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Old 10-29-2003, 09:00 PM   #31
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I can say that I too ran Fusion power at the Edgewater race and was impressed by their performance. Many people can say that they do not think those little heatsinks work. Let me tell you they do work but they are not the whole key to the lower heat of these packs. The heat sink bars do help remove heat but so does having a superior bond(less resistence) at the connection point of the cell. By having less resistance their is less heat generated, that coupled with a heatsink equals cooler running punchier packs.
Ok shoot holes in that guys.
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Old 10-29-2003, 10:39 PM   #32
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cooler packs maens punchey Heat is not bad for cells, I mean really really really hot is bad for them but in normal running situations you batts never get too hot so you need heat sinks on your bars lol. Sorry but i think this is just something for people to buy just to have kinda thing. um
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Old 10-30-2003, 05:58 AM   #33
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67/37 "eutectic" solder? I'm wondering if this a hard find, special solder..
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Old 10-30-2003, 06:18 AM   #34
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Well, it does not help his cred, coming on 2 weeks ago, making a statement, and never coming back to answer questions. Is that the way this company is going to support it's product ?
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Old 10-30-2003, 06:52 AM   #35
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Maybe he felt this formun was pretty hostile toward his product?? But then you have a point about he support of product... 67/37 solder is pretty easy to solder with.. I was just wondering his solder is special??? Oh well, maybe I'll try and go to his site...
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Old 10-30-2003, 04:20 PM   #36
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Default Battery Fact and Fiction

Like most devices batteries have an optimum window of operation on many of their specs. The temperature window on the GP3300 cell is 50F - 122F.

GP NiMh internal handbook quotes, sic.."By contrast, temperatures above 40 C (104F) adversely affect the cell's chemistry. Nickel Hydroxide decomposes (part of the self-discharging mechanism), and the rate of decomposition increases with temperature. Overall battery life is also adversely affected by elevated temperature, and cells should best be kept below 40 C (104F) during operation, storage, and charging."

Panasonic says "Discharge capacity drops at temperatures below -10C (50F) or above +45C (113F). Such decreases in discharge capacity can lead to deterioration in battery performance. As with the voltage profile, the capacity available during a discharge is dramatically affected by the cell temperature during discharge and the rate of discharge."

This issue is something being explored by the National Renewable Energy Laboratory (ctts.nrel.gov) in Golden, Colorado with regard to Hybrid Electric Vehicles utilizing NiMh as a power source. NREL's Ahmad A. Pesaran, Ph.D. says, "Battery temperature is important. Temperature affects battery operation of the electrochemical system, power and energy. Battery pack thermal management is needed (to) regulate packs to operate in the desired range for optimum performance/life, reduce uneven temperature distribution in a pack to avoid unbalanced modules/pack and thus, avoid reduced performance." The Conclusion? "NiMH is less efficient and generates more heat and appears to be more sensitive to temperature variation (than LiOn sic). So NIMH needs a more elaborate thermal management system."

Yes Virginia, the silly liitle heat sinks are what are called "passive cooling apperatus" and they help keep the pack thermally balanced and operating within the "thermal operating window" just like the the little fins in your PC, cellphone, battery chargers etc.. The combination of radiation from the outer cases and the end caps helps to keep the pack in thermal balance.

To answer another question, no they are not dangerous, they are very small and blunt, they will not not harm you or your car. There is no need to fear them for they are your friends.

Regarding the "PUNCH" issue. First let's define 'punch'. Punch is what you feel when you get an immediate reaction to squeezing the throttle. The blast out of the hole. The opposite is 'flat'. The batteries haven't dumped but they don't kick your car in the butt.
What is it? It is current on demand. The ability to supply all of the current your motor can draw instantaniously without a long spool-up. How do you get it?
LOW RESISTANCE. Remember Ohm's law? E=IxR. To solve for current it is I=E/R.
If your voltage is fixed (and low in this caes) the only real variable that will make a material difference is resistance. An example:
IR of 6 cells = 15mOhm x 6 = 90 or .09 ohms
Voltage of 6 cells = 1.175 x 6 = 7.05 volts
Current (for da' punch) = I=E/R = 78.33 amps available to ESC for motor

OK then, let's solder up those cells. The best pack I have ever received hand soldered had only .1 ohm additional resistance. Tiny fraction of an ohm. So..
IR of 6 cells = 15mOhm x 6 = 90 or .09 ohms + .1 ohm = .19 ohm
Voltage of 6 cells = 1.175 x 6 = 7.05 volts
Current (for da' punch) = I=E/R = 37.10 amps available to ESC for motor
1/10 of an ohm made a difference of half of the current!!

