help needed_ Specific safety aspects in battery pack

Batteries, Chargers, and Battery Management Systems.
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pratikdas87   10 mW

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help needed_ Specific safety aspects in battery pack

Post by pratikdas87 » Jun 15 2017 1:50am

hey guys, i recently joined the group. I am making my own battery pack. i have some specific questions regarding safety aspects.

1. are there any precautions/guidelines with respect to designing 18650 packs such as certain materials to avoid etc. particularly from safety point of view.
2. If there are people here who are making packs for EVs (e-bikes etc), what do you do for reducing vibrations and for reducing chances of mechanical damage to cells. for both top and bottom of the battery, we are considering foam pads or rubber pads and because the foam is flammable, we are considering separating it from the pack by a plastic layer.
3. If you use small fuse wire (without the glass fuse) and place the battery upside down, can the weight of the battery cause any stress on the fuse wire/solder joints and it's performance? If yes, any recommendations.
4. Do you guys wrap your packs in heat shrink/plastic casing and if you do, does it hamper the natural air cooling. is that not an issue?

With kind regards,
Pratik

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amberwolf   100 GW

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Re: help needed_ Specific safety aspects in battery pack

Post by amberwolf » Jun 15 2017 1:58am

pratikdas87 wrote: for both top and bottom of the battery, we are considering foam pads or rubber pads and because the foam is flammable, we are considering separating it from the pack by a plastic layer.
Plastic is flammable, too.

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spinningmagnets   100 GW

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Re: help needed_ Specific safety aspects in battery pack

Post by spinningmagnets » Jun 15 2017 2:31am

Here's the index of battery thread stickeys
https://endless-sphere.com/forums/viewt ... 14&t=69683

"Common pack design mistakes, and how to avoid"
https://endless-sphere.com/forums/viewtopic.php?t=84412

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dogman dan   100 GW

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Re: help needed_ Specific safety aspects in battery pack

Post by dogman dan » Jun 15 2017 5:46am

Re air cooling the pack. If it needs it, you screwed up already. If your pack is getting all hot, it's being run too hard. Ignore specs, and run it half spec discharge rates for the best results.

Ideally, your cells only get warm, and then the insulation won't hurt the pack. By warm, I mean ambient temp in hell, like Phoenix Arizona, which is around 110F today I think, sometimes 120F. So if you can't touch it, if it starts to melt your shrink, its getting too hot.

DO NOT insulate around the bms though.

Flamable plastic, like shrink, or foam shock padding, won't matter one tiny bit if you do have a battery fire. Yes it will add to the fire, but its about like tossing a match into a camp fire. No added effect, the fire is already a BIG one.

A stout metal box with a large vent, or blow out panel, can help buy you time to get the bike outside, or get off it safely. You can't contain that fire, but you can point the hot gasses in a safer direction, like down to the ground.

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