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Old 01-06-2013, 03:59 PM   #1
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Default Lipo IR

Ok on road guys explain to me all i need to know about lipo internal resistance and what is a good # for a 4200 mah 65c shorty batt any info is appreciated thanx.
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Old 01-06-2013, 04:18 PM   #2
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The lower the better, its hard to find the truth of what the IR actually is. And a lot of the companies won't tell you what the actual IR is. SMC sells a device that will tell you the IR of your batteries. I use my Thunder Power TP820 charger. It's far from the best. But its better then nothing. Here is an example of 3 of the batteries that I own.
I'll list them per cell all are 2s lipos. These numbers are fresh after a full charging at 20 amps.

CRC Maxxcell 5600mah 65C. 7...5 miliohm. 12 total
BMI Motorsports 6500mah 60C. 6....5 miliohm. 11 total
SMC 7200mah 70C. 4...3 miliohm. 7 total

These numbers are probably far from the true IR but for my testing using the same exact setup. It's good enough for me.
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Old 01-06-2013, 06:17 PM   #3
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Ya i got the orion touch charger and i noticed a read out for ir and i didnt know what is good. I think my batts are around 30 ohms for a 2s 4200 65c after chargeing 5 amps. Cause u cant have a high C rating with high IR ohms. The less resistance the faster u can discharge right no? Is this what seperates the good batts from the bad.
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Old 01-06-2013, 06:26 PM   #4
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The less resistance the more punch the battery will have. IR is directly related to the C rating. The problem is. Most if these lipo companies are a bunch of bs'ers. So far my SMC's have the best IR but I feel my BMI's have a better track feel. End voltage after s run is also better on my BMI's then the SMC's.

If your in the market for a couple great batteries you can't really go wrong with either a BMI or SMC.

www.bmiracing.com
www.SMC-racing.net

Roger
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Old 01-06-2013, 06:39 PM   #5
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Well i run 17.5 offroad and batts really arent that big of deal there is a difference but not like on road ive using the turnigy nano batts and love them plenty of punch for me ill run them 2x in a row with out charging them and my lap times are faster second run. Was just interested in the IR thing and how it works in conjuction woth the C rating.
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Old 01-11-2013, 07:03 AM   #6
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Quote:
Originally Posted by toepush View Post
Well i run 17.5 offroad and batts really arent that big of deal there is a difference but not like on road ive using the turnigy nano batts and love them plenty of punch for me ill run them 2x in a row with out charging them and my lap times are faster second run. Was just interested in the IR thing and how it works in conjuction woth the C rating.
Lap times on second run without charge is almost certainly due to the battery loosing its punch and therefore you have softer application of the throttle, resulting in less wheel spin.
As far as IR....... typical Turnigy IR from testing I have done ranges from high 4 to 6.
SMC 2s regular stick packs that are considered high IR (discounted priced) only have mid 4 with low IR packs ranging from high 1-3.
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Old 01-11-2013, 07:33 AM   #7
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info on IR.. IR causes HEAT..a high ir will result in lower C burst..longer charge time and shorter run times..it will also lead to a lipo failure and fire while charging or running..I have about 30 different lipos and all my lipos have less than .002 internal resistance ..once they hit .02 there in the scrap..

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Old 01-11-2013, 07:51 AM   #8
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I love my SMC batteries. Great IR numbers and fair prices.
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Old 01-11-2013, 09:47 AM   #9
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All of the latest 6500-7000mah batteries are coming from one source. The supplier calls them 7000's but they range from 6500 to 7000mah and in order to be honest many companies are labeling them as 6500(EA)/6600(OHP)/6800mah(Reedy). They are better than the previous generation of 6000-6500mah cells.

If you are running this latest generation of batteries they are awesome and the variance from the best to the worst packs is very small.

Typical Variance:

6800-7200Mah
0.02v average voltage under load
0.2 point in IR

EA, SMC and Trinity are now testing/sorting batteries and letting you chose the level you want to buy. If you want to get the best now you can. However, since the difference is so tiny between the best and worst of the new batteries it pretty much wont make a difference on the track.

So...if its new and 6500-7000mah buy whatever you like and have fun.

Also, every cycle is one run off the total life of the pack. I only cycle my oldest packs to see if they are still strong and I only do this maybe once a year.
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Old 01-11-2013, 08:29 PM   #10
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I don't understand why anybody even sweats the IR these days. The old 6 cell packs were 4-6 ohms (if memory serves) per cell. 24-36 ohms. I can honestly say that there are other issues that need attention.
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Old 01-11-2013, 09:32 PM   #11
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Quote:
Originally Posted by big al View Post
I don't understand why anybody even sweats the IR these days. The old 6 cell packs were 4-6 ohms (if memory serves) per cell. 24-36 ohms. I can honestly say that there are other issues that need attention.
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