The dangers of li-ion batteries!

[allotmenteer]

Hello all

I have just had the misfortune (or perhaps fortune) to discover that my li-ion battery has suffered a thermal event! This evening I noticed that the plastic casing of the battery pack had a small dimple in it that look like it had melted a bit. On removing the outer casing and taking a look at the cells inside I was horrified to see that one of the cells had burnt at one corner! Thankfully the damage was limited to just that one cell and obviously the battery pack has not (yet) gone into a castastrophic runaway thermal breakdown (or huge fire to you and me!).

I have of course placed the battery as far from my house as possible (it's in the shed and it's staying there!) while I contact electricbikesales.co.uk to claim under the 6 month warranty. I shall keep you posted as to how things go with them. I'm not sure I want a replacement li-ion though!

I consider myself lucky that I have discovered the problem prior to the pack causing a fire. I had read that li-ions must be treated with a healthy respect and thus thankfully always stored my battery outside of the house and never left the battery charging unattended either.

Let this serve as a wake up call to all li-ion owners! Store those li-ions outside your house when not in use. They are not house pets!

 

[allotmenteer]

Hello 50cycles

I'd read your page on li-ions before and it is very informative. I'm not at all sure what type I have as all the writing on my pack is in chinese. I know that there are 7 cells and when fully charged it is 29V. I believe it is a 6.8Ah pack. I am wondering about the discharge abilities of the pack as I am using it with a 15 Amp controller so it is discharging at a max 2.2C. There is the possibility that it is only a 4.5Ah pack (I was assured the pack was upgraded to 6.8Ah from the basic 4.5Ah spec on the kit). If it is only 4.5Ah then I have been discharging it at 3.3C. I am unsure if this is a safe rate for the battery pack. I was told the battery pack was made by lishen but I don't know any more than that.

Hopefully electricbikesales.co.uk will provide more info when they reply to my email.

Paul

 

[allotmenteer]

Of course I don't know whether the damage occured, while using it on the bike or while charging the pack. Perhaps the charger is faulty. It is a li-ion battery charger, 29.4V and 2 Amps but maybe it has a fault. I think until I know otherwise I shall assume it is faulty too. Well, I won't be using it anyway as I don't have another pack.

Paul

 

[flecc]

This fits with my previous posting on your batteries Paul, when I remarked on their very small capacity for your motor. They had to be discharging at a rate that's undesirable for Li-ion, which indicates a management system with a lot of tolerance to permit that, always a dangerous route.

I'd expect more like 10 Ah capacity with that 350 watt motor running on 24 volts to allow enough headroom for safety, and the management to suit.

 

[allotmenteer]

Pictures

Here's some pictures of the damage to the battery pack. I'm currently in contact with the shop that supplied the kit to arrange returning the battery and charger and to obtain a replacement. We'll have to wait and see what the cause of the damage was before making any judgements but I think you'll agree you wouldn't want one of these in close proximity to you!

 

[flecc]

This looks like a type of failure that cobalt based Li-ions can suffer. Small and sharp particles of metal can be chemically formed under some circumstances which can penetrate internal separators and cause an ignition. The very best standard of design and production can virtually eliminate that risk, but it is very difficult to maintain such high standards in manufacture, hence some manufacturers opting for safer, lower capacity types like manganese.

This one obviously wasn't one of the severe ones, so the protection circuitry probably tripped instantly and prevented further current drain at that moment which could have aggravated the situation. At least that went well.

 

[chantelauze]

i have had a Lishen battery in Paris since august 2006, i have dismanteld it many times and made measurements cell by cell , it's my impression the brand you have is not Lishen ( not the same look , not among their usual tech.spec list ) and Lishen has been using the manganic technology , not cobalt
i suggest you check with your dealer again if it's a Lishen brand ( the battery case chinese characters do not indicate at all the Lishen brand )
i had one fire accident in January 2006 ( during charge time at night but fortunately i wasn't asleep) with a Lithium battery pack sent to me by the Cyclone company from Taiwan ( i confirm the bad reputation that they fully deserve ) , that entirely burned down the 20 square meter garage attached to my house . If i were you i would require the CE certificate that such battery packs should carry to enter the EEC, the brand appears on it. It would be a pleasure for me to attach photos but apparently , i can't
i have been extremely surprised by the low mileage some eZee-50-cycles bikes owners report on this forum : 15 to 22 miles maximum in flat environment ? using ??? brand of 36v 10 ah , what brand do they use at 50 Cycles ? can they reveal it ?
anyway , my ordinary chinese brushless motor ( with planetary ratio of about 5 to 1 ) and my Lithium battery 36v 13 ah covers easily 80 kms ( not miles ...you know...i'm a frog ...not used to miles ) in flat ground , and i am 88kgs , the assistance ratio is probably 1 human to 1.5 motor and my 100% chinese e-bike has a total net weight of 32 kgs ( originally bought with SLA 36v 14 ah and covering more than 90 kms )

 

[flecc]

Hello Chantelauze, welcome to the forum.

eZee batteries are made by the Phylion Battery Co. Ltd, 10 Zhongyuan Road, Badachu High-Tech Park, Beijing 100041.

