Accidently charged turnigies to 4.6 volts

I accidentally did this with my 16s life charger on my 12s turnigy lipos. I forgot to charge my regular battery the night before so I decided to opportunity charge my 5 ah emergency lipos and stop them before 50 volts total. Unfortunately I lost track of time, and overcharged to 56 volts.

The batteries became hot, so I put them in a cookie tin. I am wondering how to dispose of these in a safe way. Should I ride with them to discharge and then soak in salt water or should I use a lower discharge rate?

Man, what a stupid thing to do.

Get the cell voltage down on them ASAP. The electrolyte in them is breaking down so fast right now, if you could listen carefully I bet you could hear audible micro-gassing.

Also, keep in mind they are particularly vulnerable to physical damage causing fireballs and things while at 4.6V/cell.

Your location might dictate your actions, but given the choice I would put them somewhere safe to burn, and discharge them with an incandescent lamp. My bbq area seems ideal. I could watch the lamp for progress, or the fireworks if it got interesting.

BMS boards start at $20 and insure you against this. Your already out of pocket, I hope your away ordering one.

I did my Turnigy batteries to 4.55v per cell for about 2 hours, before burning off the power to below 4.2v/cell

No puffing, no gassing that I could hear, and they lasted for another 2 years.

Not recommending you keep yours, just saying that catastrophe is not guaranteed.

At work right now. I can discharge them on my bike on the way home or transport them home then discharge. Do you think they can flame up at 1c load?

snowranger said:

At work right now. I can discharge them on my bike on the way home or transport them home then discharge. Do you think they can flame up at 1c load?

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They should discharge fine and just give you epic capacity. I hope you have a CA, it would be cool to chart how much capacity you get out. I've taken > 7.5Ah from a 5Ah cell from much less overcharging than 4.6V.

The important thing (aside from not burning down something you liked) is to prevent them from gassing out into all puffies before you get to discharge. If you can't discharge them right now (and I would personally take a break from work and ride ASAP to knock the voltage down), put them in a cool place that is OK to be engulfed in flames should it happen.

I rode about 8 hilly miles and the battery is still at 49 volts. It's in a enamel pot in the fireplace. I plan to knock it down further.

Inside the house ? A lipo fire is a different thing not for inside where people live and or a inside fireplace or. Do you have an outside barbeque. Lipo fire is a black billowing cloud of rubbery soot, unwashable. More like a sand blaster is needed. So be careful. Maybe 10 more miles.

Thanks. Point taken. Now outside on a metal table and enclosed in an enamel pot.

snowranger said:

Thanks. Point taken. Now outside on a metal table and enclosed in an enamel pot.

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Be very gentle handling it, pouch cells are extremely delicate things, any rough handling is abusing them to handle them. Believe it or not, you may be entirely out of the woods, aside from what gassing occurred and what damage to the active material occurred. You might just be able to continue using the pack like nothing happened and have it keep working with mildly diminished performance. OR, it may just combust for no obvious reason with no obvious warning sign, it's so hard to know what may have happened inside cells. If you happen to have a good meter, like a 6.5digit, you can instrument the cell tabs in a room or box that it temp controlled, and chart the voltage drop per 8hr period per cell, you could perhaps know which cells have damage causing side-reactions to occur from the event.

You could sacrifice them in the name of making a LiPo safety video by exploring the limits of safety for the cells. Or attempt to discharge them down as low as you safely can and take them to a recycling place (like batteries plus).

I would discharge to ~3.8V, put them somewhere safe and leave them for a good while to see if they puff. Of not, I'd recharge and leave again for a few days and see if they puff. If not, return to service

no, do not charge them up and leave them to puff up. keep them discharged until you need them and then charge them up and keep them in compression with endplates so they do not puff up. i once got pack for free that had half the cells at 0V and half were at 4.5V because he had been bulk charging them with no balancing from a BMS.

Lots of conflicting advice. Very reasonable to just say f it and discharge them to 0v with some kind of light bulb or whatever, and dump em.

But on the other hand, you might have a use for them that could take enough precautions to make it relatively safe. If so, go for it, storing them mostly discharged, and charging in a safe location for a use that won't be a life threatening disaster if they flame. I'd say these just took their last trip to the office.

