Lithium-ion battery safety 101

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jon_slider
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good questions
respect for your taking the time to learn more

my thumbnail impressions (not an expert)

LiIon safety in a nutshell
do not drain the battery/cell below 2.5 volts. IF this happens, there is a risk that during recharge the battery will overheat and explode. (IF the overdischarge created electrical reversal inside the cell)

LiIon types
ICR cells require protection..
IMR and INR are safer chemistries, and are often unprotected.

Lights designed for high output, call for high drain cells, and those are unprotected. Anduril lights tend to have built in LVP (LowVoltageProtection)

If the IMR/INR cells are used in a light with built in low voltage cutoff.. then all is well for the battery.

separate from issues related to overdischarge, lets consider heat

Anduril lights are capable of high brightness and high heat. They should therefore only and always, be carried locked out.

It is bad for the battery to overheat, so, never tailstand the light on high output levels. Instead, always hold the light in hand, when using hot outputs, and turn the light off, before it gets too hot to hold.

There are also thermal regulation features in Anduril, that let you set the step down temperature, lower.. And it is possible to set the ceiling output, to a low enough level not to burn delicate parts. Anduril also lets you select the startup brightness.. it can be set low enough not to burn holes in stuff.

just for illustration.. what not to do
1. Set the light up to come on at turbo, disable thermal stepdown, and drop the light in your pocket, unlocked…

2. When using the light on Turbo, when it steps down, turn it off and back on, over and over again. Wear Gloves, and just hold the end of the tail, where it is coolest. Thereby defeating the thermal stepdown and creating a dangerous overheating condition.

If you read this far, I imagine you can see the errors of those ways Wink

Enjoy your KR4! Thumbs Up

cabfrank
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Good stuff Jon, well put.

zoulas
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zoulas wrote:

https://www.youtube.com/watch?v=tbEfhPbqTDE


Hmmmmm…. Interesting video. I have always heard it is a bad idea to charge a LiIon battery with low voltage. ??? Shocked
zoulas
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I know, I think the person that made the video is misinformed.

jon_slider
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good link
some details about different types of “Lithium” cells

1. CR123 is a Lithium Primary (non rechargeable), with a nominal voltage of 3v

this is a disposable battery that was popular before rechargeables became available
there is still a large number of lights (Surefire), and people that use them.. particularly in places like LEO and Military applications, where batteries are stockpiled and provided for free

2. LiFePO is a Lithium cell (rechargeable), also with a nominal voltage of 3v
this is a rare cell, used in security cameras that were originally designed for CR123, but whose owners seek a more cost effective, rechargeable option. They cant use 3.7v LiIon because the voltage is too high for those old circuits

3. LiIon is a Lithium Ion (rechargeable), with a nominal voltage of 3.7v
these are the “typical” cells in high output flashlights

multifuel lights
there are many CR123/16340 lights on the market
one example is the Jetbeam RRT-01
the lights work with both types of cells, but due to the difference in voltage, the maximum output is different between the two types.

the voltage difference makes it difficult to design a protection circuit inside the light, because the LiIon cell does not like to go below 2.5v (for recharge safety), whereas the CR123 does not care if voltage goes below 2.5v, since the cell is disposable.

these dual fuel lights usually recommend using only Protected LiIon.. because the driver cannot distinguish.

there is one dual fuel on the market that has a sophisticated enough set of options, that it can use UnProtected LiIon and also CR123. That is the HDS/Novatac design.

The Anduril lights only work on LiIon, they are not CR123 compatible. Anduril lights have built in LVP, that would get confused by a CR123 (the LVP would think the battery is discharged, when it is not)

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jon_slider wrote:
good link 2. LiFePO is a Lithium cell (rechargeable), also with a nominal voltage of 3v this is a rare cell, used in security cameras that were originally designed for CR123, but whose owners seek a more cost effective, rechargeable option. They cant use 3.7v LiIon because the voltage is too high for those old circuits

LiFePO4 is usually rated at 3.2V as nominal, not 3V.
You can find a lot about it on my website.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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HKJ wrote:
LiFePO4 is usually rated at 3.2V as nominal, not 3V.
You can find a lot about it on my website.

thanks for the accuracy check

for those interested, your excellent site is here

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CRC wrote:
https://www.youtube.com/watch?v=DkvSw4b5J80&ab_channel=PluginIndiaElectr...

I feel like this might belong here?

As someone trying to learn about lithium-ion cells myself, I found this pretty informative.

