Lithium Titanate (LTO) battery bank build.

I am using Alterairnano cells. A 3.5ah military cell. Rated for 50c+ discharge, and a 50c charge rate. I have three 35ah batteries I have built to date.(for the Suburban) I built about a dozen others, with similar 11ah cells. I have one more 35ah battery pack to build, but I don't really need it now. So I am holding off until after World Finals.

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That is the best info I  have read yet on LTO vs Lithium iron phosphate. I was thinking of going with life4poe cells but was reading that even with the safety valve popping if something goes array it will cause the rest of the cells to fail as well and isn't  jy and limitless and ds18 use the life4poe cells? I'm thinking with the life span and safety of LTO I'd  just want to go with them. So no BMS is needed for this type of build?  I am just wanting to run 3k-5k rms for a while of course with it running. So would 80ah suffice my system with the LTO bank and honestly I'm  not in it like y'all are just daily driver and no comps.  Although I  wouldnt mind. I can't justify spending money on chargers and stuff. But definitely in need of 80ah worth so 3p6s. Could anyone send me fully charged cells ready for assembly? I think I'd need 18 at a decent price. Still be cheaper this way than an agm and h/o alternator.  Thanx for the info, that's  really helpful. 

 
Interesting, can you even get those new or are all the ones on the market reclaimed from EVs?   Similar style to the Toshibas.  Busing that style cell seems complicated but the top performers are that style.
These are brand new cells. As are the 11ah cells from Kokam. Bussing *****, but the end results are worth it to me.

 
So no BMS is needed for this type of build?
I'm saying it's not really possible.  What will you use that can pass 300A to charge and 500A or more discharge that can instantly open the circuit if it sniffs out trouble?   Best you could do is possibly rig up something to sniff out voltage in all cells real time and output to a display so you can see if you have a dud cell.  There is one off-the-shelf solution out there that supposedly outputs via bluetooth but reviews are very hit or miss and everything in the GUI is in Chinese.  Anyway, there's really nothing pre-made that'll do what we need and almost all the stuff that does exist (at laughably low current levels) is all designed around 3.4V cells

So would 80ah suffice my system with the LTO bank
On paper, yes.   10C rating means they can deliver 10X the amp hour rating so 80AH can deliver 800A.  Of course the lower multiple you try to use the better and longer they'll perform.  I really need to get one installed and I'll get a far better feeling for real world results.

Could anyone send me fully charged cells ready for assembly?
Cells arrive @ 40% SOC (state of charge).   Considering your alternator will never exceed 10C you shouldn't need any fancy charging to keep them safe.

But definitely in need of 80ah worth so 3p6s
3p6s would be 120AH of these cells I have. 

Still be cheaper this way than an agm
Yes, assuming they last for 3 years you're certainly ahead of the game there considering you'd probably want at least 3 group 31 batteries to really hang with a 5K amp.   Mind you, you get zero warranty and you have the PITA factor of having to assemble things yourself.  I'm a bit concerned that we're also leaving some capacity on the table with 12V application since getting the cells up to 100% SOC would require charging 15.5 or a hair over that which many amps (and possibly some factory electronics won't like).   Optimum would be going 18V and pulling off a terminal at 5S (which would sit around 12.2V) to run everything besides your sub amp.  I may do this at some point when I have time to send out my alternator for a tune up and install an external regulator and more cable to make that happen.

These are brand new cells.
Seems the ones floating around at the consumer level are "b grade", though if you're not a proper manufacturer buying tens of thousands from the actual factory and with someone there to confirm everything who else is getting anything different?

Anyway, specs claim only 10C rating on those.   Have you tested more?

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Yes,the 11ah cells are rated at 10c. I'm not running those. (I have, but I'm not now since I have my 35ah banks done). But they have been tested in our use to do 17-23c for 30 sec, to 12v.  I'm running a 3.5ah cell that is no longer available.That was designed for primarily military use. They were brand new in factory sealed cartons. Mine actually came at 0.00v, I had to charge them all.  Are factory rated for 35-50c+ continuous(mainly temp dependent) and 70c 45 second bursts. We have tested them to 130c for 15 second bursts. They do make two or three balancer/chargers with LTO profile already installed. Icharger X6 is one of them. ISDT BG 8S will work if you are charging at 15v+.  And  Chargery makes a unit with an LTO profile as well. ALTHOUGH, I have been running my LTO banks for over half a year now, with no balancer, and my cells are still within .01v of each other. 

And I'm charging at 15.6v to take full advantage of my cells capacity.

