LTO SCiB battery bank for off-grid

[fisherus]

Yeah, it's a big setup, but we use a whole lot of energy running jet pumps, Coolbot/mini-split walk-in cooler, lots of battery tools (string trimmer, mowers, etc.), electric instant hot water heater, and multiple buildings/workshops. I'm also considering getting a cybertruck (I know it looks ridiculous) so am planning on having more than enough electricity. We're always here working growing food and pre-covid ran a bed and breakfast so it makes sense to use as much of the sun's energy as possible and take as much as we can off the grid. Throughout the year we average 45kW per day, but I'm going to do a major energy audit as I install this system and tighten things up as much as possible.

I don't know if you're familiar but the honda insight forum has some really great look into these SCiB batteries as some of those folks have used them in conversions in their vehicles. You are absolutely right that the ideal voltage range is probably between 2.0-2.5v. I think that's about 90 percent of the batteries capacity if I remember correctly.

So, theoretically the Daly BMSes will keep the cells balanced so that when you set your SolArk to 48-60v range each cell will be 2.5v when the inverter cuts out at 60v? That does seem pretty ideal as far as extending the life of the batteries which already boast a lifespan that will likely outlast me. Pretty cool. Can you tell me more about your decision to go with the SolArk 12k? I haven't really dove into every aspect of the solar build I'm conceiving and know very little about inverters.

Lastly, what did you use to balance charge your cells when you first got them and did you come across any bad cells? I'm looking to buy a pl8 by cellpro which the guys over at the Honda Insight forum have worked with and set up profiles.

I received a notification from the Insight forum and read your inquiry, giving you a reply before I realized the date you made it, so disregard it. I had Daly make my BMS's set at 2.5V 40amp 24s.
I used a couple of small DROK buck converters to balance my cells but there was only a few milliamps of variance between one or two on a few batteries even though they were from 3 different lots. I removed all of the factory BMS boards before doing this. I used the same screws to attach the BMS leads which made it simple, then routed the leads back through the nipples that originally contained the wires to the original board. I might place the Daly's. under one of the covers during final installation but, I am going to be hauling my system from my home in Southern Idaho to my farm in Northern Idaho, 473 miles. This will allow me to secure them in a box for transport.
You might want to use the same system I did to parallel your batteries together by using double pole single switch breakers in a Square D breaker box. They will accommodate 20 batteries each so 2 tied together on a common buss bar should do the trick. I also wired a 300amp fuse in my box. This makes for a very clean look. When I get my battery rack finished I can send you some pictures as well as information on where to find everything I used. I am thinking about purchasing another SolArk and if you find they will meet your needs, we might get together and see if we can get a discount on the price.
I know how intimidating this is as I was in your shoes about a year ago and I have never wanted to do anything with electricity or wiring diagrams. Terminology was a big challenge for me to learn but what you will know a year from now will be mind blowing. At least it has been for me as I reflect back on some of the questions I previously asked others.

 

[AmpLee]

I received a notification from the Insight forum and read your inquiry, giving you a reply before I realized the date you made it, so disregard it. I had Daly make my BMS's set at 2.5V 40amp 24s.
I used a couple of small DROK buck converters to balance my cells but there was only a few milliamps of variance between one or two on a few batteries even though they were from 3 different lots. I removed all of the factory BMS boards before doing this. I used the same screws to attach the BMS leads which made it simple, then routed the leads back through the nipples that originally contained the wires to the original board. I might place the Daly's. under one of the covers during final installation but, I am going to be hauling my system from my home in Southern Idaho to my farm in Northern Idaho, 473 miles. This will allow me to secure them in a box for transport.
You might want to use the same system I did to parallel your batteries together by using double pole single switch breakers in a Square D breaker box. They will accommodate 20 batteries each so 2 tied together on a common buss bar should do the trick. I also wired a 300amp fuse in my box. This makes for a very clean look. When I get my battery rack finished I can send you some pictures as well as information on where to find everything I used. I am thinking about purchasing another SolArk and if you find they will meet your needs, we might get together and see if we can get a discount on the price.
I know how intimidating this is as I was in your shoes about a year ago and I have never wanted to do anything with electricity or wiring diagrams. Terminology was a big challenge for me to learn but what you will know a year from now will be mind blowing. At least it has been for me as I reflect back on some of the questions I previously asked others.

Right on. Yeah, you sold me on the SolArk. For some reason I was under the impression that the inverter needed to cover the entire battery voltage, so thanks for helping me understand it better. I think you saved me a loooooot of headache since the SolArk seems to be as plug and play as it gets.

Yeah, I think I saw you comment on Ben's youtube video regarding the QO D Breaker box. Looks like I'll need two but I'm unsure how to connect to a common busbar (still so much to learn). I'm glad to hear that you were in the same position and now seem to have a good understanding of things.

