Should I charge my EU every night or wait until it gets very low.

[Donafello]

I have 2 questions.  If lets say I ride for a hour.  When I get home should I always top it off?  And is it ok to start charging Agnes time and unplug in the morning? Also for gotway msuper owners, is there a way to know battery is completely charged. Thanks everyone

[esaj]

If you intend to ride it in the morning, charging it up beforehand might be necessary. Otherwise, avoid leaving the battery fully charged for longer periods. Keeping the battery at high voltage for longer time (well, even a few days or a week probably wouldn't matter that much yet, but weeks or months it start to show, especially if stored in higher temperature) is not good for the battery, as the maximum capacity will start to lower permanently (and there's nothing you can do the get it back). I've personally tried to avoid charging the Firewheel to full, when I know for sure I won't need it the next day (or I know I have the time to charge it before riding). If you have large batteries, you could simply charge it to something like 80%, which is less stressing for the batteries than full charge at 4.2V / cell.

Here's some data (although do note that they talk about storing it for a YEAR, except in the 100% charged state at high temperature (60 degrees), where it drops to 60% of original total capacity in just three months):

Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion, a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC.

Temperature	40% charge	100% charge	Table 3: Estimated recoverable capacity when storing Li-ion for one year at various temperatures Elevated temperature hastens permanent capacity loss. Not all Li-ion systems behave the same.
0°C 25°C 40°C 60°C	98% 96% 85% 75%	94% 80% 65% 60% (after 3 months)

Most Li-ions charge to 4.20V/cell and every reduction in peak charge voltage of 0.10V/cell is said to double cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.00V/cell should deliver 1,200–2,000 and 3.90V/cell 2,400–4,000 cycles.

 

[Cloud]

Its interesting because kingsong manual actually advises to charge the battery full, that is before riding though, maybe thats the difference. They tell you not to start riding it u til the battery is full unless absolutely necessary

[esaj]

Its interesting because kingsong manual actually advises to charge the battery full, that is before riding though, maybe thats the difference. They tell you not to start riding it u til the battery is full unless absolutely necessary

Maybe they think it's a safety issue, riding with low charged battery gives less power... If you consider laptops, the batteries usually go "bad" after a couple of years or so, depending on usage. I suspect at least in the case of laptops, that people keep them plugged in at home (and probably at work) all the time, so the battery is constantly in fully charged state, and the machine runs hot while in use, so it's pretty much the worst stress for the battery. Probably even more prominent on newer laptops, as they're smaller and thinner, so there's even less air circulation, therefore it the battery could get hotter. They would probably run a lot longer, if people either cycled them (ie. charge it to full, then run on the battery instead of keeping it plugged all the time), or removed the battery altogether when they know they're going to keep it plugged for hours. Of course most people like the convenience of just grabbing the laptop and the battery's always full when they go somewhere with it...

[Cloud]

No, i forgot what they said exactly, i have to find the manual, they were saying something about some kind of recalculation, like the battery thinks its full, and does some kind of management on itself. I have to look it up what they said exactly and will post later

[Kevin]

^What @esaj said, though I wouldn't worry too much about it unless you just let it sit for a really long time. Smartphones use the same battery technology, and the typical usage pattern there is to charge it overnight and then unplug in the morning. Similarly with laptops, they are plugged in most of the time without too much negative consequence. Apple recommends letting macbooks at least partially discharge every so often (their example is to use it on the bus or something). I've yet to notice significant decrease in capacity for either my laptop or phone following these usage patterns.

@Cloud Sounds reasonable. Unlike other types of rechargeable battery, calculating the 'percent remaining' of lithium ion batteries is something of an art - here's a link to a whitepaper on the subject: http://liionbms.com/php/wp_soc_estimate.php

I would also agree that going out on full charge is probably a good idea in general for peace of mind reasons, and if nothing else because it's more convenient not to worry about unplugging it after a specific time

 

[esaj]

No, i forgot what they said exactly, i have to find the manual, they were saying something about some kind of recalculation, like the battery thinks its full, and does some kind of management on itself. I have to look it up what they said exactly and will post later

They might also mean cell balancing which the battery BMS does and occurs last during the charging (when you charge all the way to full, most chargers probably show the green light already at this point). Doing it now and then is a good idea, but from what I've understood, quality cells shouldn't drift that far apart from each really fast, so skipping the full charging now and then shouldn't be harmful, quite the opposite... and I didn't say "don't charge to full", what I meant  was "don't charge it to full after riding, charge it to full before riding", ie. don't make it a habit to charge it all the way fo full and then let it sit like that for long    It's likely not going to break or drop it's total charge really fast even if you do, but it all accumulates over time, especially if the unit is kept in "too hot" conditions (normal room temperatures seem to be just fine). So I'd suggest to do the "top off" before riding, and for the sake of cell balancing, leave it to the charger now and then after the light has already gone green. I've tested the Firewheel with Charge Doctor, there's small charge (probably balancing) going into the wheel for up to an hour after the light has turned green (which happens when the charging current drops to around 250mA).

 

^What @esaj said, though I wouldn't worry too much about it unless you just let it sit for a really long time. Smartphones use the same battery technology, and the typical usage pattern there is to charge it overnight and then unplug in the morning. Similarly with laptops, they are plugged in most of the time without too much negative consequence. Apple recommends letting macbooks at least partially discharge every so often (their example is to use it on the bus or something). I've yet to notice significant decrease in capacity for either my laptop or phone following these usage patterns.

