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-   -   (2)2s or (1)4s (https://www.rc-monster.com/forum/showthread.php?t=31725)

dpb318 01.14.2013 05:26 PM

(2)2s or (1)4s
 
hey guys

its been a while, been out of the hoppy for about 5 years now but i want to get back into it...poor cars are in the basement itching to get driven

my last project before i stopped rc was an FLM tranny forward conversion for my x ss 4.6...which is the truck i want to get running again

going to put in:
MMM 2 :yipi: man when i left we were all dying for castle to get the original mmm out and now heres v2 and its waterproof!
2200kv castle-neu (dont want hpi-neu because the fat fins will be a pain with the flm setup)

my question is this:
with the flm tvps the battery goes inside between the tvs, not in external boxes...so i have two options for a 4s setup

1. get (1) 4s 5000mah 35-70c pack
2. get (2) 2s 5000mah 35-70c packs and run them in series for 4s

what would you guys recommend? is there an advantage to running two packs vs one? price wise its basically the same, and running in series i wouldn't get the "2p" advantage, so really it just comes down to buying two small packs or one big one. looking at turnigy nano-tech

Kcaz25 01.14.2013 09:18 PM

One 4s less wires less resistance, less weight, less wire mess.

BrianG 01.15.2013 09:36 AM

I agree; single 4s pack for the same reasons listed above. All things being equal, the only consideration to whether you run a single pack or 2 packs in series is chassis layout.

However, I don't see where you get the "2p advantage" in your post unless you parallel the packs for 2s2p?

lincpimp 01.15.2013 10:12 AM

1 4s pack is the way to go. I would get a few 40c packs from hobbypartz. I have had great success with the sky lipos.

dpb318 01.15.2013 11:14 AM

thanks guys, i was kind of leaning towards the 1 4s like you have suggested

only thought is if i kill a pack i only need to replace half of the cells rather than the whole thing

brian, the 2p i reference was acknowledging that i would not be gaining that advantage since id be wiring in series in my case

it seems that 4s2p or even 2s2p is not quite as popular as it was when i last bought lipos? is this just because cell technology has improved and 2p is not needed as much to get the proper c rating?

lincpimp 01.15.2013 12:08 PM

2p assembled packs are just a bad idea. You cannot accurately balance the cells, as 2 are connected. If those two cells are not perfectly made and matched one will work harder then the other and wear out faster.

Doing 2p with seperated packs is ok, as you can just charge all of the cells in series and balance them. Example, using 2 2s packs wired in parallel for 2s2p, then charging the packs in series for 4s1p.

Personally if you have enough draw to require 2p, why now half the motor kv and run double the voltage... I know this cannot be done all the time, but up to 8s we have the esc tech.

Get lipos from hobbypartz, at their prices if a cell dies just toss the pack and buy another. Or pull the cell and use it in another rc. You can always find use for a 3s if a cell dies in a 4s pack. A 1s pack is not much use if one cell in a 2s pack dies. Plus, it is not a good idea to run a new pack with a used pack, so if one of your 2s packs dies you will be left with a potentially useless 2s pack and have to buy 2 more 2s packs...

Thirdgen89GTA 01.15.2013 12:56 PM

Quote:

Originally Posted by dpb318 (Post 425570)
thanks guys, i was kind of leaning towards the 1 4s like you have suggested

only thought is if i kill a pack i only need to replace half of the cells rather than the whole thing

brian, the 2p i reference was acknowledging that i would not be gaining that advantage since id be wiring in series in my case

it seems that 4s2p or even 2s2p is not quite as popular as it was when i last bought lipos? is this just because cell technology has improved and 2p is not needed as much to get the proper c rating?

Pretty much. The higher C ratings are helping with that.

Quote:

Originally Posted by lincpimp (Post 425573)
2p assembled packs are just a bad idea. You cannot accurately balance the cells, as 2 are connected. If those two cells are not perfectly made and matched one will work harder then the other and wear out faster.

Doing 2p with seperated packs is ok, as you can just charge all of the cells in series and balance them. Example, using 2 2s packs wired in parallel for 2s2p, then charging the packs in series for 4s1p.

Personally if you have enough draw to require 2p, why now half the motor kv and run double the voltage... I know this cannot be done all the time, but up to 8s we have the esc tech.

Get lipos from hobbypartz, at their prices if a cell dies just toss the pack and buy another. Or pull the cell and use it in another rc. You can always find use for a 3s if a cell dies in a 4s pack. A 1s pack is not much use if one cell in a 2s pack dies. Plus, it is not a good idea to run a new pack with a used pack, so if one of your 2s packs dies you will be left with a potentially useless 2s pack and have to buy 2 more 2s packs...

This is how my Truggy runs. When I talk about 4S and 6S i'm really talking about (2) 2S in series, and (2) 3S in series. since I run a dual saddle pack layout on the truggy.


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