Which 3S Lipo?
 

I need a couple of 3S Lipos for a 1/8 Buggy conversion. I'm going to run them in series, for 6S, and have calculated that I need ~5400mAh at that voltage to get the run-time I'm after. I also need them to be as light as possible, as that much battery is always going to be heavy.

The two Lipos I have found that fit these criteria are:
Trakpower 5400mAh 3S
ThunderPower 5400mAh 3S

The Trakpower only has a 16C continuous discharge rating, which using BrianG's power output calculator, appears to be just about enough (using previous data, 18.5V, 6600mAh, 20.5 minutes, then changed to 22.2, 5400mAh, 20.5 minutes). However, it can be charged at 2C, and, as a racer, that's good news. Also, I can get these easily in the UK, and are cheaper when I get my LHS staff discount.

The Thunderpower has a much better discharge rating (20C), but can't be charged at 2C.

Which would you pick? Or is there a better alternative?

I would also consider a single 6S lipo of the same capacity, or two 6S lipos to run in parallel, but I haven't found any that fit the capacity I'm after, not at a lightish weight anyway. (I'm looking for less than 850g for the batteries really).

I know this is kind of picky, but I like to get things right.

Have you considered Zippy Lipo's at Hobby City ?

These maybe? ttp://www.specpointbatteries.com/index.php?productID=88
It says .94lb (which be pretty close to 850g total), but I'd double check the weight with them, because I'm not sure how accurate that number is. Not sure on the charge rate either.

I had a look at the Zippys, but, at the risk of sounding like a snob, I like Lipos with a strong brand behind them.

Those SMCs look good. I actually had a look on their website but nothing like that came up. Maybe a tad heavier than I really wanted (<800g is better), but I'm happy to compromise here. Nice find, and they're cheaper than the Thunder Powers.

I did a google search on the SMCs and found an RC-Tech thread where the SMC rep person said that he charges all SMC lipos at 2C - so no worries there (hopefully).

Any others to throw into the equation?

No offense taken,I'd just thought I mention them ?
I thought zippys were a joke also until I seen friends have fantastic success with them and read where many people were also content. I've bought 8 different packs and couldn't be happier. I hope you find what your looking for.

I run my 1/8 buggy on a 3S Thunder Power 40C 5000mah... I get plenty of run time for what I do, and the battery stays pretty cool...

I didn't even know those where available yet. Where did you buy it from?

Also I have 2 NEU 3s 30c lipos and I love them. Mega power! All the way until the end of the run...

Have you considered one of the newer "gen. 3" lipo packs? ex. Hyperion G3 packs, Flightpower EON X30's...

The hyperions are quite good prices over last gen. lipo packs. I bought 2 3s 4200mah 35C packs for $100 each, or you can get 3s 5000mah 25C for same price, new gen as well.

PolyQuest has some 6k packs, I'd give them a try (Mike sells them :wink:) If you need 5400 mAH you need a lipo bigger than that or you'll be running the cells under 3v/cell under load, it's best not to run lipos too low for that reason.

Why two 3S packs in series? why not one single 6S pack? it's physically stronger and much more convinient to use. Planning to run E-REVO with the same packs?

Some of us run saddle...

To be fair, in my original post I did say
It looks as though I'm not going to run saddle now, as it makes the car too rear heavy and unbalanced. This doesn't mean though that I couldn't just use two 11.1s or two 22.2V Lipos down one side. I'm also thinking about going 4S with two SMC 2S 9000mAh Lipos in series.

I got mine at RC Madness in Enfield CT... I think Amain Hobbies has them as well. Nice pack..