Compare and Contrast two versions of XTAR 1.5V AA LiIon with USB-C

[jon_slider]

I received some XTAR LR 3000mAh 1.5V LiIon as a gift from XTAR, after doing a review of some of their other batteries and chargers. This 3000mAh version, is the type whose voltage declines at a tapered rate.

I previously have been using the CLR 2450mAh version, whose voltage stays at 1.5V for the first 75% of the runtime, and then at 1.20V switches to that Voltage, to help give advance Low Voltage Warning, before the battery shuts off completely. I posted a review here.

These are the discharge curve types for the two battery designs:

I used an Emisar KR1AA w NTG 4200K, with ceiling set to 90/150 = 340 lumens

My testing goal was to determine at what Voltage the LR 3000mAh design could no longer start, when not hot, at my selected ceiling.

my results are that at 1.30V it still started at 340 lumens

(with breaks in the On time, to let the light cool down about every 10 minutes)

at 1.26V it started at 160 lumens..

The Thermal Step down in the KR1AA reduced output to between 160-180 lumens as the light heated up, this took about 5 minutes, each time I restarted the test from 340 lumens, when the light had cooled down.

What I learned is that:

Below 1.30V, the declining voltage type battery can no longer hit my chosen ceiling of 340 lm

We can infer that the constant 1.5V battery, when it switches to the 1.2V low voltage warning phase, also can not sustain 340 lm

my conclusion is that the two versions of the battery have very similar output performance..

their output is limited primarily by Thermal Step Down, Not by the Voltage

imo these 1.5V LiIon batteries are most useful for low and medium outputs, with the ability to produce a higher output briefly. They seem to work similarly well as Eneloop, with the added convenience of USB-C charging and longer runtime.

Compared to the sustained 1.5V design, rated 2450mAh, I see a couple of Advantages to the declining Voltage version rated 3000mAh:

1. Voltage check gives me more advance notice, to help me anticipate when it will need to be recharged…
2. More capacity, so it has a runtime advantage.

[Mandrake50]

Thanks for the review! Did you try to check the capacity of the cells? Just curious as to whether there is a measurable capacity difference.

[jon_slider]

@Mandrake50

Did you try to check the capacity of the cells?

I have not done a capacity test of the 3000mAh version, yet..

I did test the 2450mAh version previously, and it tested within 3% of spec.. so I have faith the 3000mAh version spec is in the ballpark

iow, I do believe the version with the tapered declining Voltage does have more capacity

[lighteater]

Potentially interesting tradeoff. The 2450 version would have the effect of turning unregulated AA lights into regulated ones. Could be useful in some circumstances although most dual-fuel lights boost the AA side so I’m not sure that I even have any that would benefit from the 2450 version.

I don’t know whether it would be better for the 2450 to step down to 1.15v or 1.1v because 1.2v may be interpreted more positively by flashlights used to NIMH/Alkaline where 1.2 is typical.

[jon_slider]

@lighteater

step down

thanks for contributing your thoughts

fwiw, when the 2450mAh Voltage reaches 1.2V (Green POVD Aux), Voltage is no longer held constant.

For the rest of the discharge cycle below 1.2V, the manual Battery check, and POVD, show declining Voltage from continued use.

When Voltage reaches 1.0V, the LVP shuts the battery off.

[jon_slider]

One of the more esoteric reasons I like to use 1.5V LiIon is because they produce less Riple in my AA Zebra than Eneloop or LiIon:

These images come from the Opple 3 Flicker Index tests. This is not about Visible flicker.

For illustration purposes I call your attention to the Level 9 charts: which show 2% Riple for 1.5V LiIon with fixed 1.5V output, 40% Riple for Eneloop, and 62% Riple for 14500.

I have not (yet) checked whether the 3000mAh 1.5V LiIon with Declining Voltage has similar Very Low Riple as the 2450mAh version that has sustained 1.5V output.

My guess is the sustained 1.5V is responsible for the lower Riple score.

Another data point that demonstrates the effect of Voltage on Riple:

The freshly charged Eneloop, on the right, has higher voltage, and much less Riple than the partly discharged Eneloop, on the left..

