How to kill a Lithium Ion Cell

[electricvehicles]

I dont like to be a pesemist but the more I look into it Lithium Batteries really are looking less likely as an alternative to PB. I know the power to weight ratio is better, their cycle life is alledged to be better. But problems with them seem to be more and more common.
Quote from a guy who has had experiences with Thundersky:

ThunderSky Lithium-Ion Cells

LiIon experiences

I was part of a group of people that decided to attempt to use some ThunderSky LiIon cells for our electric vehicles. Since they have to be shipped from China, we wanted to do a large order to reduce shipping costs.

I purchased Qty 52 of their 90AH cells, part # TS-LP90.

This turned out to be a poor choice.

When we received them, some of the cells already had some rust on their steel terminals.

Initial testing showed that the 90AH cells would be lucky to make 70AH capacity.

We’ve also discovered that they need to be HOT to work properly, up around 40 deg C seems about what they need. Of course, it’s not too difficult to heat them, since they have a rather high internal resistance, and come up to that temperature fairly quickly with only a 18A load.

They are rated at a max current of 3C (or 270A for these 90AH cells). As far as I can tell they can’t reach that without falling below their minimum cell voltage.

I have lots of data collected testing a working with these cells. Several have died in only 20 – 30 cycles of use.

We did contact ThunderSky Corp about the problems with them not meeting their rated specs.

So far, they aren’t interested in having happy customers.

So, to Summarize:

TS-LP90AH cell, rated at 90AH.

70-80 AH capacity, but only when quite warm.
10-20 AH if they aren’t warm.
Hi internal resistance, so they heat up with only a 18A draw. Likely to overheat quickly at higher draws.
NO CUSTOMER SUPPORT WHATSOEVER
Not a chance of meeting their rated max output current.
Can only charge slowly (20A or so max). Some cells overheat quickly above that rate, some just won’t accept higher rates without going over voltage.
Wildly inconsistent quality control. Cells vary by quite a bit.

[retepsnikrep]

Said lot's of stuff.

H'mm old news really, was that from the first UK or US bulk purchase?

ASFAIK Jim Fell in UK had some bad cells in the first UK bulk purchase but negotiated with TS and got them replaced with some others at reduced cost.

Yes the first buyers like me and him were guinea pigs, but we took a gamble knowing there was no support or guarantee whatsoever, so we haven't moaned about it.

Things have moved on, as has the technology and yes it's still difficult to deal with people half way round the world, but I would rather do that than go back to pb ever again. In fact I'm will be asking for expressioins of interest in another UK TS Bulk purchase on a new thread today!

[ChrisB]

I've seen those words EV somewhere as well, cant remember where mind you and it was a few years back now could be 5 or even 6years.

While I am of the opinion that theres nothing that can really beat the li-ions I feel we still have some way to go before we have a decent fool proof BMS that can be relied upon, having said that I do know that Alan Ward is still running about in my Fiesta with a set of li-ions with no BMS what so ever and to my knowledge has only had one cell go down in several years, so it is possible to do it without a BMS.

I am still in love with my Saft Nicads in the Berlingo and if push came to shove I think I'd still replace them even at £250 a pop.

PB have had their time I feel, and unless you fit huge Ah cells like they do in fork lifts and the likes then you've always going to have issues when you try to get 150A out of cells that are only rated at 100Ah over 5hrs, its pretty rare to find PB's at a one hour rating which to be fair is what you really need in an EV I feel.

ChrisB

[retepsnikrep]

While I am of the opinion that theres nothing that can really beat the li-ions I feel we still have some way to go before we have a decent fool proof BMS that can be relied upon, having said that I do know that Alan Ward is still running about in my Fiesta with a set of li-ions with no BMS what so ever and to my knowledge has only had one cell go down in several years, so it is possible to do it without a BMS.

Not an issue IMHO, Cedric's cell protectors did the job for me very nicely for nearly 5 years. Only my failure to implement a final fail safe based upon the low cell V signal from the cell protectors cost me a few of my cells. Not the cell protectors fault or the cells! It's not rocket science or a black art.

[ChrisB]

Not the cell protectors fault or the cells! It's not rocket science or a black art.

I agree , I suppose I havent yet grasped or come to terms with the fact you have to buy the batts then spend more on a BMS and finally even more on a charger. I'd like a all in one box solution, bit like Choppermans LifeBat's .

The li-ions just seem a tadge fragile for my likings but then look at the ones in mobile phones/camcorders and the likes , the are fine.

ChrisB

[PHEV]

In my opinion lifepo4 will last the distance if properly treated. Even a PB battery will suffer and die if over discharged, or not recharged immediatly after use, I've got far more dead PB batts than lifepo4's sitting around the workshop!

Also, the quality controll of thundersky cant really compare to A123's, or lifebatts!

