Inverter/charge controllers compatible with Lithium Ion profile

akallen · July 2017

Running Xantrex 5548s with Rolls batteries at the moment. Due to the now very low cost of LiIo batteries I'm looking at building a Powerwall equivalent, albeit with considerably more kWhr. First topic in my mind is what off grid inverters are out there, if any, that support or at least would allow for lithium charging? I'm specifically focused on the 3.7 volt nominal chemistry and not the polymers. I'm comfortable with custom fab of the BMS, but first want to see if there are off the shelf solutions. Leaving this pretty open-ended on purpose because I'm wondering who's doing what. Will implement as a parallel system so as to have a long development phase. My thanks.

Dave Angelini · July 2017

They all are for someone who takes the responsibility like you. If you want a simple and powerful application, check this,
http://forum.solar-electric.com/discussion/351297/conext-bridge-for-xw-li-ions-from-lg-and-hoppecke-announced-for-2nd-half-2017/p1

It is the next level up from what you propose but worth looking at.

mike95490 · July 2017

It's a simple task to decide what voltage points you are going to run your battery bank at, and program all the Controllers for those voltages. Some of the canned voltages are very close to LFP battery needs, but outside of LFP, you need to generate and load your own voltage settings. All of the top end controllers are programmable.

Dave Angelini · July 2017

Yes as Mike said it is simple, as long as you actively watch and understand the voltage and all the other parameters that can cause an issue that snowballs into a bad result. The beauty of what Schneider, Outback, and others are doing is taking the risk out! This is because they get into the shunt data inside the battery BMS and know Soc, Sol , and all the other parameters. You can't do that unless you are a Canbus programmer.

For instance, an LG battery, possibly the best in the world now, an upgrade option on the Tesla roadster will only work for 10 minutes unless the safety comms with the inverter are there. When this connection is broken, it is 10 minutes until lights out, this is there to protect your home. There are ways to always bypass this but the owner needs to know what they are doing! ! !

I am very scared by what I see on the internet with Tesla batteries at this time for offgrid! Fine for cars but be careful offgrid!

karrak · July 2017

If you are going to use Lithium Manganese Cobalt (LMC) cells, which are the same sort used in the LG chem and Tesla household power supplies your existing inverters should work with a 14s (14 cells in series) battery, or use a 16s LiFePO4 (LFP) battery which is the safer option and should last longer. I wouldn't even consider Lithium Cobalt (LCO, used in Laptops etc.) as they are the most likely to catch fire and have a limited lifespan). This article from Battery University gives a good rundown of the different Li-ion battery chemistries.

It might be false economy going for the cheapest cells you can buy. Panasonic and LG have probably spent huge amounts of money researching chemical additives and other ways to make their LMC batteries last longer and be more reliable. It is more than likely that if you buy some cheap copy of their batteries from an unknown manufacturer that they will not last nearly as long. LFP batteries should last longer as they operate at a lower cell voltage.

Li-ion batteries are safe if all the individual cells are kept within their safe voltage, power output and temperature ranges. Go outside the safe operating range and they can turn into ticking time bombs. The easiest and most dangerous thing to do is overcharge any of the cells in the battery. This can occur if the battery is over discharged which might damage some of the cells, reduce their capacity and unbalance the battery so that the next time you charge the battery those cells will be overcharged and might catch fire, this can also happen if a fault in the battery causes it to become unbalanced. This cannot happen if you have a BMS that will stop any of the cells going out of their safe operating range.

The BMS has to be able to preferably tell the charger to stop charging or the inverter to shut down, or disconnect the solar panels from the controller or disconnect the inverter from the battery if any of the cells in the battery are taken out of their safe operating zone.

Simon

Dave Angelini · July 2017

Nicely said Simon! The Panasonic are nice also but being a round battery, take up more space/weight than the flat LG.

One of the nice things from my testing of the LG RESU10 is that you can "float" the battery at say 57V and it will stay near 95% Soc .
The LG BMS will go from just the power light on, to the charge light, and then to the discharge light and so on, tracking your loads staying at 95% until sundown.

In this way you can set the Soc to whatever you want. If you do get to 100%, then the controller (Bridge) starts idling charge controllers or generator/Grid charging and of course a few other things. The BMS also gives you a state of health and several other nice data points about how the battery is doing and the corrective actions to keep it healthy.

