lephil

Hi guys, I have some used lipo I need to check as they are slightly puffed (hard case not fully flat) .
Do you have any idea of what should be the IR of an 5750 4s 50c and an 6750 4s 50c?

Something around 10?

Thanks for the help.

Sir 51D3WAYS

A brand spanking new one should be in the single figures.... A good used one should be about there or up to the teens IIRC.

lephil

Thank you very much!

lephil

here's what I have on the 1st 6750 : 39Ω 34Ω 37Ω 46Ω obviously this one goes to the cemetary
the 2nd 6750 22Ω 24Ω 21Ω 24Ω , what you guys think? should go with the first 6750 right?

The 1st 5500 : 4Ω 6Ω 4Ω 3Ω
The 2nd 5500 : 9Ω 6Ω 9Ω 5Ω
Looks incredible for an old second hand battery!
All of these are gens ace (the blue ones).

It was measurted with a Zeen Z10 charger that has An IR check feature. (same as some skyrc ones), I don't know if these are accurate or not...

both 5500 have small swelling as previously stated. So i'm wondering what to do even if they look in amazing shape considering there old and used. This was bought second hand, so I really don't know how many cycles they had.

Roelof

Get the notation right, those values are not in ohms but in milli ohms.

If the are real ohms then all is waste.

lephil

The charger did not show like 009Ω. It showed 9Ω

So yeah those are the measurements that the charger showed for each cell as noted above.

A previous member told me that if I was under 10Ω per cell it was ok? Or was he talking about the total of all cells?

because the smallest one is seventeen.

Sir 51D3WAYS

^I'm fairly sure they are milliohms, not ohms, otherwise you are toast. Are you sure it didn't show 9mΩ? Or does the manual say otherwise?

Assuming milliohms, the 2x6750 can still be used as practice/bashing....

lephil

I was happy at the begining thinking the 5500 were still good...

Ok I think I will have to recheck that to be sure it's not 9mΩ

waitwhat

iTrader: (4)

Internal resistance is but one metric for determining the health of a battery. Capacity and how well the cells stay balanced throughout use are also very important for understanding battery condition. Additionally, asking people for their specific IR numbers is pointless as different chargers and charge harnesses are going to read differently, and battery temp also impacts IR.

It seems like you have seen so many posts discussing IR, that you think it is some kind of end all be all most important thing ever. It isn't, and the only people who need to worry about having packs with really low internal resistance are people who race in a spec motor class, have the driving ability to use every bit of power, and feel the slight difference between the packs.

If the batteries are losing capacity, lose balance from use, and have high IR, the battery is bad.

lephil

yes waitwhat, I've read it was an information that could tell about battery health.

Giving that those batteries are second hand and that they are hard case with a little swelling, I'm trying to know if I can run them safely or if some are just at a point where it would be safer not to use them anymore.

I don't care about performance, I care about safety here.

Sir 51D3WAYS

Just run the damn things lol. Certainly I still would...

GerryH

iTrader: (26)

You need to be more worried if one or two cells on a 4S have significantly higher IR than the rest. Sorry, I can't quantify what significant is, but maybe something around 2X. I have a 4S that I run in my 1/8 buggy that has one cell that's 2-3X the IR of the other cells. Because the LVC is measuring total battery pack voltage, that cell can get pulled a lot lower than the others. Even though I have my LVC set high, I'm guessing that cell towards the end of a run is being pulled down to a voltage that's damaging it, making the problem worse.

The running outdoors season is coming to an end soon, so I'm retiring it.