To nitpick, modern cellphones use Li-Pos (easier to make in thin shapes), there are far fewer cells (little or no balancing needed) and the usage patterns are very different from electric vehicles (phones & laptops don't suck as high currents from the cells), so not exactly same technology   But the same principles of cell aging (faster or slower, they always age, even sitting in the corner) should pretty much apply and I believe your word for them lasting, especially with phones I don't think it's such a big problem, because people do the "normal" cycling, ie. full charge, discharge, full charge, discharge... you rarely leave a phone sitting on a charger for very long time (overnight at best), and don't probably keep it off with battery fully charged for a long time. And the usage pattern in general is much less stressful to the battery (ie. no large currents being ripped from the cells). Also, it could be that such devices don't charge themselves to full voltage anymore, which can significantly lower the stress on the battery (Battery University or some such site stated that the "healthiest" zone to keep the battery in is about between 40% and 80% of charge).

At least MacBook does seem to use some form of a "smart" system, not charging to full unless more deeply discharged, maybe even smart enough to run it partially via battery if charged closer to 100% but not removed from the charger after a while in use?

The macbook battery system is designed not to charge the battery fully in short cycles. This is to prolong the battery life. I found with my macbook pro that if i take it off the charger and run it on battery power until the battery is completely drained then it will usually go right up to 100%.

 

 

@Cloud Sounds reasonable. Unlike other types of rechargeable battery, calculating the 'percent remaining' of lithium ion batteries is something of an art - here's a link to a whitepaper on the subject: http://liionbms.com/php/wp_soc_estimate.php

Yes, the battery meters on the wheels are just voltage meters. There are other methods, but like said, it's not easy to measure the "real" capacity on the device itself:  http://batteryuniversity.com/learn/article/recognizing_battery_capacity_as_the_missing_link

Charge Doctor seems pretty good, as it's an outside device that you reset yourself to see how much charge the battery can take up, so it's not an internal BMS "fuel gauge" that could drift over time, but outside Coulomb counter.

 

I would also agree that going out on full charge is probably a good idea in general for peace of mind reasons, and if nothing else because it's more convenient not to worry about unplugging it after a specific time

Yeah, don't stress too much about it, but the question was should he load it to full overnight after EVERY ride... in my opinion, no, not every time, unless you plan on using it at the morning. The battery lifetime WILL be lower with constant full charge vs. letting it stay in lower charge (but not too low either!) when not in use, but by how much, is another matter. The Battery University estimations (based on probably shorter tests, I don't think they left the cells to sit for a year ) I quoted in the first post gives a rough rule of thumb to go by regarding state of charge & temperature especially when not used for longer.

 

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[Gimlet]

If you are going to use it every morning for commuting for instance then you could probably use a cheap plug in timer to start charging in the early hours of the morning so that it's ready for you when you need to leave. 

In other circumstances you can do as I try to most of the time and when you've fully charged it take it out for a short local trip just to reduce the charge a little from 100%, that way it doesn't take long to top it up before you go out next time.

Incidentally I do all my charging in a seperate outbuilding so the supposed fire risk isn't quite such a concern as it might be were it in the house.

[Rotator]

I do all my charging in a seperate outbuilding as well, to prevent supposed fire risk.

I use a timer, so the charger will refill the euc only during three hours.Anyway, I suspect that the ninebot charger does not fill battery energy to the 100%. May be near 90%.

[Cloud]

Ok, ive looked up what kingsong manual says about charging the battery. The say this:

 

" if not in urgent need, please wait until charging complete before unplugging, because after charging, the protection circuit will perform flow equilibrium"

 

i will let someone smarter than me clarify what this means.

[Gimlet]

I believe it's where the individual cells of the power pack are all equalised in the charge they hold. It's why I always fully charge and then run it back down a little.

I can't see any way to balance the cells if you don't fully charge and leave it for a while although I'm quite aware that it would be better to only take it up to 80-90% full charge. That is what Tesla recommend for their car batteries but they have their own way of balancing the charge.

[esaj]

I believe it's where the individual cells of the power pack are all equalised in the charge they hold. It's why I always fully charge and then run it back down a little.

I can't see any way to balance the cells if you don't fully charge and leave it for a while although I'm quite aware that it would be better to only take it up to 80-90% full charge. That is what Tesla recommend for their car batteries but they have their own way of balancing the charge.

I don't think that with "normal" BMSs there's any other way to balance the cells, except to charge it all the way up and then leave it on charger to do the balancing (if you have a Charge Doctor, you know the balancing is complete when the charging current drops to 0.00A, which happens usually quite some time later than when the charger light turns green). I don't know if the cells need to be balanced on each charge, it could very well be enough to just do it now and then (if you don't mind charging it to lower than 100%). Although, running it down a little should be good too, as it will take the worst "edge" off the voltage, and considering what the Battery University article said about the high voltage storage ( Most Li-ions charge to 4.20V/cell and every reduction in peak charge voltage of 0.10V/cell is said to double cycle life.  ) Of course, that probably only relates to longer storage(?), don't know if anything drastic will happen over few days / weeks, but the higher the voltage on the cells, the more volatile they also are (the critical "thermal runaway" -temperature actually drops with higher voltage, so the batteries catch fire easier the higher the charge).

[Rotator]

I do all my charging in a seperate outbuilding as well, to prevent supposed fire risk.

I use a timer, so the charger will refill the euc only during three hours.Anyway, I suspect that the ninebot charger does not fill battery energy to the 100%. May be near 90%.

Wrong assumption. The voltage supplied by the ninebot one charger is 63v, although the specification in the charger label is 61v. Since 63v=15cell*4.2v, this charger appears to re-fill the batteries to the 100%, unless the BMS limits the battery charge in some way.

On the other hand, the red led of the ninebot one charger goes to green (full battery) whenever the current goes down to 175ma aprox. The charger could continue to fill the battery if the BMS allows it.

More information on this post http://forum.electricunicycle.org/topic/867-charging-in-a-car/?do=findComment&comment=10476