Search found 1134 matches

by whatever
Jul 07 2019 8:35am
Forum: Battery Technology
Topic: Recovering a LiFePO4 cell (A123) at 0V
Replies: 4
Views: 267

Re: Recovering a LiFePO4 cell (A123) at 0V

i've tried to revive many a cell at various voltages, mainly cobalt oxide lithiums ( older chemistry), if I catch a cell before it gets below about 2.5v there is hope for the cell, anything below that and the capacity will likely be low. I've tried reviving lots of cells below 1volt, and there is gr...
by whatever
Jun 25 2019 4:26am
Forum: Motor Technology
Topic: variable field motor demo
Replies: 3
Views: 235

variable field motor demo

link to variable filed motor, windings move in/out of the stator to adjust speed also torque I assume, anyone care to explain this phenomenon? I vaguely remember it being discussed many years ago but I've not seen it put into action before. video link is to solar car racing team from japan [youtube]...
by whatever
Feb 17 2019 11:46am
Forum: Battery Technology
Topic: battery pack idea
Replies: 7
Views: 504

Re: battery pack idea

why couldn't you mix the electrolyte from different cells?
by whatever
Feb 11 2019 9:03am
Forum: Battery Technology
Topic: battery pack idea
Replies: 7
Views: 504

Re: battery pack idea

seems they call it "internal cooling" and another paper they used microchanels on the foils to allow electrolyte to circulate and cool the cells ( looks like theoretical paper only) Quite a nice way to circulate the electrolyte, the results they calculated showed more efficient method than external ...
by whatever
Feb 11 2019 8:50am
Forum: Battery Technology
Topic: battery pack idea
Replies: 7
Views: 504

Re: battery pack idea

did quick search found one research paper on using electrolyte for internal cooling of cell ( so its definitely been thought of before!)
https://www.sciencedirect.com/science/a ... 5315009362
by whatever
Feb 11 2019 8:30am
Forum: Battery Technology
Topic: battery pack idea
Replies: 7
Views: 504

Re: battery pack idea

to philaphlous: plenty of plastics are used with lithium battery pouches, I dont think a big issue. Aluminium also no problem with ec:dec etc. to matador: yes lipf6 does produce hydrogen and hf as you mentioned, but no water involved its a closed system. How to get the electolyte to circulate around...
by whatever
Feb 08 2019 10:07am
Forum: Battery Technology
Topic: battery pack idea
Replies: 7
Views: 504

battery pack idea

there are patents and research docs on rejuvenation lithium batteries by flushing the electrolyte then replacing the electrolyte. Some large companies holding patents including general motors. So I'm assuming the process gives good results, its based on simply flushing with ec:dc or similar electrol...
by whatever
Oct 22 2018 10:28am
Forum: Battery Technology
Topic: battery cell temp monitoring
Replies: 2
Views: 286

Re: battery cell temp monitoring

another device a micro-sensor which can monitor temperature/voltage/current of each cell https://www.mdpi.com/1424-8220/15/5/11485?trendmd-shared=0 How useful would such a device be! It would allow real time monitor of every cell whether connected in series/parallel to other cells. The article was p...
by whatever
Oct 22 2018 9:54am
Forum: Motor Technology
Topic: Fisher and Paykel motors
Replies: 111
Views: 29085

Re: Fisher and Paykel motors

yup you need to match correctly the hall wires too controller. Also you need to have correct voltage hall sensor setup to match controller ( usually 5v for ebikes or 1 to 4v more acurately). I cant remember what voltage the hall sensors are on the fp motors. What is the use for the motor? It would p...
by whatever
Oct 22 2018 9:45am
Forum: Battery Technology
Topic: using simple balance boards
Replies: 6
Views: 557

Re: using simple balance boards

interesting
by whatever
Oct 21 2018 11:52am
Forum: Battery Technology
Topic: using simple balance boards
Replies: 6
Views: 557

Re: using simple balance boards

thanks for the info
by whatever
Oct 21 2018 11:50am
Forum: Battery Technology
Topic: battery cell temp monitoring
Replies: 2
Views: 286

battery cell temp monitoring

seems taking a long long long time for something to come onto the market to monitor cell temperatures, ideally getting info on each cell temp is valuable. Optic fibre distributed temp sensing might be a possibility later on, in the mean time these folks have come up with a micro temp sensor for use ...
by whatever
Oct 12 2018 9:55am
Forum: Battery Technology
Topic: using simple balance boards
Replies: 6
Views: 557

using simple balance boards

anyone have any experience using these type of balance boards? simple balance board.jpg anyone can describe how to use them? do you just leave them attached to the battery pack permanently? here is link where I found the boards on aliexpress https://www.aliexpress.com/item/4S-4-2v-li-ion-balancer-bo...
by whatever
Jun 18 2018 1:41am
Forum: EV Business World
Topic: Tesla Model 3
Replies: 985
Views: 62636

