Lithium cell tests

[terrorhurtz]

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)

[grant_ploughbot]

Lithium cell tests

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.

[knightrous]

Lithium cell tests

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

[terrorhurtz]

Lithium cell tests

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

[leorcc]

Lithium cell tests

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

[stu]

Lithium cell tests

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

Mr Stu

[typhoon_driver]

Lithium cell tests

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)

[knightrous]

Lithium cell tests

Hi John,

Ive been ebay whoring them from the USA. I currently dont have the cells in my possession (shipping is a pain ) 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

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

[terrorhurtz]

Lithium cell tests

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

[leorcc]

Lithium cell tests

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

[cavecrusher]

Lithium cell tests

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)

[terrorhurtz]

Lithium cell tests

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

[leorcc]

Lithium cell tests

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

[ewan]

Lithium cell tests

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

[terrorhurtz]

Lithium cell tests

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