 
Wow this is the most informative thread so far that I  have read involving lithium. Y'all  definitely know your stuff and know far more than me. I  am now having difficulty staying up with the talk.

from what I  have gathered the cells you are running hISPLS would  not do a 14.4v charge? The one's I  left a link on with 5s would be 14.4v and 3p (your right my math was off) 120ah should be able to sustain  my system of 300-500 amp discharge for around  5mins at a time since they are technically discharging and charging rapidly.

 I  am wanting to avoid a H/0 alternator (as research into these cells says they work better with a smaller amp charge) not to mention the money saved from buying a $600 350amp alt (as well as at least $600 in agm) and then weight (suspension issues) and space to put all these.

The LTO seems like the best investment to get me by for a few yrs until they have mastered this technology and have mainstreamed production for car audio  applications.

I plan on getting a new vehicle and will be out the mula for the h/0 alternator as the lto cells can follow me from vehicle to vehicle install.

 Back to what y'all  are talking about. The SOC I thought when they are charged would be what they say they are rated on the cells voltage (ex. 3.5 volt cell @100% SOC would  be 3.5volts) I'm  not sure about all the SOC specs. Also the BMS that you were mentioning in order to work for our applications would be far to costly and large to be practical is what I  gathered.  

In that case could we (I) run a 120ah for a few yrs without a bms system and be okay and everything work fine. Cuz if a cell fails in an agm then the whole battery is destroyed, but usually has (warranty). these cells however,  would act the same as a agm cell in a battery bank and then there is not warranty and being out all the mula for those cells.

y'all  have far surpassed my knowledge in this field. Boominburban I  have always wondered if you could use those type cells in car audio applications. Looks good and alot juice. Anyway I  was hoping to build my own and not sure that I  want to now as there is so much to learn and not to mention special chargers n what not. Just now wanting the 120ah lto.

Hispls, as u mentioned they come 40% charged. So if I  hooked these up just like hooking another battery  up in my system couldn't  I  just hook up a resister like installing a capacitor for the first time? If so, would the one they sent me with the nvx 10 farad hybrid cap work for charging these?

As you were mentioning in  the 15.5v range (not worried about that as my amps can handle that) but  wouldn't  that possibly back feed into battery and even alternator and destroy it all? How would u isolate that higher charge. Not sure if I forgot a few questions as I have many and am really trying to understand all this to start making my own (safely) someday soon. 

 
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the cells you are running hISPLS would  not do a 14.4v charge?
All LTO cells suffer from the low voltage limitation so you're sitting at an oddball voltage.  Cells are nominal 2.3V max charge 2.7 so your options are NEVER go above 14.4V charging (and have much of your usable power happening <13V) with 5S or you go 6s and either charge at 15.5 or leave a bit on the table there never fully charging them.  Most factory charging systems will put out 14.8 at least occasionally so you'd want to externally regulate to be safe if you're going 5P, of course if you're going to externally regulate why not do 6s or even 7s, pulling off a terminal at 5s for anything that won't like >15V

120ah should be able to sustain  my system of 300-500 amp discharge for around  5mins at a time since they are technically discharging and charging rapidly.
Bear in mind you're playing with the car running so 80A or whatever the alt can spare is always being used first then dipping into reserve.  Depending on your music the average power used over time is quite a bit less.   "Fast" charging depends on being able to dump a ton of current into the cells.  80A charge current would still take an hour to charge 80AH (assuming no losses).

The SOC I thought when they are charged would be what they say they are rated on the cells voltage (ex. 3.5 volt cell @100% SOC would  be 3.5volts)
There's minimum, maximum and nominal charge ratings on each.   Nominal being the average of where 80% of your usable power is coming from.... ideally you do not want to charge at maximum especially without some very precise management system; consider just a hair over max and you start prematurely chipping away at life expectancy.

In that case could we (I) run a 120ah for a few yrs without a bms system and be okay and everything work fine.
That's my plan.  Yes, one cell going tits up would wreck the rest of the bank pretty fast, as far as all the tests have shown there isn't any catastrophic (read fire or explosion) type failure possible with LTO cells.   Consider also 50% of my cost into this is hardware, so if I had to buy all new cells I don't need to buy bolts, washers, or copper again.

So if I  hooked these up just like hooking another battery  up in my system couldn't  I  just hook up a resister like installing a capacitor for the first time?
Why?  You'd be yanking out any lead battery anyway (they'd always be fighting each other) and your alternator could only possibly deliver 1C.   If you had quad HO alternators you might need to worry, but as it stands you could charge 120AH LTO bank with 1000A in @ 5 minutes and they'd be fine.   The electric busses in China use small-ish banks and recharge as passengers load and unload at each stop.

