Small battery pack update
 

i had some problems with some of the small battery packs today. i updated the website and sent out a bunch of messages to those that have shown interest in the new chassis. the problems encountered are as follows:

the lipoly packs performed well for the first 10-14 cycles. recently, the lipoly packs are tripping the low voltage cutoff device well before the pack is depleted. This is happening while the motors are locked or stalled and full voltage is applied.

the kan1050 8 cell brick performed well for the first 6-8 cycles. today i noticed a significant voltage depression problem. the pack would not supply sufficient voltage when under heavy loads.

the 1800mah zagi pack performed well as always, so at this point that is the only pack i am recommending. i currently have two custom packs on there way. one is a AA 9 cell 1650mah pack, the other is a 9 A cell pack, 2500mah. I am sure we will find more battery pack options for use on the xtreme chassis and other crawlers, but more testing is required. there are plenty of good high discharge cells available that will work fine. www.cheapbatterypacks.com

Awsome customer support! Thank you.

Kevin i was wondering how the kokam 2000mAh 11.1volt lipo did for you. I just got one of these and was going to try it out. I just ordered a cut off voltage harness to put bewteen the battery and my super rooster. Is that really all i need i guess. right now i am running two mayhem motors but will be running two lathes shortly. i think that battery will handle 24 amps continuous. is that right or am i mistaking. Anyhow i was wondering if the two mayhems have to much amp draw to run that battery. Do i need to wait till i get the lathes put in. thanks for your help.

the kokam 2000mah 15C discharge cells worked awesome for about 10 cycles. then they started to trip the low voltage cutoff device really early. roktoy did some tests and found r/c motors drawing around 60 amps locked. i think that is what is affecting the lipoly batteries. it's too much draw.

the only thing i can think of that may help is running smaller pinions. i was running lathe motors and stock 13tooth pinions. 9 tooth pinions might help the problem, but i'm not sure. there's a guy thats a thunder power rep getting one of my chassis and he may come up with a solution.

the low voltage cutoff is all you need to run the lipolys. the mayhems will most likely draw more current than the lathe motors. a 2000mah 15C discharge pack can handle:

2000mah = 2 amp hour X 15 = 30 amps

at this point i am only recomending the zagi packs until more testing is done. i ran the lipolys again this past weekend and they were tripping the low voltage cutoff continually.

...
 

The 540 motors whether they be 55x1's or 10x1's, will put a pretty heavy draw on the batteries especially 2 motors. To really do an accurate motor draw test you will need a dyno. In my experience the IR (Internal Resistance) of a 2/3, AA, AAA or Lipo's are simply to high to produce good results. These packs work well with speed 400's (and smaller), and brushless sytems. This is due to there small nature or in the example of the brushless the efficient nature of them. However on a SubC batteries have an incredibly low IR and therefor run these motors very well.

I may be way off base but just thought that I would throw that out.

Found a good stable spot for a 6 cell Sub C cell pack. It's a temporary thing so I could try this thing out finally. Which, BTW, is absolutely killing everything else we have to compare it with.

http://img195.exs.cx/img195/2541/stiiiiick7cg.jpg

Again, everything is temporary, wires all flopping around. But damn Kevin, can you say, "No contest?" I can. And if this were a more permanent battery location, the rear located battery plate could be removed, and wheels without the added offset could be used.

That battery placement increases the CG somewhat. I was going to possibly try an end to end stick pack that runs along the length of the chassis. I believe I can get up to 12 SC cells on there and be able to move the batts. forward and aft. as needed for weight distribution. Again it gets away from the original benefit of low CG and weight on the axles, but for messing around I will enjoy long 2 hour run times with 12 3900 SC batts. :) For comps. I will just stick with the 1800 or 2000 8 cell 4/5a packs. Good luck with the battery placment and let us know how it affects the truck.

Please note that Kevin does not recommend any alternate battery placement's than what the stick was designed for at this point. There is a reason why it is where it is. I just did not want to steer anyone wrong.

those look like they would probably work.

I wonder what cells they use? AA, 2/3, 4/5...

How are the kokams working out for you? How many cycles do you have through them?

i just recently added some adj. motor mounts and 9 tooth pinions. i haven't had a chance to run the lipolys on it with this setup, but will in time. the lower gearing will reduce the amp draw and hopefully the lipolys will hold up, especially the 11.1volt batt. i really miss running them because the performance increase on real vert stuff was very noticeable.

any new info on the battery conundrum?

and how many nicd/nimh cells would you reccomend?

Hey guys. Can you fit one of those CBP 1800 packs here? Or on the rear tray sideways.
I'm just wanting to know if the four on the bottom will fit.
I know they're a little larger diameter than what I have here.

http://img124.echo.cx/img124/3046/batterystrap2qy.jpg

I'm thinking the GP2000AFHR is a pretty sweet option.

i haven't done any work with the lipoly batteries. The 1800 pack will not fit up front where the esc now resides. It would have to go length wise and would be sticking out the front.

i've been running a couple of different packs with success:

9 cell CBP-1650mAh AA NiMh
9 cell CBP-2500mAh A NiMh

I like the increased cell count, more punch. The 2500's are heavier and the tires hit them a little, but longer run times.

EeePee, what cells are those in the picture above?

The ones pictured are 700 mAh AAs.

On the other end of the capacity range, Energizer 2500 mAh AAs fit there also. And for $20 an 8 pack, might be something I test out. I haven't commited to soldering the ones I have yet. I'll post something when I do.

Offset brick 8 cell packs would fit there just the same.

Oh, I did add little spacers to the upper and lower shock mounts to move the shock a little further away from the battery. And it's still close and occasioanlly rubs the spring, but that's what tape is for. A little more spacer length and nothing would rub.

Ive been using 12 of the cbp kan 1050 cells they are awsome and small running 3 per axle corner.Ive been getting about 30 minutes of run time.

that's a good idea. split up some small packs. you could easily get a half-pack of those small kan1050 on each axle. Like two 6 cell kan1050's, one on each axle.

Syco, can you put up a picture of your battery set-up? Just something to look at...

3 per corner for 12 total?

Im still working on where is the best place to mount these.I would love to get all 12 up front.
http://www.yesalbum.com/v001/syco133/battery_3.jpg
http://www.yesalbum.com/v001/syco133/battery4.jpg
http://www.yesalbum.com/v001/syco133/battery2.jpg
http://www.yesalbum.com/v001/syco133/battery_1.jpg

So I tried out the Energizer 2500 7 cell packs at the UROC event in Indiana. The weight loss is comparable to losing 3 of the 6 Sub C cells I usually use. I don't use wheel weights, and I have the electronics mounted up front. It has a good 45 degree angle forward tilt if I put my finger in the middle body post hole and hold the truck. Scientific.

The best way I can describe the battery lifespan is by showing you guys a picture. In the lower left, the blue line. The 5A, 2C discharge graph.

http://data.energizer.com/PDFs/nh15.pdf

With the Lathe motors, they had good power, good punch, for ten minutes. Then the initial zip diminished a bit, but another 10 minutes of good power. Then they noticably started to head downhill for another five minutes. 15 minutes of usable battery juice easy. Good for comp stages I figure.