M7H

IR will stand for Internal Resistance. The lower the IR, the less voltage loss you have in the battery when under load.
0.008 Ohm will have a Voltage loss of 0.008V per Amp of load.

snabbgas

Please read my post 1 more time!

I know what IR means but what do they mean by "max IR"

M7H

The warmer the battery, the higher the IR, I think max IR is related to the max. operation temp.

ochitone

iTrader: (10)

I personaly own some of these battery packs, they 4 cell 60c 5200mHa packs to be more acurate. As for comparring Pro Amps batteries to Desirepower batteries I would not be able to make a comparrison as I have never run them packs. I can tell you that IR in which you make refference to stands for Internal Resistance. This is the max IR under load and it will not rise above this level. As for the questioning of the batteries being a B or C grade cells, I can tell you that these are neither B or C, but in fact A GRADE cells. These are the best of the best when it comes to cells. The assembly of these packs used onlt the best of materials and this shows through on the outside of the pack as well. There are alot of packs that don't take things seriously when they assemble. Pro Amps does have heavy duty Positive & Negative wire, rubber croments that surrond these leads as well as the ballancing leads. All wires are soft and very flexiable. The carbon fiber hard case has even had special attention taken with the rounded corners, color cordanated tape covering the seam, and positive and negative sides labled. These packs have even given way to those running them in serious conditions and placed the wires on the outside corners allowing the use of strapping down the center (length wise) for better holding in your vehicle.

As for your statement of the peice of paper making it less bullshit, this is not the case that Pro Amps was going for. There is no such of a thing. Pro Amps supplies this paper showing you, the customer the hard facts of the battery. Pro Amps puts more money into testing a battery than you could ever think of. If the pack is not ready for the market, it does not go out. You show me another battery manufacture out there that will provide you proof of what your battery will do and does easily, and this proof is not something you need to ask for, it is provided.

I would like to also add that I have been using venom battery pack all year. There rattings are not 100% accurate. I have been running there 2 cell lipos, but running 2 of them and they dont have the power to even get my truck to shift gears. What a joke. Venoms customer service also is something to be desired. I spent nearly 800.00 purchasing venom lipos and 2 got messed up. Yes it was my fault, but I just wanted them to fix or replace and tell me how much. I was given a BS story that they could not do this as it was against the law and they would not cover anything. They told me if I wanted to replace the battery that I should go to the hobby store I bought it from and make another purchase. What a joke for a customer service department. I would not even prop my door open with a venom lipo at this point. I am not trying to bad mouth them, but I was not happy with there packs or there service and I will never run a venom battery again.

ochitone

iTrader: (10)

I forgot to mention this too, but here goes.

The higher the "c" rating on your battery, the more power that pack will have.
The higher the "mHa" rating on your battery, the longer that pack will run.

Keep in mind that some ESC require a certian number of amps to opperate correctly, having to few of amps can damage batteries and esc when in use.

The less conections that you have in your system, the more efficient it will be. It is best to wire motor directly to esc and use plugs of some sort between the esc and battery.

I don't see how companies can sell lipo packs for 20-30-40 dollars when the cost of lipo is going up. There has to be a lot of corners cut for that manufacture to offer the lipos at that price. Think about it, would you sell a 100.00 battery for 20.00, i don't think so, so how are others doing it. They are able to do so because they cut corners and package refurbished cells, which means cells that are used or were used previously. Would you want a used battery in your car that you spend much money on, that you put your reputation on, really? I doubt it. The shipping on these batteries are normaly more than the battery itself. These are very low grade cells.

mracer

iTrader: (43)

I have "heard" that C ratings are an in-house measure. So, is it like shock oils where battery from company A is a 40c but may be equal to battery from company B that is a 50c?

snabbgas

No, it's the other way around.
A warm battery has a lower IR and thus a battery performs better warm then cold.

snabbgas

Thats almost certainly true.

Also heard that they can be rated after how many "C" you can load the battery and still get 80% of rated capacity not taking anything else in consideration such as temperature, average voltage, or even the fact that it can only be done once and the battery is dead afterwards...

