Either you can look at this and understand it - or you can't - but to the best of my knowledge this is the only time I've seen someone actually record and calculate both the power being consumed by the light - but also that actual current being delivered by the battery WITH real time voltage - which results in the most "real world" accuracy possible.

Just remember this is one test at 70 degrees, running the light continuously on medium power. It doesn't tell you anything about what happens with a different battery or light.:crash:

http://bikeforums.net/attachment.php...hmentid=202567

I've run my light to cutoff a number of times and it doesn't seem to have bothered the battery that I can tell. The protection circuitry in the pack will keep it from going low enough to cause significant damage. It's probably better if you never fully discharge it, but then again it's probably better if you never fully charge it either and few worry about that.

I've had my light switch to red after 10 minutes of use, and proceeded to run the light for 2.5 more hours. I've also had my light stay green until about 3 hours and had the light die 5 minutes after it turned to red. IMO it's just a pretty light, not actually useful for anything. I've thought about opening the light head up and just desoldering it to keep from draining the battery when the light is off.

I've considered the same...it'll save me from unplugging the head when I get to work.

Uh, are you talking about the light or yours there toots?

I'm flattered that you think my head has ever been plugged in. :D

Well, we know it's been photoshopped around plenty of times. :lol:

I emailed Geomangear about the run times/red warning light, and they basically said there were 6 versions of light heads that don't all work the same, and the new battery may not work with all the old warning lights. They also said don't worry about it, charging sooner than you think you'd need to won't hurt the battery. I guess I'll just get used to the warning light changing colors for no reason.

Getting back to Magicshine stuff actually made by Magicshine (rather than the Geoman battery made to fit the Magicshine) - yesterday I got a DealExtreme package including three Y power cables, and they have redesigned them. The original cables were fairly flimsy and I went through one every 3 to 5 months. The new ones are much heavier, the wire is thicker and softer rubber, and the strain relief feels like it's bonded properly to the wire. I think the new ones may last a lot longer.

The warning lights are always triggered by the voltage across circuit. The voltage of the circuit is dictated by the resistance of the battery.

The resistance of the circuit is dictated by the nature of the battery cells and the load across those cells. In theory, no matter what "version" of a light head or battery you use - the results are a function of battery cell resistance and the "load or power" consumed by the light.

In other words, it's the light's power consumption or the battery cell's resistance that cause warning lights to change differently. Not some "light head version."
Obviously, even posting full color charts can't seem to get that point across. I can't find any answers about voltage regulator efficiency - even on the CP forums.

Oh - one other thing - running the light on high - throws in one other wild card, the resistance associated with a "thermistor" being used for temperature control. I guess if you are running the light on high - my comments about the the rest of the circuit mean less. I don't know how a thermistor would affect the circuit.

And the current drawn, and most importantly, the charge level of the battery.
And the resistance of the wiring involved (which should be low.)

But you said it yourself -- the load of the light matters too, and various light heads may have different loads.

And don't forget that the cutoff voltages between green, red and shutoff may be different between the different heads. That's probably what people are getting at most of all.
Well, don't forget that the power consumption may vary for some "light head versions" and that the warning lights themselves can be different between some "light head versions".

Your chart only covers one light head, so it's not going to be particularly useful in showing the differences (or similarities) between various light heads.

Are you using a multimeter that gives RMS values? If not, the square wave used by the regulators in these lights is quite likely to give inaccurate results.

As I write this, I'm measuring the capacity of a new Magicshine battery pack. Discharge current is 2A and the termination voltage is 3.5V. The resulting discharge voltage curve, capacity and internal impedance will be provided.

For reference, I'll also discharge a similarly configured 4 X 18650 (2s2p) battery pack made from the blue DX Trustfires. Unfortunately, I don't have an old Magicshine battery for comparison.

For both, it will be the very first discharge.

Here's the data for the new Magicshine battery:

http://bikeforums.net/attachment.php...hmentid=205875

Here's the data for the 2s2p Trustfire battery:

http://bikeforums.net/attachment.php...hmentid=205884

Notes:
- the capacities are very low due to the high current/high cutoff voltage, and so
- much of the energy is still left in the batteries
- the Magicshine battery slightly outperforms the Trustfires

When I get a chance, I will discharge these to 3.2V/cell at 0.5A to extract most of the remaining energy.

