Recharging front light - how frequently is ok?

[Garry Booth]

I'm in the habit of recharging my cat eye front light 'periodically'. However I recently got caught out when it abruptly ran out of juice while I was out in the dark lanes.
I've always resisted putting it on charge at any opportunity in the belief that it's not good for battery life and/or it reduces its capacity.
But am I out of date: does it matter how much I plug it in, eg into my p.c. when at work?

[NATURAL ANKLING]

hi,
If they are modern Li-ion batteries, it makes no difference how many times you charge it will not harm them, as long as you have the correct charger, they should never be charged above 4.2 V.

I always carry a spare light fully charged in my pack, always a good idea.
100 g what's that then.

[thelawnet]

That is certainly not true, as any purchaser of a laptop or phone will quickly realise.

Cateye suggest 300 charge cycles to lose 30% of charge.

https://www.cateye.com/intl/products/he ... L-EL471RC/

However this will depend on depth of discharge. Generally not fully discharging is better for any kind of battery than fully discharging. And not fully charging is also better.

https://batteryuniversity.com/learn/art ... _batteries

In principle it is better to charge daily while the battery is still 25% full than to charge every 4 days at zero.

However in my opinion theoretical battery chemistry concerns aren't the biggest issue here. Things to consider also:

* The life of the socket. With micro usb this number is very high, while it was common for older versions to fail . However on a torch you may have to deal with things like seals and other elements that are not necessarily designed to withstand the same degree of use as the socket itself.

* All torches are liable to fail or suddenly die. A good design will give plenty of warning of the battery running los and allow you to switch to an economical mode. It's worth checking this when buying.

* If you are doing anything more than cycling a mile from the shops , one light is not enough and you should carry a spare. (Or spare battery.) That applies to both front and rear

[RickH]

Bear in mind that a charge cycle is not how many times you plug it in but how many full charge equivalents you do (4 X 25% charges is the equivalent of 1 full charge cycle).

I have a 2010 Exposure Toro as my main light.

In the winter it can be in use for around 2 hours some days so, if I've used the lights on any given day I will charge it overnight back to full (the supplied charger trickle charges beyond 90% so, they claim, it doesn't harm the batteries to leave it plugged in). When the light is in much less frequent use in the summer I will generally leave it until the light goes amber to indicate 50% charge & then plug it in unless I'm likely to be out on a long after dark ride, in which case I will aim for a full charge before I set off. It almost never gets run down to the red 25% light level.

When I know I'm going to be out after dark I carry a small spare "get me home" light, otherwise I don't generally bother.

[thelawnet]

Bear in mind that a charge cycle is not how many times you plug it in but how many full charge equivalents you do (4 X 25% charges is the equivalent of 1 full charge cycle).

Well no, 6 x 25% charges is probably the equivalent of 1 full charge cycle as per the points about DoD.

[RickH]

Bear in mind that a charge cycle is not how many times you plug it in but how many full charge equivalents you do (4 X 25% charges is the equivalent of 1 full charge cycle).

Well no, 6 x 25% charges is probably the equivalent of 1 full charge cycle as per the points about DoD.

That's even better

I think some people are under the mistaken belief that however much charge you put in it counts as a cycle, whereas that is far from the case.

[Steve O'C]

Does it matter how rapidly you charge the battery? I use my phone charger to charge my lights. The old chargers took hours to charge the phone but my latest one works much faster. Does that kill the battery faster?

[PH]

That is certainly not true, as any purchaser of a laptop or phone will quickly realise.

I think you're arguing against yourself, what RickH and NATURAL ANKLING are saying is the same thing as in the link you supplied

Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life.

Which answers the question asked, for the same use it makes no difference if you charge it more frequently than necessary. As for deep discharge, my understanding is that most decent cycle lights cut out before the batters is fully discharged to protect against this.

[PH]

Does it matter how rapidly you charge the battery? I use my phone charger to charge my lights. The old chargers took hours to charge the phone but my latest one works much faster. Does that kill the battery faster?

Yes, heat is bad and accelerates the ageing on Lithium batteries. From the link posted by thelawnet here's the do's and don'ts
https://batteryuniversity.com/index.php ... tery_table

[thelawnet]

Does it matter how rapidly you charge the battery? I use my phone charger to charge my lights. The old chargers took hours to charge the phone but my latest one works much faster. Does that kill the battery faster?

I'm not sure which light you are referring to, but most Cateye front lights contain a single 18650 cell.



These vary between about 2200 and 3400 mAh depending on the model.

The cells are designed not to be removable, so essentially the light is junk when/if the cell fails.

The cells have a spec sheet, similar to this one:



According to this, the maximum charging current for that specific cell is 4A.

Dedicated 18650 chargers charge at 0.5A, 1A, 2A or even 3A.

The Cateye lights are typically designed to charge at 0.5A, but some models may accept a 1A charge.

None of their lights have more than 1A charging input, though the cells are almost certainly good for it.

If you have a 2200 mAh charge then it's reasonable to allow 3 hours charging at 1A, or 6 hours at 0.5A.

Both levels would be quite safe.

In terms of the input, a very old (USB) phone charger may be only 0.5A. A newer one might be 1A, 2A or even more.

This current is only relevant when it is too low. In other words, a 0.5A charger will charge a 1A light at 0.5A. While a 2A charger will charge 1A light at 1A.

The current cannot be too high, as the current is determined by the device, not by the power supply.

So in terms of the life of the battery it seems that the Cateye specifications are rather conservative in that they only charge at 0.5A or in some cases 1A whereas the battery is almost certainly designed to be charged at a higher current. This isn't a problem only in that it takes longer to charge than it needs to.

So you don't need to worry about charging your device using the latest mobile phone charger.

These things are pretty poorly built

https://www.ebay.co.uk/itm/USB-Volt-Cur ... 2691159937

but if you're interested in the charging current you can check with that. USB cables tend to fail rather quickly and you may find that a mishandled cable is not giving the rated power. The power supply itself is typically durable, however.

If your devices are charging slowly it's worth replacing the cables, but obviously you need to be aware first of the maximum charging current the device is designed to accept.

[tim-b]

Hi

As for deep discharge, my understanding is that most decent cycle lights cut out before the battery is fully discharged to protect against this

Yes, but don't store them in a discharged state; the battery will gradually lose charge in storage and could drop into a state where chemical changes render it useless
Regards
tim-b

[Garry Booth]

Very helpful, thanks everyone for your input. G

[nigelnightmare]

hi,

100 g what's that then.

About 2 oz in old money.

[thelawnet]

hi,

100 g what's that then.

About 2 oz in old money.

?
https://www.google.com/search?q=100g+in+oz