Test of Novatac Low Battery Indication, it is not Overdischarge Protection

Testing the Low Voltage warnings on a Novatac 120T

ran down an Olight protected 16340 ICR battery

at 3.1v the Novatac stepped down to 30 lumens,
less than a minute later it switched down to 18 lumens
about a minute later it stepped down to 8.2 lumens. Battery was at 3.02v
less than a minute later it stepped down to 2.9 lumens

less than a minute later it stepped down to 1.9 lumens, it stayed at that level for about 10 minutes

10 minutes later the light stepped down to 0.4 lumens at that point the battery was at 2.99v
less than 1 minute later, the light stepped down to 0.2 lumens
less than 1 minute later, the light began to blink continuously, at 0.1 lumens
after about 27 minutes of blinking, it started to flicker on every blink, I let it keep running, Im waiting for the light to turn off so I can know at what level HDS first shuts off a depleted LiIon.
After about 3 more minutes, the flickering changed to slow flashing on some blinks and fast flashing on other blinks.. Clearly the HDS has multiple blinkies for low battery warnings.
After 42 minutes of blinking at 0.1 lumens, I turned the light off to check battery voltage, it read 2.91v
When I turned it back on, it came on at 5 lumens. a double click gave 24 lumens, and about 30 seconds later the light turned off. The battery was at 0 volts, because the battery Overdischarge protection circuit took effect.

So I do not know at what voltage the HDS Low Battery circuit might have shut the light off completely, but I do know that after removing and reinserting the battery, the light was willing to drain the cell to the level of the Battery Overdischarge Protection Circuit, which is 2.5v

btw, even though I removed and reinstalled the depleted battery to test voltage, multiple times, I did not do a battery reset, and the light continued to operate normally for LiIon, by stepping down to a very dim level. fwiw, on my Novatac, battery resets are not automatic the way they are with the latest HDS. You should not remove and reinstall a depleted LiIon with the current firmware, as the light might confuse it with a Primary cell, and attempt to drain it below 2v, unless you use a battery with a built in Overdischarge Protection circuit.

Bottom line, HDS has great Low Voltage warnings, but does not have complete Overdischarge Protection. It WILL overdischarge a LiIon if you turn the light off during the 0.1 lumen blinking. It turns on @ 5 lumens, this suprised me, I expected it to only come on at the 0.1 lumen level the blinkies were at.

The Low Voltage warning feature of an HDS is documented in the latest 2.18 firmware version of the manual as Low Voltage Indication, there is no mention of Overdischarge Protection in the Manual.

Bottom line, HDS has NO Overdischarge Protection, nor does it claim to. It Can Overdischarge, IF the operator turns the light off, and then back on after the Low Voltage Warning blinkies. Despite the commonly held belief, HDS does not have Overdischarge protection, it has Low Voltage stepdowns and blinky warnings.

Yes I think it was designed to do this so in an emergency situation you can keep using the light with a rechargeable batteries. It will trash your cell but you will have light.

Which is done on purpose. If you turn your light on after it shuts off from a low battery, then it will drain that sucker down to nothing. It assumed you need light and are willing to sacrifice the battery. That was done by design.

Also, you are testing an old NovaTac, not a current HDS. Would be similar to test my M151A1 against a HMMWV.

Caution: your flashlight will eventually turn itself off to preserve what little battery power remains if you continue to use your flashlight after your flashlight begins blinking once a second on the lowest brightness level. You may turn on your flashlight again when needed for a short period. This behavior maintains your options in an emergency.


Edit: My highlighted statement above is WRONG! Had a long discussion with Henry about this today.

Was this not the conclusion we reached in the other thread? The HDS will allow over discharge to save your life, but you'd be making an informed decision about the health of the cell. Under normal use, it's time to recharge when it blinks and steps down. An HDS equipped with an unprotected cell will not leave you in the dark, whereas any light using a protected cell could do just that.

To put it another way, you don't need true over-discharge protection in an HDS due to the low voltage warnings. I did refer to this feature as over-discharge protection in the other thread, but only because of the practical equivalence.

Modernflame said:

Was this not the conclusion we reached in the other thread?

Click to expand...

Yes.

I agree the feature is intentional, and it exists in both the Novatac manual and the latest HDS manual.

The purpose of my test was to quantify at what voltage the blinking starts, so I could know for reference., the answer is 2.99v I dont consider this an OverDischarged condition (I think 2.5v is a reasonable limit). I previously wanted to know at what voltage the step downs start, in this test stepdown started at 3.1v, this is a safe voltage also.

