dougmc

This is an extraordinary claim. Do you have a citation? Detailed data from your own testing to back this up?

I'm fully aware that they're rated to a certain number of cycles, but common sense tells me that a deep discharge/charge cycle would wear out the battery more than a shallow one. And certainly, I've found that the harder I push (higher discharge rates, deeper discharges) my batteries (I also fly R/C planes, electric ones) the fewer flights I get (batteries are charged after each flight) until the lost capacity becomes a problem.

From what I've seen, it doesn't really seem to matter how deep or light I discharge the battery -- for every X mAh of current it puts out, it loses Y% of it's capacity. However, if I discharge it fast enough for the battery to get warm or hot, it'll wear out even faster. (Though that's not really a problem for bike lights -- you're discharging at C/3 or so, where my plane might be doing 10C -- 30 times as fast.)

ItsJustMe

I think you'd better read up on LiIon batteries a bit more. That's not correct. It's not very good for LiIon cells to run them completely down every time. If you can charge them at about 50% depleted every time, you'll get more total amp hours out of the batteries over their lifetime than if you run them down to recommended minimum charge every time (or even very frequently).

megamo

I think you'd better read up on LiIon batteries a bit more. That's not correct. It's not very good for LiIon cells to run them completely down every time. If you can charge them at about 50% depleted every time, you'll get more total amp hours out of the batteries over their lifetime than if you run them down to recommended minimum charge every time (or even very frequently).

Do you charge the battery completly full after partial discahrge or not?

ItsJustMe

Yes, I put them on the charger overnight. Generally I put them on every 2 days, which is about half their runtime. I did run it dead once earlier this week, from a combination of going longer than I'd thought, and the battery starting to fail (apparently it may be defective, I may do some more tests later).

daniel58

Yes, of course they are not nickel cadmium battery chemistry and do not suffer from charge memory issues.

See the below link and research into it a bit more:

For further reading and analysis, the information was derived from reading on batteryuniversity.com link(its quite informative nontheless):

https://www.batteryuniversity.com/parttwo-34.htm

read through the article titled "How to prolong lithium-based batteries" and make ones own interpretation as I did as well; ones subsequent interpretation may vary naturally of course.

"A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges".

the batteryuniversity site has a lot of other information related to the lithium ion rechargeable battery that certainly is interesting to know in so far as background information to broaden and widen ones scope of knowledge and understanding which is all good to know information.

Happy Holidays to all

sierrabob

While I am no expert on batteries, it seems that your technique may accelerate the aging process. Here's Geoman's info on the subject:



Note the last sentence. Charging overnight is not dangerous due to protective circuitry, but because the battery stays at 100% for a long time, you reduce useful life. It's basically the problem we induce by leaving our laptops plugged in all the time.

Why not just charge up your batteries in the early afternoon before your night ride?

And if anyone is interested in a clean road bike install of the two Magicshine P7 lights (MJ-808, MJ-812) now available check this out:



The extension wire is attached to bike using zip ties, but flashlight, headlight and battery pack are easily removed for transfer to mountain bike, storage, and charging. Nominal wireless computer operation with both lights at 100% power during static indoor test.



Battery pack and its velcro pouch tuck into seat pouch along with spare tube and a few other goodies. Haven't quite figured out total waterproofing yet. Many thanks to the forum member who originally posted the seat pouch mount idea with pix.

ItsJustMe

It's only kept at full charge for about 9 hours, after it reaches charge (probably about 8PM or so I'd guess) and before I set out in the morning (5:30 or so), and then is at a lesser charge for the next 36 hours, until I plug it in after getting home the following day.

In the afternoon I'm at work; I'd have to take the battery off the bike, take it to my desk and charge it there, and remember to put it back on my bike. I'm not riding home in the dark in the evening so it's very possible I'd forget and leave the battery there, then I'd be without a good light the next morning.

Besides, charging it to 100% in the afternoon and then using it the next morning is even WORSE than my method of charging at NIGHT and then using it the next morning - the battery would be at 100% charge for another 6 hours or so.

