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LZMutant

Fast Charger Question...

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Hi - 

I use a rapid charger, with settings from 1 to 5 amps, and various percentages 50 to 100%

My settings are 1 amp, 100%.  

My problem is that the charger doesn't shut off.  Usually I'll plug in around 80% and I've left it on for over 10 hours waiting for the unit to shut off after a complete charge...

The display by then usually reads:
V:  84
A:  .004

Is this a problem with the charger?  The V10F shows 100% after just a few hours...but I'm wondering if I should leave the charger on longer or simply get in the habit of unplugging after awhile.  Or get another charger...  

Thanks!

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I guess if you want the charger to go off, set it to 99% or smaller. For balancing the individual batteries cells, the charger should, once in a while, stay on the fully charged battery for some hours, so I guess the charger just does what it is supposed to do here (and most chargers do anyway, I believe I see rather 0.04A in this situation). Other than for balancing, keeping the battery at 100% for longer periods of time (in particular at higher temperature) is pretty bad for its longevity.

Edited by Mono

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1 hour ago, Mono said:

I guess if you want the charger to go off, set it to 99% or smaller. For balancing the individual batteries cells, the charger should, once in a while, stay on the fully charged battery for some hours, so I guess the charger just does what it is supposed to do here (and most chargers do anyway, I believe I see rather 0.04A in this situation). Other than for balancing, keeping the battery at 100% for longer periods of time (in particular at higher temperature) is pretty bad for its longevity.

Thanks - I've been afraid to leave it on the charger too long.  Had one other rapid charger for my V5F and it would flip off at 100% pretty quickly.  

Maybe Ill leave it on for awhile longer and see what happens...  I've heard about battery balancing, but it seems like it just sits at .04** for hours...I'd think the number would at least get a little smaller...

Thanks a lot Mono - 
LZ

Edit:  Indeed it reads 0.04.  I misplaced a decimal.

Edited by LZMutant
Wrong meter reading.

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27 minutes ago, LZMutant said:

I've heard about battery balancing, but it seems like it just sits at .04** for hours

this could be the current to feed the balancing circuit, I also tried and I have never seen it go below 0.03A.

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1 hour ago, Mono said:

this could be the current to feed the balancing circuit, I also tried and I have never seen it go below 0.03A.

Do you think I should just leave it on for several hours after the read of 0.04?  I always chicken out and turn it off! :)

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18 hours ago, LZMutant said:

Do you think I should just leave it on for several hours after the read of 0.04?  I always chicken out and turn it off! :)

You should never charge to 100% and not use the battery directly afterwards unless you either really have to or you want to balance the cells.

I neither know how long it takes to balance the cells nor how important balancing is, but keeping the charger connected for five more hours after it charged to 100% every other week shouldn't be a problem at all.

Edited by Mono

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21 hours ago, LZMutant said:

Is this a problem with the charger?  The V10F shows 100% after just a few hours...but I'm wondering if I should leave the charger on longer or simply get in the habit of unplugging after awhile.  Or get another charger...  

Your charger is OK. There is always some small current due to shunting resistors used by balancing circuit. It may also be in part a current drawn by EUC motherboard itself - at least KS-18L/XL motherboard turns on (just motherboard, not the motor) during charging, so you can connect to it via BT and use it as BT speakers or just monitor charging process remotely.

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Thanks guys - 

I think my main question is why doesn't the charger shut off?  The fast charger's fan is really loud and I usually get some grief from my wife when it's running.  That's the main reason I hoped it would shut itself off at 100%...

I ride about 6 miles every day and usually run it down from 100% to 85% or so.  I've read a lot of material saying that performance begins to diminish below 80%, hence I try to keep it charged up.  

Again, really appreciate the help!

 

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11 hours ago, LZMutant said:

Thanks guys - 

I think my main question is why doesn't the charger shut off?  The fast charger's fan is really loud and I usually get some grief from my wife when it's running.  That's the main reason I hoped it would shut itself off at 100%...

