Lithium Titanate (LTO) battery bank build.

[hispls 5,000+ posts]

manufacturing is vital for longevity of LTO cells

I think this is true for any cells.    Short of buying enough quantity to be able to oversee production and QC yourself and having the manufacturer scared to give you any duds for fear of losing a huge contract there's nothing us regular blokes can do besides hope for the best.   



Short video.   Sorry it's so shaky, but as you see voltage barely moves.  Started at 14.0 played hard for a bit before even taking the vid.   Did I say how amazed I am at how well these cells hold up my voltage?

 

[L1ttlet]

2 hours ago, hispls said:

I think this is true for any cells.    Short of buying enough quantity to be able to oversee production and QC yourself and having the manufacturer scared to give you any duds for fear of losing a huge contract there's nothing us regular blokes can do besides hope for the best.   

I think your right on that statement.  We need to get a big group buy going. I'd  be willing to get in on that, everybody saves and as u stated above, manufacturer would definitely pay attention. That's  240ah? That's  a big battery cap. Your voltage to stay like that is awesome. How many watts is your system? Did you habe that cranked or test with burps? I need to find some competitions here in the dfw area to enter.  Be awesome to see builds like  yours in person.

 

[L1ttlet]

I've posted the name of the company I bought from.  I would totally recommend them.  Not sure if they have a large minimum order though?  Perhaps try to get a group-buy together?  I got a couple lower per-cell quote but those companies seemed a little dubious.   I'd vouch for the guys I dealt with anyway, I'm very pleased with product and service.

For the size and cost I'd suggest going "overkill" with 18 cells.  Your voltage will barely budge with a 5K amp on there and you're running things way below anywhere where you'd stress anything.   Honestly you could get away with 12 I suspect but for the price of overkill here you're still under the cost of a "just getting by" AGM bank!

"Charger" is your alternator!  This isn't a solar bank or Tesla car where you plug it into the wall til it's topped off then go out and run it dry, then repeat.  If you think you can find something that will manage this real-time, at the current draw you need for even 5K good luck.  IMO best you could hope for is just to monitor each individual cell voltage so you can quickly remove and replace if something goes out of spec.  My plan was to just pull all the cells once or twice a year and check each individually to make sure they all rest at the same voltage.   Anyway, I did a little digging into that, you MUST find something that's meant for 2.3V nominal cells (possibly things built for supercapacitors will work).   I'm just taking my chances, but if anybody finds a good montioring solution please update here.

Anybody doing LTO now is trailblazing so there is some risk.   I did do a fair bit of the work for you guys already finding a legit seller on Alibaba.  As far as cycle life only time will tell, but I'm only getting 2-3 years out of AGM and I don't think people expect a lot more out of LiFePO4.

Ah okay.  I can just check the voltage on these with a ddm? I thought like with lithium cells ( these being almost the same) I'd  have to put these on a special charger for each cell and make them match before I  can put in battery bank?

 

[L1ttlet]

I've posted the name of the company I bought from.  I would totally recommend them.  Not sure if they have a large minimum order though?  Perhaps try to get a group-buy together?  I got a couple lower per-cell quote but those companies seemed a little dubious.   I'd vouch for the guys I dealt with anyway, I'm very pleased with product and service.

For the size and cost I'd suggest going "overkill" with 18 cells.  Your voltage will barely budge with a 5K amp on there and you're running things way below anywhere where you'd stress anything.   Honestly you could get away with 12 I suspect but for the price of overkill here you're still under the cost of a "just getting by" AGM bank!

"Charger" is your alternator!  This isn't a solar bank or Tesla car where you plug it into the wall til it's topped off then go out and run it dry, then repeat.  If you think you can find something that will manage this real-time, at the current draw you need for even 5K good luck.  IMO best you could hope for is just to monitor each individual cell voltage so you can quickly remove and replace if something goes out of spec.  My plan was to just pull all the cells once or twice a year and check each individually to make sure they all rest at the same voltage.   Anyway, I did a little digging into that, you MUST find something that's meant for 2.3V nominal cells (possibly things built for supercapacitors will work).   I'm just taking my chances, but if anybody finds a good montioring solution please update here.

Anybody doing LTO now is trailblazing so there is some risk.   I did do a fair bit of the work for you guys already finding a legit seller on Alibaba.  As far as cycle life only time will tell, but I'm only getting 2-3 years out of AGM and I don't think people expect a lot more out of LiFePO4.

