Gords pointed out this could be useful so here it is.
If you want to learn more, please visit our website.
Proper Use of s
The proper use of li-ion batteries is a quite complex issue, and one of the most important as misuse of them can lead to an explosion.
What is a Li-ion Battery?
Lithium Ion batteries are very popular in flashlights for a number of reasons. One reason is that the voltage of the battery is very close to the voltage required by most LEDs. This makes it much easier to have them run an LED. They also hold a large amount of power in a small space, they are much more energy dense than Alkaline batteries. This is because unlike alkaline batteries, lithium batteries hold almost as much power at a 3 amp draw as at a 1 amp draw. The other advantage is they are rechargeable, this means we can use our flashlights as much as we want since they simply have to be recharged.
There are 2 main types of Lithium Ion batteries, the first and most common is the LiCo cell. (Lithium Cobalt) these are the cells used in laptop batteries along with many power tool batteries. They have a nominal voltage of 3.7 volts and are 4.2 volts when fully charged. Most of them can be run down to 3 volts, before you should stop using them and recharge them. They can generally supply around 5 amps maximum.
Another type of battery that is very similar to the LiCo cell is the LiMn cell or what is know as an IMR cell. LiMn cells can supply over 20 amps so are great for high current situations. Naturally, something that can supply so much power is quite dangerous if shorted. In some cases they are safer though since they do not catch on fire or explode violently if punctured or crushed.
Both LiMn and LiCo cells have the same voltage, but the LiCo cells tend to have a higher capacity than LiMn cells. Since their voltage varies a large amount during discharge the discharge curve will look like this.
The other main type of Li-ion battery is LiFePo4. Unlike LiCo batteries they have a lower voltage. They have a nominal voltage of 3.2 volts and are 3.5 fully charged. They are considered “dead” when they reach 3 volts. It is because of this that they have a very flat discharge curve. (See Below) They are also much safer, unlike a LiCo cell it is very hard to make them explode or react violently. Because of this LiFePo4 cells are not made with protection circuits. The disadvantage to LiFePo4 batteries is twofold. First, they have a lower capacity. Second, they have a lower voltage and
thus cannot be used to direct drive an LED. This means that some form of circuitry, a boost circuit, is needed in between a LiFePo4 battery and the LED.
Construction of a Li-ion Battery
I'm not going into the chemistry of a li-ion battery, this is simply a explanation of what the different parts are.
So you get something like this in the mail, a protected .
This protected battery is composed of a battery and a protection circuit.
(HKJ's picture)
The protection circuit placed at the negative side of the cell, but is attached to the positive side through a piece of wire. The purpose of the protection circuit is to prevent the battery from being over-discharged (discharged below 3 volts generally), over-charged (charged to above 4.2 volts), or over-current (letting out more than X amps, where X is a value generally around 6).
Then there is the battery itself.
It is composed of a number of different components stacked inside a metal casing which is then wrapped with shrink wrap. This is a before assembly picture.
That green roll is the part that actually holds the energy. It is made up of a positive electrode (a metal oxide), a negative electrode (carbon), and an insulator rolled up. All of these sit in the electrolyte (non-liquid).
Here a diagram of that is.
Now what about the other parts? Here a crappy paint diagram of the top of the battery is.
Ok, so the purpose of the insulator is to prevent the body of the cell (negative) from shorting to the top (positive). The PTC is a positive temperature coefficient. As it heats up the resistance increases, this is a kind of added protection as when the cell is shorted it will heat up. Then as the resistance increases the short will stop. The vent holes allow the battery to vent any gasses, rather than having pressure build up inside the casing of the battery.
There are 3 main types of positive contacts used on the batteries. First, and most common is flat top; these are a simple metal contact no higher than the surrounding label. This is the way batteries generally come from the manufacturer. (Does not apply to NCR series) Then there is raised top, or button top, this has the same contact size as the previous one, but the whole surface is raised. This is needed in lights where the batteries are stacked to ensure contact. Then there is nipple top, this has a small raised top; much smaller. Some lights that have mechanical reverse-polarity protection require nipple tops.