Good video CRC…. ✅
snerkler
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I’m new to ‘fancy’ flashlights and especially the batteries used to power them and the more I read the more paranoid I’m getting about the batteries. Im sorry if some of the questions have been asked before but obviously there’s a lot of posts to sift through.

I have ordered an Astrolux EA01s which is capable of 11000 lumens and I have been told I will need a battery with around 30A continuous discharge to be able to power the 11000 lumens so I’ve bought the Samsung 40T. This battery is unprotected but have been told that the Astrolux has built in protection to prevent over charging and overcharging and therefore minimising the risk of fire or explosion (I plan on using the flashlight’s inbuilt charging).

Would having a protected battery reduce the risk further or will it not make any difference being as the flashlight has protection? If it adds more protection the most powerful I’ve found has a continuous discharge of 15A. I assume this would be fine up to around 5000 lumens, what would happen if I accidentally switch the flashlight onto turbo (11000 lumens) would it potentially damage the battery and/or risk causing a fire/explosion or would it simply just not reach the top luminosity but the battery would be fine?

Lastly what causes a li-ion battery to over discharge?

Any help would be greatly appreciated.

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> battery is unprotected but have been told that the Astrolux has built in protection

if true, all good

> Would having a protected battery reduce the risk further

no

> what would happen if I accidentally switch the flashlight onto turbo

sudden darkness as the current demand would trigger the protection and trip the fuse on the battery. It will read 0 Volts on a meter after that happens.

> what causes a li-ion battery to over discharge?

falling asleep with the light on, in a light that has no overdischarge protection while using an unprotected battery

basically, lights with built in overdischarge protection, can use higher drain rate batteries to get higher outputs, using UNprotected batteries, so they dont shut off suddenly

at more modest, sustainable, output levels, a Protected battery, with much lower maximum drain rate capability, will power a light used at indoor brightness levels, just fine.

There are lights that can use both primary batteries and LiIon.. the primaries operate at lower voltages. The dual fuel lights, do not have Low Voltage protection. Instead the operator is responsible for choosing Protected LiIon, when they dont use Primaries..

there is also a subset of LiIon users, who choose to run Unprotected batteries in Unprotected lights.. that requires some diligence, including checking battery voltage by hand, and not falling asleep with the light on Wink

btw, respect for you doing your homework.. enjoy your lights

snerkler
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jon_slider wrote:
> battery is unprotected but have been told that the Astrolux has built in protection

if true, all good

> Would having a protected battery reduce the risk further

no

> what would happen if I accidentally switch the flashlight onto turbo

sudden darkness as the current demand would trigger the protection and trip the fuse on the battery. It will read 0 Volts on a meter after that happens.

> what causes a li-ion battery to over discharge?

falling asleep with the light on, in a light that has no overdischarge protection while using an unprotected battery

basically, lights with built in overdischarge protection, can use higher drain rate batteries to get higher outputs, using UNprotected batteries, so they dont shut off suddenly

at more modest, sustainable, output levels, a Protected battery, with much lower maximum drain rate capability, will power a light used at indoor brightness levels, just fine.

There are lights that can use both primary batteries and LiIon.. the primaries operate at lower voltages. The dual fuel lights, do not have Low Voltage protection. Instead the operator is responsible for choosing Protected LiIon, when they dont use Primaries..

there is also a subset of LiIon users, who choose to run Unprotected batteries in Unprotected lights.. that requires some diligence, including checking battery voltage by hand, and not falling asleep with the light on Wink

btw, respect for you doing your homework.. enjoy your lights


Thanks very much for taking the time to reply with such a detailed response. When you say that trying to run too much power through the battery causes it to trip the fuse and read 0V does this effectively mean the battery is ‘dead’ and will need replacing?

With regards to the flashlight having protection, it’s very difficult to know 100% as their website has no data, however a couple of reviews say that it has inbuilt protection which makes sense being as it has inbuilt charging. I have just emailed Astrolux to double check, especially regarding the overdischarge protection.

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> trip the fuse and read 0V does this effectively mean the battery is ‘dead’ and will need replacing?

on a protected cell, the battery fuse gets reset when the cell is placed on a charger. No need to replace.

as far as whether your light has overdischarge built into the driver, one way to find out is to run the battery down, until the light turns itself off, and then measure the voltage of the battery. We want the voltage to be above 2.5v, after the light stops working.

caveats, when draining the battery, use an output level that does not overheat the light.. (it may have thermal step down to prevent overheating). Do not use Turbo repeatedly, as this increases the heat level inside the circuitry.. instead use a longer slower discharge process, at a medium output.

I dont actually know the features of your specific light, but, I appreciate that you listed the model, so we can search for relevant facts.

