LifePO4 batteries for use with Midnite Classic 150?

[SunEagle]

Yeah those are riddled with problems anyway. One, it requires quite a bit of instantaneous power to keep someone upright who is leaning way above the center of gravity for the device, the batteries that are small enough to fit in those probably aren't rated for that much current. Also, those things get abused quite often from falls and other stuff damaging them. Lastly, most people have cheap crap Chinese no name "hoverboards" which are poorly designed and only cost like $200. They probably went with cheap batteries and cheap speed controllers that have a tendency to short out.

On a side note, what type of planes do you have? I have a few super cubs, I love em! I even bought the floats so I could land and take off from the water.

You are correct about those hover boards being cheap Chinese crap.

The 4 electric are; a Zephyr II made by Ritewing, a SkySurfer V 2, a small Cub (really an indoor model) and a Bumblebee 450 quad copter. I also have a Tower Hobbie Nitro Trainer that has seen better days. I haven't flown much lately but hope to get up again when the weather cools off this fall.

[laser411]

I have dozens of LiPo batteries for my RC planes without any of them going up in flames but there is always a chance something goes wrong while they are charging or discharging.

Have you seen any of those new hover boards ignite lately? I am sure they have Li batteries of some kind.

Yeah those are riddled with problems anyway. One, it requires quite a bit of instantaneous power to keep someone upright who is leaning way above the center of gravity for the device, the batteries that are small enough to fit in those probably aren't rated for that much current. Also, those things get abused quite often from falls and other stuff damaging them. Lastly, most people have cheap crap Chinese no name "hoverboards" which are poorly designed and only cost like $200. They probably went with cheap batteries and cheap speed controllers that have a tendency to short out.

On a side note, what type of planes do you have? I have a few super cubs, I love em! I even bought the floats so I could land and take off from the water.

[SunEagle]

They usually only explode when improperly charged, discharged, or damaged. I've got about 20 lithium-ion batteries in my house for use with projects and I even use them to jump start my car. Everyone of us with a smartphone holds a Li-Ion battery up to their face daily. Only one that has ever caught fire on me was one that I shot a hole through to see just how bad it was. Even then, it took a nail being shoved through the hole in the cell for it to actually catch fire.

I have dozens of LiPo batteries for my RC planes without any of them going up in flames but there is always a chance something goes wrong while they are charging or discharging.

Have you seen any of those new hover boards ignite lately? I am sure they have Li batteries of some kind.

[laser411]

Relax and take a deep breath, and relax.Let's talk about why Lithium Batteries are not used in solar systems today. Yes there are a few, but they are rare experimenters. The question is why are not people using them in Solar? Simple answer economics.Both short term and long term economics do not work out.

To compare apples to apples or Pb to LFP we must apply rule #75 which states for every 100 wh of Pb takes 75 wh of LFP to be equal usable capacity. So if we wanted to use 1 Kwh per day of usable energy we would buy either a 5 Kwh Pb battery of 4 Kwh LFP battery. Both gives us 1 Kwh per day, or 3 Kwh usable before recharge.

OK here is the deal breaker. The Pb battery will cost you $800 to $1000 and last about 5 to 7 years. A Chi-Com LFP will cost you $2000 and you would be extremely lucky for it to last 5 years.The market is not stupid, they buy the Pb battery.

As for a BMS. any commercial solution requires a BMS for the simple fact the public knows nothing. Thus manufactures must limit liability losses and include a BMS. Without a BMS is an open and shut law suit for anyone who wants to suit them. Lots of fire with lithium batteries and cases are extremely easy to win because everyone knows Lithium Batteries explode.

They usually only explode when improperly charged, discharged, or damaged. I've got about 20 lithium-ion batteries in my house for use with projects and I even use them to jump start my car. Everyone of us with a smartphone holds a Li-Ion battery up to their face daily. Only one that has ever caught fire on me was one that I shot a hole through to see just how bad it was. Even then, it took a nail being shoved through the hole in the cell for it to actually catch fire.

