Lithium cell tests

Just carried out a destructive test on one of the A123/DeWalt Lithium Iron Phosphate cells.

Tiberius pierced it. The cell was probably around 80% charged at the time.

The result is, I would say, much the same as if you did the same thing to a NiCad. Gets hot of course - maybe around 100 deg C. A lot less dramatic than piercing a LiPo.

The case of the cells is approx 0.3 mm aluminium.

http://www.terrorhurtz.com/m1test/http://www.terrorhurtz.com/m1test/

(Message edited by terrorhurtz on April 15, 2007)

(Message edited by terrorhurtz on April 15, 2007)

Ive got to admit, i was abit jubious about these cells when i was first told about them but they seem amasing!
I use lithium polymers in my featherweight, but the safety factor on these cells seems FAR superior. For the 70A continous and 120A burst i think John mentioned, they are well worth a serious look into. Seriously light too considering they are asolid state cell.

Weve had one robot over here in Australia running A123 cells for a few events now and they have proven to be quite the performer while maintaining safety. They are great and a few builders over here are shifting to them, including myself, who has just purchased 20 cells :proud:

Knightrous, have you some more info (and pics) on how you are using them?

Where are you getting the cells, how much.
How are you making up the packs.
How are you charging and balancing them
etc

These cells are are a new technology and its good to share info so that others can take advantage of these cells safely.

Ill be putting up a web page with the above info on our experiences with them soon.

Im planning to run them in TerrorHurtz for the first time at the roaming Robots event in Northampton next month.

John

Most of them use Dewalt 36V packs and open these up. Its the cheapest way to find these cells.

Cant wait to see how they preform in a battle. They seem like the dream battery.

Mr Stu

http://www.slkelectronics.com/DeWalt/packs.htmhttp://www.slkelectronics.com/DeWalt/packs.htm

http://www.rcgroups.com/forums/showthread.php?t=587606

How to take them to bits :)

(Message edited by typhoon_driver on April 17, 2007)

Hi John,

Ive been ebay whoring them from the USA. I currently dont have the cells in my possession (shipping is a pain :proud:) Roughly cost me AUD$250 for 20 cells. So AUD$12.50/Cell.

I can share some information from discussion with Trent Ellis, the aussie builder running them at the moment.

The best place to find all the information is here: http://robowars.org/forum/viewtopic.php?t=901http://robowars.org/forum/viewtopic.php?t=901 This is Trents build thread. There is a lot of information over the span of 140 posts. With a fair few pictures of the A123 in questions. Ill just briefly remark about them here :-)

Trent built 7 cells packs for Eleanor to run the Dewalt 18v Team Delta kits on 23.1v. He left them mainly in their original state, using the factory tabs and structure. He also added a 9-pin D plug (Serial Connector) and wired them up to each cell so he could run his Blinky balancer through the packs after events.

http://i41.photobucket.com/albums/e275/trentellis/IMG_0024.jpghttp://i41.photobucket.com/albums/e2...s/IMG_0024.jpg Shows them all shrinkd up and ready for combat.

Personally, when I get my cells, Ill be looking at making a solderless battery design. Previously I have built my own intercooler battle packs, but this time I want to make them solderless and will clamp the packs together. This way I can make/break packs relatively quickly.

One issue we did notice with the A123 cells is, they will charge fast, IF they are kept cool. Trent had two packs at RoboWars 4, but one was damaged in a fight (Reason unknown, Trent hasnt pulled it apart yet, he thinks a connection came loose though) and he had to resort to using the same pack repeatedly. Each battle this pack came out pretty hot and he was only able to get 70-80% back into it in the 30mins between battles. We even tried my Triton2 cranked at 7amps through the LipoDaptor+ (From SLK Electronics and now called Daptor) but we couldnt force the amps into them.

They have proven to be very safe, no cell venting, no leaks, no swelling and no fires. I think the Dewalts are a pretty tough test for them, as we have seen Glen Roses King Cobra kill a few of its 2400 NiCD Packs from thermal abuse :proud:

If you have a bit of time John, join the RoboWars.org forums, a few of the UK guys have joined us and it would be an honor to have yourself join us in our discussions :)

Thanks for the info Knightrous. Sorry, dont know you real name.

