Why not (quark AA & LD10)?

[candle lamp]

4 sevens quark AA (R5) and fenix LD10 (R4) are an AA powered lights. The input voltage of the lights is same 0.9~4.2v. When I asked the above manufacturers whether I can use a 3.7v 14500 li-ion rechargeable battery or not. 4 sevens said 'Yes' and fenix 'No'.

What do you think of the reason why LD10 can't use a 3.7v 14500 li-ion rechargeable battery?

 

[Egsise]

Because Fenix LD10 circuit operating voltage is 0,9-3V.

 

[scott2907]

for the same reason as why I can't put petrol in my car.

 

[Wiggle]

Quark has buck/boost converters, Fenix has only boost. So for a good portion of the Lithium-Ions discharge, the emitter is being direct driven at a higher than spec level.

 

[candle lamp]

Quark has buck/boost converters, Fenix has only boost. So for a good portion of the Lithium-Ions discharge, the emitter is being direct driven at a higher than spec level.

I supposed the circuits of the two lights are different. Could you explain how quark's buck/boost circuit works. Thanks

 

[Saint_Dogbert]

A boost circuit 'boosts' or raises the input voltage to keep the LED in regulation. Conversely, a buck circuit lowers the input voltage to keep it within Vf of the LED and prevents the LED from going into direct drive, bypassing the circuitry. As pointed out, Fenix lack a buck circuit, so using a li-ion direct drives the LED, which can be harmful in the long term.

 

[DeLionKing]

A boost circuit 'boosts' or raises the input voltage to keep the LED in regulation. Conversely, a buck circuit lowers the input voltage to keep it within Vf of the LED and prevents the LED from going into direct drive, bypassing the circuitry. As pointed out, Fenix lack a buck circuit, so using a li-ion direct drives the LED, which can be harmful in the long term.

Very well explained, now I get it!

 

[candle lamp]

A boost circuit 'boosts' or raises the input voltage to keep the LED in regulation. Conversely, a buck circuit lowers the input voltage to keep it within Vf of the LED and prevents the LED from going into direct drive, bypassing the circuitry. As pointed out, Fenix lack a buck circuit, so using a li-ion direct drives the LED, which can be harmful in the long term.

Thank you for your detailed explanation. :twothumbs I got it.