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I have purchased a 36v 10ah lithium ion battery for use with an electric bike.

I live in rural Australia where it gets very hot in summer and fairly cold in winter. I considered insulating the battery with silver tape to reduce the battery's exposure to the weather.

I then read that using the battery makes it hot and I thought insulating the battery with silver tape could do more harm than good.

Should this battery be insulated?

Thanks

EDIT

This is the datasheet for the battery's cells (no datasheet for battery)

This is the battery on AliExpress

This is the tape

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  • \$\begingroup\$ Add in a link (into your question - not the comments) to the datasheet for the battery. It will specify correct operating conditions. \$\endgroup\$
    – Transistor
    Apr 7, 2019 at 12:44
  • \$\begingroup\$ Also, tell us more about this "silver tape". It doesn't sound like an insulator to me. \$\endgroup\$
    – Elliot Alderson
    Apr 7, 2019 at 12:53
  • \$\begingroup\$ A "battery" is a generally a group of cells. The datasheet you have provided is for a single cell so I suspect that you are going to build your own battery using these cells. You will need to build in cell protection for charge and discharge too. I presume that the silver tape is to act as a reflective shield for solar radiation rather than an insulator. \$\endgroup\$
    – Transistor
    Apr 7, 2019 at 13:06
  • \$\begingroup\$ I bought the battery from AliExpress, and no datasheet was provided. The battery sits inside a PVC pipe and I want it to actually be an insulator. \$\endgroup\$
    – JasTonAChair
    Apr 7, 2019 at 13:10
  • \$\begingroup\$ Using these batteries on extreme temperatures results in a premature lifespan. You can add thermal sensors to trigger a shutdown and alarm but you don't want to be riding an e-bike with Dendrite growing conditions on no-name-brand batteries. There have been numerous major recalls for e-boards with pyrotechnic results that ought to cause one to "soil your shorts" before you short your cells. \$\endgroup\$
    – Tony Stewart EE75
    Apr 7, 2019 at 13:16

2 Answers 2

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This silver Duct tape is NOT thermally conducting. It is both thermally and electrically insulating plastic tape that looks like a conductor. It might be effective to stop air leaks.

enter image description here

The Li-Ion battery should never be operated in a thermally insulated case or in a high ambient temperature.

Always follow best practices found at Battery university and read more before making "grave errors" (pun intended)

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  • \$\begingroup\$ Thanks for the answer. Do you think putting a small fan, like the ones in desktop PCs, would help disperse the heat? \$\endgroup\$
    – JasTonAChair
    Apr 10, 2019 at 1:13
  • \$\begingroup\$ No that will just circulate it inside not transfer the heat to the outside which as you indicated is already too high like Adelaide high +50 this year., \$\endgroup\$
    – Tony Stewart EE75
    Apr 10, 2019 at 1:21
  • \$\begingroup\$ I was thinking to put the fan to blow air out, and allow holes at the front to allow air in. I guess there's no escaping the heat :| \$\endgroup\$
    – JasTonAChair
    Apr 10, 2019 at 1:33
  • \$\begingroup\$ The air coming in will be hot, but not as hot as the air inside, I thought. I might test this with a thermometer to see the effect \$\endgroup\$
    – JasTonAChair
    Apr 10, 2019 at 1:35
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    \$\begingroup\$ A few thermistors and temp gauge will help monitor if the batteries are safe. Then you can use epoxy or maybe duct tape to stick the sensor to the battery with thermal grease. Read up on temperature specs and warnings for Lithiumsecondary cells \$\endgroup\$
    – Tony Stewart EE75
    Apr 10, 2019 at 1:58
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From your comment:-

The battery sits inside a PVC pipe and I want it to actually be an insulator.

A PVC pipe is an insulator. The battery is also insulated with a PVC wrapping, so you don't need any extra insulation. Just make sure that there are no metal objects (screws etc.) inside the tube that could puncture or short out the battery.

I then read that using the battery makes it hot and I thought insulating the battery with silver tape could do more harm than good.

Yes. Any extra insulation on the battery will just make it harder to cool. To keep it cool you should arrange the PVC pipe so that air will flow through it (and around the battery) while the bike is moving.

I live in rural Australia where it gets very hot in summer and fairly cold in winter.

Li-ion battery lifespan is reduced at high temperature, especially when fully charged. Keep the battery indoors (hopefully at lower temperature) when not in use. In hot weather you should use it as soon as possible after charging, and store at half charge (38V) or less. Charging to a lower voltage (eg. 41V instead of 42V) also extends lifespan, but reduces effective capacity.

Above 60°C Li-ion batteries go into 'thermal runaway' which will cause them to explode. You should ensure that the battery (and its container) is not exposed to direct sunlight that could heat it up significantly above the ambient air temperature.

Performance is reduced at low temperature. However under heavy load the battery will warm itself up during use. Keep the battery indoors at normal room temperature before riding in cold weather.

Your battery does not appear to have any built-in BMS (Battery Management System) and the charger is a simple CVCC (constant voltage / constant current) power supply. Therefore you will have to use a multimeter to test the battery voltage. The bike controller should be set to cut out at 30V or higher to avoid over-discharging the battery. If voltage ever goes below 30V the battery will be damaged and may explode if you try to recharge it. Charge the battery in a fire-safe area with a smoke alarm, and do not leave it on charge unattended!

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  • \$\begingroup\$ Thanks for the answer. The add does say it has a BMS, and I think there is a small circuit under the PVC wrapping, but I will ask the supplier... these AliExpress listings are often lacking in detail. \$\endgroup\$
    – JasTonAChair
    Apr 10, 2019 at 1:14
  • \$\begingroup\$ Sorry I missed the part in the title that says 'BMS', however the description doesn't appear to mention it - though I could be wrong (the eBay link comes up in Spanish for me, and since I can't read Spanish...). \$\endgroup\$
    – Bruce Abbott
    Apr 10, 2019 at 7:43

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