[Sunking]

ook so i have a question ive read most of the post on the subject aboout lithium batteries being a pain to use with solar if your not knowledgeable , mostly all i have read is about cells with or without bms and ,keeping the cell voltage even so they dont fail from over or under voltage , you make it sound hard to keep the voltage in the cells balanced, because even if you balance them (which i heard you can do before connecting a bms by running them parrallel and letting them sit 24 hours idk if its true)that over time the voltage will be uneven because no cell is 100% the same? For the record im a noob with solar and lithium..also can i use drop in replacements for sla that are lithium? or will the same problem arise? i know technically they are still just cells with a bms...allso i gather i cant use a standard charger like midnight solar clasic? btw im looking to run my fridge and some led lights off a lithium bank nothing big ..powered by solar and wind ..was planning on using midnight solar classic to do it ....PLEASE dont be over critical to me.. but help would be appreciated

Relax and take a deep breath, and relax.Let's talk about why Lithium Batteries are not used in solar systems today. Yes there are a few, but they are rare experimenters. The question is why are not people using them in Solar? Simple answer economics.Both short term and long term economics do not work out.

To compare apples to apples or Pb to LFP we must apply rule #75 which states for every 100 wh of Pb takes 75 wh of LFP to be equal usable capacity. So if we wanted to use 1 Kwh per day of usable energy we would buy either a 5 Kwh Pb battery of 4 Kwh LFP battery. Both gives us 1 Kwh per day, or 3 Kwh usable before recharge.

OK here is the deal breaker. The Pb battery will cost you $800 to $1000 and last about 5 to 7 years. A Chi-Com LFP will cost you $2000 and you would be extremely lucky for it to last 5 years.The market is not stupid, they buy the Pb battery.

As for a BMS. any commercial solution requires a BMS for the simple fact the public knows nothing. Thus manufactures must limit liability losses and include a BMS. Without a BMS is an open and shut law suit for anyone who wants to suit them. Lots of fire with lithium batteries and cases are extremely easy to win because everyone knows Lithium Batteries explode.

[karrak]

Lithium Iron Phosphate (LFP) batteries are not that hard to use, but you can't just connect them together and then set and forget unless you buy something like a Tesla battery.

As you have said it is important to get the battery balanced before you commission it. The best way to do this is to connect the cells in parallel and use a charger to charge them to 3.6V then let the charge current taper off to nearly zero.

It is important to get the charge settings right. This is possible with the Solar Classic.

The batteries will only go out of balance very slowly, it happens over months and years. You can either check and rebalance the battery yourself, or you can buy equipment that will automatically do it for you.

As a bare minimum I would recommend installing some sort of individual cell monitoring. This could be as simple as a Cellog8, or something more complex. You should also have an accurate multimeter to measure the individual battery cell voltages. I use a Uni-T UT61E

As you have said the critical thing with LFP batteries is to not let the any individual cell voltage go outside the safe operating range of 3.6V-2.8V. The Cellog8 can be programmed to give you an audible alarm if any of the individual battery cells goes out of the safe operating range. If you want better protection you can buy extra equipment that will disconnect the battery if this occurs.

If what I have said has not been too scary you might want to look further into this.

Before you go any further you will have to work out your daily power requirements in kWh, and your peak power use in kW. Another important factor is whether or not you want to use a generator.

Have you had much experience with electronics in the past?

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

---

[matthewlee]

oh i know a bit about lithium and i would use any thing other than lithium phosphate if i did use lithium ...i see you use nickel iron batteries i heard some of those have a 80% depth of charge cost a pretty penny though have you been using it long ? im really trying to find something better than lead acid ..i think its crazy i can buy a 400ah fla or sla and only be able to actually use 200 of it or so..

[Mike90250]

ook so i have a question ive read most of the post on the subject aboout lithium batteries being a pain to use with solar if your not knowledgeable , mostly all i have read is about cells with or without bms and ,keeping the cell voltage even so they dont fail from over or under voltage , you make it sound hard to keep the voltage in the cells balanced, because even if you balance them (which i heard you can do before connecting a bms by running them parrallel and letting them sit 24 hours idk if its true)that over time the voltage will be uneven because no cell is 100% the same? For the record im a noob with solar and lithium..also can i use drop in replacements for sla that are lithium? or will the same problem arise? i know technically they are still just cells with a bms...allso i gather i cant use a standard charger like midnight solar clasic? btw im looking to run my fridge and some led lights off a lithium bank nothing big ..powered by solar and wind ..was planning on using midnight solar classic to do it ....PLEASE dont be over critical to me.. but help would be appreciated

When using LFP cells (don't even try to use other lithium mixes) you have to work in the middle of the battery capacity range, to avoid the "dangerous" area of over or under voltageing one cell in the pack. So if you need a 100Ah you have to buy a 130Ah battery, to be able to work in the "safe space".
BMS systems claim to be able to manage the imbalances, but often need a special charger the BMS can control. This is all pretty tough for well versed system owners, and for a starter system, unless the installer gives you a turnkey system and a 15 year warranty, I would not touch LFP at this date.

