Is my fear of Sanyo* rational?

M

MillennialFalcon

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Greetingseveryone.

I've seen some mixed opinions and advice on these cells. Everyone seems to agree that they have a tendency to run hot. My questions:
Do you handle these Sonya cells with any additional care?

Do you have any additionalcriteria that you factor into accepting/rejecting the cell?

Would you leave the house while these are running a capacity test?

Would you limit these cells to only particular applications due to the tendency to run hot?

Thanks all.

https://www.youtube.com/channel/UCbkA0vGuNC0y9AUI-eGbmXA?view_as=subscriber
 
Yeah, Sonya is pretty difficult to handle, that's why I like Lisa much more! :p

Do you handle these Sonya cells with any additional care?
-> No, they are treated like any other cell

Do you have any additional criteria that you factor into accepting/rejecting the cell?
-> Addtional because they are made by Sanyo? No, again, they are treated like any other cell

Would you leave the house while these are running a capacity test?
-> Not without a known working thermal shutdown and especially not if this test involves charging, but that is true for any cell

Would you limit these cells to only particular applications due to the tendency to run hot?
-> No

These answers probably don't mean anything though. You have to understand why they get hot sometimes. And how to make them stop getting hot. And how hot is too hot for a 18650. They don't just have a tendency, there is a reason why they have this tendency. And as with any problem, once you know the source you can try to get rid of it.
I generally don't put in the effort because I have enough other cells. But at the moment I have some hot Sanyo cells and I know they are as good as new so I might put in the effort this time to safe the cells. You have to cycle these cells and some/many/all will stop to get hot at some point. This takes a considerable amount of time though, that's why I usually don't bother.
 
Sonya? What are Sonya cells? I only know of Sanyo cells. :p
 
Korishan said:
Sonya? What are Sonya cells? I only know of Sanyo cells. :p
Click to expand...

Well, this is embarrassing...

DarkRaven said:
Yeah, Sonya is pretty difficult to handle, that's why I like Lisa much more! :p

Do you handle these Sonya cells with any additional care?
-> No, they are treated like any other cell

Do you have any additional criteria that you factor into accepting/rejecting the cell?
-> Addtional because they are made by Sanyo? No, again, they are treated like any other cell

Would you leave the house while these are running a capacity test?
-> Not without a known working thermal shutdown and especially not if this test involves charging, but that is true for any cell

Would you limit these cells to only particular applications due to the tendency to run hot?
-> No

These answers probably don't mean anything though. You have to understand why they get hot sometimes. And how to make them stop getting hot. And how hot is too hot for a 18650. They don't just have a tendency, there is a reason why they have this tendency. And as with any problem, once you know the source you can try to get rid of it.
I generally don't put in the effort because I have enough other cells. But at the moment I have some hot Sanyo cells and I know they are as good as new so I might put in the effort this time to safe the cells. You have to cycle these cells and some/many/all will stop to get hot at some point. This takes a considerable amount of time though, that's why I usually don't bother.
Click to expand...

Thanks for the advice. It brings a lot of clarityto the issue. I wonder whats different in the manufacturing process that leads to higher than average tendency to heat up.

After I run all of my current inventory of cells I'll upload the data into R and do some regression to see what the actual statistically likelihoodfor heaters to manufacturer.
 
You can get a lot more info on the Sanyo's if you do a search for "Heaters" in the thread title. There are several where these are talked about.

Basically, chemically, what happens when the sit for long periods of time is a type of oxidation layer, or some other layer, occurs between two layers. The heating is this layer being reabsorbed back into the electrolyte. Each time you charge the cell, the heat will get lower, until it doesn't heat anymore. Sometimes it only takes 1 recharge, sometimes as many as 4.
But, as DarkRaven mentioned, don't leave them unattended unless there is a thermal shut off.

The consensus is to pull them off the charger if they reach about 60C. At this temp you can't place your hand on them for any length of time and they will start to give off a smell. Some pull them when they get to 50C. But you don't want to let them continue on up past 60C, though. I did have one cell where it went from 40-ish C and in a matter of about 5-10minutes went to 80C. I immediately pulled the power to the charger first, then I proceeded to pull the cell out of the holder.
So, when you have a Sanyo, and it starts to get warm, start monitoring it closely.
Also to note, the heating doesn't occur until the voltage of the cell gets to about 4.1V - 4.14V. It's that last little bit of pushing it to 4.2V is when the heating really begins.
 
DarkRaven said:
...

Would you leave the house while these are running a capacity test?
-> Not without a known working thermal shutdown and especially not if this test involves charging, but that is true for any cell

Would you limit these cells to only particular applications due to the tendency to run hot?
-> No

...
Click to expand...

Indeed I agree, all untested secondhand cells should be treated with care until they are known to be safe. Cells can get hot for a variety of reasons. Sanyo have a reputation for it. But there have been cells of all makes and modals found to be 'heaters'. That is why most Li-Ion battery packs are fitted with thermal sensors.

