That surprises me, I thought Samsung cells were the best? But I don't know much about ebike batteries...

Samsung do make great cells, but that particular cell wasn't suited for my needs.

The Samsung 25R cell would have been better.

 

I hadn't researched enough at the time and paid the price for purchasing the wrong battery pack.

I'm startingto wonder if the stress of the battery pack bouncing about within the case, has broken down the adhesive to a liquid-like state - it might not have been heat? Those wires are on the sides after all. Liquids might be more flammable. Seems nuts that flammable paper is used... I suppose the combusting temperature of the paper must be lower than that of the battery cells?

 

 

 

This tape is used as heatsink backing adhesive for LED lights, and could be used to wrap a battery, were it not double sided sticky tape, and quite thin:

 

https://www.ebay.co.uk/itm/174219166098?hash=bunch-o-bananas

The BMS looks like it is 22a continuous so one could go 20a if the programming allows.

The stains I would lift the paper insulation covering to look, does it smell of electrolyte ?

 

The battery has just finished charging, the charger shone a green LED, and the display is showing 41.9V, I guess this is a healthy voltage? It's been charged and used quite a lot all year since new, and it was as smelly when new, as it is now.

 

Aside from the smell, it seems ok? But to be on the safe side, I'll set the controller back to 15A for the time being - until I buy a second battery. It's my only daily commuting vehicle.

Now the paper has been lifted it looks like heat is causing the paper glue to weep through. The sense wires with heat sleeves are laying directly across the interconnectors.

Now the paper has been lifted it looks like heat is causing the paper glue to weep through. The sense wires with heat sleeves are laying directly across the interconnectors.

 

Is that bad practice? Is it something which needs fixing or re-organising? I've learned to solder (a little) recently, but I don't fancy my chances at reorganising those wires!

Now the paper has been lifted it looks like heat is causing the paper glue to weep through. The sense wires with heat sleeves are laying directly across the interconnectors.

 

Maybe I should add thicker heat insulating material around those wires? If so, what sort of product could be used?

Now the paper has been lifted it looks like heat is causing the paper glue to weep through. The sense wires with heat sleeves are laying directly across the interconnectors.

 

Would wrapping kapton tape around those wires protect them adequately?

The paper is an insulator /protector and is quite hard wearing.

Re use the paper if poss and use a wrap or two of kapton tape to bind it again.

Once lifted it depends what the cells look like and whether leaking has occurred, leaking will show up as the cell wrap will be bubbly/rough. Electrolyte smell I can't describe but any smell is abnormal as cells don't smell.

 

 

Should I cover completely with kapton tape? Would that make the battery pack too hot?

 

 

I don't lay wires across interconnectors, I either lay them between or through the cell/gaps where I use spacers. Kapton tape to insulate against heat transfer.

The interconnector material may be heating up as it may not be capable as a very good conductor thus heat is then conducting through the wire insulator material to the paper causing the glue bleeding, that's why folks use copper now as it heat flows nicely through it being 3 or 4 x more conductive then steel/nickel.

The paper is an insulator /protector and is quite hard wearing.

Re use the paper if poss and use a wrap or two of kapton tape to bind it again.

Once lifted it depends what the cells look like and whether leaking has occurred, leaking will show up as the cell wrap will be bubbly/rough. Electrolyte smell I can't describe but any smell is abnormal as cells don't smell.

 

 

Will 100mm wide do the job?

 

https://www.ebay.co.uk/itm/294312134790?hash=whatwatwhat

For my batteries I use a 0.4mm fibreglass sheet top and bottom as an insulator.

Kapton one can use what ever width one wants to, I tend to use 20mm for most of my builds.

The laying of the sense wire across is a bit crap, but I suspect the interconnector material may be a bit below par and is getting quite warm with higher current.

For my batteries I use a 0.4mm fibreglass sheet top and bottom as an insulator.

 

Is this the stuff?

 

https://www.ebay.co.uk/itm/174735657804?hash=

Yes FR4.

Kapton one can use what ever width one wants to, I tend to use 20mm for most of my builds.

The laying of the sense wire across is a bit crap, but I suspect the interconnector material may be a bit below par and is getting quite warm with higher current.

 

 

Those interconnectors are not copper, that's for sure, bog standard nickel? Well, at least this battery has MH1 cells, hopefully not ruptured and ready to explode.

Yes FR4.

 

Thanks nealh. I'll order both FR4 and kapton tape, to reduce the heating of those wires. There were a lot of hot days this year, must have been toasty in there.

Yes FR4.

 

I might try to source a kevlar battery cover, in case of an explosion. Or perhaps my aluminium battery box for the rear rack wasn't a such bad idea after all, it might contain the blast? On the other hand, the explosion could burn my a*se with flaming aluminium shrapnel and lithium.

Edited January 23, 20224 yr by guerney

I'll give this battery pack a very thorough visual inspection, when the kapton tape arrives.

[ATTACH type=full" alt="she-canna-take-any-more-captain-shes-gonna-blow.jpg]45471[/ATTACH]

 

Not since we got married

Ebike batteries could be temperature controlled using Peltier plates, powered by the ebike battery, separate battery, or dynamo? Fans outside the case might not be required, could get away with using large waterproof heatsinks?

 

https://en.wikipedia.org/wiki/Thermoelectric_cooling

 

https://www.manomano.co.uk/p/thermoelectric-peltier-refrigeration-cooling-system-kit-semiconductor-cooler-large-radiator-cold-conduction-module-double-fans-23439670?model_id=23420563

Whilst we've slightly gone off topic and are discussing battery safety, I thought I'd mention some of the safest battery packs available at the moment. There's also a recently started thread on battery fires here: https://www.pedelecs.co.uk/forum/threads/e-bike-fires.42720/#post-641215

 

Most established forum members will have definitely heard of EM3ev.

Their battery packs are some of the safest packs around, with multiple safety features for peace of mind when charging, discharging and storing.

 

I bought mine directly from them in China, but a UK based company also supply EM3ev packs.

They are also a good company to buy from and here's the link for them: https://eclipsebikes.com/lithium-ion-c-1_8/jumbo-shark-52v-17ah-ebike-battery-samsung-35e-cells-p-275.html

 

BTW, I am not affiliated with either company.

Whilst we've slightly gone off topic and are discussing battery safety, I thought I'd mention some of the safest battery packs available at the moment. There's also a recently started thread on battery fires here: https://www.pedelecs.co.uk/forum/threads/e-bike-fires.42720/#post-641215

 

Most established forum members will have definitely heard of EM3ev.

Their battery packs are some of the safest packs around, with multiple safety features for peace of mind when charging, discharging and storing.

 

I bought mine directly from them in China, but a UK based company also supply EM3ev packs.

They are also a good company to buy from and here's the link for them: https://eclipsebikes.com/lithium-ion-c-1_8/jumbo-shark-52v-17ah-ebike-battery-samsung-35e-cells-p-275.html

 

BTW, I am not affiliated with either company.

 

 

EM3ev: Those look like copper interconnects, less heat

 

 

 

 

I'll protect those hot wires using fr4 and kapton, add cushioning, but my next battery will be built much better than this first ebike battery that I've ever bought.