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Old 02-03-2005, 07:25 AM   #1
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Default Battery cycling question

I have a couple of questions regarding numbers when you cycle your bats. A little background, I cycle my battery inventory once every couple of months (once a month when I run a lot) ....just to "rerank" then in terms of voltage and runtime. I race stock and 19 turn TC only. I cycle on a T35 6 amp charge, 20 amp discharge 5.4 cutoff.

So questions are:

1) What is the difference between the "Ds Avg Vlt" and "Ds Avg @ 1 Volt" ...more to the point which one should I use to figure out which pack has more voltage?

2) Same question with the "Int Res" and "Act Int Res" numbers

3) A related question, if I was looking for the pack with the "most theoretical punch" I would assume that will be a factor of the voltage and the IR ...saaaooo if I had a pack with 7.23 "Ds Avg Volt" and an "Act Int Res" of 17.9 is this better - the same - worse than a pack with 7.13 "Ds Avg Volt" and an "Act Int Res" of 16.7
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Old 02-03-2005, 07:43 AM   #2
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1) it's taking the average voltage at the .9 cutoff and the 1 volt cutoff, it's just two different times it's calculating the average voltage.

2)the actual and calculated internal resistance are just two different ways to give you an internal resistance reading. Calculated I believe takes into account something in the charge as well, I forget exactly what it is.

3)The pack with higher voltage and higher internal resistance will give you more top end but less punch, it's up to you to decide which is better for you. If the track is flowing and high speed I would rank the higher voltage pack first, opposites true if the track is tight and you're always accelerating.
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Old 02-03-2005, 07:50 AM   #3
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With #3 I guess I was looking/hoping for some kind of "formula" for like you say "constant accelerating/tight" track i.e. voltage * IR / PI * 4.8879 / .009328 to the 3rd power would give you a number you could compare all your bats with

I would *assume* that at some point a lot more voltage would overcome a higher resistance and vica versa where a lower resistence would make up for less voltage? ....maybe I'm just on a bad batch or crack?
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Old 02-03-2005, 07:54 AM   #4
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there comes a point when you over think things and I think you just crossed that line
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Old 02-03-2005, 07:58 AM   #5
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Havier, I'm no expert, but I can help a little...

AV and [email protected] volt basically (in layman's terms) tell you how well your cells are still matched in the given pack. The more different the two numbers are, the morse they are mismatched.

On IR numbers, (someone correct me if I'm wrong), the IR is calculated and the AIR is measured. According to one fo the top matchers in the country (assuming I remember this correctly) they care more about AIR.

On your pack comparison, I'll take a guess that those are theorhtical packs because when the AIR is lower the voltage is higher. Now obviously you could have two different kinds of cells and that could be the situation, or old cells and new cells, but typically fresh cells or cells with the same number of cycles will dictate the voltage by the AIR. If you look at new packs, you'll see that almost always the better the AV is, the better the IR is.

One note- don't be fooled by good AV numbers. Your laptimes are improved by lower IR or AIR's and consquently the voltage numbers look better on packs with lower IR's.

Hope this helps... and if I am wrong about anything please forgive me cause I have a little dain bramage
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Old 02-03-2005, 07:59 AM   #6
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Dang, how did you guys type all that so fast??? I thought I was the first reply!!!! Geeez!!
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Old 02-03-2005, 08:00 AM   #7
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Good info keep it coming ...those are real numbers, I could post a link to my "entire inventory" if you want ...last time I did something like that though I caused an uproar in a certain thread
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Old 02-03-2005, 08:01 AM   #8
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Quote:
Originally posted by Matt Howard
there comes a point when you over think things and I think you just crossed that line
....ya think?
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Old 02-03-2005, 08:03 AM   #9
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If you can feel the difference on the track between those two sets of cells I would be impressed.

There are so many things which affect punch / top speed in a bigger way than cell voltage / internal resistance. With two good sets of cells that are about the same age it will be difficult to imposible to "feel" the difference.

It's easy to overthink / overanalyze. It sounds like you are racing stock, your motors will be far more important to your speed/punch.

Chris.
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Old 02-03-2005, 08:32 AM   #10
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Chris, I understand what you are saying, but I feel I should correct you. That isn't good information to be honest. A good racer who can run consistent and knock off a few "almost perfect" laps can not only tell by feel but by laptimes that one pack is better than the other.

In your defense, I remember a time when I thought the same thing you just stated, but I have found out differently. Harsh isn't a newbie and has been around r/c racing for at least 3 or 4 years that I know of, so I doubt he's an average pipe basher that can't tell one pack from another.

I will point out that if you ARE down on motor and not geared close to perfect with a car that reacts to changes and is tuned well, you are probably right, it will be hard to tell one from the other because there are other factors involved.

Remember, a race car of any type isn't just a killer motor or well tuned suspension, it's a combination; and the better the combination of parts and tuning work together, the more one certain thing will show when it's not up to par... for a lack of a better way to explain...
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Old 02-03-2005, 08:39 AM   #11
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Yep ...well put I feel that if you can run the "best that you own" your chances increase ...of course that's assuming you have enough talent to use the equipment ...humm maybe I'm SOL
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Old 02-03-2005, 08:41 AM   #12
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BigDogRacing ...you have a PM
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Old 02-03-2005, 09:07 AM   #13
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PM back- I'm headed to work (not the fire station, Batteries Plus.. I have 2 jobs<---- sux 2 b me) so I won't be able to chat much the rest of the day.

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Old 02-03-2005, 10:42 AM   #14
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Great question from HarshGuy. I too had the same question a while back. I like to fiddle with stuff and I like to look at data regarding batteries and motors. (It's a bad habit but someone has to do it)

Matt summed it up well.

But all in all, you could definitely make a motor feel punchier with a lower "ranked" pack with the right gearing, brushes and spring combos.....right? I have bought new packs and I will tell you that I may feel the difference between the new ones and the old ones but when it comes to the "theoretical punch" of the two packs, I would think it would be a wash.....
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Old 02-03-2005, 10:49 AM   #15
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Quote:
Originally posted by BigDogRacing
Chris, I understand what you are saying, but I feel I should correct you. That isn't good information to be honest. A good racer who can run consistent and knock off a few "almost perfect" laps can not only tell by feel but by laptimes that one pack is better than the other.

In your defense, I remember a time when I thought the same thing you just stated, but I have found out differently. Harsh isn't a newbie and has been around r/c racing for at least 3 or 4 years that I know of, so I doubt he's an average pipe basher that can't tell one pack from another.

I will point out that if you ARE down on motor and not geared close to perfect with a car that reacts to changes and is tuned well, you are probably right, it will be hard to tell one from the other because there are other factors involved.

Remember, a race car of any type isn't just a killer motor or well tuned suspension, it's a combination; and the better the combination of parts and tuning work together, the more one certain thing will show when it's not up to par... for a lack of a better way to explain...

BigDog,

I would hate to disagree with you. The two packs that Harshguy mentioned I doubt that you could feel a difference. Maybe in the hands of a "professional" driver, but not in the hands of everyday club racer.

I think that is what Crimson Eagle was referring too. Not new packs versus old packs etc.


Your first post in this thread sums it up well but the two packs Harshguy talks about, I would think would not be detectable on the track........I could be wrong but, I've tested almost the exact theory and I couldn't feel a difference.
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