I googled your light, found this

https://flashlightchart.com/astrolux/astrolux-ea01-sst40-ea01sst40-714
“This flashlight has a built-in low voltage protection (LVP)”

also this:
https://1lumen.com/review/astrolux-ea01/
“I tried a 78 mm long protected Acebeam 21700 and I couldn’t screw the tailcap on”

based on those, I would not try to use protected cells

snerkler
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jon_slider wrote:
> trip the fuse and read 0V does this effectively mean the battery is ‘dead’ and will need replacing?

on a protected cell, the battery fuse gets reset when the cell is placed on a charger. No need to replace.

as far as whether your light has overdischarge built into the driver, one way to find out is to run the battery down, until the light turns itself off, and then measure the voltage of the battery. We want the voltage to be above 2.5v, after the light stops working.

caveats, when draining the battery, use an output level that does not overheat the light.. (it may have thermal step down to prevent overheating). Do not use Turbo repeatedly, as this increases the heat level inside the circuitry.. instead use a longer slower discharge process, at a medium output.

I dont actually know the features of your specific light, but, I appreciate that you listed the model, so we can search for relevant facts.

I googled your light, found this

https://flashlightchart.com/astrolux/astrolux-ea01-sst40-ea01sst40-714
“This flashlight has a built-in low voltage protection (LVP)”

also this:
https://1lumen.com/review/astrolux-ea01/
“I tried a 78 mm long protected Acebeam 21700 and I couldn’t screw the tailcap on”

based on those, I would not try to use protected cells


Thanks again, much appreciated. I feel much happier about it now. The flashlight runs Anduril and this can measure the battery voltage so I will check this periodically once the battery has drained to ensure it’s not dropping below 2.5v
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> The flashlight runs Anduril

then it definitely has LVP.. you need not worry, it is not necessary to use protected cells

the Anduril battery level indicator is also very useful.. you have a light with an excellent battery safety feature set. The UI also incorporates thermal step down.. another good thing..

some charging voltage tips

LiIon like to be recharged when they are about half empty.. any time they go below 3.7V

you can go lower, down to 3.0V, if necessary at the time… but deep discharge does not actually help a LiIon battery…

the LVP will probably shut the light off when voltage drops below 2.7v..

about the battery meter in Anduril.. it may be slightly off, by maybe 0.1v too high or too low, compared to a standalone DMM (Digital Multi Meter)..

The Anduril battery voltage display can be calibrated more closely if desired

enjoy your Anduril light!:-)

how crazy is this
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jon_slider wrote:
>

about the battery meter in Anduril.. it may be slightly off, by maybe 0.1v too high or too low, compared to a standalone DMM (Digital Multi Meter)..

Just noticed something on my Anduril light with a protected cell and then put an unprotected 30q in and got a similar result. Saw this a time or two and thought it was a glitch. Now it seems consistent and am wondering if anyone can explain it. Here is what happened:

With the protected cell in the light I did a voltage check and got 3.9. Then I ran it on turbo for 30 seconds and ran a voltage check again. This time the voltage read 3.2 on the first pass and 3.9 on the second pass. Put an unprotected 30q in and did a voltage check and got 4.1. Ran it on turbo for 30 seconds and the voltage check gave me 3.4 on the first pass and 4.1 on the second pass. After writing that, with the 30q still in the light, I ran it on turbo for 30 seconds again. This time I took the battery out and put my meter on it and got 4.0 something settling on about 4.08. The number 3 did not come up on the meter at all. Put the battery back in the light and got 4.1.

jon_slider
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battery voltage under load, or immediately after a load (turbo), is lower than the “at rest” voltage

the battery voltage rebounds after resting

so, when I want to know battery voltage, I reference the “at rest” voltage, not the “at turbo” voltage.. Wink

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Running on turbo puts a high current load on the cell which causes the cell voltage to drop as it gets pulled down; when you release the load you will get a bounce-back in the voltage as the cell recovers. This is a normal condition in a good cell. It happens fairly rapidly so you wouldn’t be able to remove the cell quick enough to see the droop on the DMM.

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

snerkler
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jon_slider wrote:
> The flashlight runs Anduril

then it definitely has LVP.. you need not worry, it is not necessary to use protected cells

the Anduril battery level indicator is also very useful.. you have a light with an excellent battery safety feature set. The UI also incorporates thermal step down.. another good thing..

some charging voltage tips

LiIon like to be recharged when they are about half empty.. any time they go below 3.7V

you can go lower, down to 3.0V, if necessary at the time… but deep discharge does not actually help a LiIon battery…

the LVP will probably shut the light off when voltage drops below 2.7v..

about the battery meter in Anduril.. it may be slightly off, by maybe 0.1v too high or too low, compared to a standalone DMM (Digital Multi Meter)..