Definitely, I would not leave any battery of any chemistry charging unattended. Unless it was not in my house. This is why people build battery sheds. Even for lead acid batteries, which are considered significantly safer.

Even after pack construction, it would be worth checking every once in a while for cells getting hot.A lot of users only run to 4.1v full charge. This drastically reduces the chance of cells getting hot, and also increases their lifespan.

There are plenty of good Sanyo cells out there. I have a good number myself, I would use them and treat them just like any other cell.
 
Certain Sanyo's seem to be much more problematic than others.

The ones with a purple insulator ring have the worst record.

The heater issue is part of the reason why I invested in the SkyRC MC3K as it has a rock solid thermal management system and cut-off per cell.

My rule if it heats I let it sit for a few days try again. If it heats a second time I discharge completely and recycle.

The test I do is:
- Charge to 4.20V @ 1A CC then CV down to 50 mA
- rest 20 minutes
- Discharge down to 2.80V @ 1A CC
- rest 20 minutes
- Charge to 4.20V @ 1A CC then CV down to 50 mA

The SkyRC can adjust all of these parameters, well worth the extra cash for my purpose.
 
Detritalgeo said:
Certain Sanyo's seem to be much more problematic than others.

The ones with a purple insulator ring have the worst record.
Click to expand...

I've heard this before and I don't believe it. I haven't seen any statistical meaningful proof yet. There is also no explanation why these would be worse than others. From my experience (and the experiences of many others) all Sanyo cells are affected. Maybe it's limited to certain production periods, like between 2009 and 2014, since we are usually dealing with reclaimed cells and they just happen to come (as of now) from this timeframe, but this is just a theory and there is no proof for that either. Maybe we will see some proof in the future but then we also have to take into consideration that Sanyo has been taken over by Panasonic and we don't know what the effects on manufacturing are.
 
DarkRaven said:
Detritalgeo said:
Certain Sanyo's seem to be much more problematic than others.

The ones with a purple insulator ring have the worst record.
Click to expand...

I've heard this before and I don't believe it. I haven't seen any statistical meaningful proof yet. There is also no explanation why these would be worse than others. From my experience (and the experiences of many others) all Sanyo cells are affected. Maybe it's limited to certain production periods, like between 2009 and 2014, since we are usually dealing with reclaimed cells and they just happen to come (as of now) from this timeframe, but this is just a theory and there is no proof for that either. Maybe we will see some proof in the future but then we also have to take into consideration that Sanyo has been taken over by Panasonic and we don't know what the effects on manufacturing are.
Click to expand...

Interesting. I do wonder. I have many sanyo cells with a purple ring that get hot. (in fact all of them so far, which is a shame because I have hundreds of them). However I do agree with DarkRaven, this does by no means produce any meaningful statistic. Many of these cells are old, and from the same time frame.


I have had others that charge and work perfectly fine. Regardless of all the talk on this forum of 'red sanyo heaters', I do think this unjustified and bias. If a cell passes a test, it is good. If not toss it.

However the topic of 'reviving' the 'red sanyo heater' is interesting. While there is no way I would dare put them in a pack, I have found that these cells after a couple of charge cycles often stop getting hot at all. I have suggested before I would try building a pack from just these cells. When that day comes - time permitting - I shall post my findings. IR thermometer and fire extinguisher on standby :p
 
I run them like all other cells. If they stay cool enough I use them. Nothing strange there its just that I take an extra look at them when testing.
 
I have a lot of Sanyo cells and they charged and discharged without any heat whatsoever.
And i got Sanyo's that i left charging for night :D and they got hot .. i mean hot hot :D.. Now i do not leave Sanyo cells without checking them once 15 min or so.. if any heat detected while charging at 1A .. i bin them.
Usually for me the heating begins from 4V ... they just resist charging to 4.2 and so heat up.

For Discharge i leave them, because you sort the heaters in charge process.
 
EGOksy said:
I have a lot of Sanyo cells and they charged and discharged without any heat whatsoever.
And i got Sanyo's that i left charging for night :D and they got hot .. i mean hot hot :D.. Now i do not leave Sanyo cells without checking them once 15 min or so.. if any heat detected while charging at 1A .. i bin them.
Usually for me the heating begins from 4V ... they just resist charging to 4.2 and so heat up.

For Discharge i leave them, because you sort the heaters in charge process.
Click to expand...

Any cell can exhibit this behavior. Never leave any battery charge unattended! Either manual or automatic cell monitoring is essential. I have seen cells from both Panasonic, and Samsung do exactly the same thing as Sanyo.

In fact, it is probably worse to have a 'heater' from another manufacturer as it its unexpected. I also wonder how many cells get left to charge unattended and get crazy hot, and it goes unnoticed.

Treat all cells equally! There is a reason most lithium battery packs have thermal sensors built in.

edit:

Call me paranoid - I won't even leave anything charging while I'm not around. Mobile phones, laptops, car battery, whatever.
 
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