People often use small round magnets to create a a nipple top from a flat top. To do this one simply places a magnet on the top of the battery, this does come with a risk. The magnet can easily slide out of space and short out the battery, it is for this reason people often place a dab of superglue under the magnet. An example of one of these magnets is this.
How to treat LiCo/LiMn Cell in Flashlights
LiCo/LiMn cells are the most dangerous kinds of Li-ion battery. They have and can explode if not treated with respect and care.
First of all, when using them in multi-cell lights make sure they are the same voltage. This means you will need to have a DMM and check the voltage before you load them in the flashlight. This is important because as they discharge if one is at 3.6 volts and the other is at 0 then the one at 0 can get reverse charged. This is how they explode.
Continuing in the mission to prevent reverse charging, one must use cells of the same capacity. This means all of the cells must be identical, and matched to each other. A few notes about this: xxxxfire cells are not considered identical and a cell that has been used a lot is not identical to an unused cell.
How to treat a LiCo/LiMn Cell When Charging
When you charge them you should always use a good charger. Do not cheap out and use a 2 dollar charger from China. Overcharging can also lead to an explosion, there are documented cases where it has.
Lico/LiMn batteries have a complicated way in which they must be charged. For this reason do not try to make your own charger. These are the directions for how Panasonic says to charge them.
As you can tell this is extremely complicated. As far as I know, there are not any chargers that follow this exactly but there are many that do do a CC/CV curve which is what matters. A CC/CV curve means that first the charger charges the battery with a constant current and lets the voltage rise. Then it switches over to constant voltage and lets the current drop. Here an example of a correct charge curve is. (HKJ)
HKJ has reviews a number of chargers so you can find one that he has approved.
My personal favorite is the Intellicharge I4 which can charge both LiMn/Lico cells and Nimh cells. It is priced very reasonably at 20-25 dollars. They also make an Intellicharge I2 which is equally capable.
Xtar also makes a number of great chargers, all of which follow a CC/CV curve.
So once you have picket out a suitable charger and need to charge your batteries you simply place them inside the charger and wait. One should stay near the batteries while they are charging, and if they start to heat up or smell unplug it immediately.
How to Treat LiFePo4 Cells in Flashlights
LiFePo4 cells are much safer than LiCo/LiMn cells, but the same rules still apply. For ease of use I repeated the information below.
First of all, when using them in multi-cell lights make sure they are the same voltage. This means you will need to have a DMM and check the voltage before you load them in the flashlight. This is important because as they discharge if one is at 3.4 volts and the other is at 0 then the one at 0 can get reverse charged. This is what often causes them to explode.
Continuing in the mission to prevent reverse charging, one must use cells of the same capacity. This means all of the cells must be identical, and matched to each other. A few notes about this: xxxxfire cells are not considered identical and a cell that has been used a lot is not identical to an unused cell.
Also, do not mix LiFePo4 cells with LiCo/LiMn cells.
How to treat a LiFePo4 Cell When Charging
Like LiCo/LiMn cells, LiFePo4 cells should be watched while in the charger.
They also have to be charged with a CC/CV curve, but the difference is they terminate at 3.6 volts.
Currently, if you want a LiFePo4 charger you have to use either a hobby charger or a untested chinese charger. Neither of these is optimal.
However for LiFePo4 cells, the Xtar MP2 is capable of charging them if set to "3.0V".
One last note about LiFePo4 cells, I have personally tortured them by overcharging, shorting, overdischarging and extremely high discharge rates. Not once have they ever vented.
Estimating Remaining Capacity in Li-ion Batteries
When you measure the resting voltage of a lithium ion battery you can get a rough idea of how much capacity is left in it. Use this table.
Choosing The Right Battery
First of all, any battery that has "fire" in it's name is not suitable for use in multi-cell lights. This is because even if they may be rated at the same capacity, they are most likely not equal and could become unbalanced under high loads.
For go to post 1, for anything smaller than a go to post 2. For anything bigger go to post 3.
Feel free to comment and correct me on any mistakes.
First of all, 99% of the graphs below are from HKJ. These were done by him, I am simply placing them in this thread for easy reference.