These observations tell me that the 2450mAh 1.5V LiIon with sustained 1.5V output will have less Riple and Lower Flicker Index, than a battery with declining Voltage such as the 3000mAh 1.5V LiIon that does not sustain 1.5V.

[jon_slider]

I have discovered a Quirk about 1.5V LiIon

please clic that link for more details

[Dc38 (The Glutton)]

weird…One strange thing I’ll note is that on some executions of anduril (IDR which lights) the voltage check does weird things, like do a single readout of 4.8V before properly reading out 3.78V on a LiIon. It might have been a non-freeman driver

[jon_slider]

I used a DMM to test 1.5V LiIon of the type that has constantly declining voltage, so I could measure change over time, and Eneloop, stored in car this summer, here are present results:

Outdoor temps have been up to 97F (the car has been parked in the sun, with a window shade and tinted windows). Temp where the batteries are stored in the cargo area of a subaru outback, has reached 115F.. Will continue storing in car longer..

[lighteater]

@jon_slider

I used a DMM to test 1.5V LiIon of the type that has constantly declining voltage, so I could measure change over time, and Eneloop, stored in car this summer, here are present results:

Outdoor temps have been up to 97F (the car has been parked in the sun, with a window shade and tinted windows). Temp where the batteries are stored in the cargo area of a subaru outback, has reached 115F.. Will continue storing in car longer..

My eneloops tend to drop to around 1.34v pretty quickly and hold that for quite some time when unused.

I’m surprised the xtar barely dropped. I’m also surprised you would risk a fire by storing a lithium ion in 100+ deg conditions.

[jon_slider]

@lighteater

surprised you would risk a fire by storing a lithium ion in 100+ deg conditions.

I am not exceeding the 140F operating temperature for LiIon.. And I dont actually use the battery at its storage temperature of 115F.

Im not aware of 115F LiIon storage being a fire risk. I also keep a jump start battery in my car.

I expected Heat might deplete the LiIon Voltage and or capacity.. As you noted the Voltage did not change hardly at all..

Im testing a variety of 1.5V LiIon that has a declining Voltage feature, specifically so I could monitor Voltage change during storage in the car.

The capacity test will come after end of summer.

If you have info that makes you think Im risking a LiIon fire at 115F Max Storage temp, please share a link. I will be grateful to educate myself further.

Thanks for confirming your Eneloop also settle at 1.34V during storage.

[Mandrake50]

@lighteater

I’m surprised the xtar barely dropped

The measured voltage should not change much as long as the internal cell has a minimum level of charge on it. That is due to the DC to DC converter/regulator, The internal cell will lose considerable charge over time due to the overhead for always running the electronics. Which is why Xtar recommends topping the cells off at least every 6 months.

The test for self discharge would test capacity with a full charge compared to the capacity at 30 /60/90 days. Then calculating the loss over time.

[jon_slider]

@Mandrake50

The measured voltage should not change much as long as the internal cell has a minimum level of charge on it.

there are different types of 1.5V LiIon discharge curves

some maintain 1.5V even as the internal LiIon charge goes down. I think that is the type you are describing, but it is not the type Im using in the car test

the particular type Im using in the car, is supposed to have a constantly declining Voltage.. that is why I chose that particular model to test in the car.. so I can hopefully observe Voltage drop over time

so, I Think the battery voltage Im getting, means the internal LiIon Voltage has Not dropped significantly in the time interval from start of test on July 9 from a fresh charge, until now.. (a little over a month)

we will know more after summer ends.. at that point I will recheck battery voltage AND determine the change in mA of the internal LiIon, using my Xtar charger, which will measure total mA used to recharge the battery…

The 3000mAh battery in my car has the discharge curve shown by the red line on right:

The 2450mAh battery on left is not the type Im testing in the car. Because it will read 1.5V the whole time the internal battery is over 25% charged.

[Mandrake50]

Of course. But if you are within the first 20% or so of the discharge curve, the measured voltage will not change much, for either cell.
It is hard to correlate with your measurements using the graphs . due to scale and because the internal voltage versus output voltage is not really shown.. Also you have no idea where you are on the horizontal axis without measuring the capacity at that point..