As you were mentioning in  the 15.5v range (not worried about that as my amps can handle that) but  wouldn't  that possibly back feed into battery and even alternator and destroy it all?
So there's the rub.   Who knows if the ECU on your car smokes at 15.4V?   IF some other bit in the car will react poorly?   I'd assume there's enough wiggle room from the factory that things can survive.  I've had issues with my regulator before and had 20V charging for a minute, under the hood battery was boiling but apart from the lights looking extra bright nothing seemed to go haywire.  But I'd hate to say "oh yeah, run your car at 15.5V and you'll be cool" then you smoke some hidden computer.

Anyway, options are 6s and leave some on the table (charging with stock charging system), or externally regulate.  If you're externally regulating  best to confirm that won't hurt any of the car's electronics.  I'd expect just about any alternator could charge 15.5 without trouble.

 
I don't think 2000-3000 cycle is accurate for lifepo4 unless we're talking about <50% DOD and not full cycles. If it was full cycles that'd be 10+ years considering AGM's have 200-300 80-100% DOD cycles and last 3 years reasonably and up to 5+ if maintained. The claims I see are that they'll last 2000-5000 cycles with 80% capacity left but theres 0 mention of DOD and their C usage over their lifespan.

The LiFePo and LiPo I've worked with generally are used up to 70-80% capacity and discharged on average to 25-40% and we get approximately 150 cycles out of them but they are worked HARD. Near max C rating for charge and discharge and high heat. Obviously we could get up to 250 cycles out of them if we went down to ~50% capacity but that hurts flight time and is just not worth it. 

However, if the ratio is still the same and you get 2-3k high DOD cycles that's a major improvement and you could expect the cells to last 10-20 years. Obviously this is just an estimate and real research is needed but I don't think any of us have the funding for that lol plus 10-20 years in electric busses as you mentioned certainly seems like an appropriate cycle life you could sell. 

edit: I looked a little deeper and the claims from companies do say those cycle numbers are at 100% DOD which is strange to me because I've never seen a cell last that long in the real world. They're still leaving out the charge/discharge standard used during those cycles so I'm hesitant to believe it

 
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I looked a little deeper and the claims from companies do say those cycle numbers are at 100% DOD which is strange to me because I've never seen a cell last that long in the real world. They're still leaving out the charge/discharge standard used during those cycles
Dig a little deeper, I've found them for various LTO and LiFePO4 cells and they're generally rated at 20% of the max C rating.   Perfect world numbers obviously.  Of course if you don't drive every day or don't cycle them that's in your favor too and ideally we size them that we're not running them at 10C outside of a couple dozen competitions per year.

 
Dig a little deeper, I've found them for various LTO and LiFePO4 cells and they're generally rated at 20% of the max C rating.   Perfect world numbers obviously.  Of course if you don't drive every day or don't cycle them that's in your favor too and ideally we size them that we're not running them at 10C outside of a couple dozen competitions per year.
It could be that I was working with low grade cells also. Even if real world we get 50% of the manufacturers claimed numbers that's fantastic. I wish more of this marketing would be standardized and talk about average DOD during testing and preferred charge/discharge that gave those numbers as well as temperature ideal resting charge/ storage charge etc

 
How does the rest of the vehicle's electronics like that?  Or do you pull a terminal at 5S?   Why not up it to 18V ?  
I'm running a 1993 Suburban w/ 5.7L TBI. Seems it could care less if I'm charging at 15.6 ish. I've already swapped to LED headlights, so that isn't even an issue. I'm running Taramps, so I'm limited to 16v for now.

 
It could be that I was working with low grade cells also.
You're dealing with different chemistry cells hopefully if you're doing drones.  Even the e-bicycle guys are mostly scoffing at the high weight and size of LTO and even LiFePO4, can't imagine the weight of these is worth the tradeoff for applications where size and weight are critical.

I'm running a 1993 Suburban w/ 5.7L TBI. Seems it could care less if I'm charging at 15.6 ish. I've already swapped to LED headlights, so that isn't even an issue. I'm running Taramps, so I'm limited to 16v for now. 
Makes sense.   If I'm going to externally regulate I'm going for 18, which might happen if I have the time.  I do have another 6 cells unused just in case.   Stephen said his amps won't like >15V so I'm not going to push my luck there.   I don't know what we'll do in my brother's car.  We'll have to see how high it charges with whatever is in there and see if he thinks it's worth externally regulating.

Going to try to get these in tomorrow if I can get someone to help.   Not exactly sure what I'm going to do to box them in so might just be something quick and ugly.