My bad. I just now saw the pictures and details. I don't  think my page loaded correctly or user error on my part. That's  a bad ass build. So your bank is starting your truck and running all electronics on it? Also what is your  bank hard to tell 6s6p? The pic of it looks confusing to me of the layout but can see the 6p. 

 

[wew lad 5,000+ posts]

Ah okay.  I can just check the voltage on these with a ddm? I thought like with lithium cells ( these being almost the same) I'd  have to put these on a special charger for each cell and make them match before I  can put in battery bank?

That's easy to do by simply putting the caps in parallel and checking that they equalize to the same DCv before putting them in series, I do the same thing with banks of caps. After 6-12 months I'll check if the cells are still within a tenth of a volt and so far no problems yet. I can see it being more of an issue with batteries due to capacity and ESR having more of an effect

 

[winkychevelle 10+ year member]

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.

Pretty much battery chemistry determines the voltage of each cell. And currently not realistic chemistry is available that would allow for such voltages. 

 

[L1ttlet]

That's easy to do by simply putting the caps in parallel and checking that they equalize to the same DCv before putting them in series, I do the same thing with banks of caps. After 6-12 months I'll check if the cells are still within a tenth of a volt and so far no problems yet. I can see it being more of an issue with batteries due to capacity and ESR having more of an effect

Awesome. Good to know. And what if one was bad. Just check each cell in that parallel bank with ddm to determine the bad one? Also I  wouldn't  need that special charger for the first initial charge of each cell at all? 

So easy diy instruction, if I'm  not mistaken

1. Research, buy lto cells.

2. Hook however many cells in parallel as desired. 

3. Use ddm and check each parallel bank and make sure they are congruent. 

4. Hook parallel banks up in series until desired voltage is meant.

5. Hook up whatever size cable to positive end of bank and negative to far negative battery.

6. Bank is complete and ready for use. Check bank every 6months to 1yr.

 

[L1ttlet]

Pretty much battery chemistry determines the voltage of each cell. And currently not realistic chemistry is available that would allow for such voltages. 

Ah okay. Makes sense. Well when are able to make large voltage cells it'll  save everyone a ton of money. Lol

 

[wew lad 5,000+ posts]

Awesome. Good to know. And what if one was bad. Just check each cell in that parallel bank with ddm to determine the bad one? Also I  wouldn't  need that special charger for the first initial charge of each cell at all? 

So easy diy instruction, if I'm  not mistaken

1. Research, buy lto cells.

2. Hook however many cells in parallel as desired. 

3. Use ddm and check each parallel bank and make sure they are congruent. 

4. Hook parallel banks up in series until desired voltage is meant.

5. Hook up whatever size cable to positive end of bank and negative to far negative battery.

6. Bank is complete and ready for use. Check bank every 6months to 1yr.

I should have said this, I just put them in parallel so they start at the same voltage before putting them in series and then charging it with a normal 12v system. I don't charge them at the lower cell voltage as that would require a low voltage charger or a variable voltage power supply. 

So put all caps in parallel so they all read, as an example, 2.3v. Put them all in series and connect it to my normal 12v system which will charge the entire bank. 

After a few current draws you can individually check each cell, even if still in series, for lower/high voltages indicating a bad cell with higher ESR 

 

[L1ttlet]

I should have said this, I just put them in parallel so they start at the same voltage before putting them in series and then charging it with a normal 12v system. I don't charge them at the lower cell voltage as that would require a low voltage charger or a variable voltage power supply. 

So put all caps in series so they all read, as an example, 2.3v. Put them all in series and connect it to my normal 12v system which will charge the entire bank. 

After a few current draws you can individually check each cell, even if still in series, for lower/high voltages indicating a bad cell with higher ESR 

Saweet this will work great. So I  have a 12v powermax 55 amp power supply. So make the power bank first. So for my application 6s3p and hook up to power supply check voltage with ddm while charging and then install. After about the first wk or a day of heavy playing check each cells voltage, is that right?

 

[hispls 5,000+ posts]

How many watts is your system? Did you habe that cranked or test with burps?

Big amp is """rated""" 4000W @ 1 ohm.  Might be a little over-rated.  (see picture).  Not going to speculate too much just in case I ever try to get into a rated power limited class.  My fronts amp is 150X6, honestly rated.  I did not try burp yet, but I went very hard on it with music for a while.  Use that would drop me over 2V before is dropping only .2V.  Anyway, what I was doing was far more strenuous than 3 second burp.  That will get a bit worse when it starts getting sub-freezing up here but as the cells warm up from use and just running the heater they should perform as normal with some use. 