I also wanted to know what level of light would be produced when blinking, the answer is 0.1 lumens

I also have used the term Overdischarge Protection in the past, but its actually Low Voltage warning. I think its a great feature, and my take away was that, IF I turn the light off, and then back on while it was blinking, then the light does NOT come on at 0.1 volts and continue blinking.. This suprised me. I expected it to continue blinking, but instead it came on slightly below my Preset B, and was willing to also run slightly below my Preset C. That is a BAD idea, as it almost immediately hits the 2.7v Protection circuit in the battery.

I dont know if the light, when turned on after the blinking, had decided that the battery was now a CR123, but I would have hoped not. I would like to think what is happening is that the Low Voltage Indicator turned off. I would prefer that IF I am in a life threatening emergency, and my light has been blinking for 45 minutes, and I turn it off and back on, that it would come back on at 0.1 blinking lumens.

There is no mention of this behavior, that the light will try to turn on at a higher than 0.1v blinking level in the novatac manual. In the FW 2.18 manual it does say that it IS possible to turn the light on at a higher level. It appears that this behavior eliminates, until battery replacement, ANY Low Voltage step downs and blinking.

what the Novatac manual does say is
Note: if you continue to use your light after it has dropped to the lowest brightness level - where it blinks continuously - it is assumed you are in an emergency situation. In an emergency situation, your life is more important than your rechargeable batteries and your light will sacrifice the batteries to keep the light on

that happens at 2.99volts, and is not a threat to the battery at that level. It runs that way for at least 45 minutes, but If I turn the light off and back on, after it started blinking, it turns on at a much higher brightness level. This is not good, but in my real world, it is pretty unlikely I would do that. I did it for the test, because I relied on the battery protection.

the current 2.18 manual does not have that note, instead it says
Your flashlight restricts the output to the highest brightness level the battery can maintain. However, if you turn off your flashlight and turn it back on again to a higher level, your flashlight will slowly step up through the brightness levels testing the battery again.

fwiw, the Novatac does not step up through the levels to test the brightness. It does sound like turning a current FW HDS off during the blinking, that it will try to come on at Preset B (over 10 lumens in stock form). This would be the same as the Novatac, and is a BAD operator behavior.

I think the blinking is a GREAT Low Battery warning. It happens at a "safe" level for the battery. The only NOT safe behavior in the Novatac is that cycling off and back on during the blinking, defeats the blinking and provides a much higher lumen level, that pretty much immediately trips the protection in the battery I used.

I do not know, but would be curious if the present HDS 2.18 firmware will cause the light to turn back on at 0.1 lumens, if switched off to save batteries when it starts blinking. But it sounds to me like the current FW HDS will do the same thing the Novatac did, cycling off and on after blinking starts, does not turn the light back on at the 0.1 lumen blinking level. Instead the light treats the battery as if it is a cR123, iow, no Low Voltage step downs, and with LiIon that results in almost instant OverDischarge.

In any case, just wanted to share the Voltage at which the blinking starts, and my discovery that the blinking does not continue if I switch off and back on. That is not so good, but, god willing, I wont ever need to use my light while it blinks at 1 lumen for over half an hour.

Hogokansatsukan said:

you are testing an old NovaTac, not a current HDS. Would be similar to test my M151A1 against a HMMWV.

Click to expand...

Im not sure I understand the difference, as it relates to the voltage at which the blinking starts, and the fact that cycling off and on bypasses the Low Voltage step downs and blinks

At what voltage does step down start, and at what voltage do the blinks start on FW 2.18?
Both Novatac and FW 2.18 seem to abandon the Low Voltage step downs and blinks, when cycling a blinking light off and back on.

I suggest that IF a light is blinking at 0.1 lumen, that it should NOT come on at a higher level when cycled off and back on. imo it should come back at at no more than .1 lumen, even if the blinking is eliminated. In fact, I would prefer the blinking was eliminated at that point.

here is a visual of the Novatac Low Battery flashing:



Im glad to know the Novatac has all these low battery warning features. I hope never to be in a situation where I need the prolonged runtime at sublumen levels. The Novatac ran for a full 45 minutes, on its flashing mode, and would probably gone much longer. But I switched the light off at that point.

I really like the low battery warnings, the step down starts at 3.1v. I like having stepdowns to remind me to load a fresh battery.