A is a battery the same size as a CR123 battery. They are also sometimes called RCR123. As described above some are 4.2 volts fully charged while others are 3.5 fully charged. Make sure your flashlight can support the type you choose.
AW IMR (LiMn)
This battery is good for lights that need high amounts of current from a .
Obviously due to the size it can only supply a maximum of 2 amps without losing a large amount of capacity.
Full review here.
Unspecified internal cell
AW 750 mah Protected (LiCo)
This battery has a high capacity, but only at loads below 1 amp. In general, the IMR battery will be better.
Full review here.
Unspecified internal cell.
AW LiFePo4 500 mah
These are very safe batteries, but have a much lower capacity and a lower voltage. For this reason they are not very popular.
The is used in lights such as the L2M. It is 2mm thicker than a CR123 cell so it will most likely not fit in lights meant for CR123 batteries.
AW IMR
The IMR is a great battery and can handle loads up to 5 amps while still having a 700 mah capacity.
Full review here.
Unspecified internal cell.
Trustfire Protected mah-LiCo
Link to CHANGINGTECH
These are protected LiCo batteries, while they do have a higher capacity than the IMR version they most likely do not do as well at higher currents. No tests have been done on them so far.
The is used to replace AA batteries, it has a much higher voltage than AA batteries so do not use a unless it is specified that it will work.
AW 600 mah IMR-LiMn
This battery handles loads up to 3 amps very well.
Full review here.
Unspecified internal cell.
AW 750 mah-LiCo
This cell does well up until the 2 amp point, at 3 amp loads the IMR cell would most likely perform better.
Full review here.
Unspecified internal cell.
Intl-Outdoor Protected 840 mah
This is the highest capacity at an approximate 800 mah capacity. Like the above battery it will do well up to the 2 amp point, but much above that and an IMR cell may be better.
Full review here.
Internal cell is URP, datasheet is here.
These cells are the size of a AAA battery. As is to be expected they have a higher voltage. Do not use these in your AAA light unless it is specified that it will work.
AW LiCo Unprotected 350 mah
This battery has a tiny 350 mah capacity, which is less at any significant current draw. It can only handle draws up to .5 amps.
Full review here.
Unspecified internal cell.
Efest IMR 350 mah
Like all batteries it has a tiny capacity, about equal to the above one. But it can handle currents up to 2 amps.
Full review here.
Unspecified internal cell
/
The is meant to be a replacement for lights that run on 2 CR123 batteries. It has a lower voltage at 4.2 volts versus the 6 volts of the CR123s. Some lights are compatible but not all are.
Keeppower Protected LiCo mah
This battery can handle currents up to 2 amps reliably, but due to the protection tripping in between 2 and 3 amps it is not as capable as it could be. It also has to be charged up to 4.3 volts to get full capacity.
Full review here.
URZT inside, datasheet is here.
Sanyo URZT LiCo mah
This battery has to be charged up to 4.3 volts for full capacity. It can only handle currents up to 3 amps.
Full review here.
Datasheet here.
Eagletac mah LiCo
This battery has a lower capacity, and can only handle currents up to 2 amps.
Full review here.
Unspecified internal cell.
Two of these are used to replace 3 CR123 batteries. They are thicker than CR123 batteries, but do have a similar voltage. (2*4.2=8.4; 3*3=9)
Keeppower mah LiCo-Protected
This battery can handle currents up to 5 amps without a problem.
Full review here.
URF inside, datasheet is here.
URF mah capacity LiCo
This is the same battery used in the above battery, except it is not protected. For that reason I reused the same graph.
Full review here.
Datasheet is here.
Before we get into specifics, you should know that there are a few different types of lithium technology — regular lithium, lithium-ion and lithium iron phosphate (LiFePO4 — also known as LFP). Standard lithium batteries are not rechargeable and, therefore, not fit for solar.
We already use lithium-ion technology in common rechargeable products like cell phones, golf carts and electric vehicles. Most lithium-ion solar batteries are deep-cycle LiFePO4 batteries. They use lithium salts to produce a highly efficient and long-lasting battery product. Since they are deep-cycle batteries, the products do very well even when the attached solar panels experience inconsistent charging and discharging.