Here is the remainder of the discharge of the Trustfire pack down to 3.2V/Cell with 0.5A discharge current:

http://bikeforums.net/attachment.php...hmentid=206264

Note the amount of energy left. This gives a total capacity of about 4Ah. These batteries are really poor at delivering current (low power density). Unfortunately, I couldn't discharge the Magicshine pack in a similar manner (I charged it again for use) but the results would be similar.

If you have any ability to modify and maintain a 2s LiPo pack such as the Turnigy's from HK then this would be a better choice for powering these lights. They would handle the current easily and maintain a much higher voltage through discharge.

Reviving the thread now that I'm using the light more...

With the original Magicshine battery, I could use it 6 hours per week on low without a recharge, I never had the indicator turn red. Now with the replacement battery, after 1.5 hours on low, the indicator turned red... the lights were still working, but I switched to my backup lights for the rest of my commute.

From reading other posts, perhaps the indicator color is not indicative of an actual warning because the new battery might just be at a lower voltage and yet still have quite a bit left in the tank. So the red indicator should be ignored.

Are others using this replacement battery and have similar experiences, or have they switched to a completely different battery?

The indicator color is simply an analog voltage meter: green= >8.0v, red=6.4v ???

The important thing is once you get to red, a very small decline in battery voltage will result in shutoff (no light). So it is a warning you shouldn't ignore.

Getting only 1.5 hrs on low mode seems pretty bad to me. You may want to pursue a warranty claim.

The replacement battery may simply have a higher internal resistance which causes more voltage drop under load.

The light on my MagicShine is a random number generator. Unless the battery is completely fresh, it could be either green or red. It means that there's somewhere between 2.5 hours and 5 minutes left when it turns red; I've had it turn red in both situations.

After the red indicator after low for 1.5 hours (as I reported), I charged the battery, and it was done in 30 minutes, so I thought it was not really depleted very much. Perhaps as rscamp said, the battery resistance is higher in this model, and perhaps it's defective.

I'm using my original charger, and haven't tried the new Geoman charger, I assumed they were the same.
At this point, I have nothing to lose, I will keep using the light, including after the indicator turns red. Then I can share what I find as to performance, etc.... It's good to have backup lights at the ready.

I usually recharge mine after 2 hours use (2 round trips for me), and the red light is always on by then. I figure I'm not going to push it and try and get 3 hours/round trips out of a charge, and have back up lights in case the Magicshine quits before I get home.

I just received my battery in the mail this past week. It looks great, but is not working properly. I am running into the problem where it shows a full charge (green light) on my charger, but when I hook it up to the light head, the light comes on red. I wasn't sure if it was the charger or the light head that wasn't registering the charge level correctly, so I hooked it up to the light head and it worked for 90 minutes, then blinked a few times and went off completely. I then hooked it back up to my charger and the light on the charger was green again?

Needless to say, I sent an email to geoman this evening. I assume they are just going to tell me that the indicator lights are not accurate, but I never had any problem with my old batteries. It is certainly going to make things difficult if I can't tell if my battery is done charging, or if it has any juice left when hooked up to the light.

Is anyone else experiencing issues with the charger coming on as green immediately even though the battery is fully drained (the light won't turn on)?

My replacement battery finally arrived about a week ago (took about six months.) Same problem, except that my pack was totally dead -- wouldn't light the light at all.

My charger would not charge it, but my friend's would and then it was fine. Geoman said that some of the old chargers weren't compatible with the new batteries and they're sending me a new charger.

One thing you can count on Geoman for is great customer service. They responded to my email today and told me the same thing about some of the original chargers not working. They are sending me a new charger.

I will post an update when my new charger arrives

My charger arrived today. They shipped it next day air (totally unnecessary, but they did it.)

I found that the connector on the new battery pack is not quite right. It mates with the light connector OK but not too well with the charger connector. It often doesn't make proper contact (and as you know, if it's not plugged in the light glows green). I'll look at it, it's glowing green, I wiggle the connector, twist it, pull it halfway out, etc, and it'll turn back to red in some position. Eventually after a few hours it'll charge to where it won't turn red anymore, then it's REALLY charged.

That was the one problem with the new pack.