Me, I'd use them on my lawnmower. I always use my old puffy junk packs to run my mower. Stored outside in an old fridge, and in use if they ever blow, I can just flip the mower over and they will dump out to burn on the green grass lawn.

dnmun said:

no, do not charge them up and leave them to puff up. keep them discharged until you need them and then charge them up and keep them in compression with endplates so they do not puff up.

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Disagree. If bad shit has happened inside the cells, making them liable to gas, you want to find out before returning them to use. Compression may aid normal cells in good health, but I don't see it "curing" damaged ones. Sure, if they turned out to be ok and are returned to service then the standard advice of applying compression is good.

I see nothing wrong overcharging lipo, I do it all the time.

What is wrong is to do it ACCIDENTALLY, that means your charging procedure is risky business.
You should monitor lipo for the whole charging time. Charging them while you are not watching is much more dangerous than overcharging.

Cant say boo about that. Don't go put lipo on charge in the basement or garage, and go to bed.

I wouldn't recommend charging to 4.6 though, unless there is a race to win or something.

Punx0r said:

dnmun said:

no, do not charge them up and leave them to puff up. keep them discharged until you need them and then charge them up and keep them in compression with endplates so they do not puff up.

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Disagree. If bad shit has happened inside the cells, making them liable to gas, you want to find out before returning them to use. Compression may aid normal cells in good health, but I don't see it "curing" damaged ones. Sure, if they turned out to be ok and are returned to service then the standard advice of applying compression is good.

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i see no logic in your statement. totally void of any experience with puffed lipo pouches too.

putting a puffed lipo pouch in compression does help and it is not good for the cell to charge it up to full voltage and leave it full charged.

that should be obvious from what we now know that it is time at high voltage and not actually the voltage it charges to that shortens life cycles.

people have wasted so much time saying that the way to conserve life cycle is just to charge to 4.15V and totally ignore the fact that we know from that lecture on the Tesla board that it is the LENGTH of TIME it is held at high voltage and not what the final charge voltage is. all this crap about charging to 4.1V totally ignores the fact that we now know better and what matters most is charging the lipo up and leaving it charged. if you want the cells to last then do not charge until used.

how many of you people even listened to that lecture and how many listened to that lecture on calorimetry where he showed how thermal runaway begins and the temperature of onset, and compared the temperature of onset of thermal runaway between lipo and lifepo4.

i bet none of you listened to either of those lectures but you still regurgitate the same misinformation about charging and what damages the cells.

If you've quite finished on your soapbox: It's called "stress testing". If a cell has potentially been damaged by over-charging, you want to find out now. Letting it sit at 4.2V for a week gives you a reasonable chance of spotting any abnormalities, and is well within the capability of healthy LiCo cell. Your suggestion of babying these potential fireballs and using compression to hide electrolyte breakdown so they can immediately be returned to service is foolish.

I normally try to avoid being confrontational but your posting style is frequently abrasive.

Yeah, I would not say return to normal service.

To clarify about 4.1v, IMO, to use an ebike in the real world, replacing your car, not a retired guy with lots of time, you have to charge the night before. But we do know for a fact it is the time at higher charge that matters. Does charging to a lower voltage help if you must store charged? We hope so.

So that time overnight, stored at 4.1v may be less stressful than the same time stored at 4.2v. Better still, charge to 3.9v overnight, but that might mean carrying even more battery, or getting up earlier to top up.

FWIW, what I do when I want to ride in the early morning, is charge to 4.1v the evening before, then in the am charge to 4.15 before I take off. The 4.15 instead of 4.2 is because I want headroom for bulk charging with no bms. It's not aimed to undercharge for life cylces, I just want my highest charged cell in this bulk pack to not be much over 4.25 or so. If I have no plans to ride soon, I store my packs at whatever voltage they ended up at. Usually 3.5-3.9v, depending on the ride I took.

I'll let you all know in about a year and a half how this works compared to charging 4.2v and storing it there all the time, as I used to do. That was no good, packs went bad in 2 years. However, some of that stuff is still not puffy, just low capacity and saggy, and can be used if I must.

dogman dan said:

So that time overnight, stored at 4.1v may be less stressful than the same time stored at 4.2v.

