What counts towards a charge cycle

[Jed]

I recharge my battery after almost every ride as I ride 12 miles to work and back. I've read that there are only a limited number of charge cycles for a battery before its performance starts to drop.

Does a partial charge and a full charge count as one cycle? Also what happens if I leave my charger connected. If the charger is trickle charging does this reduce the total number of charge cycles? I don't really want to be buying new batteries every few months as they are quite expensive.

thanks
Jed

 

[flecc]

With Li-ion batteries it's best to part charge as often as possible since this gives them the longest life. For example, one that's part charged after each short journey, say 4 to 8 miles, might lose 10% of capacity in the first year, one that's fully discharged every use before charging might lose three or more times that. These figures aren't precise since they depend on many factors like how fast discharges are and temperatures etc, but the relationship remains the same, charge Li-ion as often as possible.

NiMh batteries are the other way round. It's best to fully discharge them from time to time, say once every 5 or 6 charges, but they are less critical than Li-ion and don't vary as much.

All batteries lose life by gradually losing capacity, not voltage. No-one is sure of average Li-ion life for traction batteries yet, but the pool of technical opinion is that the effective life will be about three years. The size and harshness of usage is the limiter. I've got a very small Li-ion battery that runs a minidisc player that's heading for nine years old and has still only lost about 10% of capacity, but we won't get anything remotely like that from our batteries.

There is no trickle charge mode on our eZee chargers, once charge is completed the charger switches right off.

P.S. One other thing, don't buy spare batteries to put in store. Li-ion batteries need to be discharged and recharged at least once every three months if kept in store, and preferably more often. That nine year battery I mentioned above hasn't always been in use, but it's been discharged and recharged every two months throughout it's life.

 

[flecc]

As you've asked about leaving the charger connected before and I've previously answered that, I think you may be looking for a second opinion, and that's good. The Battery University website is produced by an industry expert and that can help you. The link to the page you want is the first one, use the Li-ion column, the second link for all battery information:

http://www.batteryuniversity.com/partone-23.htm

http://www.batteryuniversity.com

 

[Jed]

Thanks for the links Flecc. I am more than happy with your original answer! You've posted some excellent information, it just takes a while for it all to sink in

 

[aroncox]

With all this talk about charging here's a question I've had for a while. When I plug in my eZee Torq li-ion charger to the battery the light on the charger stays green and the fan doesn't come on, it's not until I turn the charger off, pause a bit, then back on that the light goes orange and the fan comes on. It does seem to charge anyway, but I wonder if it's slower to charge, or could overheat without the fan. Unfortuantely I have to crawl under my desk to reach the power switch on the charger.

Is this normal, do you turn the charger on and off each time?

 

[flecc]

I had this on one of my two chargers for a while, Aron, but it seems to have mostly cleared now, only doing it very occasionally. It seemed to be connected with the mains being "dirty", and connecting via a suppressor strip has helped. If you're in a computer environment, they're notorious for often putting rubbish into the mains.

So you could try a suppressor strip, but if it doesn't help, at least what's happening won't harm your battery or charger in any way. If it remains a very real nuisance, best contact 50cycles with a view to changing it.

 

[imellor]

I'm not sure if you are at cross-purposes here with aroncox. If after charging the bike, I unplug and go cycling and then on my return plug the charger straight back in to the bike, it does not start charging. I have to power cycle (no pun intended) the charger for the charging cycle to commence.
I had assumed this was normal operation and what aroncox was describing.
The manual is at pains to tell you turn off before disconnecting and turn on after connecting, but this maybe simply for safety.

Ian

I had this on one of my two chargers for a while, Aron, but it seems to have mostly cleared now, only doing it very occasionally. It seemed to be connected with the mains being "dirty", and connecting via a suppressor strip has helped. If you're in a computer environment, they're notorious for often putting rubbish into the mains.

So you could try a suppressor strip, but if it doesn't help, at least what's happening won't harm your battery or charger in any way. If it remains a very real nuisance, best contact 50cycles with a view to changing it.

 

[mithril]

Wasting electricity when keeping charger switched on

Someone told me that they had measured the electricity being used when the battery was connected to the charger, and also when it wasn't. He found there wasn't much difference!

So although it won't harm your battery if you keep it plugged in for longer than required, you still will be using electricy all the time the charge is switched on.

Something to do with the transformer process apparently.

I'm sure flecc will be able to confirm/refute this.

Should we be using a timer when charging overnight (from a green point of view)?

 

[aroncox]

Well, I have spent the past few months not turning off the charger ever, and the green light is always on but my battery seems to be charged, I'm pretty sure it wouldn't go a few hundred miles on one charge So while it may not look like it's charging, I think it must be. From now on I'll try to remmber to turn the charger off and on as I'm sure the fan is there for a reason.

I'm not sure if you are at cross-purposes here with aroncox. If after charging the bike, I unplug and go cycling and then on my return plug the charger straight back in to the bike, it does not start charging. I have to power cycle (no pun intended) the charger for the charging cycle to commence.
I had assumed this was normal operation and what aroncox was describing.
The manual is at pains to tell you turn off before disconnecting and turn on after connecting, but this maybe simply for safety.