 

[fisherus]

Right on. Yeah, you sold me on the SolArk. For some reason I was under the impression that the inverter needed to cover the entire battery voltage, so thanks for helping me understand it better. I think you saved me a loooooot of headache since the SolArk seems to be as plug and play as it gets.

Yeah, I think I saw you comment on Ben's youtube video regarding the QO D Breaker box. Looks like I'll need two but I'm unsure how to connect to a common busbar (still so much to learn). I'm glad to hear that you were in the same position and now seem to have a good understanding of things.

What I would do is watch some of "Dave Poz" videos as he is a friend of Ben. He is one of the best DIY YouTube experts I've found. If you watch his video regarding his "Tower of Power " it will be easier to get the idea on making a large bus bar from copper and a piece of nylon cutting board you can get at a dollar store. He uses copper pipe he scraped but I purchased a piece of 1/4" copper plate 2" x 6" that I used from Ebay (which is a little overkill. ) All you need on the Sol-Ark 12k is a cut-off switch on your exterior of your system to cut power from your panels. You will probably need two as I think that will give you all the power you can use and still keep your batteries in a healthy state of charge.
I am amazed that most people piss away money on controllers and inverters without looking into the Sol-Ark as you have realized, not only is it plug and play but cheaper overall to install. And with a warranty that is unheard of in solar equipment as most fail within the first 5-8 years.
I am in Idaho.

 

[AmpLee]

The one thing that worries me about the SolArk is that the Daly BMS won't top balance unless it reaches a certain volatage. If I'm reading my spec sheet correctly on my BMS, balance won't occur until the cells reach 2.7 volts which would mean that I'd need an inverter that could reach 64.8v. Am I thinking about this correctly?

 

[fisherus]

The one thing that worries me about the SolArk is that the Daly BMS won't top balance unless it reaches a certain volatage. If I'm reading my spec sheet correctly on my BMS, balance won't occur until the cells reach 2.7 volts which would mean that I'd need an inverter that could reach 64.8v. Am I thinking about this correctly?

You can have Daly make them to any setting you want for the same cost. I had mine made for 60V 2.5V 40A and they top and bottom balance. If you contact Daly and tell them you want 2.5V they can get them made in 3 days and ship.
Dongguan Daly Electroniccs Co.,Ltd
Wechat:+8616620740463
Tel :+8616620740463
E-mail:Ruby.zhang@dalyelec.com
Ruby Zhang is the contact person so email what I told you: LTO 24S 60V 2.5V Top Balance per cell along with your email address and cell phone number. They bill through PayPal only so you will have to set up a PayPal account if you don't have one.

 

[AmpLee]

You can have Daly make them to any setting you want for the same cost. I had mine made for 60V 2.5V 40A and they top and bottom balance. If you contact Daly and tell them you want 2.5V they can get them made in 3 days and ship.
Dongguan Daly Electroniccs Co.,Ltd
Wechat:+8616620740463
Tel :+8616620740463
E-mail:Ruby.zhang@dalyelec.com
Ruby Zhang is the contact person so email what I told you: LTO 24S 60V 2.5V Top Balance per cell along with your email address and cell phone number. They bill through PayPal only so you will have to set up a PayPal account if you don't have one.

Thanks. I already put in an order thinking that the voltage for the LTO would already be ideal (since it's based on the chemistry) but it looks like the top balance of 2.7 would not work with the SolArk, which I would prefer to use. Plus, I don't want have to charge the batteries to 2.7 just to balance. Looks like I just wasted money not doing enough research before I bought.

So your bms balance at both 2.5v and 1.9v? Is it necessary to have the bottom balance too, or is that just in case you want to alter the inverter to a different range (say 1.9 - 2.4)? What are your voltage cut-off parameters (if I ask for 2.5v balance, should the voltage cut-off exceed that to 2.7 since the inverter will cut out at 2.5 regardless)?

 

[fisherus]

I know what it's like to put the cart before the horse in solar expenditures for sure as I have a bunch of stuff I bought because I didn't research with due diligence.
Actually, LTO batteries only need to be top balanced by a BMS as they rarely get out of balance on the bottom if they are balanced on the top. The major problem you will have trying to get to the 64.8V maximum voltage is they won't hold the charge at that state of charge because they are used. They will hold between 2.5-2.6V, however, so regardless of what voltage maximum charge rate a solar charger can reach, you won't be able to keep them at that level. These are sold as 60V batteries even though they originally were 64.8V so you need to keep your charge rate at 60V Nominal and at least 40V minimal to achieve the maximum holding capacity of your batteries for many years of use. Trying to charge above the 60V rate will eventually destroy your charger because it will never top off the batteries and shut off in my opinion. These batteries will no longer work for their intended use because they won't hold the voltage they were designed for. But, they can now be used for solar purposes because they won't go below the 2.5V level until they are completely destroyed.
Your 2.7V won't work for these batteries regardless of what charger you use because they won't hold a full charge anymore above 2.5V. Hope this helps make a little more sense to you?

