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Is my Imax overcharging my 3S Lipo??
#1
Hey all!

Not sure if this is the right place! I have the malectrics spot welder which works fine & runs off of a 3S 5000mah 65-130C Lipo.
Now when i bought this Lipo it wasn't fully charged. If i remember two cells were around 3.4v & one was at 3.8v.
So I balance charged the Lipo to 12.60v(4.2 per cell) with my Imax b6 ac v2

Yet when the Imax was done I tested the voltage of the full pack & each cell with the Imax, a multimeter(UNI-T 203), & a digital battery capacity checker.

Each cell was over 4.2v.
two were around 4.219 & 4.215.v
The highest one was 4.261v

The full pack was 12.695v
Surely this isn't right? Maybe I need a new charger?

I'm charging the Lipo up again. Though it seems to be balancing the cells at the moment.
I have a feeling it won't be properly balanced when its done!

It finished & overall battery voltage was 12.717v.
cell01 4.227v cell02 4.223v cell03 4.267v

Either the Imax isn't balancing properly? or its the battery? I'm puzzled!!
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#2
The balance can take hours and several tries if it was that off that you had.

But.. Is the iMax genuine or not? Its a known charger to have fakes that doesnt work properly
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#3
Thanks daromer I didn't know it can take several tries to get it balance!
Yes it is a genuine Imax with the sticker on the back.
I have checked the number on the website that states it is genuine!

Here is a picture of a fake.

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#4
I don’t own an imax, but I do own some pretty decent to high end chargers… it should not take several tries to get it balanced… It should do it on the first try, every time, but it might just take time to complete.

At the end of a balance charge, everything is perfectly balanced.

Perhaps you have some settings turned on forcing the termination based on time… explore your menu options to see if such an option exists.

Another thing to consider is calibration… I can and do calibrate my chargers against my Fluke DMM.  Perhaps you can explore that as well.
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#5
Interesting, this certainly isn't right and it should work on first try. Also, it especially shouldn't go over the target voltage while trying to balance. This should never happen. Because the IMAX shows 4.20V I'd also say that it might be time to do some calibration. And make sure you're running the latest firmware.
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#6
Thanks Crimp Daddy Yeah!! I originally thought it should balance on its 1st charge as other cells (Li-Ion & Lipo) have!

Thanks DarkRaven! I do have the latest firmware & have checked my settings after updating latest firmware!
The collaboration allegedly can only be done with 6 cells in series. There is a video on ytube about that.
I'll have to rig up a 6s1p pack with some 18650s to see if i can get it done.

Thing is the voltage test i did with all imax then multimeter then capacity checker were all showing over charged
voltage on each Lipo cell & overall pack voltage.

I'm just running another balance charge as I used the Lipo again earlier on the spot welder to create a 6P4S from 24 IFR26550 cells.
Here is a a few latest pics on balance charge voltage of the same Lipo.
You can see it balancing but as in previous balance charges it somehow stops balancing & over charges the cells.

 
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#7
Something is wrong… you should start with a calibration and see if that helps.
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#8
Crimp Daddy and others: the reason it takes time to rebalance some packs is when they are way out of balance. Due to a time constraint built in and the limited balancing current the time it leaves for balancing will run out. I have seen this MANY times happen. This though does not answer why voltage is way way off.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#9
Oh, this is what you meant. Yeah ok, that's right, if you don't disable the time limit then you might indeed need several runs to balance the battery. I usually disable it and never thought about it. For me it's just a matter of time but it will always work first try.
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#10
Yes thanks daromer DarkRaven & Crimp Daddy. I am aware of the time constraint that is built in
though i do have "safety Timer" & "Capacity Cut-Off" switched off
as i have always had it that way even after updating firmware everytime.

I think I've had this imax for around two years maybe more.

& as I was originally thinking it should've balanced this Lipo on 1st balance charge.

Talking of calibrating the charger.

Do i do this while the Lipo is in it's overcharged state?

Or do I do a small discharge to get the cells between 4.0 to 4.2v?

There is a serious amount of disinformation on ytube about calibration on these
Imax chargers. One being "you can only calibrate once".

This Lipo "brand new" cost me £60 & I do not want to kill it in any way!

I do have "safety Timer" & "Capacity Cut-Off" switched off
as i have always had it this way even after updating firmware!
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