Several people have asked several times how hot this wire will get. We haven't seen hard evidence that it gets too hot (an "actual problem") and we can't expect engineering answers from customer liaison. Still it's a bit worrying that Lily-YOSEPOWER's response has been the opposite of what you'd hope for.

 

Presumably Teflon has been used to save space or because this wire does get hot, and indeed the photos make the gauge look around half as thick as the black BMS connection (making several times the heat). But if it gets hot you'd want to re-route it or run multiple strands to keep the temperature down, especially as the photo shows it running against the cells and YP say (2) their tape isn't for protection.

 

What we least want to hear is about how the insulation withstands 260℃ and the wire's thought to be good for 48A (probably rated at around 70℃ to 130℃), because the cells have an operating range up to about 45℃ and once breakdown begins from around 60℃ it can soon turn exothermic.

 

Regardless of any confirmed problem or not, with a battery this size if things look questionable it makes sense to point them out, and it's good that YP are here now to respond.

PTFE coated wire is used because its the safest. It's often used when wires are in the vicinity of heat, where pvc might melt. Battery cells can get quite hot when there are a lot together and they're delivering a lot of current continuously. You deal with heat that's produced in the wire by choosing the size of the copper. The amount of heat produced depends on the length of the wire and the size of the copper, so a short wire can be a lower grade or size than a long one.

I met Helen and Scott in 2013 at Redbridge.

 

And I met Russell Scott in 2007 at an e-bike event in the New Forest.

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Hi Lily

Nice to have you here. I hope you will stay.

Well said.

PTFE coated wire is used because its the safest. It's often used when wires are in the vicinity of heat, where pvc might melt. Battery cells can get quite hot when there are a lot together and they're delivering a lot of current continuously. You deal with heat that's produced in the wire by choosing the size of the copper. The amount of heat produced depends on the length of the wire and the size of the copper, so a short wire can be a lower grade or size than a long one.

That's the case for total heat in the enclosure. Where a wire crosses 'quite hot' cells you need to avoid creating a hot-spot so it's the power per unit length that matters.

 

Again, users can't know if there's any actual problem but with a safety-related item it's right to ask the question. Unfortunately YP's explanation (part 4 including the role of the fuse) seems the most questionable bit as it suggests they designed to cater for high temperature rather than to prevent it.

Edited May 6, 20241 yr by AntonyC

Unfortunately YP's explanation (part 4 including the role of the fuse) seems the most questionable bit as it suggests they designed to cater for high temperature rather than to prevent it.

It's nothing to do with temperature. The fuse isn't an important point of safety because over-current is handled by the BMS, not the fuse. They've added the fuse as an additional safety measure in case the BMS fails. The fuse therefore needs to blow at a higher current than the BMS. It all looks pretty sound to me.

YP claim that the wire can take the heat and the fuse will keep it in spec, saying the fuse would rupture at its continuous rating. As you say that's not what the fuse is for but it further suggests their concern is with protecting the wire from over-temperature rather than the cells.

 

In a way it's unfair on YP to have their design details questioned with only looks to go on, then again their response hasn't helped, and any manufacturer must expect safety related goods to get a critical eye. So the question's still open.

YP claim that the wire can take the heat and the fuse will keep it in spec, saying the fuse would rupture at its continuous rating. As you say that's not what the fuse is for but it further suggests their concern is with protecting the wire from over-temperature rather than the cells.

 

In a way it's unfair on YP to have their design details questioned with only looks to go on, then again their response hasn't helped, and any manufacturer must expect safety related goods to get a critical eye. So the question's still open.

Thank you very much for your continued attention to this issue. Your viewpoints have been immensely helpful for the upgrade of this product. We have conveyed your feedback to our professional engineers, and we will be upgrading the product, including adding temperature control to the BMS like our other batteries and providing an additional layer of insulation protection for this wire.

Hi Lily

 

Nice to have you here. I hope you will stay.

 

For a long time I have been recommending Yose Power for beginners who want to convert first bike. I am using one of your kits myself and think it offers great value for money.

Having that said in my opinion Yose has very little to offer for more advanced enthusiasts like most of people on this forum. Is there a chance you might expand your offer? There is a big gap on the UK market at this moment. By expanding offer I mean more motors from manufacturers like Bafang, Tongsheng, Toseven etc, spare parts, kits with KT controllers and last but not least batteries with better cells.

 

Kind regards

 

Unverified Az

Thank you for your support and suggestions for Yosepower. We are still continuously working on improving the quality of our existing products, and at the same time, we are developing new products. The variety of products will also continue to increase. Let's look forward to it together.

Kudos firstly to WheezyRider for having a sharp eye for a potential problem and thank you Yosepower for reviewing your design, to do so within days is all the more impressive.