# Can I use Samsung 50S 21700 25A Continuous Discharging Rate For M61HOT, M91T, and Hound Dog Super?

#### QMT93

##### Enlightened
Hi there,

Malkoff recommends the KeepPower 21700, which is Samsung INR21700-50E with 9.8A continuous discharging rate. Can I use the Samsung INR21700-50S, with 25A discharging rate, battery for the M61HOT, M91T, and Hound Dog Super?

Also, could you explain what the discharging rate means? I did some reading, but all I can understand is V x I = W, and that the higher the discharging rate, the faster I can safely charge a cell. However, I failed to see how the discharging rate affects the flashlight. I expect that voltage makes the light shine more brightly, but I can't tell what the discharging rate does.

Hope to hear from you soon.

#### kerneldrop

##### Flashlight Enthusiast
Yes.

The problem is when you have a flashlight that pulls more discharge from the battery than what the battery can push to the light. That creates a short and eventually turns into a fire.

Discharge = how much amps the battery can continually push to the light

think of it like a gas motor, throttle, and gas tank.

Note: the higher the discharge rate the lower the capacity due to the space needed inside the battery for the higher discharge parts. Ideally you want to pair the right battery for the light so you can maximize runtime. A 10 amp battery will have more runtime than a 25 amp battery.

#### QMT93

##### Enlightened
Thank you for the explanation!

If I understand correctly, if the battery discharging rate is at least the same as how much charge the light is pulling, I can use the cell. Is this correct?

I have a few more follow-up questions, if you could clarify for me:
1) Besides runtime, and short prevention as you described, does the discharging rate affect the light in other ways?
2) How to determine how many amps the light is pulling?
3) If the light can only draw 2100mAh = 2.1Ah (M61HOT), does a 10A discharging rate differ from 25A? If so, how?

#### kerneldrop

##### Flashlight Enthusiast
Thank you for the explanation!

If I understand correctly, if the battery discharging rate is at least the same as how much charge the light is pulling, I can use the cell. Is this correct?

I have a few more follow-up questions, if you could clarify for me:
1) Besides runtime, and short prevention as you described, does the discharging rate affect the light in other ways?
2) How to determine how many amps the light is pulling?
3) If the light can only draw 2100mAh = 2.1Ah (M61HOT), does a 10A discharging rate differ from 25A? If so, how?

These batteries aren't designed for flashlights. So keep that in mind. They are for vapes, motors and other devices requiring a lot of battery power. You won't have a 1 LED flashlight pull 25amps. The LED and driver will fry in a split second. Plus the tiny little wires will have a bunch of resistance and 25 amps won't reach the LED. I'm sure there's some chinese lights with 30 LEDs that pull 25 amps, but I don't mess with those.

If I understand correctly, if the battery discharging rate is at least the same as how much charge the light is pulling, I can use the cell. Is this correct? As the battery voltage decreases from use then the discharge amps will increase. So you will need a battery that has a higher discharge rate than what the driver/LED is pulling. The formula is Watts = Amps x Volts. Watts will remain constant so when one of the variables is higher the other is lower, and vise versa.

I have a few more follow-up questions, if you could clarify for me:
1) Besides runtime, and short prevention as you described, does the discharging rate affect the light in other ways? Current is what gives the light sustaining output. Current = discharging rate. So as long as you have a discharging rate that is higher than demands then the light is not affected. It's similar to having the throttle on a gas motor 1/2 way rather than wide open.

2) How to determine how many amps the light is pulling? Amp meter. Also every LED has a datasheet that gives pretty accurate measurements. For a LED to reach X lumens, it must have X amps. So you can have a good idea from the datasheet.

3) If the light can only draw 2100mAh = 2.1Ah (M61HOT), does a 10A discharging rate differ from 25A? If so, how? No performance difference. won't use near or more than 10 amps. Here is why:

Watts = Amps x Volts
Watts = 2.1 x 3.7
Watts = 7.77

Let's say you use a protected battery that shuts off at 2.5 volts.

7.77 = Amps x 2.5
Amps = 3.10

Based on above you'll never use more than 3.10 amps, assuming your battery drain limit is 2.5 volts.

So your garden water hose may can flow 25amps, but you're only flowing 3.10 amps through the water hose.
Think of it like a water hose.
Volts is water pressure. Current is how much water is flowing.
Like a pressure washer.

#### knucklegary

##### Flashlight Enthusiast
CPF Supporter
^ Good analogy kernel 🤔

#### QMT93

##### Enlightened
@kerneldrop thank you so much for the detailed explanation! Up until this point, I've always gone with the recommended cells. This will help broaden my knowledge, and thus options. Thank you again!