Clarification on sony laptop 18650

So I have a TR-3t6 (probably clone) and use some recycled laptop sony cells. I get decent run time but recently i’ve noticed it just doesn’t seem as bright as it used to. Being like everyone else here, I started measuring things.

Batteries will hold a charge at about 4.0-4.1 for weeks

to test amps i ran an alligator wire from the threads of the light to the threads of the cap. I then put the meter (set to amps) between the tailcap and the negative of the battery. This gives me a consistent .7A or so reading.

Thinking this was low, I charged the batteries overnight and then hooked them up to a lipo charger. Again .7 Amps is all that could be pulled at once. They are currently discharging at .5A and have been doing so for about 30 mins…

Is that a normal output amp for a recycled sony laptop battery? What batteries would give me 2-3A of consistent output? Does the light even care for the extra amps? It seems fairly bright as-is?

Where are you guys buying batteries that offers good rates and reasonable shipping (20 bux + to ship batteries is excessive to me)

Twelve brand-new 2400mAh 18650s, $27.

Thanks for link, but going that route would I just be buying 12 brand new battery’s with .7amp maximum output? My understanding of laptop batteries is they put them in series and parallel to get the volts and amps needed respectively. My flashlight runs 2 x 18650 in series so their individual amp outputs seem to be a limiting factor…

your 0.7a reading will be about 1.4a to the leds. I cant say I have heard of any 18650 unable to provide no more than .7a or 1.4a. im like 99% sure its the driver limiting your light

I have 24 of the cells from those packs and they are capable of higher amperage than the driver in your light will need.

I just grabbed two at random from the pile that haven't been charged in who knows how long, and connected them in series to a 6v MTG2 LED in direct drive, they deliver 4.90 amps.

I have a single cell light with two XML LEDs in parallel, also direct drive, and a single 2400mAh cell from those packs will deliver 5.70 amps.

The reason your cells are weak isn't because they came from laptop packs, but because they came from worn-out used-up half-dead laptop packs.

Welcome to the forum menace.

I think most likely your light may have a connection(s) that have developed high resistance. You can try cleaning all the electrical connection points with alcohol.

Additionally, it sounds like your cells are getting tired and have developed high resistance. Only holding 4 to 4.1 indicates that. I wouldn’t use cells in that condition in series. Parallel would be fine of them. Most Japanese laptop pulls should flow at least 3.5 amps.

You didn’t say if you are using 2 or 3 cells. I don’t know off the top of my head what the TR-3T6 should read with 3 cells. I believe the driver is supposed to deliver 4.5amps to the emitters. So the tail reading with 2 cells should be 2.25 amps plus more for losses that occur in the driver and the rest of the flashlight’s circuit. 3 cells should be 1.5 amps plus losses.

If you don’t get good quality laptop pulls, Fasttech has good prices.

EDIT: I just realized you said Lipo charger. Are your cells Lipo cells?


What cells are in those packs? Most low cost non-OEM packs generally have cheap Chinese cells.

They are China cells, but I have not had one single problem with the 24 from those packs, or the 6 of the same brand that came from a different model pack. More info of what's inside these aftermarket 9600mAh packs here:

Cool. Thank you Comfy.

I think they would do their rated capacity if taken down to 2.75v, nothing I have to test with will go below 3v.

What I’ve done before when the hobby charger stops discharge at 3v , is to run them again and Most times you get another 100 mAh.


When you were measuring current did you have the red lead/plug plugged into the normal place on your meter? Or did you move it to the “10A”?

Sorry, I just had to ask, to make sure, because I forget to do that a lot… Plus it’s kind of strange that you see exactly the same .7amps all the time.

Instead of what you’re doing, can you do a tailcap reading with the meter, but just with one lead on the negative side of the battery, and the other lead on the unanodized threads, and see what you get? Also make sure that you have the light in high mode (quickly remove one of the leads to simulate clicking the tailcap switch).

Thanks for the replies guys! I assumed it was the cells so I ordered some new panasonics from fastech. I have a new driver on order too so that should be here in the next few days—hopefully one or both of those addresses the problem. It sounds like both my cells are weak and my driver is pooched…