Ian

 

[aroncox]

It's been stated somewhere on the forum that it;s perfectly fine to leave the battery plugged in to the charger as once it's charged it pretty much turns off (except to power the red and green lights), so it's not wasting electricity to leave it on all night.

Someone told me that they had measured the electricity being used when the battery was connected to the charger, and also when it wasn't. He found there wasn't much difference!

So although it won't harm your battery if you keep it plugged in for longer than required, you still will be using electricy all the time the charge is switched on.

Something to do with the transformer process apparently.

I'm sure flecc will be able to confirm/refute this.

Should we be using a timer when charging overnight (from a green point of view)?

 

[rsscott]

Should we be using a timer when charging overnight (from a green point of view)?

Is there any possibility of the battery leaking charge back to the charger if it is turned off via a timer switch?

I have some other battery powered equipment whereby the battery will run down again if it is left connected to the charger when the charger is switched off at the wall.

 

[flecc]

I don't have an answer to that, although it shouldn't be possible with well designed equipment which has been correctly wired to the mains.

However, in case there's no answer from anyone else, I've just started a test to see if that does happen at all, and I'm going to run the test repeatedly for a while to ensure the answer is correct.

 

[flecc]

Well, the final answer is no, there is no charge drain due to leaving the charger plugged in, despite the advice in the manual to unplug immediately after charging. That's still good safety advice though.

In doing the testing, I didn't use interference methods like interposing a meter since these can modify results, but instead used charging as we do it in real life. Doing this reveals that the charging characteristics of these high density batteries can mislead one into thinking that charge loss does occur. Basically, when the voltage and charge resistance reached prompts the charger to switch off, the battery is unlikely to have absorbed every scrap of charge that it can. This is because the very high electrolyte density of these high capacity batteries resists the passage of charge and discharge, so when the charge density near the electrodes reaches the full point, the electrolyte deeper into the cell will not be at the same charge intensity. Leaving the battery off charge for a while will allow the electrolyte charge to equalise, permitting a further small charge to be absorbed, and this can happen more than once.

Here's the results of a test that I've just completed. A fully charged Li-ion was left for one hour, everything plugged in but switched off at the wall, and the charge restarted. It accepted 8 further minutes of charge. After a further two hours off, it accepted 3 minutes of charge. After a further two hours it accepted 2 minutes of charge. After another one and a half hours, 1 minute of charge, then again after one hour, 1 minute of charge. Then after each of two further hours it would accept no further charge, showing that it was saturated to the maximum. You can see that the acceptance of charge after those earlier periods could lead one to believe that leaving the charger plugged in could be draining charge, but with saturation reached it was clear there was no charge drain taking place.

Even if there had been, it would not have been serious over a few hours, since each 3 minutes of an extra charge is just 1% of the battery's capacity, or 264 yards of travel for a typical 15 mile range user. Therefore, the total of all those 15 extra minutes above would still represent well under a mile of travel in theory, although it's doubtful this multi-charging would achieve that in practice.

 

[ITSPETEINIT]

What counts as a charge cycle?

I recharge my battery after almost every ride as I ride 12 miles to work and back. I've read that there are only a limited number of charge cycles for a battery before its performance starts to drop.

Does a partial charge and a full charge count as one cycle? Also what happens if I leave my charger connected. If the charger is trickle charging does this reduce the total number of charge cycles? I don't really want to be buying new batteries every few months as they are quite expensive.

thanks
Jed

Hello Flecc:
In your answer (next posting) you gave some very useful information about batteries - but never quite got to answer the question (apologies if I missed it somehow): "Does a partial charge and a full charge count as one (recharge) cycle".
Bearing in mind that 500 recharge cycles is a 'boundary' in the life of a Li-ion battery: recharging for a short jouney, which might take (say) 30 minutes, as opposed to a fairly deep discharge which might take 4 plus hours to recharge: do they both count as "one recharge cycle"?"
Thanks
Peter

 

[flecc]

Yes, I did miss that Peter.

It is two charges if they are reasonably well time separated. Whether the charge is partial or not, following it the battery will individually equalise it's charge distribution within each cell and chemically relax. Once that's happened after a short while, any new charge is seen as such and chemically ages the battery as a new charge, though probably not quite as much as if both were full charges.

That chemical relaxation time is the same as the time for the temperature to normalise and return to battery's environment temperature.
.

 

[Ian]

Ezee Charger Power Consumption

I've just checked my Ezee NiMh Charger with a wattmeter on the mains input and found the consumption to be as follows.

No Battery Connected (Red LED) 5w

Charging (Red + Amber) 133w

Charged (Red + Green) 5w


I have also checked an Ezee Li-ion charger and found it's consumption to be 5w with no battery connected. I don't have a Li-ion battery so was unable to check this charger in the other modes but would expect its consumption to be similar to the NiMh version.

Ian.