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Very much so. Unless I'm very much mistaken the effect is also non-linear.

your "stress test" is totally meaningless. that was my point, that you guys were making up stuff about how this charging to 4.6V was making the pouch into a bomb.

but those lectures you guys refuse to vew made it clear to those of us who listened to them that the problem is caused by the electrolyte reacting with the carbon of the anode at the high voltages. that is well known. he discussed how they had determined that the previous claims about cycle life could be shown to correlate with the length of time the electrolyte is exposed to this voltage.

he says it plain as day and then creates the 1-coulombic efficiency graphs to show the correlation to the useless and outdated 20-80% charging presumptions from old ideas promulgated by legacy papers from places like battery university.

so reducing the voltage to low levels dramatically reduces the rates of these reactions but they are linear and the longer the cell is at higher voltages then these reactions continue.

what is different is the temperature at which the heating caused by the exothermal reaction of the electrolyte with the carbon as the SEI layer cracks off and begins the process of self heating as more of the SEI breaks off and continues the cell into thermal runaway.

if the cell is not being heated and the voltage is reduced to terminate these reactions then there is no risk of the cell exploding or going into thermal runaway imo. so the best course of action for him was just as i said, to discharge it to low voltage and keep in compression along with all of the other lipo pouches because they have to be kept in orthogonal compression to maintain long cycle life and compression is more important in cycle life than the charging voltage too.

Stop confusing the issue by crowbarring in your opinions about the effect of charge voltage on cycle life. This isn't a discussion about cycle life, it's about determining whether an over-charged battery is safe to use.

dnmun said:

your "stress test" is totally meaningless

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wb9k said:

100% SOC is the best place to assess cell health.

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You've mentioned SEI layer break-down, we know some degree of electrolyte decomposition will have occurred at 4.6V. These could have begun a continuing process of deterioration through mechanical damage or contamination of the cell.

Considering the sketchy quality of RC LiCo cells and that they are somewhat risky even when treated properly, I do not see how you can assert that following a significant over-charge "there is no risk of the cell exploding or going into thermal runaway imo" and that the OP should not even bother with a full charge to asses the condition of the cells.

I can certainly see how lowering the voltage immediately was the right thing to do. More time at 4.6v bound to be bad.

But I wouldn't bring the things in the house again myself. I'd keep em outside, and use them in my mower. I wouldn't want them to do anything, not even just puffing all up at the office, or in my house.

Same goes for cells with other kinds of damage, like a big ding in a corner from dropping it, or cells that have puffed more than normal.

i can say there is no risk of the pouches going to thermal runaway because there is no more charging or heating of the cell.

thermal runaway is initiated by the heating of the SEI on the anode which causes the SEI to flake off and expose more bare carbon to the electrolyte which causes the reaction of the electrolyte with the carbon to release even more heat and cause the exothermic reaction to be promoted and with no way to draw the heat energy out of the cell then it continues to go into thermal runaway.

you can see that in the calorimetry data in that lecture by the guy from Netzsch where he is demonstrating their calorimeters:

//www.youtube.com/watch?v=iieB3ePZGdQ&feature=youtu.be

thermal runaway begins at a specific temperature in the adiabatic system they are heating the cells in. you can compare lipo and lifepo4 very easily from the data he presents.

if the cell voltage is reduced and the cell cools then by definition there will not be thermal runaway, whether it is stored in a metal box or a cardboard box makes no difference.

dogman dan said:

I can certainly see how lowering the voltage immediately was the right thing to do. More time at 4.6v bound to be bad.

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Absolutely.

I believe that just because the cells were safely discharged without thermal runaway occurring, does not imply that no damage has occurred and they are safe to use. I am only advising caution and what I see as common-sense. If the cells prove not to be able to handle normal conditions (a week at 4.2V) then they were only fit for the bin anyway. Others may advise that this is too optimistic and they should be discarded as a matter of course.

My concern is that following what Dnmun *appears* to be recommending involves strapping them up tight and potentially burying them into a pack, where puffing might go unnoticed until the pouch bursts and a possible fire ensues.