AAA Ni-MH

[how2]

I got Small Sun ZY-C72.

I think it has Over discharge protection.

What would be the Voltage when the Over discharge protection kicks in.

I have measured it at 1.2v is this correct?

What is the normal Over protection Discharge for other lights.

Thanks

 

[drmaxx]

The only light with 'discharge protection' are my single AA lights (e.g. Nightcore D10) they stop working at 0.9 V.

 

[VegasF6]

The SMALL SUN ZY-C72 is a single AAA light.
I am not familiar with the electronics inside it, but at a guess I would say it isn't so much a protection circuit for the battery as it is the circuit can no longer boost at a certain point. .8 volts is about the lowest I have seen. (Zetex C310 for instance)

Also, keep in mind, for nimh batteries checking voltage is not a good indication at all of charge state.

I would check current draw at the tailcap with a fresh charged battery and at various other points. I am going to guess at LEAST .5 amp draw from a ~700 mA battery, perhaps higher. So, at .7 to maybe over 1C you can expect a significant amount of voltage sag, which would rebound once the light was off, hence your 1.2V reading.

In addition, you don't even mention if you are talking about nickel batteries or alkaline. If so, then everything I stated above only even more so.

I would just assume it is working right. Unless you have a variable power supply and a couple DMM's and the incentive to test it that is.

 

[drmaxx]

The SMALL SUN ZY-C72 is a single AAA light.

Ooops, I confused it with the larger 3AAA light. I'll edit my post accordingly.

 

[Egsise]

The only light with 'discharge protection' are my single AA lights (e.g. Nightcore D10) they stop working at 0.9 V.
The other multi-cell lights do not have a shut off point. E.g. the Apex headlamp (4AA) has a indicator that starts to turn red - but it does not shut off and runs the NiMH batteries down to a point of almost no return.

Do you mean 1.2 V for the entire pack or for each of the three AAAs?

Many single cell AA lights have overdischarge protection at 0.9, Fenix and 4Sevens for example.

For 1xAAA flashlight overdischarge protection at 1.2V sounds wrong.
When my Fenix LD10 and 4sevens Quark AAW stop working the cell open circuit voltages are 0.9-1.0V.

 

[45/70]

I think you guys are confusing "under voltage protection" with the light's circuit failing to operate below 0.8-0.9 Volts, as VegasF6 mentioned. With actual under voltage protection, the light will warn/shut down at any drive level, when the voltage becomes low enough to over discharge the cell. With the lights mentioned above, if the LED is driven at a significant level, it will effectively shut the light down before the cell is over discharged. At lower drive levels however, the current drain can be low enough that the cell could possibly be over discharged.

None of the lights mentioned above have true under voltage protection, that I am aware of. The reason the two cells lights seem to not have "protection", is the voltage is high enough in these lights to allow the circuit to keep working until over discharging of the cells occurs, regardless of the drive level.

Dave

 

[how2]

In addition, you don't even mention if you are talking about nickel batteries or alkaline. If so, then everything I stated above only even more so.

Hi Vagas F6

It's the Panasonic Nickel metal battries. It's in the title.
I don't use Alkaline batteries as i don't have any

 

[how2]

The light has 1mode.

When i use it for 30mins and turn it off. Then switch it back on, the power to the led is reduced, it still lights up at a lower level. Sometimes it boosts the power to full.

If i install a new battery it works normally.

I have checked the voltage when it doesn't turn it back to full and the reading was 1.2v.

What I'll do is to run it until the battery runs out. I will time it and see if there is a drop in light output or dimming. Then i will check the voltage again.

 

[45/70]

I have checked the voltage when it doesn't turn it back to full and the reading was 1.2v.

1.2 Volts with a NiMH cell that has rested a few minutes, is basically discharged. That makes sense with what you're saying. That would be the point where you would notice the output dropping off, as the cell is nearly depleted and can no longer supply enough current for full output. I wouldn't drain the cells much lower than that.

Dave

 

[VegasF6]

In addition, you don't even mention if you are talking about nickel batteries or alkaline. If so, then everything I stated above only even more so.

Hi Vagas F6

It's the Panasonic Nickel metal battries. It's in the title.
I don't use Alkaline batteries as i don't have any

Oops, from the time I hit reply till I finished typing I forgot, hah.

The light has 1mode.

When i use it for 30mins and turn it off. Then switch it back on, the power to the led is reduced, it still lights up at a lower level. Sometimes it boosts the power to full.

If i install a new battery it works normally.

That sounds like voltage sag as well. Age and condition of the battery? Capacity? Report back current draw with a full battery and I think we will find 30 mins is about right.

 

[45/70]

That sounds like voltage sag as well.

Yeah, discharged NiMH cells do exhibit fairly obvious signs of voltage sag.

What I'll do is to run it until the battery runs out.

I wouldn't run the cell much farther down than you already have. Your Sun ZY-C72 basically uses a direct driven boost circuit. When the cell can no longer supply enough current for normal output, it's time to recharge. Running the light down much past this point will likely damage a NiMH cell. If you were using a NiCd, you could run it all the way down, but discharging a NiMH below 0.8-0.9 Volts under load (or 1.0 Volt rested), will just damage it. There is no miracle circuitry in this light that is going to save your battery. Trust me.

Dave