Also, the couple of people that I know that actually work in battery research say that the advice against keeping LiIon batteries at full charge for "a long time" have told me that that means for weeks or months, not hours. Obviously if you couldn't keep batteries at 100% charge for a few hours, you'd have to wait until just before you wanted to use your laptop, and then charge it up at the last minute before using it.

daniel58

Put out some additional background information on new more definitive information to hopefully clarify lithium ion batteries regarding cobalt based lithium ion cell chemistry makeup, workings, guidelines and questions regarding discharge loading and recharging partial/full cycles and issues with lithium ion to maximize lithium ion productivity and life:

The positive electrode(cathode) is made of Lithium cobalt oxide, or LiCoO2.

The negative electrode(anode) is made of carbon.

When the battery charges, ions of lithium move through the electrolyte from the positive electrode(cathode) to the negative electrode(anode) and attach to the carbon.

During discharge, the lithium ions move back to the LiCoO2 positive electrode(cathode) from the carbon.

Lithium ion chemistry prefers partial discharge to deep discharge, so it's best to avoid taking the battery all the way down to zero, because the (pcb) protects and prevents the battery from being recharged if it falls to low.

Since lithium-ion chemistry does not have a "memory", you do not harm the battery pack with a partial discharge; like on a nickel cadmium battery for example..

If the voltage of a lithium-ion cell drops below a certain level, it's basically ruined.

Cobalt based Lithium-ion batteries also suffer from the effects of "aging".

Cobalt based Lithium-ion batteries only last two to three years on average, even if they are sitting on a shelf unused.

Avoid exposing the lithium ion battery to heat, which degrades the batteries by accelerating the "aging" effects.

Brain, Marshall. "How Lithium-ion Batteries Work." 14 November 2006. HowStuffWorks.com. <https://electronics.howstuffworks.com/lithium-ion-battery.htm> 06 December 2009

Below source material discharge/charge characteristics curves that show relative longevity of lithium-ion as a function of discharge and charge rates.

A moderate discharge and charge rate puts less stress on the battery, resulting in a longer cycle life.



This is from the BatteryUniversity website in an article titled "How to prolong lithium-based batteries" at:

https://www.batteryuniversity.com/parttwo-34.htm

Some simple guidelines put out by BatteryUniversity website:

Avoid frequent full discharges because this puts additional strain on the battery.

Several partial discharges with frequent recharges are better for lithium-ion than one deep one.

Recharging a partially charged lithium-ion does not cause harm because there is no memory.

(In this respect, lithium-ion differs from nickel-based batteries.)

Short battery life in a laptop is mainly cause by heat rather than charge / discharge patterns.

Keep the lithium-ion battery cool. Avoid a hot car.

For prolonged storage, keep the battery at a 40% charge level.

If you have a spare lithium-ion battery, use one to the fullest and keep the other cool by placing it in the refrigerator.

Do not freeze the battery. For best results, store the battery at 40% state-of-charge.

Buchmann, Isador "How to prolong lithium-based batteries" www.batteryuniversity.com and is the founder and CEO of Cadex Electronics Inc., in Vancouver BC.

Mr. Buchmann has a background in radio communications and has studied the behavior of rechargeable batteries in practical, everyday applications for two decades.

Happy Holidays to all.

sierrabob

Yes, I try to do just that with my Magicshine lights--charge them in the afternoon to be ready for an evening bike ride. I leave the batteries in the cold garage after my ride and also charge them in the garage. Hopefully this is the optimum conditioning method. After 300 cycles we should compare battery life to see if my method was worth the effort.

megamo

Thanks Daniel for the info.

electrik

Do not freeze the battery... but what temperature does LiCoO2 freeze at?

I know lithium batteries perform quite well at -20c where a nickel based one will lose 80% of it's charge.

rumrunn6

WOW, you guys are amazing! How much of a discharge am I providing by doing the following:

Fully charge in the evening
Ride 1 hour in temps in the 20s
Light stands all day with pilot light disconnected
Ride 1 hour home with temps in the low 30s

I have no idea if this is a 10% or a 40% discharge. hanks for whatever insight you may have.

daniel58

Lithium cobalt iion battery can perform quite well even in low temperatures that is quite well known, what must not be done is the recharging of the lithium cobalt ion battery while it is in a frozen state as this will result in "cladding/plating" damage.