 

[AmpLee]

I know what it's like to put the cart before the horse in solar expenditures for sure as I have a bunch of stuff I bought because I didn't research with due diligence.
Actually, LTO batteries only need to be top balanced by a BMS as they rarely get out of balance on the bottom if they are balanced on the top. The major problem you will have trying to get to the 64.8V maximum voltage is they won't hold the charge at that state of charge because they are used. They will hold between 2.5-2.6V, however, so regardless of what voltage maximum charge rate a solar charger can reach, you won't be able to keep them at that level. These are sold as 60V batteries even though they originally were 64.8V so you need to keep your charge rate at 60V Nominal and at least 40V minimal to achieve the maximum holding capacity of your batteries for many years of use. Trying to charge above the 60V rate will eventually destroy your charger because it will never top off the batteries and shut off in my opinion. These batteries will no longer work for their intended use because they won't hold the voltage they were designed for. But, they can now be used for solar purposes because they won't go below the 2.5V level until they are completely destroyed.
Your 2.7V won't work for these batteries regardless of what charger you use because they won't hold a full charge anymore above 2.5V. Hope this helps make a little more sense to you?

So on the spec sheet of the BMSs that I ordered the over charge is 2.85v and over discharge is at 1.7v. Did you specify with Daly the parameters you'd like for these charge and discharge cut-offs so that they'd match the range you're shooting for (say 48v-60v (2.0v-2.5v per cell)), or is it better to have the over charge and over discharge to be outside of those ranges? I'm not sure if my question makes sense.

The other thing I'm concerned about is the balance current which is set at 20mA. Is this sufficient for your setup, or did you specify a number that makes more sense?

 

[fisherus]

I had Daly set my BMS to 2.7V after I found out that they are to protect overcharging the batteries it would be fine to set them at that limit for a top cut off. In your case, at a 2.85V top, because it is 0.15V over, it seems that you won't have overcharging protection on your batteries. I'm more concerned about top balance (including overcharging) than bottom because the settings in my Sol-Ark 12k allow for disconnect of battery bank from the inverter at a minimum setting and as I stated previously, most tests I have seen on LTO batteries show little, if any, value to bottom balance if you bottom balance manually before installing (I took each battery down to 1.5V per cell and charged them up to 2.5V before I paralleled all of them.
If you are using two Sol-Ark 12k then you can set each group of 20 to each one separately without a bus bar connection and wire your AC circuits to proper demand accordingly.
Initially I purchased a couple of the BMS'S in two different configurations before deciding to order the rest of them. I was advised to do this and I wish I could have caught you earlier about it. If I were you find out if Daly can reconfigure the ones you have. You'll only be out the freight charge.
I found out that they misconfigured one I ordered for the 2.5V top to a 2.5V bottom which they are giving me credit for. If you want to wait until I get the 15 I ordered, I will send you a copy of the configuration report when I get it.

 

[Craig]

I had Daly set my BMS to 2.7V after I found out that they are to protect overcharging the batteries it would be fine to set them at that limit for a top cut off. In your case, at a 2.85V top, because it is 0.15V over, it seems that you won't have overcharging protection on your batteries. I'm more concerned about top balance (including overcharging) than bottom because the settings in my Sol-Ark 12k allow for disconnect of battery bank from the inverter at a minimum setting and as I stated previously, most tests I have seen on LTO batteries show little, if any, value to bottom balance if you bottom balance manually before installing (I took each battery down to 1.5V per cell and charged them up to 2.5V before I paralleled all of them.
If you are using two Sol-Ark 12k then you can set each group of 20 to each one separately without a bus bar connection and wire your AC circuits to proper demand accordingly.
Initially I purchased a couple of the BMS'S in two different configurations before deciding to order the rest of them. I was advised to do this and I wish I could have caught you earlier about it. If I were you find out if Daly can reconfigure the ones you have. You'll only be out the freight charge.
I found out that they misconfigured one I ordered for the 2.5V top to a 2.5V bottom which they are giving me credit for. If you want to wait until I get the 15 I ordered, I will send you a copy of the configuration report when I get it.

