same math conclusion here
that is why I suggested your sample is defective, since it is NOT between 4-6V w lithium primaries
the best way to solve your issue is to communicate privately w the seller, and I hope you end up w a light that works on Lithium too
the failure to work on Lithium is a bug, not a feature
"Low voltage warning: Yes(14500) / No (AA)"
So no LVP for AA,
So I can't really use Ni-MH AA because there's no LVP for them, so I'm risking over discharging.
But can't really use alkaline AA (because if they leak, they will ruin the flashlight)
lithium AA apparently don't work (we have to wait for others to test)
So it's actually a 2 x 14500 flashlight, that can take normal alkaline AA battery im emergency, but they shouldn't be stored inside of it.
Ps. On web page, it only says AA, no type is specified.
A bit over the top. Lock out the light when not in use. Charge or change your batteries and using Alkaline or NiMH AAs is not an issue. Most AA lights have no low voltage protection so the T4 is no different.
Not quite. The discharge curve for Ni-MH is very different from Li-ion: the voltage pretty much stabilizes at 1.2-1.3 during the entire run, and then rapidly drops off, as opposed to decreasing near linearly. A consequence is that when its rest voltage is at around 1.1V, even a small amount of current drawn from it would immediately sag its voltage to below usable, which means the light would rapidly dim by an order of magnitude; it doesn't take LVP to notice that. Once you take out the battery again, the rest voltage would rise up again, resulting in no damage.
In a sense, the Ni-MH chemistry comes with intrinsic LVP. Also, the Ni-MH chemistry is more robust than Li-ion, and it takes much more abuse to do the same amount of damage. I've recently found a stash of 10-year old Ni-MH's that test at 0.00V. My charger revived more than half of them with no apparent loss in capacity (compared to the labeled capacity anyways, not excluding the possibility that the capacity is underrated). Doing the same to Li-ion would be far too dangerous.
thanks for the link
looks like the T4 has a driver bug, making it incompatible w Lithium Primary
question… would Eneloop work as well as Lithium Primary?
I think this is a valid and undersold aspect of NiMH, and partly why a few of my most-used lights remain NiMH.
That makes 2 of us. One of several reasons I bought it.
For longer term storage it seems the only option. They just aren’t as temperature tolerant as straight up lithium, or so I’ve read. I don’t have much experience with NIMH. I just bought a 4 pack of AAA standard eneloops to use in some recently acquired WK1/WK2 pen lights. The only rechargeable AA’s I have are the green Energizers (which I used to test viability in the T4), and have been using them in my AA Tool backup work light. However, that’s brought in from my van nightly and rarely sees temps below 15°F.
Mine came today. It works great with Eneloops. I haven’t tried it with Energizer Lithium primaries. I’m going to be pretty unhappy if it doesn’t work, because that’s the scenario I bought it for.
Lithium Primaries and Eneloop, operate in climates where I do not operate. LOL
google sez:
“Lithium primary batteries can continue to function properly at temperatures from –67°F to 302°F”
“Nickel–metal hydride (Eneloop) cells can operate in the temperature range of –4°F to 113°F”
“Alkaline batteries are best suited for operating temperatures between 14°F and +113°F”
“The use of a lithium-ion battery is possible in a temperature range of 50°F to +131°F”
I did not realize until now, that LiIon does not work below 50F… that does not ring true to me… I just put a LiIon light and an Eneloop light in the freezer, to test for myself…
There are Li-ions rated –40 degrees. Normally at a cost of capacity and max amp.
Molicel claim their P26A, an extremely high drain 18650, can do –40C. Haven’t tested yet.
Ive had these two lights in my Freezer for 4 hours… they still work. One is LiIon, the other is Eneloop:
.
I also have three lights in my car with AAA Eneloop, and they still work too. We have had a cold winter, as low as 10F… It seems the batteries are doing fine… they also live in the car in summer… which gets up to 90F outdoors… in the car much higher… I do not store LiIon lights in my car.
I do have a LiIon Jumper pack that lives in my car. It seemed unaffected by freezing weather, as it worked to start my car on one of the colder days this winter…
for my needs, Lithium Primary seems unnecessary, since Eneloop is working fine.
in low temps, generally capacity and max current are lower, because of slow chemical reactions.
For flashlights it's usually not to the point of it not working, but it depends on the device.
Ps. Just bought programmable bench power supply 40V/20A (will have it probably in a month). 
Now I only need T4 for LVP testing, and lowest voltage for operation on AA.
If there will be a version on 12/13 mode driver and nichia 519A, I will buy it and test it.
Mini review of the Convoy T4 (and a few other lights). A runtime graph is coming later this week (when I have the time).
Did a short walk with the dogs last night and my Ts21 was in my jacket pocket (Lithium Ion) and my E02 II (NiMH) clipped to the outside of my jacket. Was able to put the EO2 II into high at the end of the walk. Not sure if it would have maintained high. Sometimes when it is cold out even a fresh battery will not go to high once the battery gets cold. Low works fine even when really cold. Didn’t really use the TS21. However, when I took my coat off in the house I checked the temp and it was reading 248. Clearly the Liion batteries work much lower than 50 degrees! When I was playing with it on other cold nights I would put the TS21 on regulated level for a minute or two to get the chemistry moving. Then I could put it up to Turbo and wait to see if I could get thermal regulation to kick in. On the coldest nights I could not. Warmest temp I measured was 44 after several minutes on turbo. Last night was pretty darn cold for the second week of march but at only a few degrees below 0 F wind chill I would have been able to trigger the thermal regulation after several minutes. Did this a few times this winter and the battery seems just fine.
Received my lithium primaries today and tested on my T4.
Bad news: nope. They don’t work.
sad… however, Eneloops are cheaper and work just as well
I suppose Simon should mention “not compatible with Lithium Primary”, in the T4 listing. (or solve the problem)…
UNBLF - thanks for the update.
jon_slider - not to stray off onto a tangent, but I noticed in the pic of your ‘freezer’ lights (thank you for that experiment, BTW), you run eneloop pro’s in one of your torches. Do you prefer/ recommend them over the standard white? It seems from what research I’ve done, aside from more gas in the tank, people recommend standard over pro version. As stated, I don’t have much experience with NIMH. Curious as to your take. Thanks.
I think he just needs to tweak the LVP. If it were actually 4-6v like he says there wouldn’t be a problem.