 
Umm.....so after reading all that it sounds like the best thing to do is run either 5s or 6s and 3p for 120ah bank and keep the cells charged  at nominal voltage. I won't  have any this variable regulated. Rather, just have a volt meter hooked up to bank to just keep track of banks voltage. 

So what your saying is my stock 120amp alternator should only charge up to a possible 14.8 volts max? So with 6s in cells it won't  hurt the bank seeing that voltage? Probly won't  hurt even having 5s in my vehicle as I  have a xs power d3400 agm under hood and this bank will be in trunk on amp rack. Please correct if I'm  wrong. So I  think the most this bank would see is 14.4v as that is the most I  have seen my agm see. 

You mentioned you have half of funds tied up in busbars and hardware. You went with copper busbars (expensive). Why not 6061 aluminum bars? What type of hardware? I was thinking all stainless steel.  Order my busbars from  remmington undustries. Super cheap.

I am wanting to order some cells. What would you recommend?

 
You're dealing with different chemistry cells hopefully if you're doing drones.  Even the e-bicycle guys are mostly scoffing at the high weight and size of LTO and even LiFePO4, can't imagine the weight of these is worth the tradeoff for applications where size and weight are critical.

Makes sense.   If I'm going to externally regulate I'm going for 18, which might happen if I have the time.  I do have another 6 cells unused just in case.   Stephen said his amps won't like >15V so I'm not going to push my luck there.   I don't know what we'll do in my brother's car.  We'll have to see how high it charges with whatever is in there and see if he thinks it's worth externally regulating.

Going to try to get these in tomorrow if I can get someone to help.   Not exactly sure what I'm going to do to box them in so might just be something quick and ugly.
Why not put them in an ammo can if they can fit? 

 
You have taramps? Do u like those? I was going to start with the 3.5k taramps I  think it was. Just got nervous with how finicky the brazilian amps are. Then I  was youtubeing and ran across bid d wiz review on wolfram audio a old school Korean board and saw they were on sale and so picked up thw wolfram 3k rms for 359$. Thought it was a steal myself. Lol now have there a/b 4 channel as well.

 
I am using Alterairnano cells. A 3.5ah military cell. Rated for 50c+ discharge, and a 50c charge rate. I have three 35ah batteries I have built to date.(for the Suburban) I built about a dozen others, with similar 11ah cells. I have one more 35ah battery pack to build, but I don't really need it now. So I am holding off until after World Finals.

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question. Why don't  they make single cells in higher voltages such as 6v/12v etc? Wouldn't  it make more sense to have less cells in series and more in parallel for more ah and less cells altogether. 

To my understanding wouldn't  6s3p still only be 120ah of juice. So in that case the other parallel  packs are doing nothing to provide more juice? Is that correct? Or does each parallel bank have 120ah of continuous discharge but u can't  add them together? It's  confusing. It seems to me that other five parralel groups are wasted. 

 
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question. Why don't  they make single cells in higher voltages such as 6v/12v etc? Wouldn't  it make more sense to have less cells in series and more in parallel for more ah and less cells altogether. 

To my understanding wouldn't  6s3p still only be 120ah of juice. So in that case the other parallel  packs are doing nothing to provide more juice? Is that correct? Or does each parallel bank have 120ah of continuous discharge but u can't  add them together? It's  confusing. It seems to me that other five parralel groups are wasted. 
In the case of 6s3p you pretty much have 3-6cell 40ah batteries which are wired in series to increase the voltage to typical 12v automotive levels. You then wire the sets in parallel to combine the 3 40amp hour batts into essentially 1 big 120amp hour batt..

It's the same way when using super capacitors. 

 
In the case of 6s3p you pretty much have 3-6cell 40ah batteries which are wired in series to increase the voltage to typical 12v automotive levels. You then wire the sets in parallel to combine the 3 40amp hour batts into essentially 1 big 120amp hour batt..

It's the same way when using super capacitors. 
I  understand that. Wouldn't  it make more sense to have less cells in series to reach nominal voltage desired (12-16v)?

For example either 5s or 6s now each cell being 40ah would be 3 in parallel to reach 120ah. You would need 5 or 6 groups in parallel. Now to me it seems like a bunch of wasted cells as you cannot add each parallel group  toether to reach more ah. 

Would it not make more sense to have just 1s or 2s that would reach desired voltage as stated above ( if they made 6v/12v cells) be less in series and be able to have less cells in series and parallel and in terms save money and space. 

Why are they not made like that?

It seems to me there would be way more pro's in less cells used to make battery bank. Less things to go bad. Only downfall is if one went bad system would drop a large amount of voltage.

 
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