LTO SCiB battery bank for off-grid

[fisherus]

Right on. Thanks for the advice. I'm not putting another BMS order in until I'm sure of the specs.

In the message you posted above from Daly, I'm curious why you want the charge voltage cut-off at 2.5 instead of something higher like 2.7. Wouldn't having your charge voltage cut-off and balancing voltage both at 2.5 potentially mess with the BMS ability to balance. For example, say a cell reaches 2.5 while the rest of the cells are under and the BMS cuts off before it can balance. I was thinking of asking Daly to do the balance of 2.5 like you have, but the cut-off at 2.7 (which would be the natural high-point for the tech).

I forgot to tell you what I ended up ordering:
LTO 24S 64.8V 40A w/common port. Cut-off at 2.7V
This should be the best setup for the Daly's to function properly with these batteries. My advice would be to run your system without any BMS for a year and check each cell for balance at that point. It would be easier to prewire your batteries for a BMS and use it to test each cell with your tester leads. Then, if you find some out of balance get a BMS.
I was told to get a couple of them made and just use on a battery that had out of balance cells after a year. I just didn't want to have to bother with them but it would have saved me unnecessary expense. You can use me for your Guinea pig if you desire.

 

[fisherus]

Right on. Thanks for the advice. I'm not putting another BMS order in until I'm sure of the specs.

In the message you posted above from Daly, I'm curious why you want the charge voltage cut-off at 2.5 instead of something higher like 2.7. Wouldn't having your charge voltage cut-off and balancing voltage both at 2.5 potentially mess with the BMS ability to balance. For example, say a cell reaches 2.5 while the rest of the cells are under and the BMS cuts off before it can balance. I was thinking of asking Daly to do the balance of 2.5 like you have, but the cut-off at 2.7 (which would be the natural high-point for the tech).

My friend said you can use the BMS'S you purchased but it will take longer to balance your batteries with such low current, although it can be done if they can charge long enough before resting. Because your cut-off is so high, they should continuously be balancing so they can never cut-off. He could not tell me about any adverse effect other than it might cause failure of your BMS prematurely. Hope that helps you.

 

[AmpLee]

My friend said you can use the BMS'S you purchased but it will take longer to balance your batteries with such low current, although it can be done if they can charge long enough before resting. Because your cut-off is so high, they should continuously be balancing so they can never cut-off. He could not tell me about any adverse effect other than it might cause failure of your BMS prematurely. Hope that helps you.

I think I'll just put the BMS that were sent even though I won't get balance capability with using the Sol-Ark. I'll at least get the overcharge and over discharge protection and will be able to manually monitor the cells like you said you would be doing. Here's the latest I heard from Daly about the balance current...


Hi Dan,

1) balance voltage set as 2.5V, and charge cut off as 2.7V ,is no problem.
2) Li-ion and Lifepo4, our standard balance current is 30+-5mA. Because the norminal voltage is higher than LTO. You can count by yourself. I=U/R.
LTO's norminal voltage is: 2.2V. And our balance resistance is：100Ohm. So it should be: 2.2/100=0.022*1000=22mA

If you want to change it, we should purchase special PCB,the MOQ is 500pcs.

So we don't suggest you do like this. You should make sure the batteries's consistency. Use the same consistency batteries to make battery pack.

 

[fisherus]

I guess I am missing something when he says the nominal voltage of the LTO is 2.2V. because you can set your nominal voltage with your Sol-Ark easily to 2.5V and minimal to 1.9V (I am using 2.0V for mine)
I think that you might find your cells balancing at the top voltage setting on the Sol-Ark as you just won't reach the cut off settings on your BMS's. If the batteries level off at high state of charge they should be balanced.
With the cycle rate of the LTO batteries we have, the BMS charge rate at 35+/-5 should be fine, so I'm told by my friend who has built many LTO battery banks.
So, the charge rate of 20+/-5 is what you have?

 

[RD Alternators]

Check Ebay for the SCIB cells. For the yinlong cells I have 150 on order and will be placing another order soon. I test them all and then sell them on eBay but give discounts to forum members. You could also add to one of my orders as well if you wish. These are not cheap though the 45Ah cells retail for $70 each on ebay in a set of 6. That includes shipping.

Can you please provide me with an reputable celler for yinlong 40ah cells, would like to purchase around 100 cells

 

[fisherus]

So I’ve been parsing through the internet to find info on this battery technology as there are some used Toshiba SCIB units available on e-bay. There's a lot to like of LTO technology if you can overcome some of the hurdles. The hurdles seem to be price, BMS, space, and odd voltage attributes. Physical space to store the batteries isn't an issue for me, and while price for used LTO cells are expensive, I believe that their exceptionally long life make them fairly affordable spread out over time.

