What's the best procedure for long term battery life ? Let the battery run down, then charge it back up fully, or keep the battery "topped off" so it's always pretty well charged ? Or another option ?

I'd recommend running it down to the point where the "low battery" indicator light comes on when the headlight's on high, but goes out when set to "medium". That's nowhere close to being fully depleated, as is warned against to keep battery life normal, and you will still have plenty of runtime on "medium" or "low" before the battery's empty.

Lithium Ion: charge before it gets dead. There's not much debate on this. It'll last longest if recharged when it gets down in the 50% range, more or less. And don't let it sit around for weeks or months fully charged either, that's not good for it.

As for going to when the low battery indicator is on, that depends on how well yours works. Mine came on at about 3:05 out of a 3:10 runtime. The light died 5 minutes after the low battery indicator came on.

After a few cycles, my low battery indicator doesn't work at all. It now shows "low" all the time, even with a freshly charged battery.

Thanks for that information about your low battery indicator!

It doesn't matter.

Odds are the driver will start going wonky after a short time, and your MS runtime will eventually decline to whatever value the driver now operates at - making the whole "charging strategy" argument moot.

My MS light now shuts off at a voltage of 7.2-7.6v (and red light even sooner). That means each cell is still at 3.6-3.8v - not even 50% discharged. 18650 cells can be safely discharged to ~2.7v. Full charge is 4.1-4.2v (8.2-8.4v in the 2S2P MS battery).

I hope you have better luck with your MS. My take on the MS is it's a light system built to the same low quality standards as a DealExtreme P7 flashlight, but a little more complex, and thus overall less reliable. Which is a worrisome conclusion if you have owned any DX P7 flashlights.

Top it off if feasible. All rechargeable batteries last longer with shallow cycles.

This is certain not true of all rechargeable batteries. Anything with Nickel in it (NiCad, NiMH) will have greatly reduced life if treated this way.

Li-ion batteries don't have memory, the primary factor in degrading battery performance is age. The best things you can do for an Li-ion battery are to store it in a cool place, don't run it all the way down, and don't overcharge it.

https://www.batteryuniversity.com/index.htm

The instructions that came w/ mine from Geoman say to top it off frequently, not to let it run down. Every once in a while, it pays to RTFM.

Except that the manual here is rather incomplete.

The general rules for Li Ion batteries are that that you should not store them in a "discharged" state (or you risk falling below the threshold at which the protection circuitry will no longer allow them to be recharged), you should charge them when they have run down a bit (not topping them off if they have not been used), and that you should store them in a cool place.

You don't need to be obsessive about NOT charging them (as you would with a NiCad) but for best battery life, charge them only when they need to be charged.

No, it basically is true of all rechargeable batteries. NiMH batteries don't really have memory effect. Even NiCad will have more total life (cycles * cycle life) with shallow cycles.

I can't find a good link for it now, just a bunch of articles with footnotes that say "shallow cycles are better than deep cycles" for a variety of types.

The BatteryMan is the source you may be thinking of.

While that's true of NiCad, I believe NiMH generally likes being recharged before being reaching maximum discharge as well. It's complicated - apparently it lasts longer if topped off, but still has a slightly memory effect, so it requires very occasional full discharge/recharge to maintain peak capacity.

I agree that different battery materials need to be treated differently, but I believe the 2 most common nowadays (lith-ion and nimh) react best to shallow recharge cycles.

If you want more than just the battery university page on nimh, go read articles on how the Prius's nimh battery pack maintains it's longetivity - it's never drained all the way, or charged all the way, which says to me that it isn't good for nimh to be completely drained constantly.

I've always wondered - lith-ion batteries don't like heat. If I wasn't using the battery over the winter (winter bike has a generator hub), if it would be best to bring it to half charge and put it in the refrigerator or freezer over the winter.

The main thing that will seriously damage either LiIon or NiMH is running the cells below critical voltage. For NiMH, it's about 0.95 volts, for LiIon, somewhere between 2.4 and 2.8 volts. Going below that (or storing them for so long that the voltage drains to below that) can result in permanent damage. In the case of NiMH, it will permanently take a percentage of the capacity from the battery. In the case of LiIon, it can crystalize the electrolyte and make the battery useless.

