Fuses on BMS balance wires?

[Swe]

I have not seen much information about this. I have tried to search some but not found much. Are most people building there own batterys skipping this?

Is there any good examples out here how to fuse the wires? Material and build example?

It should be dangerous if the small wires gets damage on insulation?

 

[AfdhalAtiffTan]

My battery pack recently caught on fire because of the damaged insulation of the balancing lead.

Because of that, I planned to add polyfuses on my non-dissipative active balancer project.

Be careful!

 

[Swe]

Did it just happend suddenly or was it when you were working on battery or riding?

Any example of recommended polyfuse to use? Anyone has any picture of someone using some kind of fuse on their pack?

 

[Swe]

on my non-dissipative active balancer project.

What does this mean? Tried to google dissipative but is still not sure what you mean by this on your balancer/battery? If you would try to explain for a five year old...

 

[flat tire]

Nearly nobody making DIY ebikes is fusing their balance wires. Most of us aren't even fusing the high amperage leads lol.

I recommend high quality teflon insulated wire for your balance leads. Very strong stuff.

 

[Matador]

I have shorted a balance lead on one of my BM'S once.
Guess what acted as the fuse :lol: :?

https://endless-sphere.com/forums/viewtopic.php?f=14&t=87134#p1273091

 

[fechter]

Most packs I see don't have fuses on the balance wires. If they short, the wire will burn very quickly and act like a fuse. This may or may not be OK depending on what the wire is touching. For sure it makes a lot of stinky smoke and could set your pack on fire.

PTCs are generally not used. I think because they have too much resistance and that interferes with the balancing shunts.
I have seen 2A pico fuses used, which seems to work fine. Most shunts run under 100mA.

I have also seen fusible wires used. A short section of skinny wire coming off the cells going to a thicker wire to the BMS. The short piece will burn if the wire shorts but being a small piece is less likely to be against something that will catch fire. They can be insulated with Nomex or non-melting insulation.

 

[Swe]

I have shorted a balance lead on one of my BM'S once.
Guess what acted as the fuse :lol: :?

https://endless-sphere.com/forums/viewtopic.php?f=14&t=87134#p1273091

In your case the BMS? But if you have a failure closer to the battery then there is nothing to stop the current.

 

[Swe]

Most packs I see don't have fuses on the balance wires. If they short, the wire will burn very quickly and act like a fuse. This may or may not be OK depending on what the wire is touching. For sure it makes a lot of stinky smoke and could set your pack on fire.

PTCs are generally not used. I think because they have too much resistance and that interferes with the balancing shunts.
I have seen 2A pico fuses used, which seems to work fine. Most shunts run under 100mA.

Found this topic (were you also wrote) and as one says emv3 uses PTC. But you are saying Pico is better? Less voltage drop? Dont know anything about them, can you just pick anyone with correct amp? I have adaptto BMS for now.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=86621

 

[fechter]

Maybe the PTCs work OK then. I have never actually tried them in this application.

The fuses are like these:
http://www.mouser.com/ProductDetail/Littelfuse/0251002NRT1L/?qs=sGAEpiMZZMuMS2dUaCDnDLY6AWy6KTIs

You would want to install them right at the cell, so the wires are protected. The fuses can be blown by the heat from soldering, so you need to clamp the lead with a heat sink when soldering.

I'm not sure what the balancing current is on an Adaptto.