These particular cells have an on board BMS but it seems no one has figured out how to get it to balance the cells, so if you want cell balancing then you'd need to get an external BMS for every 24 cell battery (1.1kW). In a 40 kw battery bank that would amount to 36 separate BMS. So my question is, are BMSs necessary with this technology and if not, how would I be able to operate my system without one, and what downsides would there be. I guess I'm wondering what are the options here?

The other thing that seems to be a negative is that these batteries have unusual voltage attributes. It looks like there is 48v MagnaSine 4000W inverter that can handle the voltage range of the batteries, but I'm not seeing any other inverters that can both reach the upper and lower ranges. Is being stuck with this inverter a deal breaker? It's a pricey inverter, but it seems that installing a couple of these would allow me to use shop tools and water pumps. Are there any thoughts to this particular inverter or use of inverters with LTO batteries.

Lastly, I'm just hoping to learn more about working on these cells. I'm not very experienced with working with electricity or storage, so I'd like to know if I'm biting off more than I can chew by building a 40kw/h battery bank with these cells. Thanks for any input.

OK. I must first ask you what voltage you are wanting to build your solar system? With these batteries you can either go 24V or 48V. I have both. My primary power is going to come from the 48V system that I am currently working on. I plan to use the 24V system as a reserve backup system as I also have wind turbine generator power running through a hybrid charge controller that does the job with my PV setup. All that is necessary to use them on a 24V system is to disconnect the buss bar between each 12 cell bank and parallel the banks together with all the batteries you are going to be using. In this case, if you want to add a BMS you will have use a 12S BMS made for your cells voltage which is 2.5V ea. Then you set your charge controller to a 30V Nominal and 24V Minimal. Simple and easy. My experience with LTO batteries has found very minor deviations of cell charges to a point of questioning whether I needed a BMS on these batteries. Perhaps not, if I wanted to take time to check each cell with my meter annually and use a Buck converter to charge each cell that was out of balance (which would be few from my previous experience)
My 48V System is a little bit different. First, let me start by saying I wanted a system that I can depend on when I am gone from my farm in the winter months. After using lead-acid and AGM batteries for my 24V system, they didn't do the job unless I hired someone to maintain them and that didn't work well either. So I started researching the LTO batteries a couple of years ago because I didn't have a way to keep a Lipro4 from freezing and charging it below 32F. So, these were the answer. One thing is, and I want to overemphasize, you can't compare this battery to lead-acid anymore than lithium. They don't function like either in a solar bank system. They have some similarities, which I consider to be the best part of each but, that's where it ends. The C rate on lead-acid batteries is dismal at best and the C rate for Lipro4 is quite favorable but inherent to temperature changes and varies. This battery has the highest C rate available and can also be charged 20K cycles without ever dropping below 80% of it's maximum voltage. So, figuring the variables, even though acquisition costs are high for the batteries if you convert the cost over a 25 year lifespan of a solar system, they become the least expensive per watt you can purchase for this period of time. Actually , you will reach the lowest price per watt in 12 years or less. I run my Sol-Ark 12k at 60V Nominal and 48V Minimal with float set at 60V but, I might drop minimal down to 1.9V per cell as they still have a lot of energy left between 2.0V and 1.9V. Because they charge so fast, I feel that they are capable of reaching full charge even on days I run my 600' 1hp well pump at 7gpm to refill my 2500gal storage tank and possibly welding during high sun hours.

 

[Jason Barrett]

I know I’m digging up an old thread here. I’m curious. Did you ever get the battery bank assembled/racked? I have 28 of these I am racking together some day.
I am currently running 5 without a BMS. I have Daly’s for them, but they don’t seem to perform as I would expect. I’ve experienced strange cell unbalancing and units not low volt disconnecting like they should.
DALY = ?

 

[AmpLee]

I did. It's been running great since this summer. I found the individual cell voltages to be remarkably balanced without the need for bms balancing. The Dalys are hooked up, by I ask nothing of them other than low voltage and high voltage cut-off. That said, I keep my battery bank between 51 and 60v so am 10% off the top and about the same off the bottom, so I don't anticipate needing the Dalys unless a cell goes bad. But so far so good.

May I ask where you got your scibs from? I wouldn't mind getting a few more to fill out my load centers.