The Classic can be programmed to do many things, but YOU have to know the how and why you chose a particular group of settings for it,

[matthewlee]

ook so i have a question ive read most of the post on the subject aboout lithium batteries being a pain to use with solar if your not knowledgeable , mostly all i have read is about cells with or without bms and ,keeping the cell voltage even so they dont fail from over or under voltage , you make it sound hard to keep the voltage in the cells balanced, because even if you balance them (which i heard you can do before connecting a bms by running them parrallel and letting them sit 24 hours idk if its true)that over time the voltage will be uneven because no cell is 100% the same? For the record im a noob with solar and lithium..also can i use drop in replacements for sla that are lithium? or will the same problem arise? i know technically they are still just cells with a bms...allso i gather i cant use a standard charger like midnight solar clasic? btw im looking to run my fridge and some led lights off a lithium bank nothing big ..powered by solar and wind ..was planning on using midnight solar classic to do it ....PLEASE dont be over critical to me.. but help would be appreciated

[PNjunction]

Note too that "18650" refers ONLY to size, and not specifically the chemical makeup inside.

Most consumers think of laptops, flashlights and so forth that do not use LFP, but a different li-ion chemistry. Yet if you look closely at many hobby-type chargers like Nitecore, Xtar etc and others used by flashlight fanatics, most have an option specifically designed to put them into the LiFeP04 mode. Very important. See Candlepower forums for that type of application.

For instance, and this is VERY important, you can get "18650's" with either LiFeP04, or any other li-ion chemistry, such as LiCo02. LFP is a nominal 3.2v cell, whereas all the rest are nominal 3.7v cell, which are REALLY fussy about charge termination and so forth.

For example, had you not purchased the GBS cells, you could have also gotten some hands-on with smaller LFP 26650 cells detailed here:

https://www.solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/lithium-ion/300609-low-cost-lifep04-learner-bank

What we find here is that in the case of either the large prismatic GBS or the cylindrical 26650 LFP's used in that project, the overall characteristics, other than capacity, are nearly the same. In this case, both cells, whether prismatic or cylindrical are mostly "energy cells", aka "3C" cells, rather than others like Headway cylindricals, which are "power cells", aka "10C" cells.

You CAN use "power cells" for a low-current solar storage product, but that would be mostly a waste of money since you'll never use that capability - unless you are designing an improperly small solar storage bank to begin with.

[Sunking]

Now I understand why everyone uses 18650 cells. That's kind of like magic.

Well yes and no. Application and economics dictate what needs to be used. If you make battery operated power tools that demand 10C batteries, you can justify the cost of using clylindrical cells.

This is why I was pounding on you so much You can buy a CALB 100 AH cell all day long for $130. Works great for applications using 3C or less applications. Do the math and the Cost is $130/ [3.2 volts x 100 AH] = $0.4065/ watt hour. Want to do that with 3.2 volt 1.1 AH 18650 cells with 10C discharge rate for a 3C application? That will cost you $4.05 / [3.2 volts x 1.1 AH] = $1.15 watt hour. You are paying over 100% more almost 200% more for something you have no use for. Not to mention a lot heavier and bulkier.

[createthis]

No Sir that is not what it means. You are not comparing Apples to Apples leading you to the wrong conclusion. Stop and think what is different.




Did you figure it out?







Hint: Amp Hours








You are comparing a GBS 100 AH cell to what size E-Bike cell? 2.9 AH maybe? To equal you have to compare 100 AH to 100 AH. Those cells are what 2.9 AH? It would take 34 of them in parallel to = 100 AH. 34 cells in parallel is:

.006 Ohms / 34 cells = ..00017 Ohms. A hell of a lot lower than the GBS like 1/10th as much. Not even close. If the GBS sag 2.0 volts, the other sags 0.2 volts

Now I understand why everyone uses 18650 cells. That's kind of like magic.

[PNjunction]

That was my logic, yeah, but I ended up buying a PowerLab 8 v2 to aid in automatically pulling the battery voltage down to 2.5V. Didn't feel like babysitting it, and I figure I'll probably make more battery systems in the future, so why the hell not?