Awesome. Good to know. And what if one was bad. Just check each cell in that parallel bank with ddm to determine the bad one? Also I  wouldn't  need that special charger for the first initial charge of each cell at all? 

So easy diy instruction, if I'm  not mistaken

1. Research, buy lto cells.

2. Hook however many cells in parallel as desired. 

3. Use ddm and check each parallel bank and make sure they are congruent. 

4. Hook parallel banks up in series until desired voltage is meant.

5. Hook up whatever size cable to positive end of bank and negative to far negative battery.

6. Bank is complete and ready for use. Check bank every 6months to 1yr.

If you wanted to worry about it, charge 6S banks individually to equal voltage resting then parallel them up.  In the series they will share the charge equally.  Cells would want to be checked individually for matching voltage.  Not sure if or how much testing parallel banks would show if one cell was self discharging or weak.

Otherwise, that's about the size of it.  You will want to remove any AGM batteries in your vehicle, they will be very parasitic.

Well when are able to make large voltage cells

I wouldn't hold my breath.  At this point if they could even make 3V cells they'd be doing it.  All these super storage high current technologies (supercaps, fancy batteries) seem to be voltage limited.  Even the old technology is low voltage cells..... your standard lead acid/agm/etc. car battery is just 6 2V cells still.  Consider also from manufacturing standpoint end users of batteries want all kinds of voltages so if you only made a 12V cell you'd lose the business of everybody who needed 2, 4, 6, 8, and 10V supplies.   Yes series-ing piles of cells is inconvenient for complexity but offers more flexibility and of course if you really cared you could use some monitoring or smart charging to keep an eye on things and replace only cells as needed.... replace only one cell out of a 6 cell bank if only one dies.  A lot of consumer electronics die prematurely because just one cell goes out.  I know a guy who used to get used batteries from wherever he could, carve them open and just save the cells that are still good for projects. 

Saweet this will work great. So I  have a 12v powermax 55 amp power supply. So make the power bank first. So for my application 6s3p and hook up to power supply check voltage with ddm while charging and then install. After about the first wk or a day of heavy playing check each cells voltage, is that right?

If you want to really be safe do just 6S and charge each 6S set separately.   Consider these jokers are probably sitting in a warehouse for a while before they ship, they spend a month and a half on a boat/truck to get to you, so if they're all holding within a couple hundredths of a volt when they get to you they're probably pretty solid.  I'd expect an unhealthy cell would rest different or self discharge way out of line with the rest of them.

 

[Boominburban]

   Anyway, I did a little digging into that, you MUST find something that's meant for 2.3V nominal cells (possibly things built for supercapacitors will work).   I'm just taking my chances, but if anybody finds a good montioring solution please update here.

Anybody doing LTO now is trailblazing so there is some risk.   I did do a fair bit of the work for you guys already finding a legit seller on Alibaba.  As far as cycle life only time will tell, but I'm only getting 2-3 years out of AGM and I don't think people expect a lot more out of LiFePO4.

I did list the three known and tested charger/balancer/monitors that work with/have LTO profiles already.  1- Icharger X6, 2 - ISDT BG-8S( if you are charging at 2.5v per cell + only. which is 15v+ in a 6p configuration), 3 - Chargery makes one with a dedicated LTO profile as well.

Those are the three, that we know of, that have been tested and proven to work with LTO cells. And those are the ONLY ones proven to work correctly. These are NOT a BMS. 

That is what the six blue and one gray wire are for coming out of my battery. One + off each pack of cells( so six for 6p), and one - . those connect to a charger/monitor/balancer unit.

I will be using Icharger X6 units.

And for those of you that don't know how to size bussing. There is an easy formula for aluminum, and copper. Aluminum will carry 700 amps per cross sectional inch of material. Copper = 1000.

SO, a 1" x 1.5" bar, up to 48" would work out like this; 1 x 1.5 =1.5 x 700 =1050 amps - 1.5 x 1000 = 1500 amps if copper

A 1" x .250" bar would work out like this; 1 x .25 = .25 x 700 = 175 amps if aluminum - .25 x 1000 = 250 amps if copper

This formula is ideal. For NO buss induced voltage drop, or heat build up. Will smaller work? Yes it will. But the smaller you go from here, the bigger the % of buss induced voltage drop gets as you get up to you peak amperage draw.

Think about that when you're trying to run a 7k amp off of those 1 x 1 bars, filled full of 1/0 holes, and wonder why you have voltage drop ....

