greasy orange dirt

Batteries, Chargers, and Battery Management Systems.
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ltosolini   100 mW

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greasy orange dirt

Post by ltosolini » Feb 23 2018 4:58pm

Experts,
it has been one year since I put version 2 of my Elettra2500 e-scooter on the road and now I have decided to open it for a thorough check-up. All looks good apart from a greasy orange dirt on the top of one of the Winston 40ah cell.
Do you have any idea of what it can be? And above all, do you think it is safe to keep the cell?
Thanks,
Luca.
battery-02.jpg

Voltron   1 MW

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Re: greasy orange dirt

Post by Voltron » Feb 23 2018 5:25pm

How does it smell?

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amberwolf   100 GW

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Re: greasy orange dirt

Post by amberwolf » Feb 24 2018 3:31am

It looks similar to the crystalline deposits I've seen on leaking batteries of assorted chemistries over the years.

I suspect electrolyte is leaking from around the terminal/plastic interface, and most likley is being forced out when the cell swells up at portions of teh charge or discharge. (since its' probably compressed at it's sides in a way that prevents the casing from swelling).

Might not be from the terminal but could instead be from under the vent cap (the red/blue logo sticker)

If it has a kind of sweet smell, or nail=polish-remover smell, that's probably what it is--electrolyte.

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dogman dan   100 GW

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Re: greasy orange dirt

Post by dogman dan » Feb 24 2018 8:29am

Yeah, its a leaker.

Joachim   100 W

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Re: greasy orange dirt

Post by Joachim » Feb 24 2018 9:16am

overcharged lfp no bms?

ltosolini   100 mW

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Re: greasy orange dirt

Post by ltosolini » Feb 24 2018 1:15pm

This substance doesnt smell and in some places it is christallized looking like cane sugar. So consensus is for a leak. The cell is still performing well.
Do you think there is any security concern?

I dont have BMS but rule out any overcharge because I have developed a system that cut off charger as soon first cell reaches 3.6Volt
Luca

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amberwolf   100 GW

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Re: greasy orange dirt

Post by amberwolf » Feb 24 2018 2:12pm

Does the system actually measure each cell's voltage?

Or is it measuring the whole pack voltage? (and basing cutoff on 3.6v x number-of-cells)

If the former, then you wouldn't get overcharge, but you could have other cells that are undercharged, and if there's a severe enough imbalance, could be overdischarging them as you get to the bottom of the pack.

If the latter, then there's no way to know if any cells are undercharged or overcharged, as any imbalance means all cells could be completely different states of charge.

dustNbone   10 kW

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Re: greasy orange dirt

Post by dustNbone » Feb 24 2018 8:05pm

When I saw the thread title I assumed it was about American politics :(

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