They are Li-ion manganese too.

P.S. I'm quite sure you aren't a frog.
.

 

[chantelauze]

OK ...thanks fr yr warm wellcome
tks fr yr clear answer , the chinese call this company Xingsheng , it's a subisdiary of Lenovo computer ....strong financial assets & R&D....surprised to hear about such low mileage performance....anyway the max.achievable mileage is a magic formula where the battery is not the only variable to account for the final result
and i confirm to you i was born in Frogland
i'm thinking of using a new pseudo "Lullaby of Frogland" , it sounds great for the dummy saxophonist i used to be...i will see

 

[coops]

Hi chantelauze et bienvenue

I don't have an Ezee Li-ion, but I believe they would give at least 30-35 miles (if run till empty) at around 15mph (25.5km/h?) with similar terrain & assist to yours: the figure you quote for them could be due to a lower assist ratio, higher speed, hilly terrain, reduced capacity due to battery ageing/fatigue, or a limited (non-full) discharge to try to reduce premature battery ageing .

Stuart.

 

[flecc]

...anyway the max.achievable mileage is a magic formula where the battery is not the only variable to account for the final result

Yes, the eZee Quando folding bike is single geared for the cyclist to help on hills, so when it goes at 25 to 28 kph, the cyclist cannot help since the gear is too low, so it only goes 25 km on the battery.

The eZee Torq using the same motor has the motor geared to reach 35 kph and can only go for 25 km on a battery if used that way in hilly areas. If it's restrictor is used to make it keep to the legal speed of 25 kph, it can then go for 50 km or more on a battery.

It's partly because eZee bikes are so powerful that they use the most current from the batteries.

Thanks for the information that the parent company of Xingsheng is Lenovo. As you say, they are a large sound company and making the former IBM PCs now.

By the way, Lishen's Li-ion batteries still use cobalt, since their cathodes are manganese cobalt hybrid types.
.

 

[ITSPETEINIT]

Ezee Torq and Li-ion (Phylion)

OK ...thanks fr yr warm wellcome
tks fr yr clear answer , the chinese call this company Xingsheng , it's a subisdiary of Lenovo computer ....strong financial assets & R&D....surprised to hear about such low mileage performance....anyway the max.achievable mileage is a magic formula where the battery is not the only variable to account for the final result
and i confirm to you i was born in Frogland
i'm thinking of using a new pseudo "Lullaby of Frogland" , it sounds great for the dummy saxophonist i used to be...i will see

The most I got out of my 10 Ah battery was 30 Miles (50Km). Very Flat terrain for 24 miles, then a 2 mile hill (about 7%)and 1 mile flat. The battery was exhausted when I reached the flat again after 30 miles.
My profile is 78 years: many medical issues:88 kgs - too much Ros-bif. I put in as much work as I can but I doubt it is ever greater than 100 watts (I must try one of those athletic tester bikes that measures everything: if I can find one). Currently in very hilly terrain I am getting about 20 miles on an eZee Sprint. The batteries are always Fully Charged (Force fed after the first green light).
Felicitations
Peter

 

[chantelauze]

avg. energy consumption mostly related to controller

tks you'll fr your comments and greetings to my miserable personn...

my dominant impression for being an e-bike addict since 2 years :whatever is the brand of the Lithium battery pack ( Phylion, Panasonic, Lishen , Kokam etc...) , the consumption is mostly influenced by the controller

when maintaining all outside variables constant ( e-bike, rider, circuit , brushless geared motor 5 to 1 ratio , 36v Lithium battery pack ) the e-bike behaviour and consumption will widely vary in regard ot the controller's you're using : i.e travelling at full 15 miles / hour on a closed and flat circuit , my consumption at that constant speed will be in between 5 watt per km to 9 w/km ...that's a hell of a difference !
with 3 different brands that all look alike and are sold in mainland China about 110 RMB ( 11 euros )

 

[flecc]

I think that's true chantelauze, the controller usually being the key, though of course motors like eZee's will always consume more unless the controller cuts the power, making the powerful motor a bit pointless then.

The Panasonic motor system has an interesting strategy in addition.
.