High resistance lipo

[alyon187]

Are there any issues for batteries that have a high resistance value? My 6s and 3s have low 20 to 30 resistance values but noticed that my two 3s pulse batteries have a resistance of 93 and 76. Thats a huge jump from my others. They aren't puffy and I really dont see any flight degradation when using them so I was wondering if I should be concerned w these values or just keep flying them as long as they aren't puffy and are still provided the power I need?

[kirby_]

I use this guide from this HeliFreak post from redbird300:

a) Packs that are as good as new: between 0 and 5 milliOhm/cell
b) Packs that have been used dozens of times, but still feeling fairly good: between 5 and 10 milliOhm/cell
c) Packs that have been used even more, and start to feel weak: between 10 and 20 milliOhm/cell
d) Packs that almost won't hold your heli in the air anymore: over 20-25 milliOhm/cell

[Slyster]

VERY dependent on size/capacity if lipo. Little 1s packs can have 100+ and be good.. a 3s2200 generally good is around 10-20.... 6s5000s good is 1-5.

Please post your full lipo information

[alyon187]

Nm, im not sure what happened bit I went ahead and plugged it in again to charge it and its only reading 31 for one and 26 the other for total resistance which is more of what I would have expected it to be around especially since theres packs have close to 100 plus flights on them. Thanks though guys!

[Xrayted]

Originally Posted by alyon187

Nm, im not sure what happened bit I went ahead and plugged it in again to charge it and its only reading 31 for one and 26 the other for total resistance which is more of what I would have expected it to be around especially since theres packs have close to 100 plus flights on them. Thanks though guys!

As Slyster posted, there is no one size fits all good resistance value for lipos. The 2010 sticky post that everyone loves to reference from this forum reading healthy lipo IR being 5 or under for all lipo cells is nonsense and misleading information!

The lower the mAh, the higher the resistance of a lipo will be and this is normal. A 5000 mAh pack might be good at 5 or under, but those value means absolutely nothing when it comes to smaller capacity packs as they will be much higher.

Anyone notice that when you parallel charge, your IR magically goes down very low into single digits? Did the packs IR magically get better vs the values shown when charging them individually? Of course not! This is because you are increasing the capacity of the packs by combining them as one big giant high capacity battery and the charger sees it as such. Bottom line is you can only compare values of same capacity packs to each other, and that is only one variable of others that must be controlled

Temp of the pack also plays a big part as well. A warm pack of any capacity will read lower IR than the exact same pack will when cooler, so there are variables that must be exactly the same or your values will appear to be all over the place from one measurement to the next on the exact same pack

This is why your values came down, because charging it warms the pack over room temp and you likely tested it again after it had warmed up later in the charge cycle

[alyon187]

Actually no, these batteries hadn't been on the charger all day and it was over 10 hours since they were flown. I plugged them in to start charging them and saw the resistance right off the bat so I stopped the charge and tried the other. Saw and did the same thing so I again stopped and then posted on here. After about 2 hours I decided to go ahead and charge them since they weren't puffy and were still providing me with plenty of power. Thats when I saw that the resistance was back down to where I thought they would be at. My charger isnt all that fancy. Its a replacement charger I got from hh after I had sent my passport 200w ac/dc charger in for repairs and since they dont make or carry that charger anymore then sent me a brand new dynamite passport ultra force 220 w ac/dc touchscreen that can measure the resistance of the whole pack, not individual cells.

[Xrayted]

Originally Posted by alyon187

Actually no, these batteries hadn't been on the charger all day and it was over 10 hours since they were flown. I plugged them in to start charging them and saw the resistance right off the bat so I stopped the charge and tried the other. Saw and did the same thing so I again stopped and then posted on here. After about 2 hours I decided to go ahead and charge them since they weren't puffy and were still providing me with plenty of power. Thats when I saw that the resistance was back down to where I thought they would be at. My charger isnt all that fancy. Its a replacement charger I got from hh after I had sent my passport 200w ac/dc charger in for repairs and since they dont make or carry that charger anymore then sent me a brand new dynamite passport ultra force 220 w ac/dc touchscreen that can measure the resistance of the whole pack, not individual cells.

Once again, you cant compare the IR values between packs unless they all have the exact same capacity. Your lower capacity packs can have higher IR than your higher capacity packs and this completely normal.

Something is not right with your chargers stated IR values if they are changing randomly with the packs being tested at the exact same temp from one time to another. Maybe a poor or dirty connection contact between the battery and charger?

[frankiexp2]

Originally Posted by Xrayted

As Slyster posted, there is no one size fits all good resistance value for lipos. The 2010 sticky post that everyone loves to reference from this forum reading healthy lipo IR being 5 or under for all lipo cells is nonsense and misleading information!

The lower the mAh, the higher the resistance of a lipo will be and this is normal. A 5000 mAh pack might be good at 5 or under, but those value means absolutely nothing when it comes to smaller capacity packs as they will be much higher.

Anyone notice that when you parallel charge, your IR magically goes down very low into single digits? Did the packs IR magically get better vs the values shown when charging them individually? Of course not! This is because you are increasing the capacity of the packs by combining them as one big giant high capacity battery and the charger sees it as such. Bottom line is you can only compare values of same capacity packs to each other, and that is only one variable of others that must be controlled

Temp of the pack also plays a big part as well. A warm pack of any capacity will read lower IR than the exact same pack will when cooler, so there are variables that must be exactly the same or your values will appear to be all over the place from one measurement to the next on the exact same pack

This is why your values came down, because charging it warms the pack over room temp and you likely tested it again after it had warmed up later in the charge cycle

This is very good info. Most people confuse cells and mah. I would like to add, it is a good practice to measure your IR when you first get your pack and then you can better measure the condition moving forward. I parallel charge but I charge individually the first time and when I suspect a battery is degrading so I can compare apples to apples.

[kramrle]

Originally Posted by Slyster

VERY dependent on size/capacity if lipo. Little 1s packs can have 100+ and be good.. a 3s2200 generally good is around 10-20.... 6s5000s good is 1-5.

Please post your full lipo information

It depends as well on the C rating. The higher it is the lower the iR should be.

A good 3S 2200mAh 40C Batterie should have an iR of <5 milliohm