# Looking for 10-15C rated LiFePo4 Prismatic Cells



## Monstarr (Feb 10, 2016)

Plug-in batterypacks normally have high power capacity but around 10C the most I reckon. These are not LiFePO4 for a reason I guess.
You better want NCA (Panasonic/Sanyo) then NCM. Thermal safety is less though.
Prius plug-in packs have NCA cells for example.

Or try RC lipo from a good brand if you really want very high C rating.. 

In any case, you better know what you are doing with those currents. Do not spare cost on a cooling system.


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## RyanM923 (Mar 15, 2016)

Yeah I have been talking to Carl over at electric car company and he's been a ton of help trying to get something together for what I need. I'm using it for car audio, which needs high discharge for periods of time. I've been talking to him about using those 70ah blue CALB cells and just testing it out to see what I can get out of them. If they work well I'm wanting to start providing lithium batteries for the car audio market, at a more affordable price than the current offerings.


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## RyanM923 (Mar 15, 2016)

Just found out about LTO tech...how legit is this? The discharge rates are exactly where I need them, and the cells look very easy to wire via buss bars...might have to order a set of these along with a 4-pack of the blue CALB SE70 and do some comparison testing. 40ah vs 70ah, but different discharge rates...it'll be interesting so see what happens with a 500amp load. 

Only down-side I see to these LTO cells is the voltage...with the average car alternator running between 14-14.5V, and with aftermarket high output alts capable of raising voltage to 15-15.5 in some cases, I'm kinda stuck in between needing 5 or 6 of the LTO cells, since max charging voltage of 5 is 14V, and 16.8V for 6. I feel like I'd be putting them in danger with 5 cells, and not getting a complete charge with 6. 

http://www.ev-power.eu/LTO-technology/Lithium-Titanate-Oxid-Battery-Cell-LTO-2-4V-40AH.html


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## pm_dawn (Sep 14, 2009)

Hi !

What about A123 pouches in parallell.
They will provide 10C-15C.

Regards
/Per


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## ishiwgao (May 5, 2011)

RyanM923 said:


> .... aftermarket high output alts capable of raising voltage to 15-15.5 in some cases, I'm kinda stuck in between needing 5 or 6 of the LTO cells, since max charging voltage of 5 is 14V, and 16.8V for 6. I feel like I'd be putting them in danger with 5 cells, and not getting a complete charge with 6.
> 
> http://www.ev-power.eu/LTO-technology/Lithium-Titanate-Oxid-Battery-Cell-LTO-2-4V-40AH.html


Hello and welcome to the forum. I'm guessing you're a little new to batteries, or at least lithium batteries. 

batteries in general have a charge and discharge curve. it differs for battery chemistry, battery types etc etc. for each type, if you want to keep it simple, you can assume both to be the same curve.

I've just did a simple google search on LTO battery curve, and one would look something like this. http://img.deusm.com/eetimes/2015/01/1325358/ivc-bats-0014-05.jpg. let's focus on the blue line at 50A (1C charge rate). if you notice, while max voltage is 2.8V, you're usually at >95% by the time you reach 2.6V. the mechanics of why it is so is due to battery chemistry etc, but you don't need to know this if you are not that interested. so basically, if you use 6 LTO cells, charging at 2.6V per cell gives you 15.6V, just a little out of the range of the 15.5V from aftermarket alternators, but I'm sure it'll be fine if you want to go that route.

while i've given a very generic case, please check the exact charge curve for the above mentioned battery that you are intending to purchase to work out the exact voltage.

just an ending note, charging at lower voltages is also good for the battery. usually people try to keep the battery within 20-80% of its charge to ensure longer battery life, and not charge or discharge to the max.


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## okashira (Mar 1, 2015)

I have a bunch (332) of A123 20Ah pouch cells that are like new. They are 20C rated. They are taken from a Spark EV with 1400 miles on it. They say the pack cost GM $13k...

One cell is rated for 500A burst. Three in parallel could do over 1000 amp and 60 amp hour capacity.


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## RyanM923 (Mar 15, 2016)

Thank you guys so much for the info, I am new to the lithium world of batteries, at least the DIY sector of it. I will need to read up on those a123 pouches and see if those will work. I need something that doesn't need any kind of cooling since I plan on making a battery-esque looking case for final production in order to fit the look of the car audio market.


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## RyanM923 (Mar 15, 2016)

Do these A123 pouches need cooling? I've been trying to find some info on them here and online but haven't seen anything regarding the need for a cooling system.