 

[JimJr]

I did. It's been running great since this summer. I found the individual cell voltages to be remarkably balanced without the need for bms balancing. The Dalys are hooked up, by I ask nothing of them other than low voltage and high voltage cut-off. That said, I keep my battery bank between 51 and 60v so am 10% off the top and about the same off the bottom, so I don't anticipate needing the Dalys unless a cell goes bad. But so far so good.

May I ask where you got your scibs from? I wouldn't mind getting a few more to fill out my load centers.


View attachment 79916

Those batteries have a max cell votage bms in them , I have 5kw worth of them.

 

[Jason Barrett]

Those batteries have a max cell votage bms in them , I have 5kw worth of them.

I would like use the factory BMS to monitor cell voltages. Are you doing this? To have a monitor that will disconnect/fault the batteries would be awesome. I know there were guys working on cracking the CAN, and I need to see where their work stops.

 

[Jason Barrett]

I did. It's been running great since this summer. I found the individual cell voltages to be remarkably balanced without the need for bms balancing. The Dalys are hooked up, by I ask nothing of them other than low voltage and high voltage cut-off. That said, I keep my battery bank between 51 and 60v so am 10% off the top and about the same off the bottom, so I don't anticipate needing the Dalys unless a cell goes bad. But so far so good.

May I ask where you got your scibs from? I wouldn't mind getting a few more to fill out my load centers.


View attachment 79916

I got them from Greentecauto also. As you are aware, they sold out. I would like to find more also.

 

[JimJr]

I would like use the factory BMS to monitor cell voltages. Are you doing this? To have a monitor that will disconnect/fault the batteries would be awesome. I know there were guys working on cracking the CAN, and I need to see where their work stops.

I only use the max cell bleed off , no other BMS. I hope Greentec gets more in

 

[Jason Barrett]

I only use the max cell bleed off , no other BMS. I hope Greentec gets more in

Can you explain your method of max cell bleed off, or provide a link to such an explanation.
I am not using factory or Daly BMS. I bottom balanced at 1.6V and set inverter to run 50-62V.
I doubt they do get more in. I believe the FIT EV was offered in Japan also. I have hopes there are some intact over there.
I think these cells are packaged up every day by toshiba, and we just need to find a recycler that has 12 or 24s packs. Or, set up a group buy that will get toshibas attention.
There is a new SCIB

Toshiba Launches 20Ah-HP SCiB™ Rechargeable Lithium-ion Battery Cell that Delivers Both High Energy and High Power | News | Toshiba

www.global.toshiba

The possibility to expand our systems is not dead.

 

[JimJr]

Can you explain your method of max cell bleed off, or provide a link to such an explanation.
I am not using factory or Daly BMS. I bottom balanced at 1.6V and set inverter to run 50-62V.
I doubt they do get more in. I believe the FIT EV was offered in Japan also. I have hopes there are some intact over there.
I think these cells are packaged up every day by toshiba, and we just need to find a recycler that has 12 or 24s packs. Or, set up a group buy that will get toshibas attention.
There is a new SCIB

Toshiba Launches 20Ah-HP SCiB™ Rechargeable Lithium-ion Battery Cell that Delivers Both High Energy and High Power | News | Toshiba

www.global.toshiba

The possibility to expand our systems is not dead.

I am referring to it's internal BMS , it bleeds the cells to 2.4v when it is done , let it sit 24 hours and it will be around 28.8v.

That 20ah hp version looks like the 10ah one , Like it puts out 1900w and 825ah at a pulse current . I use the 3ah version to start big blocks motors

 

[AmpLee]

I am referring to it's internal BMS , it bleeds the cells to 2.4v when it is done , let it sit 24 hours and it will be around 28.8v.

That 20ah hp version looks like the 10ah one , Like it puts out 1900w and 825ah at a pulse current . I use the 3ah version to start big blocks motors

I was under the impression that the internal bms does not function without an external power source. In Fits, the bms were powered by the starter battery iirc. There’s a bunch of guys at the Honda Insight forum that have done a ton of work in these modules.

 

[SolarPrep]

I was under the impression that the internal bms does not function without an external power source. In Fits, the bms were powered by the starter battery iirc. There’s a bunch of guys at the Honda Insight forum that have done a ton of work in these modules.

AmpLee: Peter Perkins in Australia (?) is one of the guys who has done a lot of work on the Fit battery BMS. You can find him on the Insight forum.

As I understand from Greentec, the Fits in the US were only leased. Greentec got all the batteries when they were scrapped out. I have some of the modules from Art at Greentec.