Li-ion cells and cold temperatures – Part 2

26F Cold tests 2 Descr

Please click on the image to enlarge it.

After the first cold tests I decided to go a step further and do some tests with even colder temperatures to see the behavior of the cells.

For the Orange tests the cell was padded this way:

IMAG0765

Side view with padding on the sides removed:

IMAG0764

These tests are interesting for people like me that uses lithium ion cells in cold climates. Especially in my case, I use the cells in an electric bicycle. It’s important to have some sort of thermal insulation on the battery when riding in cold temperatures, the performance improves dramatically and the battery cycle life is preserved.

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9 thoughts on “Li-ion cells and cold temperatures – Part 2

  1. According to datasheet
    http://www.tme.eu/en/Document/40f2659afab69dbec94c09cc473a0e25/ICR18650-26F.pdf
    Chapter 7.4: at -10C temperature you are good to expect 50% of initial capacity, so your results are pretty good.
    Unfortunatelly specification for this battery doesn’t say what discharge rate is applicable for different temperature ranges. For instance for my LG D1 batteries vendor specifies following rates:
    -20…+5C – 0,5C
    +5…+45C – 2C
    +45…+65C – 1,5C
    So, I think similair rules should be applied for Samsung batteries as well.

    • Hi Andriy, I wanted some more “realistic” data because what the datasheet provides is very limited and the tests are conducted at 0.2C at -10°C. My typical use on the electric bicycle will be 0.5-0.8C continuous so 1C is more realistic to me. I expected much worse results to be honest. The datasheet appears to be a bit “conservative”. LG D1 cells, should’t they be charged at 4.35v to reach full capacity? One of the reason I choose the 26F is that they reach full capacity at 4.2v and they have 2600mAh which is fairly decent. they are cheap as well compared to other 18650 cells on the market.

      • Hi gianrodi,
        Well, you are right, LG D1 should be charged to 4.35V to get full capacity, however I think it’s a advantage rather than disadvantage. Its working range is higher (4.35-3V) than other’s 4.2V cells(4.2-2.75), so you need less cells to get your voltage. For instance, it’s enough to have only 13S D1 cells, with ending total voltage about 40V, however for other 4.2V cells in case of 13S ending voltage will be around 36V, so you need to make 14S config in order to fit into typical 48V voltage range. In addition, D1 batteries are about 10% more expensive than 26F, providing about 0,3-0,4 Ah (10-15%) more capacity.
        Of course, if your charging your cells with RC chargers it’s a problem, however if you have bulk 48V charger with adjustable upper voltage – it’s not a problem at all.
        However, that was not my mesage. Just tried to say that if you care your cells you would not discharge them under non-recommended conditions. Personally, I never ride my bike when there are less than 5C, however if it would be necessary I would try to not discharge at more than 1C. Btw, it’s not very comfortable to ride a bike at lower temperature – care you health 🙂

      • Hi Andriy, I know what you mean about the LG D1, but still it’s not a good idea to bulk charge without any sort of control/balance on the HVC. If the pack is new there is no problem, but as it gets used it can be dangerous and lead to pack depletion too soon. There are ways to balance at 4.35v and make a bms that works with those voltages but are not commercially available (I made an adjustable cell balancer myself for example). The prices I found for the LG D1 are 35-40% more expensive than the 26F..the D1 might be a better cell as well but it’s too hard in my case to extract all the capacity.Where are you from? If you have the LG D1 I can look into ways of making a cell balancer/bms as an experiment..I see there is some interest in those cells.

        Back on topic my weather conditions can be strange, here the temperature can drop or increase a few degrees during the day, for example it can be -5C in the morning and +5C in the evening when I come back from work or the opposite. We are lucky there are beautiful bike paths in this city where I can ride safely to work. I normally don’t ride at temperatures below -5C.

  2. Hi,
    LG D1 can be purchased here http://www.aliexpress.com/item/18650-3-7v-li-ion-LG-ICR18650-D1-3000mah-rechargeable-battery/754841987.html for just 3.92$ piece (buying 100pc at once).
    I’m from Ukraine, however I’ve purchased my cells from Russia, their market is quite loaded with these cells so I could buy any quantity I need. My config is 13S4P. Lot of people are using these cells due to thier low cost and high capacity. Another downsite of these cells is quite high internal impendance, but it is lower than 26F has 🙂
    Of course, your are right, balancer is quite necessary in case of bulk charging, and it’s not a problem actually. There are plenty BMS supporting this voltage, I’m using for instance this one http://www.bmsbattery.com/smart/330-lifepo4lithium-ion-smart-bms-for-513-cells-in-series.html. It is programmable, so I can set almost any levels for my batteries.
    Btw, I run few cycles just with these cells (about 4-5) without any BMS and voltage difference is not that dramatic (about 30mV max), so it’s really possible to use these cells without any bms in case they are not absolutely discharged and fully charged.

    I live in similair weather conditions 🙂

    • Hi Andriy,

      I hope you are safe where you are. I have to manually authorize every comment in the blog a I had problems with spam in the past, sorry I missed your last reply.
      I have a supplier that sells me the 26F cells at $2.00 a piece and $2.80 the D1. For me it was just easier to go with the 26F, maybe I will try out the D1 in the future for other projects. Other than the bms you quoted here, do you have any other link to bms for the D1 cells? I have friends that might be interested. The smart bms is limited to 13 series…I would be interested in something like 20-24S…

      • Hi,
        Yes, I’m in safe, I’m leaving near Romania border. But that is disaster in Crimea.
        Speaking of BMS:
        http://bestekpower.com/74v20spcmbmspcbforli-ionli-polymerbatterypack/
        There are plenty of available BMS, just browse site. Unfortunatelly I don’t know their prices, but usualy larger than 20S goes beyond 100$.
        Btw, that SmartBMS from my previous post accepts cascading, so with 2 such BMS you can make up to 24S almost easily.
        Regarding batteries price. That price is awesome. I have contacted some supplier from China with similair price but shipping from them costs abother almost 1,5$ to cell cost so it’s almost useless to order batteries from their location. How much do you pay for shipping from your supplier?

      • Hi Andriy,

        I am glad to hear you are safe. Thank you for your BMS links. I ordered from China, and paid about $1 per cell for shipping. This was the best price I could find for any cell, probably with large orders the shipping cost per cell will decrease.

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