The Anduril battery voltage display can be calibrated more closely if desired

enjoy your Anduril light!:-)


Thanks once again. I don’t have a multimeter so will rely on the Flashlight, however I will ‘assume’ that it is reading 0.1v too high to be on the safe side.

I don’t understand the relationship with volts and amps in a battery yet, but plan on doing more research. I understand that a battery may have a capacity of 5Ah/5000mAh, and that if you use a device that uses for example 5A the battery will last 1 hour before running out of charge, but where Volts fits into this I don’t know.

Looking at the spec of the Samsung 40T I’ve bought the nominal voltage is 3.6V, which is below the 3.7V (half charge) you mentioned. As you can tell I’m a little confused Wink

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> Looking at the spec of the Samsung 40T I’ve bought the nominal voltage is 3.6V, which is below the 3.7V (half charge) you mentioned. As you can tell I’m a little confused

you are learning quickly.. I respect your focus and specific question

3.6v is the “nominal” voltage of a LiIon that charges up to about 4.1 to 4.2 volts, hot off the charger

batteries often ship at half charge, and fall below, depending on storage time..

do charge new batteries fully, before use..

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jon_slider wrote:
> Looking at the spec of the Samsung 40T I’ve bought the nominal voltage is 3.6V, which is below the 3.7V (half charge) you mentioned. As you can tell I’m a little confused

you are learning quickly.. I respect your focus and specific question

3.6v is the “nominal” voltage of a LiIon that charges up to about 4.1 to 4.2 volts, hot off the charger

batteries often ship at half charge, and fall below, depending on storage time..

do charge new batteries fully, before use..


Thanks again. So in this example, when fully charged the 40T will have around 4000mAh and 4.2V of charge. If I use it until the flashlight goes out it will have (hypothetically) 0mAh and say 3.0V charge, however it it goes below 2.5V charge this could potentially become dangerous?

For ‘normal’ use I plan on using my flashlight at around 2000 lumens which I believe requires around 6A, which will drain a 4000mAh battery in around 40 mins. My dog walks are around 30-40 mins in a morning meaning that I’m going to take it well below half capacity, nearly until empty. Is this going to be an issue?

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> it it goes below 2.5V charge this could potentially become dangerous?

your light will turn itself off before the voltage goes below 2.5V

you do not need to worry about overdischarge, in your light

> I’m going to take it well below half capacity, nearly until empty. Is this going to be an issue?

not a problem.. they are made to be used…

your light is safe,
at worst the batteries will run out and you will be left in the dark..

then simply insert a fresh battery, or turn on a backup flashlight..

once you have actual experience, you may find it convenient to lower the output to increase battery life

you may not need 2000 lumens for an hour.. you might find 500 lumens sufficient, and get 4 hours

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jon_slider wrote:
> it it goes below 2.5V charge this could potentially become dangerous?

your light will turn itself off before the voltage goes below 2.5V

you do not need to worry about overdischarge, in your light

> I’m going to take it well below half capacity, nearly until empty. Is this going to be an issue?

not a problem.. they are made to be used…

your light is safe,
at worst the batteries will run out and you will be left in the dark..

then simply insert a fresh battery, or turn on a backup flashlight..

once you have actual experience, you may find it convenient to lower the output to increase battery life

you may not need 2000 lumens for an hour.. you might find 500 lumens sufficient, and get 4 hours

Thanks for all your help. I shall now leave you in peace Wink

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snerkler wrote:

For ‘normal’ use I plan on using my flashlight at around 2000 lumens which I believe requires around 6A, which will drain a 4000mAh battery in around 40 mins. My dog walks are around 30-40 mins in a morning meaning that I’m going to take it well below half capacity, nearly until empty. Is this going to be an issue?

You won’t be able to run 6A with that light for 30 – 40 min. 6A is over 20 Watts at nominal voltage. I wish there were a spec for how many watts a light could dissipate but of course that varies widely depending on the temperature of the environment it is used in and how it is held. In one review the reviewer thought it could sustain 1000 lumen. Whatever the number really is I doubt it will be anywhere near 2000 lumen. If you set out to use it at that level you can feel good and not worry that you will deplete your light in a 40 min walk. Your eyes may not even notice it but unless your walk is really cold I am certain that the current draw will be cut considerably to control the temperature of the light.

