Wohlt]

Jess....could you shoot a pic of the para bullet connector you made?

So I am wrong about C rating but it basically does the same thing in the fact it doubles amp output. I thought that was right.

[Jesse J]

4P plug adapter

here you go. Version one was not soldered... these are V2.

I took 8GA wire, attached the appropriate bullet connector, then inserted into the hole and clamped down (the guys on the right are what I used - don't know their names), then flooded the whole caboodle with flux then solder. Once it cooled, I plasti-dipped to ensure good insulation. I use shrink wrap on the unused plugs - here I was using it as 3P connector.

[FighterCat57]

I did something similar, only used the "solder blob" technique and some safety wire.

Basically stripped the ends of the wires and tied them together and soldered it up like a bundle of sticks. Taking turns, flipping it around making sure each wire get's good solder flow...

It's held up great so far. =) I had some photos of the soldering with the safety wire in a thread somewhere... I'll link to it if I can find it.

[chuff]

In reality with higher draw setups, paralleling packs does not halve the total draw. By reducing the internal resistance (going 2P) the packs can deliver a higher watt output; this is why you will see a speed increase in a hot setup when going from 1P to 2P.

But to return to the original post: a 4S1P/20C/2600 mAh pack has a "maximum" recommended discharge of 52 amps. A 4S2P/20C/2600 mAh pack has a "max" discharge of 104 amps.



.

Sorry, but I beg to differ slightly once again…. Fluid is quite correct , changing from a ?S1P setup to a ?S2P setup does reduce the internal resistance of the battery/wires/ESC/motor circuit and therefore the current draw will increase, but only comparatively slightly. For comparison, going from say 12 gauge wire to 8 or 6 gauge wire will deliver a similar reduction in internal resistance. Nevertheless, the current draw per cell has roughly halved (this is partly why the internal resistance of the circuit has reduced). This halving of the current per cell is a BIG change, and this is the main benefit (particularly from a battery pack life point-of-view). Remember that the ESC & motor still see ALL the increased current, so by going to ?S2P we will have slightly increased the stress on them. Hopefully the slight increase is not the final straw – If the ?S1P setup is already over-stressing the circuit, going to ?S2P will only make things worse….

We should also keep in mind what the C-rating of a cell really means. It is not the max current we can draw from the cell. Clearly with a short we can draw many hundreds of amps, even thousands. No, the C-rating is the current the Manufacturer believes it is safe to draw from the cell (assuming he is telling us the truth, which is another matter…) So far, I have been unable to find any Industry Standard applicable for determining the published C rating on our Lipos. (Someone may be able to advise). I can only presume it is a relationship between time, current, and resulting temperature rise.

In short, parallel set-ups offer significant benefits - either reduced stress on the cells or, on the other hand, giving us a safe way of increasing amp draw, but is is important to understand what we are doing .

and another thing ...
If you buy a single 4S2P/20 C/2600 pack, I would be a little cautious about pulling 40C (104 amps) out of it. If its made out of 20 C cells and this is what the printing on the pack means then OK, but if the manufacturer is being tricky and has made it out of 10 C cells, the pack is only safe to 20 C as he has warned you on the label.....???

[Jesse J]

Remember that the ESC & motor still see ALL the increased current, so by going to ?S2P we will have slightly increased the stress on them. Hopefully the slight increase is not the final straw – If the ?S1P setup is already over-stressing the circuit, going to ?S2P will only make things worse….

This doesn't make sense. If you run same voltage and increase your amp CAPACITY, you will still only draw what you need, right? BUT in the XS2P config, you are drawing less off each individ batt, and therefore the current bouncing around is more dissipated and therefore easier on all the electronics involved.

Correct me if I am wrong - I am not an electrical engineer nor a battery guru, just trying to hone my understanding of the inner workings of the power system.

[ED66677]

It does make sense Jesse J! if you double the capacity of a pack, you will certainly see a smaller voltage drop under load, this will result in a slightly higher voltage at ESC/motor, few tenth of volt may be... higher voltage, higher rpm higher amp draw!

[FighterCat57]

This is when I would leave the room in college and say you "EE" guys are weird and I would go design real systems while they were trying to calculate stuff.

Here's my xS2P harness:


PSA- 4 3s 20c 4k packs is enough to melt EC5 connectors feeding a Turnigy 180 ESC.

[chuff]

This doesn't make sense. If you run same voltage and increase your amp CAPACITY, you will still only draw what you need, right? BUT in the XS2P config, you are drawing less off each individ batt, and therefore the current bouncing around is more dissipated and therefore easier on all the electronics involved.

Correct me if I am wrong - I am not an electrical engineer nor a battery guru, just trying to hone my understanding of the inner workings of the power system.

Hi Jesse
Pleased to see people seeking understanding.

You are mostly right. In a 2P arrangement its only the cells that have an easier time. The full current (actually a little more) must go through the ESC and motor. The motor in particular must see all the current and as much as possible of the voltage - that's were all the useful work gets done. Everywhere else we just get useless heat.

Chris

[Jesse J]

It does make sense Jesse J! if you double the capacity of a pack, you will certainly see a smaller voltage drop under load, this will result in a slightly higher voltage at ESC/motor, few tenth of volt may be... higher voltage, higher rpm higher amp draw!

I see your point. thanks for the clarification.

In a 2P arrangement its only the cells that have an easier time. The full current (actually a little more) must go through the ESC and motor. The motor in particular must see all the current and as much as possible of the voltage - that's were all the useful work gets done. Everywhere else we just get useless heat.

That helps too.

Thanks guys

[tdonnellyem]

Hi Jesse
Pleased to see people seeking understanding.

You are mostly right. In a 2P arrangement its only the cells that have an easier time. The full current (actually a little more) must go through the ESC and motor. The motor in particular must see all the current and as much as possible of the voltage - that's were all the useful work gets done. Everywhere else we just get useless heat.

Chris

im new to the fe stuff so i make examples up to see how it works. say you have a 4s 4000mah 30c battery by itself. the draw would be 120a(30c x 4000/1000=120a). if you took a pair of 4s 2000 mah 30c batteries in parallel (4s2p) you still have the same amp draw (30c 2 2000/1000 x2[batteries]=120a. the difference to me is that you are getting the same draw out of 8 cells rather than 4 cells,thus easier on the cells themselves, and using a lower mah battery. so chris as it right on about a ?s2p setup being easier on a battery pack

[graill]

As folks have touched on here the esc and motor will get what they can in regards to request and available potential.

Your C rating will only release energy at a fixed rate up to its max, over that and fun things happen, that cant be changed until you simply buy a battery with a higher C rating, what you can change is the workload over several packs by paralleling.

One pack will work harder and degrade faster (and possibly burn up if your figuring is wrong) than three of the same pack paralleled in the same setup under the same load, though now your heavier, you decide what you want to do.

[H2OCamel]

Ah now this is cool stuff!! I like paralleling my A123's since I can recarge them quickly. I have first hand experiance with batteries being arc welders......just remember that lightning is 7 times hotter than the surface of the sun! I haven't had the time to check the tempature of a shorting battery!

Thanks for the info!