Great! Now you can decide for yourself if bottom balance, or top balance is your thing. Yawn.

AND, you can also try the 3rd KISS method (still top-balance per se), of using the PowerLab 8 in a single-cell charge mode (1S), charge each cell individually to 3.60v until current drops to 5A (for your 100ah cells, aka .05C). Try to use more than .05C for charge - if you can at least 10A to 30A - it will depend on your supply capability...)

Let them sit fully charged for a few days. They should eventually settle to near 3.38 3.40v. If any cell is drastically lower, then it has a high level of self discharge and should be inspected / replaced under warranty.

Discharge normally as a pack now, no faster than 0.5C, (who even DOES that with properly sized lead acid anyway??), and stop when any cell reaches 2.7v under load - preferably sooner. Me, I go no further than 3v under load - ie loads no larger than about 0.1 to 0.2C. Easy to remember - 12v on your 4S bank is the lowest I'd ever go, and 10.8v *under load* would be a dead-man kind of thing. Lo and behold!

SHHH .. Don't tell this to anyone .. WHAT?? My LVD's on my inverters kick off at 10.8v under load, and some even 11.7v. Sure, designed for Pb, BUT that's a total dead-man lvd, but at least you'll save the bank from going to zero. Obviously, better to not hit this at all, but it is there right? I don't rely on these but use my own external LVD with higher voltages, but for dead-man failures, at least *something* lvd is there.

Reset your Powerlab to charge as a pack to no more than 3.40v (13.6v for your bank) and you can let current taper to near nothing - it won't be fully charged anyway.

The reason I keep mentioning this over and over is that your solar controller as far as I know has no way of incorporating individual cell monitoring, and this solution of fully charging to 3.60v first individually, and then charging to no more than 3.40v as a pack thereafter, can at least get you in the ballpark without endangering the cells. You are relying on the manufacturer to be providing reasonably close cell characteristics, and in *our low current application* as far as the cells are concerned, fretting over internal resistance and minute voltage differences and the like is fun, but not a deal breaker. If you feel like it, repeat the individual cell charge to 3.60v / 0.05C end current on a regular basis - maybe once a year or whatever floats your boat.

Essentially, YOU are the bms, without any vampire boards, or in this case not even individual cell monitoring / balancing. But go ahead and do the individual cell thing if you feel like it. You aren't putting these things into an EV, or a remote cell tower. Perhaps you'll do just fine being the bms. Again, the emphasis here is that at some point, your Midnite controller comes into play without the individual cell stuff.

You'll see. These things aren't made of glass. Go forth and experiment and find YOUR level of comfort. I wish more would do the same.

[Sunking]

This page seems to indicate the internal resistance is 0.06 ohms for a 29E cell: http://lygte-info.dk/review/batterie...lue)%20UK.html

That's weird, because that would mean it has a higher internal resistance than GBS LifePO4.

No Sir that is not what it means. You are not comparing Apples to Apples leading you to the wrong conclusion. Stop and think what is different.




Did you figure it out?







Hint: Amp Hours








You are comparing a GBS 100 AH cell to what size E-Bike cell? 2.9 AH maybe? To equal you have to compare 100 AH to 100 AH. Those cells are what 2.9 AH? It would take 34 of them in parallel to = 100 AH. 34 cells in parallel is:

.006 Ohms / 34 cells = ..00017 Ohms. A hell of a lot lower than the GBS like 1/10th as much. Not even close. If the GBS sag 2.0 volts, the other sags 0.2 volts

[createthis]

There are a ton of e-bike systems out there, but mine is the Bosch Powerpack Performance line: http://www.bosch-ebike.de/en/kompone.../powerpack.php
It uses 18650 cells: https://endless-sphere.com/forums/vi...p?f=14&t=75748
They're either Samsung 29E cells or LG 11865, from what I can tell: https://endless-sphere.com/forums/vi...p?f=14&t=66277
Far as I can tell the 29E cells are NCO chemistry: http://batterybro.com/blogs/18650-wh...ally-explained
I don't know what the LG 11865 chemistry is.

This page seems to indicate the internal resistance is 0.06 ohms for a 29E cell: http://lygte-info.dk/review/batterie...lue)%20UK.html

That's weird, because that would mean it has a higher internal resistance than GBS LifePO4.