40C Continuous Discharge?!

Superior Matching Concepts and Thunder Power are coming out with new lines of batteries in the next month or two, which will have 40C continuous discharge ratings. THAT IS INSANE!!!!! Thunder Power claims that they will have a burst discharge rate of 80C. Superior Matching Concepts hasn't said what theirs is yet, but I would assume that it is comparable.

Thanks for the heads up...we were looking at some 30C thunders...maybe we'll hold off a bit....that's some serious amps....think we'll need it???

well, our batteries were clearly overkill as far as amperage was concerned. We had 22.2V @ 5000mAh Thunder Power's with 30C discharge. the peak voltage was consistantly 25V abouts, and we never discharged them below 23V, even after a full match with the weapon working the whole time. So, the capacity is too much for us. What the goal is now, is to have the system run, with the smallest, and lightest most importantly, battery pack possible. And, the Higher the C rating, the lower the capacity needs to be if you want a given discharge rate, and 40C would achieve that beautifully!

We were looking to go to A123's except for 1 bot which will probably go Lipo....possibly 2 separate packs....

Did you notice any drivetrain hesistation with the weapon drawing a lot of amps

Also..what the heck are you using for drivetrain motors at 22 volts???

no hesitation whatsoever! we did a funny thing with the batteries.. I won't go into detail, but we soldered another connector to a cell on the battery pack, so we had a positive lead with 14.8V for drive and one with 22.2V for the drum, all with a common ground. it worked out and nothing blew up! the problem with high voltage is the controllers. At anything above 14.8V, the banebots controllers crap out. they get super hot and the temperature cut off kicks in, thus eliminating a direction in drive. that's why last year @ Nationals, X-Termination did so poorly. the drive would quit, and we couldn't move.

Ever thought of getting the schematics for some kind of open-source ESC and trying to make the most compact, insane version possible? (Hmm... I'll start a thread up on this). I'm thinking around Victor-level performance.

isn't impossible.. haven't really tried it yet. one Idea my dad and I had was to take a very small controller, like one of the tiny banebots or an antweight controller, and use it to control some giant MOSFET's which would run your motor.

Will Bales wrote:

no hesitation whatsoever! we did a funny thing with the batteries.. I won't go into detail, but we soldered another connector to a cell on the battery pack, so we had a positive lead with 14.8V for drive and one with 22.2V for the drum, all with a common ground. it worked out and nothing blew up! the problem with high voltage is the controllers. At anything above 14.8V, the banebots controllers crap out. they get super hot and the temperature cut off kicks in, thus eliminating a direction in drive. that's why last year @ Nationals, X-Termination did so poorly. the drive would quit, and we couldn't move.

That's how our K2 packs are setup....we can tap off for 14 or 16.5 v...we abandoned the idea after a while....

I thought soldering to lipo's was a less thatn great idea???

surprisingly, no! we thought that the abnormal discharge of cells would be a bad idea, but the cell balancing of the charger solves that problem!

rjw wrote:

Will Bales wrote:

no hesitation whatsoever! we did a funny thing with the batteries.. I won't go into detail, but we soldered another connector to a cell on the battery pack, so we had a positive lead with 14.8V for drive and one with 22.2V for the drum, all with a common ground. it worked out and nothing blew up! the problem with high voltage is the controllers. At anything above 14.8V, the banebots controllers crap out. they get super hot and the temperature cut off kicks in, thus eliminating a direction in drive. that's why last year @ Nationals, X-Termination did so poorly. the drive would quit, and we couldn't move.

That's how our K2 packs are setup....we can tap off for 14 or 16.5 v...we abandoned the idea after a while....

I thought soldering to lipo's was a less thatn great idea???

Not the best, but if you good at soldering its not to bad, you just have to do it quick so the cell doesnt overheat, if it is then your screwed
AN uncharged cell always is safer too

We were talking lipos, but decided that for our rattlers and whatever else, the kids would be safer with Li-ions....

But we do have one bot that will probably get the treatment......

Will Bales wrote:

the problem with high voltage is the controllers. At anything above 14.8V, the banebots controllers crap out. they get super hot and the temperature cut off kicks in, thus eliminating a direction in drive.

Um, I'm using Banebots 45 amp speed controllers at 17v (5 cell a123 packs) and they worked perfectly. The only problem I had was with the banebot motors that kept giving me the smoke of death.

I know nothing about making speed controllers but if you make a victor performance kind of speed controller, I'll defiantly buy one. OH make a brushless controller too.

SenaiERI

we'll see what we can make.. 17V might work, anything over 19.8 definitely doesn't work at all..

Did you see the blue smoke of death? I love the smell of fried electronics in the morning.

SenaiERI

jetis burn orange btw

As will already knows
Alex got ahold of a horizon hobby catalog early since he works in a hobby shop and the thunder 40c are listed in them
Coming soon!!!!!

where did you find 30c thunders? on their website they only show the extreme v2 with 25c... and how does the discharge C rating relate to the max continuous current rating? how do these compare with a123 packs which don't even list a discharge rating on their website? although robot marketplace says they have a discharge rating of 30c... a123s are the lightest though

Dan Curhan wrote:

where did you find 30c thunders? on their website they only show the extreme v2 with 25c... and how does the discharge C rating relate to the max continuous current rating? how do these compare with a123 packs which don't even list a discharge rating on their website? although robot marketplace says they have a discharge rating of 30c... a123s are the lightest though

Go to RC Lipo for some info....http://www.rclipos.com/RCL.html

A lot of places sell them....continuous around 70 amps with bursts to 130 ( higher ma packs)

Lighter than A 123's which are 10 grams per cel lighter than K2's

great site btw, thanks a lot!
so basically, I came up with a list of viable battery options, all giving me 22V and ~4000 mAh...



the blue ones are what I think my better options are, and the green one is what I think the best one is.

I'm gonna be running two banebots 550s for drive and an Axi 5320/18 for the weapon... does this seem reasonable? I know the axi is overkill - i like it that way.

BUT. I know there were some reservations and some controversy about allowing LiPo's in competitions... will I definitely be able to compete in whatever competitions I can for a 15 lb with these LiPos? I'm considering starting this project in the next month or two...

There hasnt actually been a rule set revision released that says lipos are allowed so you still need to be careful.
A kid from our team told me that at Rotunda Rumble there allowing lipos this year bot not next.

Cody Harris wrote:

There hasnt actually been a rule set revision released that says lipos are allowed so you still need to be careful.
A kid from our team told me that at Rotunda Rumble there allowing lipos this year bot not next.

Bahwaaaaaaahh !!!

Did they have an incident?

As technology develops...they need to go with the flow...but carefully of course

Not to sure
I know the MRL has used lipo and humdinger switched to A123s but i was on the phone with one of the kid on our team and they werent sure on what lipo rule was being used, they read the rules off to me on the phone and he said that they would be allowed for this years national competition but not after