Molicel P26A - Rejects

Darren2018

100 W
Joined
Aug 18, 2018
Messages
223
I have 215 Molicel P26A. All of them have very slight dents on the bottom of the can. I have tested all of them for self discharge and also capacity tested around 30 random samples. They all drift inconsistently from each other but anything more than 10mV over 1 month I removed. The capacity of the ones I tested were all right around 2600mAh. No other testing has been done. I won't use these myself as they require too much work to sort into groups and I don't personally believe in having to rely on a BMS.

£350
IMG_0062.jpegIMG_0063.jpegIMG_0064.jpegIMG_0065.jpeg

I also have 74 Sony VTC5 which were removed from new battery packs. Some of these had sat at 2V for a few months but from my testing seem unaffected. These are consistent with one another but I won't use them. I have another 28 which I will include that have not been removed from the packs.

£90

IMG_0066.jpegIMG_0067.jpeg
 
Darren2018 said:
I have 215 Molicel P26A. All of them have very slight dents on the bottom of the can. I have tested all of them for self discharge and also capacity tested around 30 random samples. They all drift inconsistently from each other but anything more than 10mV over 1 month I removed. The capacity of the ones I tested were all right around 2600mAh. No other testing has been done. I won't use these myself as they require too much work to sort into groups and I don't personally believe in having to rely on a BMS.

£350
IMG_0062.jpegIMG_0063.jpegIMG_0064.jpegIMG_0065.jpeg

I also have 74 Sony VTC5 which were removed from new battery packs. Some of these had sat at 2V for a few months but from my testing seem unaffected. These are consistent with one another but I won't use them. I have another 28 which I will include that have not been removed from the packs.

£90

IMG_0066.jpegIMG_0067.jpeg

What’s the story behind the molicels? Been used in a no-weld pack? Must be a reason for all the dents, right?
 
larsb said:
Darren2018 said:
I have 215 Molicel P26A. All of them have very slight dents on the bottom of the can. I have tested all of them for self discharge and also capacity tested around 30 random samples. They all drift inconsistently from each other but anything more than 10mV over 1 month I removed. The capacity of the ones I tested were all right around 2600mAh. No other testing has been done. I won't use these myself as they require too much work to sort into groups and I don't personally believe in having to rely on a BMS.

£350
IMG_0062.jpegIMG_0063.jpegIMG_0064.jpegIMG_0065.jpeg

I also have 74 Sony VTC5 which were removed from new battery packs. Some of these had sat at 2V for a few months but from my testing seem unaffected. These are consistent with one another but I won't use them. I have another 28 which I will include that have not been removed from the packs.

£90

IMG_0066.jpegIMG_0067.jpeg

What’s the story behind the molicels? Been used in a no-weld pack? Must be a reason for all the dents, right?

I think they were customer returns. They have inconsistent drift but there are none which are too bad. If you don't mind sorting them into groups and using a BMS which can monitor and balance without charging they will probably be fine. The Sony cells are completely fine and require no balancing.

There might be nothing wrong with the Molicel cells but I have never used them before so I can't say if this is just a general trait for them or not. I personally do not like having to use a BMS as I believe that this is a protection device not a maintenance device. I have used Sony VTC6 in the past which showed a similar problem but where fine when put into groups. I have noticed that the lower the IR the higher the probability there is of seeing inconsistent drift which could be in some part due to the interconnects resistance when balancing them against the others in the group (which is often 100+). I do leave them connected for more than 24 hours and I do check they are all the same voltage when they are disconnected but from my experience that doesn't always mean they have exactly the same state of charge. I am not saying this is the reason why these Molicel drift I am just saying that I have seen this before and there are reasons why this can sometimes happen.
 
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