Resistance difference in battery cells
02-28-2017, 12:45 PM
#1
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Resistance difference in battery cells
I have a 3600 mah 2s battery fairly new. It is a flat pack I purchased for transmitter use. On the first charge I saw a resistance reading like cell one 100 and cell two 3.9. I thought maybe my charger was messed up so I installed the battery and set up some planes and looked around in it since the transmitter was new. The voltage was at 7.9 after some use so I decided to charge it up and noticed the strange resistance readings again. I have two Power Lab 8's so I discharged and charged the battery a few times. Final reading today was cell one 70.1 and cell two 4.1. Th other Power lab had different numbers but very similar and with the big discrepancy between cell one and cell two.
How do you translate these numbers and the status of this battery?
Is it near its end and unsafe?
Will it serve me with some good use n the transmitter.
Should I ask for a new battery?
Thanks.
How do you translate these numbers and the status of this battery?
Is it near its end and unsafe?
Will it serve me with some good use n the transmitter.
Should I ask for a new battery?
Thanks.
03-12-2017, 05:03 AM
#3
I think OP is reading 3.9, and 100 Ω (ohms) from the cells.
I am curious as well to what the numbers mean in terms of the life of LiPo cells. I've recently begun to log cell readings on my packs. This is done with a charger's IR measurements, and a "5-in-1" battery meter. I'm sure the readings are not the most accurate, and a person will also get different readings from temperature/load of the cells. I just use my readings as a "tool" to help identify possible trouble cells/packs.
I have read some threads that state general numbers and their meanings to the health of a cell. All that searching/reading made my head spin. I'll try to find the page that had the so called "stages" of battery life.
I am curious as well to what the numbers mean in terms of the life of LiPo cells. I've recently begun to log cell readings on my packs. This is done with a charger's IR measurements, and a "5-in-1" battery meter. I'm sure the readings are not the most accurate, and a person will also get different readings from temperature/load of the cells. I just use my readings as a "tool" to help identify possible trouble cells/packs.
I have read some threads that state general numbers and their meanings to the health of a cell. All that searching/reading made my head spin. I'll try to find the page that had the so called "stages" of battery life.
03-13-2017, 10:13 AM
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The lower the cell resistance the better.
Lower resistance equates to better sustained output and less heat build up.
I am seeing 2-3 ohms per cell on newer high output Graphene 45C batteries.
On my older well used LiPo's I'll see up to 20 ohms. The packs that are in the best shape are in the teens.
Once they get beyond 30+ ohms, I find that the batteries do not produce more than 75% of their rated capacity and I consider chucking the packs.
You want all of the cells in a pack to be as close as possible to the others. The OP's post indicating 4 ohms and 100 ohms indicates one good cell and one fairly bad one.
Lower resistance equates to better sustained output and less heat build up.
I am seeing 2-3 ohms per cell on newer high output Graphene 45C batteries.
On my older well used LiPo's I'll see up to 20 ohms. The packs that are in the best shape are in the teens.
Once they get beyond 30+ ohms, I find that the batteries do not produce more than 75% of their rated capacity and I consider chucking the packs.
You want all of the cells in a pack to be as close as possible to the others. The OP's post indicating 4 ohms and 100 ohms indicates one good cell and one fairly bad one.
