Yose Power Triangle Battery Recall

[Voltsnamps]

An innocent bystander’s viewpoint

No dog in this fight at all, but I can see Lily has won.
Local village id called her out, perhaps inadvertently or mistakenly.
Lilly took him outside and corrected him, cool.

 

[saneagle]

No dog in this fight at all.

Are you sure? Maybe a badger then!

 

[Voltsnamps]

Are you sure? Maybe a badger then!

Don’t even think of the elephant in the room !

 

[matthewslack]

Sorry to have ruffled feathers, not my intention, I just like to understand things from first principles. If my concern is unfounded, happy to have that explained.

The answers I would want to find are (1) at continuous 50A i.e just not quite blowing the fuse, how hot does the 2.5mm2 cable get, in its installed position within the battery; (2) is that temperature level a concern given its proximity to the lithium ion cells?

I do understand that the majority of ebikes, and all 250W rated legal pedelec motors are never going to draw anything like 50A, and so will not have a problem. But big 21Ah, 50A capable batteries will get used by some people to their maximum capabilities, and that is where the problem lies.

I would be either reducing the fuse rating or increasing the cable size to achieve a cable significantly more capable than the fuse rating, adding to safety at very low cost.

 

[cyclebuddy]

I would be either reducing the fuse rating or increasing the cable size to achieve a cable significantly more capable than the fuse rating,

That's conventional electricians logic...

A standard UK ring main today is wired with 16A 2.5mm copper PVC insulated, fused at 32A.
In the 1960's/70's there was a period where the UK wired that same circuit with 1.5mm copper MINERAL insulation and still fused at 32A. In other words, a 1.5mm gauge is rated the same as 2.5mm to carry the same current and that's only down to the change in insulation (yes, that is in BS7671!).

I don't know how Teflon/PTFE insulation behaves/allows higher current other than YOSE's comments here as a result of their own design testing, but the point is is that you can't make assumptions on current carrying capability based purely on wire gauge; the insulation has a big part to play.

A 13A BS1363 British plug fuse typically doesn't blow until 26A. A fast blow equivalent blows in milliseconds at the rated current.

I'm no expert, but YOSE's logic does seem to make sense even if it defies the usual "thick wire, smaller fuse" thinking.

 

[jamesporritt]

Technical Description：Teflon wire is a kind of wire made of polytetrafluoroethylene (PTFE), which is widely used in various fields because of its excellent high temperature resistance, corrosion resistance and insulation properties. Heat resistant temperature. Teflon wires can withstand temperatures ranging from -180 ° C to +260 ° C；The maximum carrying capacity of the 2.5mm² Teflon line reaches 48A；And it can withstand 50A power for some time, so we are equipped with a 50A fuse. When the current reaches 50A, the fuse will disconnect the protection circuit. This is a technology fully recognized by our engineers and engineers from testing and certification agencies.

How hot does this thin wire become in use?

 

[saneagle]

How hot does this thin wire become in use?

Power lost in the wire is current squared times the resistance. The resistance is 6.88 mOhms per meter.

 

[Sturmey]

........ you can't make assumptions on current carrying capability based purely on wire gauge; the insulation has a big part to play.

I agree with you here. A conductor with a high temperature rated insulation can run hotter and will be capable of shedding more heat as this ability is proportional to the difference between the conductor/wire temperature and the ambient temperature.

PS Sometimes cables/conductors are made bigger for a different reason. e.g. on long runs to prevent voltage drop .

 

[jamesporritt]

I agree with you here. A conductor with a high temperature rated insulation can run hotter and will be capable of shedding more heat as this ability is proportional to the difference between the conductor/wire temperature and the ambient temperature.

PS Sometimes cables/conductors are made bigger for a different reason. e.g. on long runs to prevent voltage drop .

Where does shed heat go?

 

[saneagle]

Where does shed heat go?

Mainly through the roof into the sky to contribute towards global warming. A lesser amount goes through the walls into the garden. Unfortunately, it's the wrong frequency to make the flowers grow, so it too ends up in the sky.

Global warming is why our weather is getting colder, so it's important to keep the heat in your shed by good insulation, and also by not have the temperature too high, and don't forget to keep the door closed.