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heated jacket power bank

Discussion in 'Power Electronics' started by R791945, Nov 23, 2018.

  1. R791945

    R791945

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    Jun 19, 2015
    I am proposing to buy a power bank to power a heated jacket. I would just like to check if this is a good choice:

    https://rover.ebay.com/rover/1/710-...www.ebay.co.uk/itm/142894134069?ul_noapp=true

    Shell material: Plastic
    USB port quantity: 2
    USB input: DC 5V 1A
    USB output: DC 5V 1A/ 2A
    Battery: Polymer Batteries (Not Included)

    The heating elements in the jacket draw in total 8w, 5v ie 1.6A. I assume that the 2A USB output will therefore be acceptable to power the jacket.

    I have a number of spare 18650 batteries. Would it be reasonable to assume that size will fit in the power bank?

    Although it does not state the number of batteries needed I guess it is 4.
     
  2. Audioguru

    Audioguru

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    Sep 24, 2016
    50,000mAh needs seventeen 18650 cells that certainly will not fit in it. A "polymer" (Li-PO) battery is usually flat but an 18650 Li-Ion battery is a cylinder.

    Will you buy this cheap kit without having any important details about which battery cells and how many?
     
  3. 73's de Edd

    73's de Edd

    2,442
    818
    Aug 21, 2015
    As a further supplement to Uncle Scr o.o.o.o.o.o.o ges sage advice . . . .AND if you do get it all packed up . . .we gonna be callin' you . . ." the hunchback of Notre Dame".

    And of course we will be there with the further answer, to your forthcoming query, as to WHY it is taking thutty tew days, 'fo hours, nine minnits and 'lebenteen seconds to charge up from that punky USB charge source.
    CONSIDERING . . . . that it doesn't experience a total meltdown.
     
    Last edited: Nov 24, 2018
  4. R791945

    R791945

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    Jun 19, 2015
    Thank you both for your reply. It is a good thing I asked your advice.

    My previous jackets only had packs of 4 batteries and so I had better stay with that number otherwise the packs will get too heavy, as you suggest.

    I have been advised to get a MT3608 DC-DC step-up converters and convert Li-ion's 2.5-4.2V to 5V as the the new heater elements run off USB2.

    To charge the batteries I propose a www.aliexpress.com/item/TZT-TP5100-double-single-lithium-battery-charge-management-compatible-2A-rechargeable-lithium-plate/32870421460.html?
    How many will I need for 4 batteries?

    How would you suggest I package the batteries, MT3608 and TZT_CP5100 charger board (s) to use for everyday heating and charging of the jacket?

    Robin
     
  5. R791945

    R791945

    61
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    Jun 19, 2015

    I would appreciate a reply


    I have been advised to get a MT3608 DC-DC step-up converters and convert Li-po's 2.5-4.2V to 5V as the the new heater elements run off USB2.

    To charge the batteries I propose a www.aliexpress.com/item/TZT-TP5100-double-single-lithium-battery-charge-management-compatible-2A-rechargeable-lithium-plate/32870421460.html?
    How many will I need for 4 batteries?

    How would you suggest I package the batteries, MT3608 and TZT_CP5100 charger board (s) to use for everyday heating and charging of the jacket?
     
  6. Audioguru

    Audioguru

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    Sep 24, 2016
    Did you forget to calculate how many seconds the four 18650 Li-Ion cells can power the boost converter that heats the jacket?

    Have you ever tried a heated jacket that uses only 8W?
     
  7. R791945

    R791945

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    Jun 19, 2015
    Did you forget to calculate how many seconds the four 18650 Li-Ion cells can power the boost converter that heats the jacket?

    I wrongly described the batteries and corrected my last post so as to show that the batteries were Li-po not Li-ion.
    Is my guess below a reasonable estimate of available heating time?

    4 batteries in parallel produce 4*[email protected]
    MT63608 is up to 93% efficiency per attached data sheet

    Heater elements draw 1.6A at 5v using 8w
    4 Bats 8.8A @ 3.7v
    assuming 100% efficiency 8.8A @5v = 5.5Ah 8 Watts Say 4 hours

    Have you ever tried a heated jacket that uses only 8W?
    My previous jacket used 4400mAh @7.4v
    The heater elements I have bought that run on 8W 5V had users commenting that it produced sufficient heat. The 3 heating elements are designed to be sewn into a jacket and then plugged into a battery pack with USB2 output. I am hoping that the heating elements do produce sufficient heat. Practically I have to set up a battery pack, hence my question about how to do that physically ie what (small) box to buy that will give both the batteries and the converter sufficient room.
     

    Attached Files:

  8. Audioguru

    Audioguru

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    Sep 24, 2016
    I do not know if the Li-PO batteries are name-brand or cheap fakes, new, old or used. They each might be able to produce 2.2A for 1 hour. 4 in parallel might be able to produce 8.8A for 1 hour.

    The datasheet for the MT3608 shows 93% efficiency when the current is low but about 85% at 1.6A output.
    The conversion of 3.7V to 5V is 35% plus the 15% for the converter =50%. Then the batteries must provide 1.6A x 2= 3.2A. 8.8A/3.2A is 2.75 hours.
     
  9. Audioguru

    Audioguru

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    Sep 24, 2016
    I watched a video on You Tube of tests of the cheap Chinese MT3608 module that looks like the AliExpress one. He bought 20 of them and 2 caught on fire and the remaining 18 did not work. I am glad that I did not tell you to put the module and batteries in your pocket for some extra warmth.
     
  10. R791945

    R791945

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    Jun 19, 2015
    The diy approach is getting very risky, especially with the risk relating to MT3608 mentioned by Audioguru. I need to sort out the battery otherwise I could end up having a freezing time over winter!

    I am therefore reconsidering a power bank, but as I have been warned here not to dash in and buy please allow me to use your experience on what should be ok.

    I think what I have learned from our discussions is that provided I buy a decent make and the power bank has the correct outputs and inputs for a usb 2 port ie 5v 2A (for a 1.6A draw) it should be compatible with my heater elements. It is then a matter of just considering the weight and the capacity as I do not mind it taking all night to recharge.

    Have I understood you correctly?
     
  11. Audioguru

    Audioguru

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    Sep 24, 2016
    You did not consider the mAh rating of how long a battery can produce the 1.6A. A tiny lithium battery in a toy drone can supply 1.6A, but for maybe only a few minutes. It might be rated at 200mAh. A battery rated at 2Ah should produce 2A for 1 hour. The battery voltage boosting to 5V also uses some of the mAh so you need more.
     
  12. R791945

    R791945

    61
    0
    Jun 19, 2015
    I feel very relieved that I now have sufficient grasp of the problem of supplying power to the heater elements that I can proceed to buy a battery pack that will not be inappropriate from the start. Thank you for your care and help. Robin
     
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