Our typical solder/assembly adds .02 ohms for a total of .11 ohms.
IR of 6 cells = 15mOhm x 6 = 90 or .09 ohms + .02 ohm = .11 ohm
voltage of 6 cells = 1.175 x 6 = 7.05 volts
Current (for da' punch) = I=E/R = 64.09 amps available to ESC for motor

THE PUNCH THING IS ABOUT A COMBINATION OF TEMPERATURE MANAGEMENT (heat sinks) AND THE PROCESS USED TO PUT ALL OF THE CELLS INTO A BATTERY (soldering).

please note that nothing here is discussing charging. That is an entirely separate subject with far more implications to battery health, life, and longevity. The heat -sinks are NOT about charging or soldering.

I hope that helps. Boy you guys must have been brutal on the guy who suggested matching cells was a good idea!
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Old 10-30-2003, 04:48 PM   #37
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Jeff, thanks for the explanation. R/C racers as a whole are skeptical until proven otherwise. Can you answer my question. ?

Quote:
Originally posted by TimPotter
For the average racer without the tech speak, how many degrees differnce is there between a pack with the heatsinks and a pack without.

Thanks
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Old 10-30-2003, 05:01 PM   #38
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To me(average racer), probly wouldn't notice the difference.

I saw some cooling fins that Masami use to put on his batteries a while back to do some kind of cooling. If it is not okay to keep batteries cooler, I wonder why Masami did that???
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Old 10-30-2003, 07:45 PM   #39
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I think we may be skeptical since we do more testing, each, individually, than ANY testing facility does - think about it.

I've, personally, individually, owned over 100 packs (600 cells) and run each of those packs, let's say, probably 100 times each or more. That would make over 10,000 cycles that I've, personally, run. Add to that our combined empirical knowledge and combine that with contradictory knowledge from SMC and others, I think we get a bit skeptical.

Just a note to you - the url you provided does not work. ctts.nrel.gov gives an error (so does cts.nrel.gov) and I can't find anything on the site that relates and searches for Pesaran come up blank.

Expect us to be brutal when we're told we need to spend more for something with little spikes on it and that it dissipates 300% more heat. . .and when we're told that batteries that heat up or are charged on fans are worse than yours, especially when empirical evidence says opposite - those 10,000 cycles, remember.

Also, internal handbooks, company releases, etc. are commonly dismissed by those of us who actually use the items. Remember, Intel actively discourages overclocking their processors, but they do it themselves. Remember, operating temperatures are always listed as a more restricted range than is actually used - liability reasons.

Also, remember, we're using these batteries far in excess for what they're "really" designed for. None of these batteries is supposed to deliver the extremely high amperages we're demanding from them. The vehicles that the NERL, Robotwars (which doesn't even allow NiMH cells, only NiCad), the Mars Rover, etc. don't demand a quarter of the amperage that we routinely (constantly) demand of our cells. So, when you use internal memos and research done on limited runs and government publications that can't be found and are for other, less demanding applications, yeah, I'm gonna be skeptical and jump all over you.

Sorry about that.

So - do you have empirical evidence to show us for the .02ohm job you do in connecting your batteries? If it's not a solder job, it must be a weld job, right? (brazing is pretty much a solder joint, but using brass/bronze instead of lead/tin) What method are you using to measure the resistance?
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Old 10-30-2003, 08:42 PM   #40
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Default Re: Battery Fact and Fiction

Quote:
Originally posted by jeffchaskin

IR of 6 cells = 15mOhm x 6 = 90 or .09 ohms + .1 ohm = .19 ohm
Voltage of 6 cells = 1.175 x 6 = 7.05 volts
Current (for da' punch) = I=E/R = 37.10 amps available to ESC for motor
1/10 of an ohm made a difference of half of the current!!