All of the Bridge grid programs for zero export or self consumption look great from what I have seen at a test sites in Australia and Spain.
Offgrid as many know, it is use it or lose it

Solray · July 2017

> @karrak said:
> If you are going to use Lithium Manganese Cobalt (LMC) cells, which are the same sort used in the LG chem and Tesla household power supplies your existing inverters should work with a 14s (14 cells in series) battery, or use a 16s LiFePO4 (LFP) battery which is the safer option and should last longer. I wouldn't even consider Lithium Cobalt (LCO, used in Laptops etc.) as they are the most likely to catch fire and have a limited lifespan). This article from Battery University gives a good rundown of the different Li-ion battery chemistries.
>
> It might be false economy going for the cheapest cells you can buy. Panasonic and LG have probably spent huge amounts of money researching chemical additives and other ways to make their LMC batteries last longer and be more reliable. It is more than likely that if you buy some cheap copy of their batteries from an unknown manufacturer that they will not last nearly as long. LFP batteries should last longer as they operate at a lower cell voltage.
>
> Li-ion batteries are safe if all the individual cells are kept within their safe voltage, power output and temperature ranges. Go outside the safe operating range and they can turn into ticking time bombs. The easiest and most dangerous thing to do is overcharge any of the cells in the battery. This can occur if the battery is over discharged which might damage some of the cells, reduce their capacity and unbalance the battery so that the next time you charge the battery those cells will be overcharged and might catch fire, this can also happen if a fault in the battery causes it to become unbalanced. This cannot happen if you have a BMS that will stop any of the cells going out of their safe operating range.
>
> The BMS has to be able to preferably tell the charger to stop charging or the inverter to shut down, or disconnect the solar panels from the controller or disconnect the inverter from the battery if any of the cells in the battery are taken out of their safe operating zone.
>
> Simon

How many laptop fires have you had? I have never heard of a laptop catching on fire. Smartphones and airplanes but not laptops.
You say it's more likely; exactly what are the odds of a laptop battery catching on fire?

You say they probably spent money to make their batteries last longer, where did that come from? Are you just guessing? Do you have any actual data to share showing how much was spent and the resulting increase in battery longevity?
I think it's just as likely they didn't make any changes to the battery but altered programming to minimize processor cycles to increase battery time if it indeed is longer in their products. A firmware update on a cell phone can give you longer battery life without any changes to the hardware whatsoever.

mcgivor · July 2017

http://www.snopes.com/horrors/techno/laptopfire.asp
http://www.nbclosangeles.com/investigations/I-Team-Investigation-Battery-Lithium-Ion-Fire-Laptop-Computer-412459303.html
http://nypost.com/2017/05/31/jetblue-flight-diverted-after-laptop-battery-catches-fire/

Laptops never catch fire, 30 second search, no comment.

Dave Angelini · July 2017

Great! another useful thread turned into ? Good for Banzai attacks! Hang in there Simon!

mcgivor · July 2017

I generally do not comment on subjects I'm not familiar with, preferring to read in an effort to gain knowledge, you learn a lot from others, Dave and Simon seem to have the knowledge, which interests me at least , sorry if I'm the one who polluted the waters, it was not the intention.

akallen · July 2017

Ok. Thanks to all for your thoughts. Firstly, I'm retired EE/CS, so if there are other engineers on the forum you can get more technical if you so choose. I understand trying to keep it at a shareable level. I attempt to do that as well.

As you are all aware, there are a number of chemistries for LiIo, the category that specifically does not include the LiFePO 3.2v category. In the automotive world, which stresses batteries much more than stationary applications, the NMC (nickel, manganese, cobalt) tend to be favored. Nominal is 3.7v with a charge profile up to around 4.2v, although the caveat is that 4.2v topping of the batteries ages them at a higher rate than a constant current charge up to 4v. Trade off is obviously that one needs more batteries. I can buy first quality LG, Samsung and Panasonic 18650 batteries all day long for less than $1 apiece. That, and the fact that I'm willing to customize the BMS to not float above 4V will give thousands of cycles. Other advantage is that LiIo at below 4v are close to self-balancing and so very little is wasted. My rule of thumb with the Surrettes is to never go below 50% SOC and they've done pretty well. High maintenance unfortunately. I'm looking at an array design using low C 18650 2500mah cells and never drawing more than 1000mah per cell. The data is still coming in, but Tesla batteries are up to about 500,000 miles and a remaining average capacity of 92%. That's really (to me) kind of amazing given the automotive duty cycle and the nature of Superchargers. Shows the power of proper BMS and temperature control. Still thinking about how precisely I want to control charge / discharge and temperature, so no firm design yet.

What I learned herein is that the modern inverter/controllers are now apparently programmable so as to fit a lithium profile. My Xantrex are old enough that such capability isn't there. They insist on a type of float that is wrong for lithium. They seem to be bulletproof, so in a perfect world it would be great if Schneider could do a code upgrade that allows these new features. In any case, I need more than the 11kW capability I currently have. Between the heat and driving an EV, I'm using serious power. Xantrex only seems to go up to 6kW, so I'm going to look into Outback and SMA first so as to see what is possible. Again, thank you.

Solray · July 2017

mcgivor said:

http://www.snopes.com/horrors/techno/laptopfire.asp
http://www.nbclosangeles.com/investigations/I-Team-Investigation-Battery-Lithium-Ion-Fire-Laptop-Computer-412459303.html
http://nypost.com/2017/05/31/jetblue-flight-diverted-after-laptop-battery-catches-fire/

Laptops never catch fire, 30 second search, no comment.

