Sofirn TK70 issue

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Funtastic
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Sofirn TK70 issue

EDIT: seems it’s been fixed on new batches.

I just received 2 out of 3 TK70’s and they have a big problem that I’m surprised passed testing.

The springs are too short or the tube is too long. 1pc flickers when shaking and the 2nd completely turns off and on. Both batteries are shaking loudly at both ends

The SP70 springs are quite a bit longer

I’m also using Sofirn’s HD 26650 button top so it’s not an issue of flat top’s poor contact.

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

Edited by: Funtastic on 03/13/2020 - 18:21
Myke
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wow thats poor quality control from Sofirn. I noticed the Sofirn batteries in mySp 70 rattle around a little as the body of the light is a larger width . The length ia fine. I wrapped a piece of masking tape on each end of the 2650 cells and no more rattle. I would send the two lights back if possible. Best of luck

sarge12
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Might want to check and see if protected batteries are recommended. In truth, I would not use unprotected batteries if the batteries are stacked. Protected batteries will be 3-5 mm longer than unprotected batteries. With stacked batteries, If 1 battery goes bad, it can result in the other battery also going bad. A flashlight pcb protection will treat 2 stacked batteries as 1 large 7.4 volt battery. Since it can’t check both batteries individually, the pcb in the light is not as effective as a safety, even if the light has the safety circuits. The SP 70 does have protection circuits, but if 1 battery is low in voltage it can cause the other battery to overheat, and even vent. In any case if the batteries used are not protected, using protected batteries will likely solve the problem, as well as being safer. They have to set up the light for protected batteries which will be 6-10 mm longer. That is a lot of added length for the 2 springs to compensate for. In general, protected cells should be used in lights having more than 1 battery. Edit::: I assume you know this, but for anybody reading this, just having button tops does not mean a battery is protected. If it is not 3-5 mm longer, it is not protected. Unprotected will be about 65mm long, protected will be 68-70mm length.

d_t_a
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What are the usual overcurrent protection for protected 26650 batteries? Some protected 26650 don’t list at which over-current they will cut-off.

I did tailcap current measurement of the SP70 before, and got around 13 Amps (ie. 2× 26650 @ 13 Amps).

Funtastic
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I’d never use protected batteries in a flashlight that’s built for high drain unprotected cells. If you can get protected cells with a high current cut off on the pcb, they would still give high voltage drop from the added resistance.

For flashlights that have no battery light indicator I’d stick to protected like the Convoy L6. Low voltage protection should kick in even if the cells are badly uneven in voltage and the low battery indicator will also be lit red. I don’t see an issue.

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

Funtastic
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sarge12 wrote:
Might want to check and see if protected batteries are recommended.

Unprotected are recommended

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)