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Are these LifePo4 cells good enof for a rustler?
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BOOGIE444
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Are these LifePo4 cells good enof for a rustler? - 05.22.2008, 02:09 PM

http://www.battlepack.com/LFP26650P.pdf

They are super cheap at $10.00 a piece. I was thinking of running a 3s2p or 4s2p in a rustler with a mamba max and feigao "s" motor. Do you think these things can support the amps that this setup will need? Will they out perform my current gp3300 as far as discharge rate and what not?

My current setup uses 8 old gp3300 and I am getting sick of the these cells.

What do ya think?
   
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Motoman
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05.22.2008, 02:34 PM

I think you would definately have to run them at least 2 in parallel maybe more. So I'm not sure they would even fit if you did 2 or 3p. The capacity is kind-of low at 2600 and the discharge rate for a single parallel pack is also low at 10A recommended and 42A max. I think that for the price of building a 3s2p($60) or 4s2p($80) you could probably just buy a TrueRC 3s1p($75) 4000 or maybe a 3s2p 8000($150)? I don't know it's just something to think about.

They look like they might be comparable to the GP3300's, maybe better if you did 2p. Also, it looks like they might be kind-of heavy compared to lipos, 483g(3s2p), 640g(4s2p). The 3s1p lipo I mentioned is only 312g.
   
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BrianG
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05.22.2008, 02:43 PM

According to that document, those cells are good for:

The recommended continuous discharge current is 10A (~3.8C) and 2.5A (1C) charge current.

For our use, I think the "absolute maximum ratings" section is the one to look at. It will shorten the lifespan, but such is life.
42A continuous (16C) and 50A burst (19C) discharge. 5A (1.9C) charge current.

However, from looking at the discharge graph, the cells seem to drop voltage substantially at currents over 20A (7.7C) to ~3v. Paralleling two would give you 40A (15.4C) continuous, and you have a decent burst value of 100A for the brief high-current draw when taking off.

In a lighter vehicle like a Rustler, they should work pretty well, especially if you go with 4s2p along with a decent wind motor.
If you parallel two, that's good for 20A continuous
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Getter Robo
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05.22.2008, 03:59 PM

Those cells look like they perform like the Yuntong Fepos. I'm using a 5S2P setup in My E-LST2 and they perform pretty good. I think they'll do just fine in the Rusty.


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MetalMan
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05.22.2008, 05:04 PM

I don't think it'd be worth it to go with these over A123 cells from a Dewalt 36V pack. A123 cells can be gotten for ~$13 a cell from Ebay, depending on the price of the Dewalt pack. A123s will have a longer lifespan and can put out more current, two factors which more than make up for the ~$3 price difference per cell.


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SpEEdyBL
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05.22.2008, 06:08 PM

I agree with MetalMan. You you usually get what you pay for when it comes to r/c.


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