None of us rc car people uses todays high continous discharge rate capabilities because if we did, a 60C battery would give a runtime of 1min. And if you have a runtime of 20minutes you are using an average of only 3c!

But as been said earlier a higher rated battery (if true) has a lower IR (Internal Resistance) and thus will have a lower drop in voltage under a certain load resulting in higher amps and volts = more power (W).

COBRARACING

My reputation in this business is very important to me more than money and why i say that is if your honest with your ratings and tests as well as your quality then you have no reason to worry about anything no matter what people say about your brand or your quality .

Honesty is a long term business with many rewards including a top reputation and many financial benefits .

I have no reason to cheat people with low quality and poor performing products especially batterys and alot of people who know me they know im all about quality and performance and nothing less as those attributes are long term .

I took the advice a long time ago from my mother inlaw (which sounds strange right as alot of you wouldnt like your own mother in laws) but what she said was the cheat and the thief only laughs for a year and from then its down hill with no return .Im a true believer of that and i do believe there are alot of r/c companies that do lie about product performance to make sales but soon many will come undone and thats life .

anyway gents may all of you have a merry christmas and a happy new year .

regards Angelo

revsinc

iTrader: (15)

Boy o Boy
I have come so close to throwing up in my own mouth
But i was happy to read that you have done a complete and absoutle U turn on you business model ..
Now can you send me the $200 that you have rip me off for on my credit card ??

thanks

snabbgas

Aouch!!! Pretty harsh accusations there.

Can't say i'm that impressed so far with Cobra either. Every time someone comes with difficult questions something completely irrelevant like his last post seems to come out...bla bla bla.

He is a good source for support in the Hobbywing thread though.

But the topic is not about Cobra and how good he is to push for his products in every way possible.

But about Lipo C ratings and how far they can go.
It seems that higher c rated batterys is heavier. I think the copper inside needs to be thicker to support the higher currents so there is not only positive things about higher c ratings.

Example:
My About 10year old Etec 6-8c 1200mah 3cell weighs 79g
A Polyquest 30c 1200 3cell weighs 116g

Balance taps and thicker cable makes for some of the differance.

jjfo80

iTrader: (1)

everyone has a opinion but never a open mind.... Its amazing that just because someone uses one or another brand that its the best... but until u buy 5 of each battery that is made out there and hopefully 1 out of those 5 is the best that, that company can make then have your say after you do all your testing...

Gee its just like setups with cars and so on... You can have your car perfect and running the right temps and win the a main and tq but then hand the controller over to the next guy that finished second in the a main and got a faster laptime than you in the final race with his car but was 3 seconds a lap off the pace....

Until you try it you will never know.... So until every battery is tested in the scenario I typed above " everyone has a recommendation and a opinion " based on their knowledge which is bugger all... While technology gets better and better we will still have forums for opinions and recommendations and not a "buy this as its the best" thread on the forum.

1101

I think the real fact is Most companies dont manufacture lipo's, they rebrand them.
So they may be selling $20 lipos for $100, and in many cases are

exactly the same as chinese $6 2.4G RX's being just as good as the brand name $100 2.4G RX's
Same as the $80 Xerun escs being just as good as most of the $200 escs
same as $80 xerun's being rebranded & sold for considerably more
etc etc etc

rccartips

iTrader: (3)

Hi,

Would be helpful if those who believe or do not believe in C ratings share track test results.

Example, I've done lap times on a car where the only thing I've changed is the battery, back to back so track condition is the same.

Car = 1/10 on-road touring
Motor = Johnson 540
Test time = Time in seconds to complete 3 laps, done several times to get a consistent result

Orion Platinum 4800/25C (255grams) - 68 seconds
Peak Power 5000/50C (300grams) - 65 seconds

Conclusion: For me, the cheap China made Peak Power was 45grms heavier, yet 1 second a lap faster in a Silvercan TC class. 5% improvement in laptime is big.

hth.

M7H

Nope, ANY electrical component will have a higher internal resistance when heating up. I'm sorry, but that's just the way it is.
It is possible that the battery will have better performance when warm, but the internal resistance will be higher.