So on the spec sheet of the BMSs that I ordered the over charge is 2.85v and over discharge is at 1.7v. Did you specify with Daly the parameters you'd like for these charge and discharge cut-offs so that they'd match the range you're shooting for (say 48v-60v (2.0v-2.5v per cell)), or is it better to have the over charge and over discharge to be outside of those ranges? I'm not sure if my question makes sense.

The other thing I'm concerned about is the balance current which is set at 20mA. Is this sufficient for your setup, or did you specify a number that makes more sense?

View attachment 15527

I would not be too concerned about the 2.85 cut off. They will balance sooner or later if they are not balanced when you set them up. The number 1 thing to worry about with LTO is not overcharging any 1 cell. If the BMS cuts off at 2.85 that solves that problem. What will happen is the BMS will stop charging and as Fisherus said they will drop rapidly and start self balancing the lower ones will not drop in voltage as much if at all.. There is so little energy above 2.4 volts less than 4% that it will not matter if you stop charging the batteries at a cumulative total that fits your devices parameters. I love my LTO cells and wish that I had a SOL-ARK so do not feel like you did the wrong thing at all. 90% of the energy in these things is between 2.38 and 1.94 volts per cell or 57 and 47 volts. if your inverter and charger can work with that then you will be fine.

 

[fisherus]

Here's a copy of the email Daly sent me.
BATTERIES

Hello Mr. Craig，

Double checke with our engineer, we can set up the charge voltage cut off: 2.5V , the discharge voltage cut off:1.5V.

For your mentioned " BMS plays is twofold -- it Top and Bottom balances the cells of the battery between a high charge (Top) voltage" , I need to highlight it to you, our BMS its balance current is very low ( 35+/-5mA）， so it need your battery material with good cosistancy.

 

[AmpLee]

Here's a copy of the email Daly sent me.
BATTERIES

Hello Mr. Craig，

Double checke with our engineer, we can set up the charge voltage cut off: 2.5V , the discharge voltage cut off:1.5V.

For your mentioned " BMS plays is twofold -- it Top and Bottom balances the cells of the battery between a high charge (Top) voltage" , I need to highlight it to you, our BMS its balance current is very low ( 35+/-5mA）， so it need your battery material with good cosistancy.

Interesting. The gal I've been in communication with says that they cannot go above 20mA +/-5mA for charge current. This presents a bit of a problem for my setup as under ideal conditions with 12kw of panels, I would be well above 20mA. Although, I'm not sure ideal conditions would ever be a reality, especially with east facing panels, but still a bit concerning as I would like some headroom.

 

[fisherus]

Interesting. The gal I've been in communication with says that they cannot go above 20mA +/-5mA for charge current. This presents a bit of a problem for my setup as under ideal conditions with 12kw of panels, I would be well above 20mA. Although, I'm not sure ideal conditions would ever be a reality, especially with east facing panels, but still a bit concerning as I would like some headroom.

I wanted you to see this because I was amazed by how low the balance voltage was on your BMS. It will probably work but I have pause due to the extremely fast recharging rate of these batteries. If the batteries are fully charged and stay at that level they might be OK but,I feel they need to be what I requested at the 35+/-5A level. I have a resourceful friend who knows the inside out of lithium titanate batteries and I will check with him if you want.
This is why I bought 2 different set-ups of the Daly BMS'S, to try before I ordered the rest. I have bought too many unnecessary components in the past. Figured I would save money by testing a couple first, per advice of my acquaintance. Expensive learning experience but, I am finally getting there and so will you. Guarantee you that you can't go wrong with the SolArk 12k, as I don't think it presently has a close second.

 

[AmpLee]

I wanted you to see this because I was amazed by how low the balance voltage was on your BMS. It will probably work but I have pause due to the extremely fast recharging rate of these batteries. If the batteries are fully charged and stay at that level they might be OK but,I feel they need to be what I requested at the 35+/-5A level. I have a resourceful friend who knows the inside out of lithium titanate batteries and I will check with him if you want.
This is why I bought 2 different set-ups of the Daly BMS'S, to try before I ordered the rest. I have bought too many unnecessary components in the past. Figured I would save money by testing a couple first, per advice of my acquaintance. Expensive learning experience but, I am finally getting there and so will you. Guarantee you that you can't go wrong with the SolArk 12k, as I don't think it presently has a close second.

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).

 

[fisherus]

The reason for the 2.5V is because I originally requested that they make them at a 2.5V level. I did this knowing my SolArk would never be able to exceed that amount of charge and thought it would serve as as additional safety mechanism. But, I am having them made to the 2.7V top and 1.5V bottom.
After all the research I have done on these batteries, I really think a BMS is pretty worthless as LTO batteries drift into balance continuously. I just wanted a way to check them annually for balance and after exploring what was available, this appeared to be the easiest. Necessary, probably not.

 

[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.


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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.