But I was really replying to the statement expressing surprise that the measured voltage had not changed that much over your test period. Regardless of which of the two cells being considered. I am not surprised that it did not change much in a 30 day or so period.

[lighteater]

@jon_slider

@lighteater

surprised you would risk a fire by storing a lithium ion in 100+ deg conditions.

If you have info that makes you think Im risking a LiIon fire at 115F Max Storage temp, please share a link. I will be grateful to educate myself further.

I don’t have anything specific that says at 115F you will increase fire risk by x%. We have a lot of recommendations to store lithium ion batteries in a cool, dry place. And I think we can agree that 115F is not cool. I was more curious that someone with your level of experience and attention to detail would do it, particularly given all of the handwringing people have over battery safety in the community. I’m interested in the results of course.

By way of comparison, I have become concerned enough about the impact of heat on batteries that I typically rush to grab my flashlight packages out of the summer heat (when they are placed in a parcel locker) so that they aren’t exposed to excessive heat for too long).

Here’s what Xtar’s website says about it.

How should batteries be stored?
1. Batteries should be stored at room temperature or in a cool, dry place, away from direct sunlight and high temperatures. The ideal temperature range is 10-25℃.

Can the battery be used in extreme temperatures?
It is not recommended to use the battery in extreme temperatures (above 45℃ or below -20℃). High temperatures increase the risk of explosion, while low temperatures affect battery performance and lifespan.

Can batteries be left in the car for a long time?
It’s best to avoid leaving any type of battery in the car for extended periods, especially in hot weather. The high temperatures inside the car can make it difficult for the battery to dissipate heat, increasing the risk of fire. Additionally, high temperatures accelerate battery aging, and poor-quality batteries might swell or even explode.

[jon_slider]

Thank you for having this conversation and offering info.

I do want to be safe.

I took some IR thermometer readings of my car at 1PM. It is not the hottest day of the summer. Weather report says 82F (28C).

The outside of my white car hood in direct sun reads 128F (53C).
The windshield is covered by a window shade. Inside the glovebox the temp is 99F. (37C)

I store my batteries in a cooler part of my car, the rear cargo area. The windows are tinted. The rear cargo area has a tonneau cover, similar to this picture:

The batteries are in a metal box.
The batteries Im storing are at 82F (28C) right now.

Xtar claims the operating temperature range for the 1.5V LiIon is -20C to 60C (140F):

[Mandrake50]

I am confident that you are not doing anything crazy Jon.
Of course those temps would be considerably higher if the car were out in full sun parked for several hours with the windows up…

Heck I have a couple of 18650 lights and an a LiIon jumper pack in my trunk here in Denver. Have for years. So far, so good. I honestly don’t worry about it. I am aware of safe LiIon cell safe handling. Have safely charged and used many hundred cells. Built many battery packs… Some things I just can’t get too excited about.

[jon_slider]

@Mandrake50

Of course those temps would be considerably higher if the car were out in full sun parked for several hours with the windows up…

The car IS parked in full sun with the windows up, all day long until 1 PM when I took the IR readings.

There have been a few clouds, so its definitely not The Hottest it ever gets here.. but what Im learning from my IR thermometer is that the cargo area is MUCH cooler than the outside body of the car.

@Mandrake50

a LiIon jumper pack in my trunk

I keep a LiIon jumper pack in my car too. On the floor behind the driver seat, because that is lowest spot in the car.

[Dc38 (The Glutton)]

I’ve got some of the CLR4300 in a couple of dark colored cams that read the temperature to be 122ºF during overhead noon sun…I’m confident in their accuracy because they read out the proper ambient temp at night. I can’t imagine that running these types of cells in a sunburnt device is any LESS safe than cooking LiIon cells under a sustained runtime test where the SURFACE temps may EXCEED 70C for over an hour anyways…

[jon_slider]

Update
By 5pm batteries in car have reached 90F

Outdoor temp has dropped to 79F and cloudy