ItsJustMe

Yes, but what temp constitutes freezing for that chemistry? I charge my NiMH in the garage down well below zero, but this will be my first winter with any LiIon stuff.

daniel58

what ambient room temperature constitutes freezing for consumer grade cobalt based lithium-ion batteries?

Basically, consumer grade lithium-ion batteries cannot be charged below 0°C (32°F)

The acceptable charging temperature range is 0° to 45°C or (32°F to 113°F)

Although the packs appear to be charging normally at freezing temperatures, what is going on "behind the scenes" is the cell impedance goes up and the acceptance of the "lithium" ions on the anode(negative electrode) is drastically reduced(electrolyte composition becomes viscious and slows chemical deposition of the lithium ions on anode(negative electrode).

What is most troubling also, is the "plating" of metallic lithium that occurs on the anode(negative electrode).

The higher the charge rate, the more pronounced this undesired "plating" will be on the anode(negative electrode).

A prolonged charge at cold temperatures will eventually compromise the safety of the pack.

The "plating" on the anode(negative electrode) is permanent and no amount of cycling can reverse this effect.

Unknown to the user, such a "plated" anode battery will become more vulnerable to failure if subjected to impact, crush or high rate charging due to this "plating" action.

Quality chargers reduce the charge current at cold temperatures and avert a charge altogether below 0°C (32°F).

When charging a cold battery, allow the pack to warm up before putting it onto the charger.

Discharging a lithium-ion battery at cold temperature does not cause any harm.

There are specialty Li-ion batteries that allow low-temperature charging.

These packs are made for military and aerospace applications and are typically expensive.

The lower viscosity of the electrolyte of these batteries may reduce the rate capability and decrease the cycle life.

Remember the workings of lithium ion battery chemistry by referrring to below to help one to better understand above explanation:

The positive electrode(cathode) is made of Lithium cobalt oxide, or LiCoO2.

The negative electrode(anode) is made of carbon.

When the battery charges, ions of lithium move through the electrolyte from the positive electrode(cathode) to the negative electrode(anode) and attach to the carbon.

During discharge, the lithium ions move back to the LiCoO2 positive electrode(cathode) from the carbon.

daniel58

see my reply to ItsJustMe

daniel58

I have sent inquiry into all-battery online store which is a subsidary of tenergy batteries in china regarding stock status of 31009 the DC connector 7.4Vdc lithium ion battery rated at 8.8aH.

Unfortunately, I have not received a reply from them as of yet and I even requested reply response from three different contact listed e-mail addresses from sales, information, and customer service.

I should be set for awhile myself, as I have two of the 7.4VDC 8.8aH lithium ion batteries to go with the two Magichine Led Lightsets but if I get a third Magicshine Led Lightset; I will probably need a "third" 7.4VDC 8.8aH lithium ion battery power source "at that time" but no rush here in the "short term" time frame.

Hope all of you got a chance to get in on the deal. Let all of us know how you made out with the enhanced 8.8aH capacity 7.4VDC lithium ion battery in so far as how much actual run time you get out of it "in the field".

ItsJustMe

Ouch. The majority of the time I'm using my lights it's < 0*C in the garage. I've already charged it in temps as low as -10*C at least a dozen times.

Guess I'd better start bringing the battery inside to charge, though I've noticed a 30% decrease in run time already (about 3 months, maybe 30 x 50% charges).

daniel58

unfortunately there is probably some of the undesired "plating" action inside the lithium ion battery but.

its not the end of the world of course (one can currently obtain a 5.2aH capacity/7.4VDC lithium ion battery from all-battery online store for only $20.32($3.90per amp/hr)-in stock as of this posting and 18% more capacity than stock Magicshine kit 4.4aH lithium ion battery, while costing even less and still fitting nontheless in the original Magicshine kit battery pouch);

the "plated" lithium ion battery will still run, operate and work even "in the cold" but will experience all of these directly observable signs and describeable symptoms of:

"reduced battery amp-hour capacity",

"total battery reduced run times" and

"reduced battery service life"

which will probably lead directly to the resulting severely curtailed undesired "plated" battery running characteristics:

global reduction in "battery service life",

global "compromised battery run times" and

global "curtailed battery amp/hr capacity"

Future purchased lithium ion batteries probably should be charged in above 32 degrees F ambient room temperature lithium ion battery charging conditions, to prevent premature "plating" action damage from occurring, via rewarming them slowly over a prolonged period of time after bringing them out of sub 32 degrees F temperatures.