 

[L1ttlet]

Big amp is """rated""" 4000W @ 1 ohm.  Might be a little over-rated.  (see picture).  Not going to speculate too much just in case I ever try to get into a rated power limited class.  My fronts amp is 150X6, honestly rated.  I did not try burp yet, but I went very hard on it with music for a while.  Use that would drop me over 2V before is dropping only .2V.  Anyway, what I was doing was far more strenuous than 3 second burp.  That will get a bit worse when it starts getting sub-freezing up here but as the cells warm up from use and just running the heater they should perform as normal with some use. 

If you wanted to worry about it, charge 6S banks individually to equal voltage resting then parallel them up.  In the series they will share the charge equally.  Cells would want to be checked individually for matching voltage.  Not sure if or how much testing parallel banks would show if one cell was self discharging or weak.

Otherwise, that's about the size of it.  You will want to remove any AGM batteries in your vehicle, they will be very parasitic.

I wouldn't hold my breath.  At this point if they could even make 3V cells they'd be doing it.  All these super storage high current technologies (supercaps, fancy batteries) seem to be voltage limited.  Even the old technology is low voltage cells..... your standard lead acid/agm/etc. car battery is just 6 2V cells still.  Consider also from manufacturing standpoint end users of batteries want all kinds of voltages so if you only made a 12V cell you'd lose the business of everybody who needed 2, 4, 6, 8, and 10V supplies.   Yes series-ing piles of cells is inconvenient for complexity but offers more flexibility and of course if you really cared you could use some monitoring or smart charging to keep an eye on things and replace only cells as needed.... replace only one cell out of a 6 cell bank if only one dies.  A lot of consumer electronics die prematurely because just one cell goes out.  I know a guy who used to get used batteries from wherever he could, carve them open and just save the cells that are still good for projects. 

If you want to really be safe do just 6S and charge each 6S set separately.   Consider these jokers are probably sitting in a warehouse for a while before they ship, they spend a month and a half on a boat/truck to get to you, so if they're all holding within a couple hundredths of a volt when they get to you they're probably pretty solid.  I'd expect an unhealthy cell would rest different or self discharge way out of line with the rest of them.

View attachment 1646

Alright. Well I'm ready to build this bank now. That's  a big amp. You running 1ohm on that? 

Question....so the Agm will be parasitic to this setup you stated. This power bank will start the car and charge everything and run lights, a/c / heater.  All the lil electronics it wil need to and not take away a bunch capacity from the audio side? 

Starting the vehicle in cold weather won't  affect this bank u think? 

So when I  get the cells in I  should just check each cell with my cheapy ddm?

 

[L1ttlet]

I did list the three known and tested charger/balancer/monitors that work with/have LTO profiles already.  1- Icharger X6, 2 - ISDT BG-8S( if you are charging at 2.5v per cell + only. which is 15v+ in a 6p configuration), 3 - Chargery makes one with a dedicated LTO profile as well.

Those are the three, that we know of, that have been tested and proven to work with LTO cells. And those are the ONLY ones proven to work correctly. These are NOT a BMS. 

That is what the six blue and one gray wire are for coming out of my battery. One + off each pack of cells( so six for 6p), and one - . those connect to a charger/monitor/balancer unit.

I will be using Icharger X6 units.

And for those of you that don't know how to size bussing. There is an easy formula for aluminum, and copper. Aluminum will carry 700 amps per cross sectional inch of material. Copper = 1000.

SO, a 1" x 1.5" bar, up to 48" would work out like this; 1 x 1.5 =1.5 x 700 =1050 amps - 1.5 x 1000 = 1500 amps if copper

A 1" x .250" bar would work out like this; 1 x .25 = .25 x 700 = 175 amps if aluminum - .25 x 1000 = 250 amps if copper

This formula is ideal. For NO buss induced voltage drop, or heat build up. Will smaller work? Yes it will. But the smaller you go from here, the bigger the % of buss induced voltage drop gets as you get up to you peak amperage draw.

Think about that when you're trying to run a 7k amp off of those 1 x 1 bars, filled full of 1/0 holes, and wonder why you have voltage drop ....

View attachment 1647

So you keep your charger hooked up at all times? That is not a bms u said? Have alot of extra line. Lol

I did not know that bus bar formula. Thank you.

 

[Boominburban]

So you keep your charger hooked up at all times? That is not a bms u said? Have alot of extra line. Lol

I did not know that bus bar formula. Thank you.

You leave it hooked up as a monitor all the time. Only balance cells when needed. No, these technically are not a BMS. As they don't control input or output of the bank. Just monitor/balance, and charge cell packs as needed. Your alternator will keep the battery, as a whole, charged.