dpaton

Interesting. It sounds like your CET process combined with the Gold Peak
chemistry is amazingly consistent, not to mention creating a very well buffered cell.
That kind of resiliency is amazing. If I can get some more disposable income in the
next few weeks your Paypal account will be hearing from me. Again.

Altho I worked intimately with NiMH cells for several years, these GP330s have
some very different characteristics than I've dealt with in the past. I've been
devouring the GP tech docs, and I'm trying to get them to send me some
more developer docs for their cells and charging components. In school I was
known as the knowledge hog. I guess I didn't break that little habit in industry

I'm not planning to dry cycle my GP3300s. At least not the matched ones
I got from you guys. I was thinking of using this as an after-run discharge, to
burn off the extra mAh from the 4 minute races I run. I've ben dry cycling
older packs, trying to get them back up to capacity after sitting for a veeeery long
time (damn..has it really been 10 years?). I've had good luck with my old
Sanyo 1700 bash packs, which went from ~380mAh to about 1300 after a few
cycles.

Specific to the GP3300s, iit's my belief that more intelligent (on the part of the
equipment that is) discharge and charge management will significantly increase
the useful life of the cells we racers use. My parking lot runs with your packs have
me wondering what I need to do to keep them working this well for an entire
season before I start to see wear-induced degradation like I did with my NiCads
after only a few months (2, maybe 3 ona good pack) of 3-4 cycle race weekends. It
looks like CEI has charging pretty well taken care of with the new GFX (drool..)
but discharging seems to be something largely ignored by the most technical
developers in RC. I've seen some progress from Integy (Saddle Pack discharger) and
a little from Trinity (RealTime 2.5), but I think there's a lot of room for
improvement, and that's where all of my bench time has been in the last two
months.

I'm not gonna talk details yet, but think of the GFX of dischargers

<blush>

Aww shucks... I'm just a geek from the 'burbs....

Actually, I have a personal motivation with some of this research. Being
unemployed has left me with a lot of free hours, and if I can come up with
something cool enough, I might be able to license or sell it to CEI or Orion or
someone else with some cash. I'm still a long way away from anything I could
show to other engineers, but I do have some early prototypes

As for your compliments, while I was in school I spent a few years teaching, and
it was one of the most rewarding experiences I had there. I guess the
whole sharing knowledge thing stayed with me

Thanks

-dave

Maj. Teeth

dpaton,

You've got PM.

Dan

holycow

Interesting.. my old 1700 packs are still some of my punchiest packs!

holycow

Dan,

I have a couple of sanyo 2000 packs, that were on the shelf for 2 years. What would be your recommendations on getting these packs back up to speed? I like having the extra practice packs so I don't put unecessary wear and tear on my good 2400s or my good 3300s.

How many amps in? How many out? any info would be appreciated.

Brandon

Maj. Teeth

Yes,

Those were the days. *sigh* For some reasons, those 1700 had the perfect combination in IR and damn it they would just hold 3000mah LOL

Dan

John Fontaine

iTrader: (2)

Great conversations guys. I do agree that technology has leaped greatly with charging cells, but discharging has been lost. It's basically slap it on at a predetermined amperage and stop it once it hits a certain voltage.

Just look at the GFX charge screens vs discharge. They have three for charge (its very complex) while discharge only has one.

Charging is important to get voltage and runtime, but when you put them in your car, you're DISCHARGING.

Great conversations...I can't wait to see where it leads.

John

rinkrat99

************************************************
Our C.E.T. system does graphs as well but on a computer screen and the discharge curves are a lot better in terms of voltage vs. runtime and only a slight drop throughout it's discharge until the very last 30 seconds. Maybe I can have one on our website.[/PHP]
************************************************

Thanks for the response Major Teeth!

Those graphs are from your competitors cells. The 1500mAH packs were store bought as sticks and converted over. These are probably 3 yrs old and work fine for playing around.

As for the ones labeled HPI or Green, these were from batteryspace.com which sells 3000mAH 6 cell packs for $18. You get what you pay for. The intention of the post and I tried to PM Jimmy was to determine if your packs maintain a more consistent voltage for a longer duration. Specs games can be just that games. If your cells maintain a constant voltage (1.15V per cell from 0 to 360 seconds) regardless of how much more time you get until the cell voltage drops below cutoff) then this is a top cell. The voltage provided for your cells 1.15 thru 1.17 V could be misleading depending where the constant V stays for the longest time. My graphs reflect a lower avg V above 6.6 V for approx 275 secs. Would you want to be racing and get only 4+ mins of decent runtime?

Just trying to fully understand where better cells stand in comparison to cheapo's

Thanks

dpaton

Back at ya.

-dave

dpaton

I'll tell you when I turn one of these crazy ideas into rent money

In all seriousness, the discussion is great. The more that people talk about stuff like this, the faster things happen.

-dave

RBLove

iTrader: (90)

rinkrat99,

Front bumper brace is to keep the front end from sagging. When running a Buds or RPM bumper they have a tendancy to sag pretty bad.....

PitCrew

Rink

The GP3300 cells do exactly what you are talking about. They maintain a VERY high voltage output untill the last 30 seconds of the discharge. If you can visualize a line graph, imagin the line would stay almost perfectly horizontal untill the last 30 seconds where it would drop off sharply. At 20 amp discharge, I am recording my numbers every fifteen seconds. At 300 seconds, most of my packs are right at 7.0 volts, which is an average of 1.167. That in not the average voltage for the whole discharge up to that point but the ACTUAL voltage taken at 5 minutes. At around 7 minutes. I am seeing AVERAGE voltage of 1.2 per cell.

The GP3300 cell BLOWS AWAY every cell before it.

OH NO Here comes LI-POLY. By By GP..

Maj. Teeth

Hmmm?! how'd you know we're already working on that?@!

Dan

dpaton

Despite what one particular RC mag said recently, LiPolys are restricted to more reasonable discharge rates than RC cars have right now. If you try to pull 20A out of a 4200mAh prismatic LiPoly cell you'll damage it severely. Most of them can't be used at more than 1-2C, which is why they're used for the park flyer aircraft, which have small motors and low, constant current, amperage requirements.

All of the LiPoly cells I've seen are designed mainly for loads that have consistent amperage requirements (laptops, MP3 players, cellphones, etc). I give it a few more years before the chemsitry evolves to be tolerant of our requirements.

-dave

JohnA

Some interesting stuff!

On the subject of more advanced discharging techniques has anyone used the Pro-trak ICS(intensive Care System) I beleive Integy do a similar device.

I only live a few miles from the where Pro-trak's are made and was going to pick one up, but thought I'd get a bit of advice first.

You can read about it Here

David Root

Nicad packs can be taken down to 0 volts, think twice about doing that with Nimh. I use a smart tray from Promatch that takes them down to .7 which is a little low, but they are all exactly the same. I also have some itegys tray with bulbs. I unscrew the bulb when it goes out so the rest of the cells can catch up.

Just my $.02
David Root