Can 4S1P A123 power a Feigao 7XL - RC-Monster Forums

hardmankam · **Can 4S1P A123 power a Feigao 7XL -** 09.15.2009, 07:05 AM

For all those A123 users.... here is my background & question:

Background:
Due to limited space in an e-converted 1/8 Cen Matrix (buggy), I can only fit 4 cells of A123 under the body. I have also bought the Hobbywing 150A + Feigao 7XL motor.

Question:
Can 4S1P A123 (2300mah) have enough discharge current to power the feigao 7XL?

I have already killed 2 packs of 4S lipo 5000mah@22C because of the high discharge rate the 7XL requires. So I dont want to kill my A123 batteries.

Thanks in advance!
HK

timaneli · 09.15.2009, 07:08 AM

they powered my mamba on a e-revo iun these specs so they easily power that feigao too!!

regards

hardmankam · 09.15.2009, 07:23 AM

timaneli: you run 4S1P or 4S2P in your e-revo?

hardmankam · 09.15.2009, 10:18 PM

Thanks for all the advice.

I will look into either 4S2P or 3S2P config. and run my buggy with the body.

Arct1k · 09.15.2009, 08:23 AM

A123 in 1p is NOT going to be happy IMO. Max is 30C which is only 70amps or so and that motor can pull 100amps...

You'd need 2p...

hardmankam · 09.15.2009, 08:47 AM

yeah, i think 4s2p would be easier on the batteries.... but how do people fit 8 cells (4s2p) in a 1/8 e-buggy? anyone who uses this config... would you mind posting a picture for reference?

Maciolus · 09.15.2009, 09:44 AM

I am recording peaks of 164A with Medusa 36-60-1600 with 6S1P.

http://picasaweb.google.pl/Maciej.St...79553515560514

Those cells are undestructable :)

J57ltr · 09.15.2009, 02:26 PM

They will do 60C for 10 seconds. I run 4s1p in my Rustler on several motors in the 3-5k Kv range

Jeff

BrianG · 09.15.2009, 02:45 PM

Instead of starving the ESC/motor with batteries that can't put out the juice, I would look at ways to give the buggy more room internally. A simple mod to the body mounting posts can give you 5mm+ more clearance easily. Or, find a buggy body with a more battery-friendly shape. Or, how about centering the motor (using a different mount) over the CD and using dual 2s2p packs in series, one on each side?

Yeah, 1p A123s can supply ~70A, but their voltage does tend to drop quite a bit from graphs I've seen. You'd probably end up with close to the same voltage with a decent high C-rate 3s lipo than 4s1p A123 because of voltage drop (and weight/size will be better). Not to mention runtime on 2.3Ah will be pretty short using A123s.

J57ltr · 09.15.2009, 03:25 PM

So how much does good 3S high C pack weigh?

Jeff

BrianG · 09.15.2009, 04:09 PM

Depends on capacity. I would assume you want between 3500-5000mAh, which would weight around 300-400 grams (10.5-14oz).

J57ltr · 09.15.2009, 04:35 PM

The A123's aren't that much heaver I weighed 2, 3s1P packs and they were about 100g (3.5 oz) grams under a Duratrax 4200 NiMh pack at 15 oz. Don't know why you guys always say that A123's are Sooo heavy. I'll weigh my 2s2P packs tonight and see what I get but they are not That much difference between the Lipo and LiFe

Jeff

BrianG · 09.15.2009, 04:44 PM

They maybe aren't as heavy as NiMHs, but they are heavier than a lipo of similar capacity and voltage.

J57ltr · 09.15.2009, 05:03 PM

But not by as much as you guys make it seem. You are talking maybe an ounce or 2 for about the same capacity, and they are bullet proof.

Jeff

E-Revonut · 09.15.2009, 05:30 PM

Quote:

Originally Posted by J57ltr

But not by as much as you guys make it seem. You are talking maybe an ounce or 2 for about the same capacity, and they are bullet proof.

Jeff

Ahh, but if they where in fact bulletproof then you wouldn't be asking this question!!! Send me one cell and I'll show you just how NOT bulletproof they are when I send a .223 hollow point through it or obliterate it with a .40 S&W