Lipo, One cell IR higher question?

[nitros]

This is the graph of the first full charge, are 6s x 6 4000mah in parallel, as you can see from the file, IR of cell 6 is double of the others, today i done the second charge and still was higher but around 4/4.5 should i worry and start to investigate which pack is it, or i shouldn't worry?

[LaurenceGough]

Take IR ratings with a pinch of salt, I've stopped logging my IR readings, or even looking at them now.

If the pack puffs then you should discontinue use, even if one cell puffs you should be able to see it.

[nitros]

Take IR ratings with a pinch of salt, I've stopped logging my IR readings, or even looking at them now.

If the pack puffs then you should discontinue use, even if one cell puffs you should be able to see it.

That's the graphScreen shot 2012-04-06 at 19.36.31.jpg

[Andy from Sandy]

Take IR ratings with a pinch of salt, I've stopped logging my IR readings, or even looking at them now.

Take IR readings very seriously if the device you use to take the measurement can do it accurately.

The IR of a pack will allow you to determine what the safe current flow from that pack can be. The IR cannot lie unlike the C number printed on the label!

The IR could be considered as a series resistor in the circuit. This resistor dissipates the power flowing through it as heat. As the value increases so does the amount of heat. Heat in a lipo spells disaster.

[Mark_T]

Are you using the FMA MPA board by any chance?

If so then I may have the answer.

[p4ddy]

Are you using the FMA MPA board by any chance?

If so then I may have the answer.

Node setting

[milly0812]

So what is a safe IR to continue flying. My align 5200s have ir under 3. My nanotech 5000s are under 4 whereas my kokam 5000s are around 7. Whats too high ??

[nitros]

no i "cheap" para board?

[LaurenceGough]

Take IR readings very seriously if the device you use to take the measurement can do it accurately.

Which to be honest I don't think any of our chargers can do - it varies far too much from what I have seen.

So would you not fly a pack if it says that a cell has high IR?

Sorry but for me if a pack has not been crashed or any other physical damage and no puffing I'm flying it no matter what IR it says. If perhaps a pack is not acting quite right I'll check it's IR's but I've always either seen high heat, or physical signs of a bad pack whenever if I find a battery has a problem.


Charge each pack by it's self - see what the readings say then.

[nitros]

these are new pack, this is the first full charge, but today i done the second and still the cell 6 was higher but less that the first time(graph showed)?

[Andy from Sandy]

So what is a safe IR to continue flying. My align 5200s have ir under 3. My nanotech 5000s are under 4 whereas my kokam 5000s are around 7. Whats too high ??

What is safe can only be calculated once you know how much current your motor / ESC is drawing. Based on that figure you can then calculate how much power is having to be dissipated in the pack. To put it the other way round that kokam lipo should only be used if you can keep the continuous current draw at 65 amps or less. More than that and the heat build up in the pack will be at a point that it will seriously reduce the packs life.

The Align pack should be good for about 100Amps continuous and the nanotech 86 amps.

[Mark_T]

So what is a safe IR to continue flying. My align 5200s have ir under 3. My nanotech 5000s are under 4 whereas my kokam 5000s are around 7. Whats too high ??

So your Aligns have a real C rating of at least 20 so they are good for about 104A, the Nanotechs about 17C or 85A and the Kokam 13C or about 65A.

Figure out what your heli needs and you know if they are still able to handle it

Edit: you may guess we've been looking into this area rather closely of late

[LaurenceGough]

these are new pack, this is the first full charge, but today i done the second and still the cell 6 was higher but less that the first time(graph showed)?

How are the cell voltages - are they all balanced?

Did it fly ok? Next step is just to try charging them separately.

[Mark_T]

no i "cheap" para board?

There is an issue with the IR reading for one cell showing about double the 'real' figure when using the XH wiring setting.

There is a new version of the firmware for the PowerLab chargers due out shortly to fix this.

If you have a normal CellPro balance board you can prove this by checking each pack on its own.

If you only have the XH wired board then you are going to have to wait for the firmware change.

[Andy from Sandy]

Sorry but for me if a pack has not been crashed or any other physical damage and no puffing I'm flying it no matter what IR it says. If perhaps a pack is not acting quite right I'll check it's IR's but I've always either seen high heat, or physical signs of a bad pack whenever I fly an under performing pack.

You don't need to apologise for lack of knowledge. If you have seen high heat then it is a direct result of the amount of power being dissipated in the pack. If you have caused a pack to overheat then you have drawn too much current from it.