FYI: the internal resistance of lipos, and the inevitable consequences... - Page 3

summa1988 · 08-13-2012, 10:54 AM

does anyone know where i can find the new gens ace 5300 30c lipos for my trex 550,
these batts have getting amazing results but everyones out of stock!!!!

somebodies got to be selling them

2000SS · 08-31-2012, 12:12 PM

Tell me if I'm doing this right. I'll use 1 of the 3 cells to make this easy.

At rest I get 4.13 volts.
I plugged battery into some LEDs pulling 1.17 amps.
The cell now reads 4.08 volts.

4.13 - 4.08 = .05
.05 / 1.17 = .04

Is this correct? What does the .04 mean? The cell is in the 0-5 range or do you have to move a decimal point?

TignMeg · 09-14-2012, 06:59 PM

0.04 is in ohms you want milliohms so divide by 1000 gives you 40 milliohm. (Well 43 milliohm actually 0.05/1.17*1000=42.7)

2000SS · 09-14-2012, 10:54 PM

So 20-25 won't hold a heli in the air and I'm at 40?

That pack will fly but has no punch.

TignMeg · 09-15-2012, 02:33 AM

If there's anything I've come to realize about IR its that its extremely difficult to get an ACCURATE reading but its relatively easy to get a PRECISE reading.
What I am saying is that you may find your calculated IR is very repeatable but it might be 10x higher than the actual value.
So your reading is really only useful as a monitoring method to compare one battery to another. You need to find and measure a battery you KNOW is bad to get an idea of what IR is bad for your measurement technique.

I have a commercially made meter that gives IR and the readings for a new battery are normally 20-28milliohms. The batteries work great but when the resistance gets to >100milliohm I doubt they will be much use.

So use your experience and feel of the heli to know whats bad. You can use the IR to gauge how quickly they are aging or if you have damaged cells.

Cheers

REVOJohn · 11-05-2012, 11:12 PM

REVOLECTRIX signs contract with Toll Logistics & DHL to ship LiPO cheaper than mail services within 4 days. Keep a look out on our site for new LiPO shiping rates all over the world. www.revolectrix.com

I have more technical info on IR so I'm writting a paper on it and will publish soon. But with conventional chargers........it just can;t be done with any consistancy

markhull · 04-01-2013, 12:06 PM

Hey guys... What are you getting for LIfe Source batteries? I am getting low 20s on new backs.

08-13-2012, 10:54 AM	#41
summa1988 Registered Users Join Date: Jun 2012 Location: hartlepool	Gens ace 5300mah 6s 30c?????? does anyone know where i can find the new gens ace 5300 30c lipos for my trex 550, these batts have getting amazing results but everyones out of stock!!!! somebodies got to be selling them

08-31-2012, 12:12 PM	#42
2000SS Registered Users Join Date: Jun 2009 Location: Ohio	Tell me if I'm doing this right. I'll use 1 of the 3 cells to make this easy. At rest I get 4.13 volts. I plugged battery into some LEDs pulling 1.17 amps. The cell now reads 4.08 volts. 4.13 - 4.08 = .05 .05 / 1.17 = .04 Is this correct? What does the .04 mean? The cell is in the 0-5 range or do you have to move a decimal point? __________________ T-Rex 250. Tarot 450 Sport.

09-14-2012, 06:59 PM	#43
TignMeg Registered Users My HF Map location Join Date: Apr 2012 Location: Australia, WA, Drummond Cove	0.04 is in ohms you want milliohms so divide by 1000 gives you 40 milliohm. (Well 43 milliohm actually 0.05/1.171000=42.7) __________________ T-Rex 500* Flymentor (experimental) and Tarrot ZYX Flybarless Blade120SR (The Toy) Phoenix 4.0.j DX8

09-14-2012, 10:54 PM	#44
2000SS Registered Users Join Date: Jun 2009 Location: Ohio	So 20-25 won't hold a heli in the air and I'm at 40? That pack will fly but has no punch. __________________ T-Rex 250. Tarot 450 Sport.

09-15-2012, 02:33 AM	#45
TignMeg Registered Users My HF Map location Join Date: Apr 2012 Location: Australia, WA, Drummond Cove	If there's anything I've come to realize about IR its that its extremely difficult to get an ACCURATE reading but its relatively easy to get a PRECISE reading. What I am saying is that you may find your calculated IR is very repeatable but it might be 10x higher than the actual value. So your reading is really only useful as a monitoring method to compare one battery to another. You need to find and measure a battery you KNOW is bad to get an idea of what IR is bad for your measurement technique. I have a commercially made meter that gives IR and the readings for a new battery are normally 20-28milliohms. The batteries work great but when the resistance gets to >100milliohm I doubt they will be much use. So use your experience and feel of the heli to know whats bad. You can use the IR to gauge how quickly they are aging or if you have damaged cells. Cheers __________________ T-Rex 500 Flymentor (experimental) and Tarrot ZYX Flybarless Blade120SR (The Toy) Phoenix 4.0.j DX8

11-05-2012, 11:12 PM	#46
REVOJohn Registered Users Join Date: Aug 2012 Location: Singapore	REVOLECTRIX signs contract with Toll Logistics & DHL to ship LiPO cheaper than mail services within 4 days. Keep a look out on our site for new LiPO shiping rates all over the world. www.revolectrix.com I have more technical info on IR so I'm writting a paper on it and will publish soon. But with conventional chargers........it just can;t be done with any consistancy __________________ REVO John facebook.com/likeREVO

04-01-2013, 12:06 PM	#47
markhull Registered Users Join Date: Apr 2012 Location: Atl, GA, USA	Hey guys... What are you getting for LIfe Source batteries? I am getting low 20s on new backs.

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