I don't think I'll be using mine in the spring and summer when my commute is in daylight. I have a 1 watt strobe that;s adequate for being seen along the road. any suggestions for storing the magic shine for a long duration?

Don't run it down, when the low battery comes on recharge it asap. As for long term storage, i heard it was best to give it a 60% charge or something and then store it somewhere cool and dry. If the battery is stored in a discharged state it can corrode either the anode or cathode, i forget which one... but there is another posting about it somewhere on this site amongst all the ms posts!

Put the battery at about 60% charge and toss it in the refrigerator. We have a crisper drawer in our fridge that has a box of batteries and the rest holds seeds (some from a few years back). The battery will discharge much more slowly at cold temps.

Anyone have problems a sub zero F. temps? Charged mine to full last night and this morning ran it on medium for about 45 minutes and the red light came on...never had that happen before even after an hour and a half on medium in above zero temps....

Possibly your driver has gone bad.

Mine originally ran over 3 hrs on H. I actually measured it a few times in a rundown test in the garage with a fan for cooling. Now it consistently goes ~2hrs on H to red light.

The battery and charger are fine. I have 2 and they charge/discharge normally. The problem lies in the driver and it's sensing of voltage. Mine now gives a red light at 3.75v. Nominal voltage for 18650s is 3.6, and they can be safely discharged to 2.7v. So, my defective driver has artificially reduced runtime by 1/3 or more. Only practical solution is a new lighthead @ ~$55 with S/H.

If yours is <90days old, send it back under warranty. Good luck, I hope I'm wrong in this analysis.

I did a test in my freezer last fall. The freezer only goes down to 10*F, and it cut the runtime from 3:15 down to something around 2:30 (I didn't actually witness it shutting off). I could easily believe that runtime starts to drop rapidly in that range. 45 minutes is a heck of a drop, but I wouldn't be surprised to see it at something like -10*F. Batteries really suffer in really cold temps.

If you have a long cord, you can find out by dropping it in your pocket and seeing if your runtime goes back up.

I've been using my MS for about a month now, and the past couple of days haven't been particularly cold (25F-30F) for the ride home. I have been consistently going from green to red on high beam after about 28 minutes. I charge every other day, at approximately 50% battery life depleted. This is new behavior. I thought the cold would help it last longer, but now not so sure. I'm going to try insulating the battery in some socks (I store it in my seat bag while in use) to see if keeping it warmer helps.

Will report back.

EDIT: Sent GeoMan an inquiry to see if this is a common complaint after only a month of use.

cold is only good for battery storage. cold shortens runtime. however not that short!

ask geomangear about your issue - the company is very responsive with information

I wrap mine in bubble wrap and shove the wholem thing in a water bottle, then cover it with plastic bags and rubber bands. it's water proff and provides some thermal protection, but really riding below freezing - that wrap doesn't keep it any warmer, not after 15 - 30 minutes, you know? anyway, mine lasts much longer on green in even lower temps.

Geoman knows customer service:

No worries, we'll take care of you. The colder weather has affected run-times.

On another note, run the battery to empty and fully charge for 6 hours or more to reset the programming. Retry the run-time. Keep the battery warm when testing outside in your jersey front, etc... Advise.

Thank you!!! We appreciate your support very much.

Best regards,

GeoMan

Have you tried actually seeing how log it is until the light shuts off?

The low battery indicator on my MS light is utterly random. Sometimes it goes red on a freshly charged battery. Sometimes it goes red about 30 seconds before shutoff, after 3 hours of running. Sometimes it goes red, then half an hour later goes green again. No connection to anything.

I just ignore it and charge on a regular schedule.

I actually just switched to a P7 flashlight. I should probably try to sell the MS while it's still new and both my battery packs are still new-ish and good.

can't believe they would suggest running the battery down. I guess that just proves that selling something doesn't mean you understand it.