Ive got some pics of my pack building:
http://www.terrorhurtz.com/a123/http://www.terrorhurtz.com/a123/
Should get some more info on there in the next day or two e.g. charging+balancing.

John

John, I have a Shulze Chameleon capable of charging 36V packs, how would i charge the A123s with it then?

lipodapter, because the A123 cells have a base voltage of 3,6v instead of 3,7v

http://www.slkelectronics.com/lipodapter/index.htm

(Message edited by cavecrusher on April 21, 2007)

Yup, use a Dapter. The Chamaleon is designed to switch off when the voltage starts dropping when NiCads are fully charged. This never happens on Lithiums - the voltage keeps on going up.

So the Chamaleon would just be used as a high-voltage, current-limited supply. It jacks up a standard 12V power supply to around 60 Volts.

And the Dapter will switch off when you reach 3.7 Volts per cell.

John

My chameleons ROM is upgraded to LiPo Li-ion and Li-Fe, none of these are A123?

I think the A123 are a slightly more complicated formulation of Li-Fe? :s

It looks like the Chamaleon isl 6 range of chargers with V 8.41 or later handles A123 cells:
http://www.schulze-elektronik-gmbh.de/isl6-e.htmhttp://www.schulze-elektronik-gmbh.de/isl6-e.htm

As long as it cuts off at 37V, youre fine.

John

John, I would be interested to hear if you have had anymore experience with these cells. I have since discovered that the nicads i have will not be powerful enough for my new featherweight (they got very hot, very quickly!) and I need something light but with a large capacity and hence these seem ideal.

Now I know why fans could be a nice idea in a lightweight. Would PC fans work in feathers? Like, large fans?

David, I think so, but they would make one heck of a noise, like in my home computer, even the new ones. :)

(Message edited by kodster on May 15, 2007)

I am planning on fitting some 60mm fans to keep the nicads cool but even still they heat up to ouch this is a bit hot to hold temperature in around 30 seconds.

Not too surprising when I am running a 3hp mag off them :)

Been browsing the net and come across the Xtrema charger from TME.

http://www.tmenet.com/http://www.tmenet.com/

Apparently it will handle 10 lithium cells and is usable with A123 cells. Looks like quite a nice charger.

(Message edited by woody on May 16, 2007)

Yup, the Xtrema looks good.
The Astroflight 109 Lithium charger also apparently now handles A123 M1 cells. It costs $120. Around £90 in UK model shops.

What NiCads are you using Gary? We just did another test with the Lithiums, running THz round on a nice grippy tarmac carpark for four mins, doing a fair bit of heavy pushing. Pulling up to 150 amps (briefly). And we accidentally only had three out of the four Lithium packs connected. They were only warm at the end.

With the A123 Lithiums, you will dramatically shorten their life if they get over 60 degrees C.

You should connect a 100 amp shunt (or a whattmeter - http://www.westlondonmodels.com/product1836/Astro-Super-Whattmeter/http://www.westlondonmodels.com/prod...er-Whattmeter/ or http://www.alshobbies.com/shop/lookupstock.php?pc=4870http://www.alshobbies.com/shop/lookupstock.php?pc=4870) to your battery pack to see what sort of currents you are drawing.

Just for my frame of mind, are the A123 cells under FRA rules now allowed in heavies or not?

Because for now it stated ALL lithium based batteries are allowed up to featherweights only.

From experiences they have had with the Victor speed controller in the states, it would seem that it is quite hard to get a fan to survive inside a robot. And those are only 40 mm fans.

No, Lithiums batteries of any type are not currently cleared for use in heavyweights.

We have been chosen as one of the teams to evaluate them for use in heavies.

Gary - note the Astro whattmeter only handles up to 70 Amps, which may not be enough for your needs. Pity those poor NiCads....

(Message edited by terrorhurtz on May 16, 2007)

the nicads that i have currently have are the Sanyo RC 2400 12v Sub C NiCads sold on overlander. Not too surprising that they are having a hard time off a 3hp mag. I am looking at running the mag off the nicads and get around 6 spin ups and the drive off some nimh i have lying around.

I wish I had the cash to invest in lithium batteries but sadly its not available at the mo. I will just have to win a few events through the summer :)

Gary you must be doing something iffy then coz Vortex used the same batteries to great success and they were fine. And also i beleive Dizzy Tilly is running 3700mah NiMhs which dont give out as much current as the RC2400 Nicad Cells but is still using them fine and lasting fights and come out only a bit too warm but there fine.