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## Karter2 (Nov 17, 2011)

Cooling depends on your use, duty cycle, ambient conditions , etc
If you check the A123 site, they have those same cells in packs...ready to replace conventional car batteries.


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## RyanM923 (Mar 15, 2016)

Karter2 said:


> Cooling depends on your use, duty cycle, ambient conditions , etc
> If you check the A123 site, they have those same cells in packs...ready to replace conventional car batteries.


I did see that but I'm looking to do something custom made, unique looking, etc. I just don't want it to look like a run of the mill car battery.


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## RyanM923 (Mar 15, 2016)

Just bought a 4-pack of the CALB SE70 prismatic cells from Carl over at ECPC to do some testing on and see what I can get out of them. The fact that the A123 20ah pouches do not have normal threaded inserts for terminals is a little worrying, since It's just a pain to get everything wired up properly versus just using buss bars with the larger prismatic cells. I think going with a larger prismatic cell that I can still put a solid amp draw on, while also having the ah rating to provide that power for a longer period of time, may be the way to go...although I'm sure eventually I will try out the A123 pouches or some LTO cells.

I appreciate all the help, chime in with anything else you think I should know.


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## Semper Vivus (Apr 13, 2011)

It seems that weight is not the first priority for your application and you want to go without active cooling...and need high C-rates.
That is the ideal application for LTO in my opinion. LTO has no problem with running at high temps, let's say up to 50 degree celsius. Doing that with other Lithium chemistries for a long time, will damage your battery.


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## RyanM923 (Mar 15, 2016)

I will definitely have to look into those LTO cells, on issue is the voltage like I mentioned earlier. nominal puts me in a weird inbetween area when wanting to use (at least I think it does). Here is the cell I was looking at, although I am sure there is some other more cost effective option: http://www.ev-power.eu/LTO-technology/Lithium-Titanate-Oxid-Battery-Cell-LTO-2-4V-40AH.html

If max charging is 2.75V, then I'm looking at 16.4V with 6 of them for an ideal complete charge. Now, how much would it make a difference if charging voltage only got up to 15-15.5V? In a car audio situation where it will only be used when the car is on, alternator charging...is it really an issue if it's not getting the complete charge it's capable of and instead getting something like 50-70%?


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## RyanM923 (Mar 15, 2016)

Also, sent an email to CALB is this is what I got back.


Dear Miskin, 

We thank you for your letter inquiring about our lithium ion batteries. As requested, we take pleasure in recommending you our latest battery with higher discharging rate, CAM20, for this battery, the max continuous discharging rate will be 10C, which means 200A. Here i enclosed a catalogue for your reference.Shipment will be effected within 20 days after receipt of the full payment by T/T. 
We are manufacturing various capacity LiFePO4 batteries, enclosed a product catalogue for your reference. We hope some of them meet your taste and needs. 
If we can be of any further help, please feel free to let us know. Customers' inquiries are always meet with our careful attention. 

Sincerely, 

Mike


I tried to email him back with some questions and ideas, and my yahoo account says that it's no a real email haha.


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## ishiwgao (May 5, 2011)

RyanM923 said:


> If max charging is 2.75V, then I'm looking at 16.4V with 6 of them for an ideal complete charge. Now, how much would it make a difference if charging voltage only got up to 15-15.5V? In a car audio situation where it will only be used when the car is on, alternator charging...is it really an issue if it's not getting the complete charge it's capable of and instead getting something like 50-70%?


hey. please look at my previous post. i mentioned that 15.6V gets you 95% of charge, or thereabouts.


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## RyanM923 (Mar 15, 2016)

Ah yes I must have overlooked that. Now I guess the goal is to find an affordable one from a reputable company. I was talking to Carl about these 20ah LTO cells and he gave me a half hour horror story of the LiYuan "factory" he went to visit in China. I hate how mysterious and questionable these companies can be to the untrained eye. 

Does anyone here have any experience with certain LTO cells?


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## Karter2 (Nov 17, 2011)

Be careful with claimed "maximum discharge" rates unless there is data to back it up..IE is it continuous ?, what voltage sag at the claimed rate ?, temperature increase ? , effect on cycle life ?, etc.


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## RyanM923 (Mar 15, 2016)

Yeah I realize that posted specs are jot always true, which is why I was planning on testing out 3-4 different cells to see what works best, put them through the ringer and see what shows me the best characteristics for what I'm wanting to use them for. I do appreciate your help, I'm probably getting some a123 cells as well.


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