Thorfire s70s Parasicit drain question.

I wanting to know if anyone could check parasitic drain on this torch while it is in standby mode.

It seems to have a bit of drain problem but I have no way to actually assess

Thanks

Use a 1kOhms resistor
Measure voltage drop over it mV equals uA drain

Do you have a multimeter? Since the light does not come on with the tail switch you can just put your test leads on the tail cap area and measure the current from battery to tube.

The LED alone is probably 0.15 to 0.20 milliamps. This is very tiny and would take a year or more to drain. As for the driver, I can’t say.

Some are way less than the LED current and some may be 1.5 milliamp.

The main thing is just to not leave the tail switch on for months at a time and you should be fine.

Are you having issues with yours?

Thanks for the help I could not measure current at tail with my meter. No reason top think there is problem

You might ask here since there are lots of guys there with these lights.

@marsalla,

You can leave it on overnight without noticing any battery drain. Think battery dropped much less than 0.1v.

I have an S70S coming today, so I could measure it maybe this evening.

With a precise DMM that goes to 1000's of a volt and doing a 24 hr test, that may help to tell you. Might be a specific issue with your light. Got a USPS notice the S70S was delivered home, but picking up a new car later (lease), then heading home.

That is a big drop. No way it should drop that much in 24 hours. That’s like fully charged 4.2 volts to mostly drained 3.5 volts in a week. No way they would design it with that much drain.

If the LED switch light has a 135 µA (0.135 milliamp) drain and you use 5,000 mah batteries it should take 4 years to fully drain them.

I have a TA FET driver in my L6 using an LDO and it only has a 0.08 milliamp drain. So combine that with the switch light and your still at 4 years to fully drain the batteries.

Now I assume Thorfire built their driver with parasitic drain in mind so as not to have a bunch of unhappy customers. I assume.

We shall have to wait and see someone’s S70-S drain numbers.

You don’t say!

I just measured the parasitic drain of the S70S just received today, and it's 4.37 mA on two EFEST 4200 IMR's @4.10V.

That's pretty darn high. Even if the LED took 500 uA, the draw should be 600 uA or so at worse. With this high of a draw, something is wrong with my driver or the driver was not designed with low parasitic drain in mind.

I guess I gave Thorfire too much credit.

I’m running 2 leds and I set them up to be bright and that’s only 0.4 milliamp. Thorfire’s single led is probably under 0.2 milliamp so the driver itself is about 4.0 milliamps.

The Q8 driver has a 0.02 mA draw with switch led turned off and a 0.135 mA draw with it turned on. That’s very good.

I guess Thorfire expect their customers to always turn it off with the tail switch?

I’ve got a FX30 with a 1.4 mA draw and a TA FET with LDO and that has a 0.08 mA draw.

I’m not too familiar with zener diodes on these 6 volt lights, but everyone says they have too much drain and an LDO is the best choice.

Is it possible the S70-S has a zener diode on it?

Does the side switch have a light?

Yes, the single switch led should draw under 0.2 mA so the driver is drawing the other 4 mA.

The older S70 also had a switch light, but it didn’t have a standby mode so parasitic drain was not an issue.

A rough calculation using 5,000 mah batteries shows a complete discharge in just 47 days.

If the driver doesn’t have a proper bleeder resistor it could be playing with the switch and current draw.

I wonder if the new S70 has the same driver as the old S70 or a new driver? The old S70 i have has a tail switch.

I am now locking out all my electronic switch lights the drain on some are bad.

Are you talking about a bleeder resistor for the switch led? I’m sure it does just to not burn it up. Still, 2 bright leds only pull 0.4 mA. So the single, not so bright, led in the S70-S can’t be more than 0.2 or 0.3 mA. The big 4.0 mA draw has to come from the driver.

Or do you mean a bleeder resistor that is part of the driver circuit? I’m not familiar enough with driver dedigns to comment on that.

It’s not that big a deal if you turn the tail switch off when your done using it or you recharge the batteries every week or 2 already.

Oh yeah, the new model is the S70-S. The older one is just the S70.

I know the new driver is slightly small in diameter and the sense resistors are a larger smd size. The firmware is definitely different. I don’t remember too much else about the 2 drivers.

Both models have tail switches and side switches.

The driver its self should have a resistor for the LED in the side switch. Some thing has to limit the current to the LED in the switch.

Can some one take a pic of the driver?

Yea just click the tail switch of if it has one. Problem solved but you lose the “beacon mode” on the side switch which some people might want.

Here’s the old one. It’s 29mm.

Here’s the new one. It’s 27mm.

Edit: I just bought a S70S in Oct 2018 and it’s driver is 29mm.

Still possible to order TA drivers from me
30mm will fit sanded down