JosB

I know that too, just asking for a bit more explanation. Been racing against a M06 lately and kinda surprised how good it goes on our track, we're always tinkering around with those traits.

True, should have thought it more through. I'm a co-rulemaker at our club and things are tough all over... always two sides to a story

Granpa

Thank you for that. The battery stuff came about because one of the TCS regional races wanted to restrict batteries to no more than 50C. So there were numerous complaints about that. There was much more on the Tamiya thread in the Racing Forum, so some were commenting w/out knowing the whole story. Some of that stuff bleeds into this thread, which is unfortunate , but impossible to separate.

One of the things many who don't run the TCS races don't know is that there are separate rules for the Regional races and a different set of rules for the Nationals. Never totally different, but there are some differences. I've never understood this, but have come to expect and accept the situation.

OVA

iTrader: (86)

..I agreed with Granpa

torg

...also allows the use of shorty packs.. and if you didn't have a shorty pack already buying one today with <50C cuts down on the selection greatly or you enter the "sold out" realm. quick tqrc seach to see what I mean.

As someone mentioned earlier, what's the current draw from a mini again? I'll have to hook up my Novak sentry and check on a couple of systems.

JosB

Tamiya is strange that way I guess. I too run TCS, well, not a full series yet but allready aware of the differing rules here in Holland and Europe. We are fortunate our rules are not so strict.

markpoleon

iTrader: (41)

You can find them on eBay by searching: Tamiya-M03-A-Parts-Chassis-Black-M-03

eBay item number: 380931437943

rccartips

iTrader: (3)

Probably not just amp draw, but newer/expensive/high c rating batteries would have a higher avg discharge voltage. Can take higher charge amps. In fixed gearing mini... extra voltage is an advantage, no matter if the battery is heavier.

Sample:
Fantom 65c ($100+) = 7.85v
Turnigy 25c ($30+) = 7.36v

Around 7% voltage difference from my test. Just my thoughts.

JosB

I too have found some difference in lipo's. I used to run IP4200's but they puffed so needed new ones, found the cheapest for me and ordered two. Turnigy 4200 40~80C it says on the decal... IP's were 60C and the Turnigy's are similar at 40~80C but half the price... and I go faster now... That's comparing fastest lap times, not old vs new.

I concluded it doesn't matter what's on the decal but what happens on track... can't wait to put some really cheap square lipo's in a M05 and see what happens!

sosidge

Please share your testing method.

Robert_K

iTrader: (2)

Shiny! Thanks.

Regards Robert

oeoeo327

iTrader: (75)

+1 - that's a huge disparity between packs. I'm assuming both packs were of the same mah rating, as those test figures suggest otherwise. I'm also curious with regard to the number of cycles on each test pack prior to the test being performed.

Granpa

I'm not one of the "engineering" types so please excuse my questions cause they won't be couched in technical terms.

The first question is will you use up the same amount of "juice" in a 5 minute race regardless of whether you're using a "big" battery or a little battery????

Will the battery with the higher C rating show a lower voltage at the end of the race as one with a lower C rating other things being equal?????? Never really understood the C rating, but have been told that many batteries are mislabeled by some who should know.

Will a battery with a higher capacity show a higher voltage throughout the discharge curve than one with a lower capacity??????

Also, isn't the "age" of a battery more of a function of the number of charging cycle it's been through rather than how long you've had it????? For example, a 3 year old battery with 50 cycles through it will be "fresher" than a 6 month old battery that has 150 cycles through it?????

If two racers are equal in driving and their cars equal in speed, the better battery wins, right?????? Sometimes I wonder whether these stories of someone winning such and such a race with a 3 year old "clapped" out battery isn't more to emphasize that persons driving ability and set up skills. Or how much better they are than their competition.

As a side note, in the TCS Series USA, if you win the Nationals as a Trip winning class, you're done. You have to move on to the GT1 class so we don't have the situation where you have a few people dominating the class for years. It keeps the class interesting.

niznai

Yes, the better battery wins, but you have to define "better". Most people look at capacity, C rating and so on when in fact the most important factor is the internal resistance of the battery (especially when large currents are drawn). This is of course assuming voltage is the same and I have to confess, I don't understand why some batteries claim they deliver higher voltages. If you know anything about electricity (in Australian high schools there is this one experiment that students perform to highlight how much impact the internal resistance of the battery has on the current delivered through a circuit, so I would expect everybody should know at least that much) you would realise that is the most important factor. Maybe the "extra voltage" batteries want to suggest they have a lower internal resistance?

But internal resistance of batteries is difficult to measure, hence that isn't given. Besides, most people probably can't tell why that is important (my assumption above is obviously wrong), whereas Volts and current ring more familiar and can be made to sound impressive.

Not that the C rating has anything to do with anything. In principle, it could have something to do with the internal resistance, but I doubt in reality this is true. And even if it did, measuring the C rating is not standardised, so it is impossible to compare two batteries on the basis of C rating and draw any meaningful conclusion. Perhaps that is why manufacturers don't talk about internal resistance but C rating. Kinda like all the numbers you see on shock oil bottles. Very few manufacturers actually put cst there (which is the standardised unit) but use their own made up measuring meaningless dowacky. True, in recent times, the situation got better with shock oils.

The fact that matters is that there are by my knowledge only two manufacturers of Lipo cells in the world (Kokam in South Korea and another one I can't remember, still in South Korea - I think), so I would imagine if there is any significant difference in internal battery resistance it will come from how the cells are assembled in battery packs.

That said, I agree the difference might be quite large, and perhaps that is why we pay what we pay for good batteries. But my personal conclusion is that one should do their own testing on each individual battery to find out exactly what's what. Make a simple circuit with good components (low tolerance), put a number of loads (low tolerance), run some current, measure it, make a graph and the slope of the graph will tell you the internal resistance of the battery. Kinda like the silver can freaks selected the best motors to tune to go another extra 1/100 of a second faster.

Pointless as far as I am concerned. A bad wheel bearing or a grain of dust might take out all your hard earned advantage. But yes, the old crappy battery your friend brags about might just be that one with the lower internal resistance.

Granpa

Very interesting and informative. Still, if you were trying to answer my questions, you left out a few.

bertrandsv87

iTrader: (2)

Each lipo pack has to be tested on the track....That's the way to find the best pack, even when the packs have the same specs on their label... The thunderpower 3200mah 40C is the lowest spec pack I would start with...