Those are stories and videos of people having their laptop vents covered by fabric cushions and a bed and overheating the laptop, the batteries did not catch on fire, the fans are made to keep temperatures down, but if you block them by being stupid, bad things happen.
I bet if you block all the vents on your TV similar things will happen. I bet if you disable all the fans in your desktop, it will burn up too.
The moral is don't be stupid and block the vents on electrical equipment.

lolakallen said:

Ok. Thanks to all for your thoughts. Firstly, I'm retired EE/CS, so if there are other engineers on the forum you can get more technical if you so choose. I understand trying to keep it at a shareable level. I attempt to do that as well.

As you are all aware, there are a number of chemistries for LiIo, the category that specifically does not include the LiFePO 3.2v category. In the automotive world, which stresses batteries much more than stationary applications, the NMC (nickel, manganese, cobalt) tend to be favored. Nominal is 3.7v with a charge profile up to around 4.2v, although the caveat is that 4.2v topping of the batteries ages them at a higher rate than a constant current charge up to 4v. Trade off is obviously that one needs more batteries. I can buy first quality LG, Samsung and Panasonic 18650 batteries all day long for less than $1 apiece. That, and the fact that I'm willing to customize the BMS to not float above 4V will give thousands of cycles. Other advantage is that LiIo at below 4v are close to self-balancing and so very little is wasted. My rule of thumb with the Surrettes is to never go below 50% SOC and they've done pretty well. High maintenance unfortunately. I'm looking at an array design using low C 18650 2500mah cells and never drawing more than 1000mah per cell. The data is still coming in, but Tesla batteries are up to about 500,000 miles and a remaining average capacity of 92%. That's really (to me) kind of amazing given the automotive duty cycle and the nature of Superchargers. Shows the power of proper BMS and temperature control. Still thinking about how precisely I want to control charge / discharge and temperature, so no firm design yet.

What I learned herein is that the modern inverter/controllers are now apparently programmable so as to fit a lithium profile. My Xantrex are old enough that such capability isn't there. They insist on a type of float that is wrong for lithium. They seem to be bulletproof, so in a perfect world it would be great if Schneider could do a code upgrade that allows these new features. In any case, I need more than the 11kW capability I currently have. Between the heat and driving an EV, I'm using serious power. Xantrex only seems to go up to 6kW, so I'm going to look into Outback and SMA first so as to see what is possible. Again, thank you.

You may be able to get the new profiles by doing a FOTA update.

For charging cars, they have new tech that lets the car charge as it passes over plates in the soar surface. pretty neat.

Dave Angelini · July 2017

akallen said:

Ok. Thanks to all for your thoughts. Firstly, I'm retired EE/CS, so if there are other engineers on the forum you can get more technical if you so choose. I understand trying to keep it at a shareable level. I attempt to do that as well.

As you are all aware, there are a number of chemistries for LiIo, the category that specifically does not include the LiFePO 3.2v category. In the automotive world, which stresses batteries much more than stationary applications, the NMC (nickel, manganese, cobalt) tend to be favored. Nominal is 3.7v with a charge profile up to around 4.2v, although the caveat is that 4.2v topping of the batteries ages them at a higher rate than a constant current charge up to 4v. Trade off is obviously that one needs more batteries. I can buy first quality LG, Samsung and Panasonic 18650 batteries all day long for less than $1 apiece. That, and the fact that I'm willing to customize the BMS to not float above 4V will give thousands of cycles. Other advantage is that LiIo at below 4v are close to self-balancing and so very little is wasted. My rule of thumb with the Surrettes is to never go below 50% SOC and they've done pretty well. High maintenance unfortunately. I'm looking at an array design using low C 18650 2500mah cells and never drawing more than 1000mah per cell. The data is still coming in, but Tesla batteries are up to about 500,000 miles and a remaining average capacity of 92%. That's really (to me) kind of amazing given the automotive duty cycle and the nature of Superchargers. Shows the power of proper BMS and temperature control. Still thinking about how precisely I want to control charge / discharge and temperature, so no firm design yet.

What I learned herein is that the modern inverter/controllers are now apparently programmable so as to fit a lithium profile. My Xantrex are old enough that such capability isn't there. They insist on a type of float that is wrong for lithium. They seem to be bulletproof, so in a perfect world it would be great if Schneider could do a code upgrade that allows these new features. In any case, I need more than the 11kW capability I currently have. Between the heat and driving an EV, I'm using serious power. Xantrex only seems to go up to 6kW, so I'm going to look into Outback and SMA first so as to see what is possible. Again, thank you.

Xantrex sold to Schneider Electric about 8 years ago. Their Mppt's the 600vdc, the 150vdc are scaleable up to 100's of KW. They are networked and interfaced to Combox that gets you out to the WEB if you need it. Did you look at the link in thread 2? The XW+ 6848 Inv/Chg is now scaleable for microgrids to 100KW and will be 300+KW in the near future.

Mangas · July 2017

As Dave pointed out, for example, I have two pair of stacked Schneider XW + plus' 5548s inverters.

Inverter/charge controllers compatible with Lithium Ion profile

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