True RC Batteries
 

I am reaching the finish line of m maxx and all i need is the motor and batts and it will be finished in about 2 weeks. I have decided on everything except batteries. I want to go cheap but i don't want to sacrifice battery quality. I would really like to keep it under 170$ for 2 packs. I was looking at true RC batteries because they seem to be about half of the price of the max amps. I will be using a Neu and quark combo. I was looking at the 4000,6400,and 8000 packs. i realized the 4000s had to low of a current draw so they where out. but the 6400 had a 96amp consistent current draw and 128 peak(i can pick 2 up for about 150). i was also looking at the 8000s. i knew a place where they would sell me 2 for 150 and they have a amp draw of 120 amps and 160 bursts. Weight does not matter to much to me but here is my dilemma. First i want something that will get me about 25-30 minutes runtime. Second i want something a little on the cheaper side. Third i want something that takes less time to charge (so maybe the 6400 )because i am charging on an ice. Also less weight is good but is not a big factor when i am chosing my batteries. Also if the place that sells 2 8000s for 150 goes out of stock it would have to be the 6400s or the 8000s for about 50 more. So what do you guys think of these batteries. with the 6400s work for my purpose (i will try to get the 8000s,but only a 50%chance) or do i need to go automatically to a higher amp draw like the 8000s. Thanks guys for your input.

I think the 6400's will work fine for you (I'm assuming you want to run 4S). I don't recall what motor/ESC combo you're using, so that info would be helpful. I'm a guy who likes to keep his amp draw under 100A, so if I felt I was going to be hitting a draw that high, I'd add another cell to up the voltage...of course that may require other changes on your part.

However, a pack that can supply 96A continous with a 128A burst should work. I've heard lots of good stuff about truerc's packs.

I had both the 8Ks and the 6400s. I think the 6400s were actually a bit more powerful and my more fav batteries, both are good tho. The 6400s are a bit more narrow, so a bit easier to fit as well. I actually ordered a 8S in the 3200 pack for my HV setup I liked them so much @ 4s2p.


I was pulling ~120A on mine and both did great. Either choice is a winner. BTW I got ~ 1hr bashing on the 8ks and ~45min on the 6400s.

was 120 constant finnster? i've run true-rc's 5s1p 4Ah, and 5s1p 5Ah packs. both give tons of power, and i never had any problems other than user error (pinion digging into the ends of the cells oops..) here's a graph of the 5s1p 5Ah pack. i'm because i'm running 2 packs as a 5s2p pack, and the truck being heavier, i've been breaking stuff more than if it weighed less.. diffs included. I'm wondering how the cells would work w/ just one 5s1p... didn't mean to hijack, just interested in finn's opinion.

Well, power during driving is so peaky that its hard to say what is const. It would pull upto 120A for 1-2s, but would quickly drop off to ~30-40A at full speed. If you pulled 120A non-stop you would drain the batts fast.
Here's one example of what I mean. Its just a long spd run so things are easy to see. Peak here ~110A and voltage says above 14V (better than 3.5V/cell @ 14C) This is a 4S2P "10C" 8K pack. IDK how far you can push the 5K cells, I've been curious myself, but should be ~= to the 4k cells in capability I think. They seem like same formulation just slightly bigger. I would bet 15C would be a fair rating.
4S 8K pack
http://i7.photobucket.com/albums/y25...4/495214f3.jpg
5S2P A123 pack
http://i7.photobucket.com/albums/y25...4/e978f2b9.jpg

your graphs would be easier to read if you put the current on the left instead of the power in watts.

not bad; 3.85 volts on a 40A load.

3.5V on a 100A load in 2P.

Looks like a solid 15C to me... 3.5v @110A (13.8C).. if you were to pull 120A (15C) I doubt it would drop below 3.2-3.3 which is a pretty common watermark for testing max C.

But opinions vary of course on what exact standards should be used. Also, our test runs only show spikes and not a constant load, so it may be different than what a proper mfg test would yield.

I'm also curious to see how a "1p" A123 would do.

Yeah, these A123's in 1p are pretty poor in preformance, but the good thing is they are tough as nails.

Here's the results from my Losi 8ight on 10S A123 geared 15/48
2300 10S is 3v avg
My Kokam 5S 3200's 20C avg 3.7v. I guess thats why they cost so much...

That's actually kind of impressive... average peaks of 1500watts and the pack hit 2.7v per cell at 93 amps (2500watts)

Here are 2 graphs that I got from my DPR. One is with 2 36V packs in parallel and the other is with one 36V pack. BTW the truck was geared to go around 165-170MPH LOL.

True, but I made them to show something else, and I don't feel like going back and redo them to highlight the amps. So you'll just have to squint >..<
:)

The A123s are great IMO, I was getting lightly better results than w/ the 4S packs. They are lower nominal, but 5S~=4S lipo I think.
Only downside is they are heavier than lipos, but they are so tough, long-lasting and safe they are well worth it for everyday driving.

Here's a graph of them put to the limit @ 10S1P. It was a torture test of my system. Blew the whole pack in 7.5min running hard uphill in long wet grass. Packs were 105F at the end. Motor was 110F max.

http://i7.photobucket.com/albums/y25...4/f983a983.jpg

My setup will be running 4s lipo on a neu 1515 1y on quark and reciever pack on metal maxx. BTW finster what was your setup with the 6400s that you got 45min bashing time.

Man, if that isn't a testament to the virtues of high voltage, I don't know what is. Really impressive Finnster!