Its ok to run lithium ion batteries in -10 degrees C; no problem there of course;

its in the recharging action of the "ions of lithium" trying to move through the electrolyte from the positive electrode(cathode) to the now undesired "plated" negative electrode(anode),

that now cannot as effectively re-attach the lithium ions back to the carbon negative electrode(anode).

Remember the workings of lithium ion battery chemistry by referrring to below to help one to better understand above explanation:

The positive electrode(cathode) is made of Lithium cobalt oxide, or LiCoO2.

The negative electrode(anode) is made of carbon.

When the battery charges, ions of lithium move through the electrolyte from the positive electrode(cathode) to the negative electrode(anode) and re-attach themselves to the carbon negative electrode(anode).

During discharge, the lithium ions move back to the LiCoO2 positive electrode(cathode) from the carbon negative electrode(anode).

P.S. it appears all-battery has posted Li-Ion 18650 based 7.4V 8800 mAh PCB protected Rechargeable Battery with 2-Hole connector for $31.75 which is a pretty decent buy.

for all of you out there that missed the other 7.4V 8800 mAh Li-Ion Rechargeable Battery sale pricing.

Happy Holidays to all.

dougmc

It's below freezing in your garage? -10 C? wow.

In any event, your battery will be a tad warmer than the air around it, as the act of using it and charging it will warm it up a bit, and the holder it comes with is padded -- which means insulated. Might not be 10 C worth, but 5 C, perhaps ...

seeker333

How about starting a new thread on batteries?

Your long, repetitive posts are OT and make it difficult for others to read about and discuss the Magicshine light.

DallasSoxFan

I had my first ride with the MS this AM. It gets a rave review from me. The strobe mode seems horrible, but WOW. Much brighter than my 20W Halogen running on a 12V 5Ah battery. It is the first time I have seen my headlight reflect off of puddles onto the tree canopies.

ItsJustMe

Well, it's pretty much at ambient temp; our garage isn't heated. Maybe 5 degrees or so warmer, but my bike comp has a thermometer and it's registered as low as 18*F in the garage this year so far, about 10*F when out on the road.

AdamDZ

I got mine yesterday and rode today for this first time.

The first impression is good. It is probably the brightest light you can get for the money and a great value. However, I've seen some people claim this is "the brightest bike like" or "as bright as a car light". These claims are heavily exaggerated. This is a very bright bicycle light, yes it will blind anyone looking into it directly but it doesn't hold a candle against an average car light, it's not even as bright as a Vespa scooter light.

This is not to say it's a bad light. I'm very happy with it and the vendor doesn't make any such outrageous claims but set your expectations appropriately: if you expect a car light kind of brightness, it is not. When stopped at a dark intersection a car or even scooter behind me will easily drown my MS beam and project well ahead of it. No one complained, no one flashed their lights at me.

Maybe in a rural area in complete darkness things would look differently though. I can see it blinding an oncoming cyclist on the trail, but not a car. I did notice, however, that pedestrians would back off more than usual and l was able to see much better on dark streets.

My few issues with it:

- weak mounting system, I really hate those rubberband mounts, what's wrong with a clamp and a screw?

- too many many modes: high, low and low strobe would be enough.

- strobe mode too fast.

- green LED too bright.

- charger cable way too short: I will have to remove the battery to charge it, the cable won't reach to the wall outlet.

Adam

dynodonn

The mounting system is definitely weak, I added a zip tie to each of my two lights along with the rubber o-ring. The zip tie helped stiffen the mounting system enough that the lights stay aimed where I set them, but still be movable if I chose to.
Since I use the light on high all the time, the other modes don't bother me. I also realized that by holding the switch for a few seconds, that the light will turn off without having to going through all the modes. The green battery indicator lights are definitely too bright, now I just unplug the lights when I get home after dark, and since I don't need them on my morning commute, I just plug them in back in when I leave work at night. I bought extension cables and store my batteries in my rear panniers, which keeps them dry, plus making them easily removed for charging.