Before Tesla developed its Powerwall I lithium-ion solar battery , most solar batteries used lead-acid battery banks. There are now many lithium-ion solar batteries on the market, allowing a range of options for homeowners and their various needs.
Here’s a helpful video to learn more about the differences between lithium-ion batteries and lead-acid batteries:
The best battery type for your solar system will depend on several factors, like what your system powers, if you are on or off-grid, and how often the system is used.
There are a variety of benefits of lithium-ion and LFP batteries over lead-acid batteries, but they might not be ideal for every solar setup. Let’s take a look at some pros and cons.
Pros Cons Higher depth of discharge (DoD) Premium Cost Long lifespan Thermal runaway High efficiency High charge rates High energy density Low maintenanceThe DoD of a battery is the amount of the stored energy in the battery that can be used relative to its total capacity. Most batteries come with a recommended DoD to maintain the health of the battery.2
For example, the Tesla Powerwall II has a 100% depth of discharge (or so it advertises), which theoretically means that you can use 100% of the energy in the battery before it has to be recharged (we believe that it’s closer to 80% — fully draining the Powerwall between charges will significantly lower the battery life).
Lithium-ion batteries have a high depth of discharge, meaning homeowners can use more stored energy without having to charge it as often. Lithium-ion batteries can handle discharging around 80% of their charge before needing to be refilled, as opposed to a lead-acid battery, which should only be run to 50% depth of discharge.
Lithium-ion batteries have a substantially longer lifespan than lead-acid batteries because of their high DoD. A high DoD means that they don’t have to be recharged as often. The more you recharge a battery, the shorter its lifespan will be (similar to an iPhone).
Battery efficiency refers to the amount of energy you get out of a battery relative to the amount that you put in.
Lead-acid solar batteries are notoriously high-maintenance. Inconsistent use can lead to damage and deterioration of its lifespan. This is not a concern for lithium-ion batteries. Lithium-ion batteries accept a larger amount of charge current, leading to shorter charging times.
Partially charging lithium-ion batteries also has little to no effect on their lifespans and performance. But with lead-acid batteries, it is recommended to fully recharge the batteries after discharging any amount of energy. Partial charges can reduce a lead-acid battery’s lifespan.
Lithium-ion batteries store more power with less space than lead-acid batteries. This makes them a great choice for homeowners, as lithium-ion batteries can be stored in garages or even mounted on walls.
Unlike lead-acid batteries, lithium-ion solar batteries do not need regular maintenance. This can save you time, money and the hassle of servicing your batteries.
Lithium-ion batteries are typically the most expensive residential battery storage option. The upfront price tag can lead to sticker shock, especially when compared to lead-acid batteries.
However, they are more cost-effective in the long run. Lead-acid batteries need to be replaced more often and require more maintenance. Keep in mind that solar battery systems qualify for incentives like the federal solar investment tax credit. Certain states even have standalone tax credits for solar energy storage systems.
Thermal runaway is one of the primary risks related to lithium-ion batteries. It is a phenomenon during which the battery enters an uncontrollable, self-heating state. Thermal runaway can result in the ejection of gas, shrapnel, particulates or fire.
When properly installed, the risk of a lithium solar battery overheating is slim to none.3
The total cost to install a lithium battery storage system can range anywhere from $4,000 to over $25,000. While that is a big cost range, the total price depends on:
The higher price tag comes with the benefits that lead-acid batteries can’t provide, like a longer lifespan and lack of needed maintenance.
There are many high-quality lithium solar batteries on the market in , but the most well-known choice is the Tesla Powerwall II battery. It is one of the most cost-effective lithium-ion solar batteries, costing around $12,000 with all parts and installation factored in. Below, you’ll see our picks for the best lithium solar batteries and a side-by-side comparison.
To get the most out of your entire solar system, you will need more than just state-of-the-art solar panels. A reliable and efficient solar battery can help you save energy and money in the long run. Make sure you explore your options and account for your home’s specific energy needs when choosing the best solar batteries for your system.
Are you interested in learning more about Lithium-ion Battery? Contact us today to secure an expert consultation!