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> I shall now leave you in peace

lol
pay it forward Thumbs Up

feel free to private message me,
if you would like to brainstorm further, from time to time

I look forward to hearing your results
enjoy the walks Wink

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how crazy is this wrote:
snerkler wrote:

For ‘normal’ use I plan on using my flashlight at around 2000 lumens which I believe requires around 6A, which will drain a 4000mAh battery in around 40 mins. My dog walks are around 30-40 mins in a morning meaning that I’m going to take it well below half capacity, nearly until empty. Is this going to be an issue?

You won’t be able to run 6A with that light for 30 – 40 min. 6A is over 20 Watts at nominal voltage. I wish there were a spec for how many watts a light could dissipate but of course that varies widely depending on the temperature of the environment it is used in and how it is held. In one review the reviewer thought it could sustain 1000 lumen. Whatever the number really is I doubt it will be anywhere near 2000 lumen. If you set out to use it at that level you can feel good and not worry that you will deplete your light in a 40 min walk. Your eyes may not even notice it but unless your walk is really cold I am certain that the current draw will be cut considerably to control the temperature of the light.

Are you saying that it will get too hot at 2000 lumens/6A? The reason I thought this would be OK is that a fellow dog walker uses an Exposure Diablo which apparently is 1800 lumens and it only gets slightly warm. Obviously I have nothing to measure that it’s at 1800 lumens and so it could indeed be lower than that but it’s plenty bright enough Thumbs Up
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jon_slider wrote:
> I shall now leave you in peace

lol
pay it forward Thumbs Up

feel free to private message me,
if you would like to brainstorm further, from time to time

I look forward to hearing your results
enjoy the walks Wink


Thanks, will do Thumbs Up
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snerkler wrote:
Are you saying that it will get too hot at 2000 lumens/6A? The reason I thought this would be OK is that a fellow dog walker uses an Exposure Diablo which apparently is 1800 lumens and it only gets slightly warm. Obviously I have nothing to measure that it’s at 1800 lumens and so it could indeed be lower than that but it’s plenty bright enough Thumbs Up

It only gets slightly warm because it has thermal management and that won’t let the light get that hot. 5A 6A for 1800 or 2000 lumen seems in the ballpark. Different LEDs have different efficiency.

https://budgetlightforum.com/node/54947

Don’t know what light they use and I am not certain how the electronics inside the light will change the output vs the chart linked above. Nearly certain the output would have to be be lower than the chart but not sure how much. The specs for the light pretty much confirm that your friend is not walking around at 1800 lumen the whole time. They list a minimum run time of one hour with a 3500 mAh battery. That would be an average of 3.5 Amps. Looks like you coud get maybe 1400 lumen from that but given the fact that it starts at 1800 Lumen it would be drawing more for some time and therefore must settle down lower than 3.5A. Hopefully someone who understands how an actual flashlight is different from that chart can add to this.

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here is a runtime test, to help visualize how different output levels behave:

.
pic is a link to a review with more details

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how crazy is this wrote:
snerkler wrote:
Are you saying that it will get too hot at 2000 lumens/6A? The reason I thought this would be OK is that a fellow dog walker uses an Exposure Diablo which apparently is 1800 lumens and it only gets slightly warm. Obviously I have nothing to measure that it’s at 1800 lumens and so it could indeed be lower than that but it’s plenty bright enough Thumbs Up

It only gets slightly warm because it has thermal management and that won’t let the light get that hot. 5A 6A for 1800 or 2000 lumen seems in the ballpark. Different LEDs have different efficiency.

https://budgetlightforum.com/node/54947

Don’t know what light they use and I am not certain how the electronics inside the light will change the output vs the chart linked above. Nearly certain the output would have to be be lower than the chart but not sure how much. The specs for the light pretty much confirm that your friend is not walking around at 1800 lumen the whole time. They list a minimum run time of one hour with a 3500 mAh battery. That would be an average of 3.5 Amps. Looks like you coud get maybe 1400 lumen from that but given the fact that it starts at 1800 Lumen it would be drawing more for some time and therefore must settle down lower than 3.5A. Hopefully someone who understands how an actual flashlight is different from that chart can add to this.


Wow these things are complicated, whatever happened to just turning a light on and off again lol.

So if I’m understanding this correctly, whilst I might set my flashlight to 2000 lumens (hypothetically) it might only stay there for several mins and then drop down to stop it from overheating? If so is there something in the specs that tells me what the max setting is that it will run at without dropping down (at least for an hour or two)?

P.S. The Astrolux EA01s I’ve ordered is the XHP 50.2 version, I’ve no idea how efficient these are.

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