I honestly don't know about the NovaTac and how it is supposed to function, but the current HDS light...
This taken directly from the FAQ, and confirmed with Henry. The HDS will NOT over discharge a battery or let a protection circuit trip.
The reason the light can be turned on for a short time, is that there is a chemical "bound back" if you will within the battery. That is, the battery when not being used, has some voltage increase due to the chemical nature of the batteries. This is the reason you can get a little bit more "juice" from the battery after the light shuts itself off. This bounce back will become less and less.

Rechargeable lithium-ion (Li-ion) batteries provides you with a dramatically lower cost of operation for your heavily used HDS Systems EDC flashlight while at the same time allowing you to always head out the door with a full capacity battery. Lithium-ion batteries can be conveniently recharged when only partially used without any detrimental affects such as the memory problems that plague Ni-Cad batteries.Our flashlights are designed to accommodate the higher voltages generated by lithium-ion batteries - up to 4.2V when fully charged, 3.6V nominal. In addition, our flashlights automatically detect lithium-ion batteries and protect them from over-discharge when used as directed. These two features are unique to our line of flashlights and make using lithium-ion batteries safe and convenient.There are three different lithium-ion battery chemistries compatible with our flashlights - often designated as ICR, IMR and INR.The oldest and most common lithium-ion battery chemistry is know as ICR - Lithium Cobalt Oxide (LiCoO2). This chemistry requires a protection circuit to be used safely due to the chemistry's inherent instability. The advantage of this chemistry is its higher total capacity - allowing 50% greater capacity in the larger battery sizes compared to the IMR and slightly higher capacity compared to INR chemistries. The disadvantage is the required protection circuit, which increases the battery size slightly, lowers total performance at high discharge rates and adds one more potential thing to fail to the battery system.A more recent lithium-ion battery chemistry is the very safe chemistry known as IMR - Lithium Manganese Oxide (LiMn2O4). In fact, this chemistry is considered safe enough to use without a protection circuit and is thus more reliable when used in harsh conditions, such as gun mounted applications.The newest lithium-ion battery chemistry is the very safe chemistry known as INR - Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2). This chemistry combines the safety of the IMR chemistry with the capacity of the ICR chemistry. And no protection circuit is required, making this a very reliable battery. We believe this is the battery chemistry of choice.We have designed our flashlights to prevent battery over-discharge and thus our design also prevents the protection circuit from activating. In other words, our design prevents sudden unexpected darkness.When the battery protection circuit detects the battery is being over-discharged, the protection circuit turns off the battery to prevent further discharge - which causes the device containing the battery to suddenly stop working without warning. This is no different than a catastrophic failure of the device. The battery will remain off until it is recharged, leaving you with no light and no options. This is how our competition designs their flashlights.It is dangerous to simply turn off the flashlight unexpectedly to prevent over-discharge. Instead, our flashlights reduce the output brightness as the battery is discharged. When the lowest brightness is reached, your flashlight will begin to blink about once a second. When your flashlight begins to blink, you should immediately find a safe place to change your battery, wait for the sun to come up or wait for rescue. Your light will continue blinking for a short unspecified amount of time before the voltage reaches a critical level for the battery and your flashlight turns off to preserve the battery - and your options. You can turn your light back on again for another short burst of light as needed. A tiny amount of light is far better than no light at all.The smaller 123 size rechargeable lithium-ion batteries provide less emergency time than primary(non-rechargeable) batteries due to their lower total capacity. That means that once your flashlight begins to step down to lower brightness levels as the battery is used up, the step-downs will occur more rapidly and you will have significantly less time before the light becomes very dim compared to primary batteries. So we recommend you immediately take action to reduce output and find a safe place to change your battery.In general, you are better off recharging a lithium-ion battery after less use and more often rather than after longer use and less often. So do not be afraid of swapping a lightly used battery for a fully charged battery.Lithium-ion batteries require special chargers that are designed for the battery being charged. In general, lithium-ion batteries should never be charged at a rate that exceeds half of their rated capacity and the maximum terminal voltage should never exceed 4.2V. You should only use a high quality 4-phase (TC/CC/CV/off) charger to charge your batteries.Lithium-ion batteries are sensitive to temperature. Higher temperatures accelerate aging and contribute to the permanent loss of capacity. Lithium-ion batteries may be used from -20°C (-4°F) to 50°C (122°F). However, they should be brought to room temperature before recharging - from 15°C (59°F) to 35°C (95°F).Do not use the new IFR - Lithium Iron Phosphate (Li-FePO4) batteries with our products. Although this is a very safe battery chemistry, it cannot be reliably distinguished from a primary lithium battery and handled appropriately - leading to unreliable behavior.