11.1V System

[ctwo]

Some of you will recall my discussion about using a Li-Ion solar charge controller. There are many of such controllers designed around a 3S system, but I am wondering what is their application?

Why would someone choose this voltage? This is not a system that could run a typical off-the-shelf AC inverter very effectively because the typical low voltage cut-off is ~10.5V.

Oh, and I read there are some Li-Ion based UPS systems. Do these use a 3S configuration?

[Sunking]

Some of you will recall my discussion about using a Li-Ion solar charge controller. There are many of such controllers designed around a 3S system, but I am wondering what is their application?

Toys and experimental. We have been through this already. You have LCO batteries which are 3.6 volt nominal so 3S = 10.8 volts, or what you are calling 11.1 volts for some reason unknown. LCO cells are not compatible with Lead Acid battery systems.

Why would someone choose this voltage? This is not a system that could run a typical off-the-shelf AC inverter very effectively because the typical low voltage cut-off is ~10.5V.

No one would use it unless they want a proprietary that is not compatible with anything else like an Apple Product. LCO is primarily used in EV's, Cell Phones, Laptops, and Cameras.

Oh, and I read there are some Li-Ion based UPS systems. Do these use a 3S configuration?

No not normally, only in proprietary systems not compatible with anything else. Off the shelf would use 4S, 8S, and 16S LFP. You got to get your head wrapped around that. 4S LFP (Lithium Iron Phosphate) cells are 3.2 volts, and configure as 4S = 12.8 volts with a operating range of 12 to 14.4 volts which is DROP IN REPLACEMENT for lead acid batteries. They will work with most Solar Charge controllers and operate any equipment made for 12 volt battery. 8S = 24 volt, 16S = 48 volt.

So here is the deal. If you use LCO cells in 3S = 10.8 volts, or in 4S = 14.4 volts. Neither is compatible with 12 volt systems. YOU HAVE TO USE 4S LFP. You do not seen to understand there are basically 5 Lithium battery types, and all have a different operating voltage. Of the 5 voltages only LFP is compatible with lead acid battery systems.

As for charge controllers there is only one manufacture, Genasun you can use, and you already know what it is. So if you insist on using 3S LCO cells you can charge then with the Genasun Controller, but you will have to design and build all the equipment to operate @ 10.8 volts.

[SunEagle]

Well the batteries used in Radio Control equipment have a 3S label that are rated 11.1V. They are Lithium Polymer (LiPo) chemistry and have been know if over heat if charged or discharged too fast.

You must use a specially designed balance charger for these batteries.

They would not be a good choice for a solar deep cycle system due to their limited number of lifetime cycles.

[ctwo]

I was just asking about the types of li-ion controllers one finds in great magnitude on ebay. I do not have a use for the one I bought and was curious what folks would be using them for. I can toss mine out without much thought since it was only $12 shipped.

These are the batteries I received, but do not plan to use them in my solar system: https://www.imrbatteries.com/content/samsung_22P.pdf I was probably going to buy a 500W front wheel ebike kit for the 36V pre-built packs, and not use lithium based cells with my 100W solar panel.

[Sunking]

ctwo there is not anything wrong with the battery. It is made for a specific applications like an eBike in a 10S 36 volt. Target market for the batteries is OEM's

It is possible to charge them with Solar, but no real good way to implement with solar because the cells have very specific charge requirements that solar cannot perform well. The batteries are HOT and unstable and will not tolerate any abuse. They require a 1C to C/2 charge current held at 4.25 volts per cell until Current tapers to 2% of C. That is extremely difficult to do with solar because most controllers can limit charge current or terminate when current tapers to a specific value. It could be done, but you would have to design the controller.

Take the Genasun GV 10 with your 100 watt panel. You can order one with a voltage of 12.75 volts. With a 100 watt panel charge current is roughly 8 amps. That is roughly 400% higher than the battery can handle. Two ways around that are use a 3S4P battery or use a 25 watt panel. Take your pick. However the Controller does not have the ability to terminate the charge when charge current tapers top a specific value. That is something you woul dhave to design and build externally to the controller like a BMS. Just impractical to do any of that especially when you consider in 3S will not work with anything you can use. It is an expensive adventure to no where.

For solar and equipment that uses 12, 24, and 48 volts LFP is used in multiples of 4S cells. LFP cells are extremely safe, 1/4 the cost, last 4 times as long, and require no special equipment like a BMS. You can use most off the shelf controllers and any equipment like an Inverter made for 12, 24, and 48 volt battery systems. You would use Prismatic cells. If you needed 100 AH, buy 100 AH cells. No complicated and risky parallel configurations. The reason you do not see LFP cells in an EBike is because of energy density. LCO have considerably higher energy density, but the trade-off is stability and safety. To get the same amount of energy in a LFP cell requires them to be roughly 1/3 larger and heavier. An eBike or EV's do not have the luxury of added weight and space. In a Solar system space and weight is of no real concern.

[Sunking]

Well the batteries used in Radio Control equipment have a 3S label that are rated 11.1V..

That had occurred to me, and eBikes certainly use LiPo's, but those cells are not LiPo, nominal is 3.6 volts. They are a LCO variant.

For me if I had an eBike I would look at RC LiPo's. Even thought about it setting a World Record 1/4 mile in a golf cart using LiPo's. Right now it sets at 118 mph in 12.24 seconds using Optima AGM batteries. That is 500 pounds of lead that could be reduced to less than 75 pounds with a hotter battery, LiPo's. Surprised they have not done that yet.

[ctwo]

I've worked for companies that have first created a product, because they could, and then tried to create a market for it. That reminds me of the li-ion solar charge controller I bought. If it could be used for silly things and experimental purposes, it seems those folks would be rolling their own anyway. I see it was just a SMOP to put a new label on an old product and squeeze a few more bucks out of it.

I'll figure out what to do with my 100W solar panel at some point. The solar panel calculator link here is not working. Sunking, I think you told me in the other topic what I could expect from my panel, but would like to explore that further. That was one purpose of my diving into this on a small scale, to be able to measure it.

[sensij]

Use PVWatts to see what your panel might be capable of producing. 10% loss is a good stab at what to put into the model for grid tie systems... Batteries are more complicated, but at least it gives you the upper bound.

[ctwo]

OK, that gave me 155 kWh per year, or about 425 Wh per day, which is about what I was expecting. So I could probably run a 15W device and suffer some down time during the rainy winter times.