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Battery Fires
- Thread starter saneagle
- Start date
We ditched LFP batteries because they all swelled up and stopped working after a few months - maybe 50 cycles. I've still got a few of the salvaged ones if you want to try one. You get slightly more power because they immediately drop to 3.33v per cell (x12) and stay like that until they're nearly empty, then drop off a cliff, so throughout the discharge, they hold around 40v instead of continually dropping down to 31v.
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Ghost1951
Guest
Thanks for the offer Saneagle. Were those cells of a particular bad brand or are you saying that this is what they are like now? Is swelling an inherent failing of the technology, or was it a bad batch or poor manufacturer? They are big players in the power storage business and also coming in strongly in electric cars and busses. Surely that would not be happening if the problems you people had in the past were a feature of the technology rather than just a bad batch or bad cell maker.
I'm not being contrarian here - There are more and more being made outside the ebike market. I have been looking online for ready made e-bike LFP batteries as opposed to bare cells, and there are not any in this country. I saw one maker somewhere abroad offering a battery, but it just looked like an unpackaged square sided lump. The packaged ones are mostly 12v and not made for ebike applications.
To be honest though - Nealh's account of owning an ordinary lithium ion battery and running it for about ten years with minimal degradation does suggest what we have is good enough. How the owner treats them is very important in how long they work - witness the current thread you started on the dead cell surgery.
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Ghost1951
Guest
Swollen LPF cells
I googled, "Why do lfp cells swell up?" and received the following reply:
"Swollen LiFePO4 batteries are the result of too much current inside a cell of the battery, which causes a build-up of heat and gas. This can be caused by overcharging, deep discharge, overheating to battery, or manufacturer defects, or environmental reasons."
Topping out at about 3.65v, they obviously need a charger specific to that technology. Just like other cells, you would need a cell rated to produce the current required by the particular e-bike motor, battery configuration, and controller set up.
I googled, "Why do lfp cells swell up?" and received the following reply:
"Swollen LiFePO4 batteries are the result of too much current inside a cell of the battery, which causes a build-up of heat and gas. This can be caused by overcharging, deep discharge, overheating to battery, or manufacturer defects, or environmental reasons."
Topping out at about 3.65v, they obviously need a charger specific to that technology. Just like other cells, you would need a cell rated to produce the current required by the particular e-bike motor, battery configuration, and controller set up.
Eve are one of the biggest makers of LFP 3.3v modules , one simply bolts them together via the buss's and nuts suppplied. Their LFPs' vary from 100ah - 305ah per module for static power storage .
LFP the new name for lifepo4 still swell and need mechanical clamping to prevent them expanding in their enclosure.
One ofthe last bikes we know that used lifepo4 was the Kudos safari step thru , it came in at 30kg and was fully specced with all extras conceiveable .
LFP the new name for lifepo4 still swell and need mechanical clamping to prevent them expanding in their enclosure.
One ofthe last bikes we know that used lifepo4 was the Kudos safari step thru , it came in at 30kg and was fully specced with all extras conceiveable .
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I should add that my previous comments were made in relation to the fad for LFP batteries about 13 years ago, when most Chinese factories hadn't figured out how to do basic quality control. Ordinary 18650 lithium ion cells were leaking all over the place as well. Things have improved a lot since then. I even have three massive LFP batteries (10kwh total) right in the middle of my house powering it.
The main issue with using LFP instead of Li-ion for ebikes is weight.
Li-ion 21700 5000mAH 3.6V 18WH, weighs 68g
LFP 32700 6000mAH 3.2V 19.2WH weighs 141g
Let's say you want to build a small 36V pack.
You can do 10S1P with 10 x Li-ion 21700 cells, 680g.
You'll need 11S1P with x LFP 32700 cells, 1551g.
Costwise, LFP costs about half Li-Ion.
Li-ion 21700 5000mAH 3.6V 18WH, weighs 68g
LFP 32700 6000mAH 3.2V 19.2WH weighs 141g
Let's say you want to build a small 36V pack.
You can do 10S1P with 10 x Li-ion 21700 cells, 680g.