Re: Tesla Model 3

Seems tesla has removed the two fuses normally found in 18650 cells ( cid fuse and the other one I forget the name of), the only protection at the cell level is the thin fuseable link. Seems the 2170 cells also dont have the internal fuses either ( one is pressure based the other one is temperature ...
by whatever
May 31 2018 5:09am
Forum: EV Business World
Topic: Tesla Model 3
Replies: 985
Views: 62636

Re: Tesla Model 3

looks like the tesla cells might be only relying on the thin wire fuse external to cell, seems they dont have
cid or ptc inside them after all.
by whatever
May 28 2018 8:32am
Forum: EV Business World
Topic: Tesla Model 3
Replies: 985
Views: 62636

Re: Tesla Model 3

In that article above by Jack Rickard, he says first line of defense is the thin wire fuses, but inside the 2170 cell lids, there are two other fuses .....one CID and one PTC......, CID is simple pressure fuse ( small aluminium disc that pops out when pressure too high, it disconnects cell permanent...
by whatever
May 27 2018 8:21am
Forum: Battery Technology
Topic: 18650 gassing auto disconnect built in
Replies: 18
Views: 690

Re: 18650 gassing auto disconnect built in

I had no idea 18650 cells had the CID feature and also a PTC ring. CID being the pressure type fuse ( dome shaped plate) causing cathode disconnect, and PTC being a polymer/carbon ring that changes resistance with temperature ( another type of fuse but resets when temp drops back down)( the annular ...
by whatever
May 26 2018 5:04pm
Forum: Battery Technology
Topic: 18650 gassing auto disconnect built in
Replies: 18
Views: 690

18650 gassing auto disconnect built in

just came across some info, not sure if discussed here already, seems some 18650 cells have an auto disconnect under the caps, very simple and clever design, once the cell gas level reaches a certain level the cell cuts off the pos connection. this video explains very clearly how it works ' https://...
by whatever
Dec 01 2017 6:40am
Forum: Battery Technology
Topic: tesla battery temp monitor
Replies: 3
Views: 602

Re: tesla battery temp monitor

seems there is a technique recently developed called distributed temperature sensing using optic fibres. in this paper https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0ahUKEwjJ68762ejXAhXCJpQKHZAPBvYQFghMMAU&url=http%3A%2F%2Flunainc.com%2Fwp-content%2Fuploads%2F2012%2F08%2FDis...
by whatever
Dec 01 2017 6:20am
Forum: Battery Technology
Topic: tesla battery temp monitor
Replies: 3
Views: 602

Re: tesla battery temp monitor

there are probably many ways to do it, but here is an interesting example of how a very thin optic fibre
could be used to gather the individual cell temp data
https://www.jove.com/video/54076/fiber- ... ture-field
by whatever
Dec 01 2017 6:00am
Forum: Battery Technology
Topic: tesla battery temp monitor
Replies: 3
Views: 602

tesla battery temp monitor

just a thought: the white silicon type material which is in contact with the cells and transfers heat from the cells to the cooling tubes . Since it is in contact with each cell, it might be possible to monitor the temp of each cell. Some sort of strip built into the silicon with thermocouples or si...
by whatever
Sep 12 2017 5:43am
Forum: Battery Technology
Topic: Video-New Lithium Battery Research,Jeff Dahn,Dalhousie-Tesla
Replies: 9
Views: 1424

Re: Video-New Lithium Battery Research,Jeff Dahn,Dalhousie-T

another good video from jeff dahn " https://www.youtube.com/watch?v=9qi03QawZEk " It gives information on the premature failure of nissan leaf batteries, lots of excellent technical info on how lifespan of batteries can be determined by short time frame tests and some nice info on electrolytes and a...
by whatever
Jul 11 2017 7:38am
Forum: Battery Technology
Topic: volt and temp display bms
Replies: 0
Views: 263

volt and temp display bms

this looks promising for voltage/temperature monitor of cells, nice video showing 196cells being monitored here: https://www.youtube.com/watch?v=DrsO2EwLFIE&feature=youtu.be uses Batrium bms, just looked at their website, prices seem fairly reasonable, still too high for me though. I'm still waiting...
by whatever
Mar 10 2017 5:16am
Forum: E-Bike General Discussion
Topic: How do police test compliance of ebike (Australia)
Replies: 115
Views: 11759

Re: How do police test compliance of ebike (Australia)

so the police and confiscate your ebike for testing, and if it doesn't pass they dont give it back????????
crikey