Our typical solder/assembly adds .02 ohms for a total of .11 ohms.
IR of 6 cells = 15mOhm x 6 = 90 or .09 ohms + .02 ohm = .11 ohm
voltage of 6 cells = 1.175 x 6 = 7.05 volts
Current (for da' punch) = I=E/R = 64.09 amps available to ESC for motor

And Pigs can fly!!
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Old 10-30-2003, 09:21 PM   #41
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I hear you on that skeptical issue, but I have been in the portable DC power source business for 34 years and would not just spew some crap for grins. That 300% numbver has been discussed a few times here so let me clear that up. The line reads 'surface area thermal dissipation increased by over 300%'. That means the heat dissipated from the surface area of the battery bar was tripled. The base line was a Deans Probar (both 2 and 3). The deans bar dissipated 1/3 the colories as did the Fusion bar. The little spikes are heat sink fins, just like the ones on your PC CPU, or your battery charger. We did not invent this method of radiating heat from a surface area, rather applied it to open frame battery packs ( and applied for global patents). This passive radiation technique works very well on the RC car application as the stream of air moving through the vehicle (in motion) creates turbulance and convection, effectively multiplyiing the heat dissipation factor considerably. The overall affect is to allow the core of the cells to dissipate heat at or near the same rate as the outside case of the cell, there by keeping the entire cell thermally equal. We have measured this via telemetry in moving vehicles and it is quite effective, keeping the entire pack within the optimum thermal operating window for the various nickel -based electrolyte formulations. Internal pressure is also substantially reduced, which, by the way was the original goal for both spacecraft (outgassing) and medical applications. Our cute little fins will look awfully good if you find them in the portable defibrilator that restarts your heart.

About the soldering, it is in fact soldering. A eutectic (direct liquidus to solidus transition with no pasty state) solder whose composition is proprietary which is heated by Radio Frequency Induction allowing direct heating of the parts with minimal thermal velocity to the surrounding of underlying parts. This is a soldering technique (process patent applied) which reduces the temperature at the point 1mm from the junction by over 200F. This has the effect of creating a near-perfect metalurgical bond between the cell case/tip and the battery bar. It cannot be duplicated by hand. This process has the effect of creating a battery of cells with virtually no material added resistance. When we are dealing with voltages of 5.4 - 7.2 vdc low resistance is an absolute requirement. The pack is built to NASA-STD-8739 series technical standards for space flight hardware workmanship.

Our cells are matched to the same standards as SMC, ProMatch, Trinity etc., as our advantage is in the assembly not the matching. An SMC pack made by us would run better than the same cells hand assembled. Why does that seem to bother the posters on this board? Have you seen what a bad soldering job (which is prolific in hand soldered packs) looks like? The damage in assembly is irreversable. It must make reputable matchers sad to see the way many of their perfectly matched cells are destryed by bad soldering. How many times have reputable matchers received warranty claims against their cells which are due to amateur assemblers who believe solder is some type of metal glue and that 200 is a nice round number? ProMatch addresses this issue on their site.

Things do improve and that is good. Why don't you gather some empirical evidance by running our pack? Our list price is no more than the list for a box of cells by any reputable matcher. You get the improvements essentially for free. In addition to being the same fine GP3300 matched and voltage enhanced cells they are soldered perfectly, glued perfectly and perform with excellence. This is bad?
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Old 10-30-2003, 09:27 PM   #42
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To popsracer,

That my friend is the laws of physics. Regarding the pigs, with the proper genetic engineering they probably could fly. Better buy a big freeking hat.
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Old 10-30-2003, 09:46 PM   #43
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out of business in less than a year! any takers? lol packs should be about 150 deg when placed in car..they wont get much cooler after 5 minutes of running? we could cut a small hole in our bodies for better air flow and i bet the nbatteries would be 1000 times cooler after a run? lol GP bateries are not blue panasonics! they are rock solid..the soldering service would is great for the noobs..

have you ever seen a ADX oval car? how would you solder up a pack for that car? how about soldering up a pack for a 12th scale car like a 12L where you need a jumper wire? he he
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Old 10-30-2003, 09:54 PM   #44
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150F is OK if the temperature is relatively constant throughout the pack.

Check out this pack
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Old 10-30-2003, 10:03 PM   #45
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Check this out as well. By the way the hole in the body is a great idea for not only the power source but motor and ESC as well. The problem is the aerodynamics , specifically lift you would introduce. But don't stop thinking, that's how things improve and our lives get better.

I've been in the extreme power source business for going on 30 years and I'm betting the RC segment won't put us out of business in less than a year.

But you get credit for the nastiest and child-like post to date.
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