You'll need 11S1P with x LFP 32700 cells, 1551g.
Costwise, LFP costs about half Li-Ion.
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Ghost1951
Guest
I liked the look of these which bolt together with bus bars and nuts.
These are 6Ahr, so something like 12s2p, or 12s3p might work out well.
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New E-Bike Positive campaign launched, with 23% of UK adults put off by battery fires
Campaign aims to set the record straight over perceived risk from faulty batteries
Campaign aims to set the record straight over perceived risk from faulty batteries
"About 23% of UK adults are hesitant to buy an e-cycle after reading about recent battery fire incidents
25% worry about batteries charging nearby."
bikebiz.com
25% worry about batteries charging nearby."
UK cycling industry launches biggest ever e-bike battery safety campaign - BikeBiz
E-Bike Positive, a new initiative with support from across the cycling industry, is set to equip the
bikebiz.com
I am not surprised. For years, Chinese rewrapped cells found their way into our homes. Now we may have to sit out for perhaps 10 years to see them gone out of business.
That is a VERY good question. Is there a person/organization who would represent our interests in UK or again something will be imposed on us?
In terms of new legislation? NOTHING. Absolutely nothing!
I would enforce existing law and remove idiots from road. Take e-bikes and e-scooters from idiots and you will see how drastically number of fires will drop.
I would stop hypocrisy and bigotry from politics and law making. I know it is a lot to ask. For example how is that possible to legally sell illegal scooters ???
The way I see it, this whole battery safety is yet another money grab.
That sounds a great idea - is it very expensive to do ?
That sounds very easy to do - 24v, 36v, 48v and 52v have distinct ports and chargers and people can't get it wrong. Idiot proof.
What does this involve ?
None of these things add to the current costs or a couple of £ at most. It's just legislation. Doing nothing is not progress. Bad products will continue getting into our homes.
PS:
Data logging in the bms will enable predictive replacement and stop overcharging old or damaged batteries.
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Google, Facebook etc. buy information about everything we buy, from banks and credit card companies etc. The land registry has data about private land owned by whom. Automatic fines could be issued to all owners of ebikes and escooters bought for "off-road" use. Prove it or pay.
We're pyssing in the wind because it's all being decided and decidedly locked the fsck down by vested interests, despite anything we say or do but, if these dudes were going down the route of keeping things largely as they are bar additional certification: It's not just the cells that need to be certified, doesn't the BMS require certification too? And whether whichever particular BMS had been installed into a particular battery is also appropriate and certified for use with the certified controller used. Lots more certificates would be required. Fortunately most certificates these days can be paperless, global warming and all that.
We're pyssing in the wind because it's all being decided and decidedly locked the fsck down by vested interests, despite anything we say or do but, if these dudes were going down the route of keeping things largely as they are bar additional certification: It's not just the cells that need to be certified, doesn't the BMS require certification too? And whether whichever particular BMS had been installed into a particular battery is also appropriate and certified for use with the certified controller used. Lots more certificates would be required. Fortunately most certificates these days can be paperless, global warming and all that.
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Bms needs to be specified to meet standard norms. It's the weakest link atm. Loads of quality batteries will stop charging when the bms detects a dangerous condition. Why shouldn't all bmses be forced to have that feature?
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Ghost1951
Guest
You mean built in obsolescence. You MUST get a new battery when Big Brother says so. Fk that!
This is pretty much a NONE ISSUE. In the whole of the UK there were 183 ebike /scooter battery fires last year out of 26,974 domestic fires and 145,313 fires overall. You are FAR more likely to be harmed by your tumble drier, washing machine, or cooker. Ten thousand fires were caused by cooking appliances.
Innumerate people misuse percentage stats when the numbers of cases are tiny and in doing so they exaggerate the problems, usually ending up demanding draconian controls. Another example is the upcoming ban on owning a machete - even in your garden shed. A few bad people misuse an inanimate object and the total dross of the political class ban the object, while pleading special gentle treatment for the people who misused it.
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That's what I was thinking. I can remember laptops that you couldn't charge after the battery had a set number of charges. I've never heard of an ebike battery catching fire because it's too old.
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