[electricvehicles]

PB have had their time I feel, and unless you fit huge Ah cells like they do in fork lifts and the likes then you've always going to have issues when you try to get 150A out of cells that are only rated at 100Ah over 5hrs, its pretty rare to find PB's at a one hour rating which to be fair is what you really need in an EV I feel.

ChrisB

Sorry Chris I beg to differ on this one. OK I am only a humble electric vehicle engineer looking after slow moving vehicles. But a lot of our equipment is fitted with Flooded PB cells. Yes a lot of the stuff we supply and look after comprises of a battery mass in excess of 1.5 tons. Thats only to act as a counter balance weight or to give the vehicle its balast to allow it to tow in ecxess of 20 tons. We also look after 100s of golf buggies fitted with the ubiquitous Trojan T105. OK theses are humble 6V monobloc batteries with a rated capacity of only 195 AHC @ 5HR. But they do have the added advantage of being flat plate construction opposed to the tubular plate construction on full traction batteries.
This consequently allows for quite a high discharge current. According to Trojan Battery Co they can be discharged at 488 amps for 25 mins or 132 amps for 75 mins. Not bad really for a battery that costs next to nothing and from 1st hand experience I have seen these last for well in excess of 7 yeays, albeit working in a constant temperature environment.
Also lets not forget CMP batteries -- Designed for a 1500 cycle life. 5 Years warranty + 1 pro-rata. OK they cant handle the very high discharge currents against their rated AHC @ 5HR but what a warranty

Sorry but is still dont have 100% faith in Li batteries yet, maybe in a few years time when they have had proper day to day testing in proper vehicles, then I might be converted

One other point -- If LI batteries are being developed and re-developed on a day to day basis -- How can the figures regarding discharge, capacity, cycles etc be verified My reckoning is that to test something it has to be cycled on an hourly basis and as far as I am aware time cannot be incresed or decreased Thats unless the far east have managed to perform the impossible

Added quote tag so quote worked correctly ChrisB

[PHEV]

Its already got a low voltage cutout on the bike (each cell monitored individually)

Good to hear the rest of the pack looks OK What sort of LVC have you got on the pack, is that homebuilt as well? Just curious as I want to build a small foolproof A123 pack for my wife's bike.

It is a homebuilt unit, basically the same as the ones gary sells on ES forums. I'll knock you couple up when your ready Malc, it won't take long.

[ChrisB]

PB have had their time I feel, and unless you fit huge Ah cells like they do in fork lifts and the likes then you've always going to have issues when you try to get 150A out of cells that are only rated at 100Ah over 5hrs, its pretty rare to find PB's at a one hour rating which to be fair is what you really need in an EV I feel.

ChrisB

Sorry Chris I beg to differ on this one. OK I am only a humble electric vehicle engineer looking after slow moving vehicles..............................

Dont be humble matey, what you do is what I'd love to do for a job

I will agree you cant go far wrong with T105's they are still really the masters in cyclic PB batteries.
They are absolutely bomb proof and dont need anything in the way of special charging, grab a large transformer and a couple of large diode's and thats about it , OK thats a real crude charger but they will charge quite happliy with that set up. Even if you go oooops I've left my two diode charger on a bit to long the worst you'll do is boil off a bit of water.
BUT and its a big BUT look how heavy they are no probs if you just want to go slowly and need a lot of weight to keep the back wheels on the ground, but if you want to go fast and quickly they really are a bit of a perfomance killer So yes they are still pretty good but heavy.........

......when compared to the likes of the Saft STM 5-100's Nicads , which surprise surprise are fitted to the berlingo
which although I doubt they could match the 105's maxium discharge curves but then they weigh almost a third of the 105's and are microscopic in size ...well ok there not that small but much smaller than the 105's. The Safts while do benifit from some sort of charger intellengence can still be charged with a pretty basic charger like PB's

I'm not sure why liquid Nicads have not become more widely used as from my experience which to be fair isnt any where near like your own, these Safts have so far outlasted any PB's I ever owned by 3 times Although I will add the first set did go pop, but then that was due to a known issue thats suppose to have been cured now.

ChrisB

[ChrisBarron]

I'm not sure why liquid Nicads have not become more widely used as from my experience which to be fair isnt any where near like your own, these Safts have so far outlasted any PB's I ever owned by 3 times Although I will add the first set did go pop, but then that was due to a known issue thats suppose to have been cured now.

ChrisB

I was visiting a local traction battery supplier/maintainer near Cu mbernauld last year. He had racks full of liquid nicads. Many in nice metal cases aith flip top lids and other such engineering niceties. They are used as the power maintenance batteries for the local high speed trains, and similar but larger cells are used as the starting battery.

It is quite closed loop between the battery manufacturer, the end application and the service department, adn complete recycling seems to take place. Perhaps that's why they aren't often seen for sale, because they are immediately re-used[/quote]