Mr Stu

Alpha has blew both the Sanyo 2400nicads and GP3700 NiMhs, the 3000nicads (Botpacks) although can handle it but weigh too much so i can only run at 12v (not 14.4v) for comps. Im looking into these lithium cells but as i only run 14.4v (or maybe 13.2 or 16.5 for these) maybe its worth me taking a different route rather then using a modded Dewalt 36v pack.

Ditto what Stu said - we used the same cells in Vortex and whilst Im sure its opponents wished it would only spin up 6 times, it would happily do a 3 min fight... what is the tension like on your weapon drive system, are you making the Mag work harder than it needs to ?

the cells in vortex came out warm but that was about it

Somethings wrong there...........

Ed
http://www.teamstorm.comhttp://www.teamstorm.com

Leo, the FRA is making its decision on the use of these batteries based on results from the Lithium testing John Reid is currently undertaking.

This was posted in the http://www.fightingrobots.co.uk/meetings.htm

Ok, thank you.

Ed, I think there are a few reasons that I am not getting full performance out the nicads.

They have been sitting in my garage since the last UK champs and after a few cycles I am noticing a difference in their performance. What doesnt help is that my charger is relatively cheap and can only do a max charge of 600mA. So I manage to get one cycle done a day with them :)

I am using a 20mm timing belt on the disc and have a tensioner in place. This was a quick job with a piece of aluminium bar I had sitting around. I am going to replace this with one of the slippy plastics to reduce the friction. I may reduce the diameter of the bar as well to give it a bit more slack.

I have however noticed that running normally, without any load, the mag gets hot after around 4minutes, is this normal or does it sound as if something is not quick right inside it?

A mag C28 150 runs warm even unloaded after a few minutes.

buy a shunt off ebay for £10 and find out what is really happening. Stop guessing. Get the facts.

(Message edited by terrorhurtz on May 17, 2007)

Well I think I have managed to find the facts without a shunt.

I took the assembly apart earlier on and discovered that the hole that the shaft passed through had been polished on one side, in other words it had been fouling slightly on the inside. I turned the shaft of the motor as well and it seemed to snag ever so slightly at one point. Took it to bits and it seems as thought the magnets have shifted around. They are bunched in two pairs across from one another. It also seems as if the armature has been rubbing on the magnets at certain points.

Looks as though I am going to have to reglue them into place.

Thanks for the advice and help btw guys, really appriciated

Nick Martin down in Oz had the problem of the magnets moving as well. IIRC, he found that regluing them only held them in place for a short period of time before theyd come off again, due to all the high impact stresses etc from the spinning bar. He talked about it in his build thread (http://robowars.org/forum/viewtopic.php?t=74&postdays=0&postorder=asc&start= 0&sid=23f9aadcd81ee1d7826f7b3d620e69f6http://robowars.org/forum/viewtopic....asc&start=0&si d=23f9aadcd81ee1d7826f7b3d620e69f6) but its been a while since I read it so I cant remember if he came up with a solution to solve it (think he was looking at something similar to the Bosch mod kits)

He also had problems when trying to reglue it of not getting the magnets lined up properly because as soon as he lowered the magnet into the can, it would just pull against the side before he got a chance to line it up.

If youve got some spare time (when youre not studying :lol:), the thread makes good reading (although it is 130+ pages)

(Message edited by K_C_R on May 17, 2007)

We have had the same problem also. Glue does work, he must not be doing it right, the only time it will fail is if you overheat the glue and it soffens too much. What we did was to make some end caps and put these a few mm away from the magnet edges and the fill the casing with glue. Repeated this 4 times to fill all the inside of the casing with glue, then using a file made room for the 2 bolts again and its done.

You must be careful to set the timing correct again after or it will heat up and waste too much power just as before.

We also had problems with the cases twisting (ie altering the timing) causing the same effect. So we have now also keyed the end caps to the case as well.

Mark, can you recommend a glue to use or with your bog standard araldite out of B and Q work?

I have heard scotch 2216 mentioned in this article here http://www.madoverlord.com/Robots/MAGMOTORREPAIR.thttp://www.madoverlord.com/Robots/MAGMOTORREPAIR.t but have not been able to source a UK supplier.