New User - New Battery IR advice please?

[2RGJ]

Hi Everyone
I am a new H user and have bought 3 batteries from China. I have seen and read some posts regarding Internal Resistance (IR) and understand that this changes with temperature, charge and that they should all be low values and closely matched for a good battery etc.
I took the IR when i received them yesterday (uncharged / storage charge) and again 30 minutes after the 1st balance charg today. All values are milliohm's. I am using a Reaktor Quadcore charger bought from HobbyKing a few years ago.
My question is - As the new battery cells IR are not all closely matched to each other - should i return them as defective or am i worrying to much about them?

The IR results are posted below:

Battery 1 - Cell 1 (new = 9, charged = 6), Cell 2 (new = 8, charged = 5), Cell 3 (new = 13, charged = 10), Cell 4 (new = 11, charged = 10)
Battery 2 - Cell 1 (new = 10, charged =7), Cell 2 (new = 9, charged = 6), Cell 3 (new = 12, charged = 12), Cell 4 (new = 13, charged = 11)
Battery 3 - Cell 1 (new = 10, charged =7), Cell 2 (new = 8, charged = 5), Cell 3 (new = 14, charged = 11), Cell 4 (new = 13, charged = 10)

 

[wrench567]

Hello.
You're measuring milliohms. That's millinths of an ohm. Also I have found that lipo cells stabilize after a few charge/discharge cycles. I never do a balance charge until the pack has been cycled several times. This is coming from years of charging 3s and 6s packs used by helicopters. I have packs that are over 5 years old and still give 5 minutes of flying.

Give them time to stabilize before condemning them. Full charge and check voltages. Then place a load on it and monitor cell volts as the load is on. Any cell dropping quickly compared to others is bad.

Pete.

 

[DoomMeister]

You're measuring milliohms. That's millinths of an ohm.

Actually it is 1/1000th of an Ohm, and microOhm is 1/1,000,000th of an Ohm. I know still very small values.

I am a little concerned with new batteries having IR values above single digit milliOhm values, but you are spot on about giving them several cycles to stabilize.

 

[wrench567]

Actually it is 1/1000th of an Ohm, and microOhm is 1/1,000,000th of an Ohm. I know still very small values.

I am a little concerned with new batteries having IR values above single digit milliOhm values, but you are spot on about giving them several cycles to stabilize.

Ya. I'm not an electrical genius but I know enough to get me in and out of trouble. My years of dealing with lipo packs and I have about a half dozen plug in testers that use the balance plug. I also use the alarms for my 6s packs. I prefer to go by voltage drop under load rather than internal resistance. If I suspect a faulty pack or post crash. I charge it on my 4 button charger and then discharge it while looking at the individual cell volts. My charger will discharge at up to 3 amps.
I once drove my 450 helicopter into a dirt banking so deep that only the tail was sticking out. I figured after that crash the battery was toast. It was in fact folded about 15 degrees at the strap and the plug was torn off but tested good and lasted another year before finally dying. The bird was a total wreck. Except for the ESC and gyro, I have enough parts to build at least two complete helicopters. That's the beauty of the 450. Cheap to crash.

Pete.

 

[DoomMeister]

Ya. I'm not an electrical genius but I know enough to get me in and out of trouble. My years of dealing with lipo packs and I have about a half dozen plug in testers that use the balance plug. I also use the alarms for my 6s packs. I prefer to go by voltage drop under load rather than internal resistance. If I suspect a faulty pack or post crash. I charge it on my 4 button charger and then discharge it while looking at the individual cell volts. My charger will discharge at up to 3 amps.
I once drove my 450 helicopter into a dirt banking so deep that only the tail was sticking out. I figured after that crash the battery was toast. It was in fact folded about 15 degrees at the strap and the plug was torn off but tested good and lasted another year before finally dying. The bird was a total wreck. Except for the ESC and gyro, I have enough parts to build at least two complete helicopters. That's the beauty of the 450. Cheap to crash.

Pete.

I agree with testing under load and monitoring the individual cells as the pack discharges.