My fast charger shuts the (also) loud fan off, once the current goes down sufficiently. Yours unfortionately not...:(

Chargers "normaly" Have three trim potentiometers inside - one for the max voltage, one for max current and one for minimum current (shut off) while the constant voltage phase. But yours could be different (with the choosable current?) and the fan controll can be made different fir each charger - yours seem to just run whenever it is plugged in - or the wheel is charged although almost no current is flowing... :(

There seem to be no real easy solution but changing the charger... Or disabling the current fan and using one which is controlled by temperature (of the switching mosfet) or output current. But this means tinkering with the electronics.

Maybe easiest cpmpromise solution could be changing the fan with some more silent one...

 

Quote

I ride about 6 miles every day and usually run it  down from 100% to 85% or so.  I've read a lot of material saying that performance begins to diminish below 80%, hence I try to keep it charged up.  

With 80% charge (~80% of fully charged pack voltage available) the max torque over speed limit decreases to 80%. ( Edit: See the next two posts for correct numbers - this was bs)  (You can test it with the lift cut off speed - this max speed is direct proportional to battery voltage). So the safety margin gets lower. But within this limit the performance stays still quite the same.

Feelable less "performance" starts somewhere around 40-50% or even a bit lower. Depends imho on the number of parallel cells in the pack. Imo cells getting on lower charge have higher internal resistance/lower "current delivery capability" - so the limit decreases "overproportional" and not only with the remaining voltage. This is at least my actual hypothesis trying ti understand the noticable difference while driving...

Ps.: If one drives at least a bit relaxed there should be not too much difference between using the wheel between 100 to 85% or 90-75%. Even 80-65% should be very ok (with a not to small battery pack). Just the inmotion have the "variable" max speed limit (tiltback) with charge (voltage) going down?

Imho the 100-85% are only "needed" if one wants to drive at the limit - unrestricted max speed, full acceleration, taking bumps/potholes/etc at breakneck speeds...

Edited by Chriull

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3 hours ago, Chriull said:

With 80% charge (~80% of fully charged pack voltage available) the max torque over speed limit decreases to 80%. (You can test it with the lift cut off speed - this max speed is direct proportional to battery voltage).

@Chriull, what? I am totally puzzled reading that from you of all people. Are you suggesting at 80% charge we see 80% battery voltage? My battery has roughly 96% voltage left at 80% charge. At 84V I have 100% charge and 10% at about 70V. That is, 67V=80% of the full charged voltage indicates essentially an empty battery. In principle, the voltage can even go down below 60V, but the wheel will not allow riding at these voltages and there is only little battery capacity to be yielded between 70V and 60V anyway, as Keith pointed out some time ago. Very puzzled.

@LZMutant, if you don't want to be irritated by fan noise, like me, just use the original InMotion charger, which is dead silent. Then, a simple measure to turn off the charger is using a timer.

Last try: keeping/storing the battery at 100% and 25ºC for one year reduces its capacity already to 80% without even having done any cycling.

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6 hours ago, Mono said:

@Chriull, what? I am totally puzzled reading that from you of all people. Are you suggesting at 80% charge we see 80% battery voltage? My battery has roughly 96% voltage left at 80% charge. At 84V I have 100% charge and 10% at about 70V. That is, 67V=80% of the full charged voltage indicates essentially an empty battery. In principle, the voltage can even go down below 60V, but the wheel will not allow riding at these voltages and there is only little battery capacity to be yielded between 70V and 60V anyway, as Keith pointed out some time ago. Very puzzled.

Totally agree with your numbers! Must have had some severe mental hickup yesterday....

Just showed these (right) numbers yesterday here in a graph...

 

In the above linked graph i did not consider that most wheels show 100% for cell voltages from 4.2V downto ~4.1V.

So (if 100% charge goes downto 4.1V and 0% is at 3.3V) the correct numbers would be:

Charge %    Voltage    lift cut off speed/max torque available (% from max)
100    84.0    100.0
100    82.0    97.6
90    80.4    95.7
80    78.8    93.8
70    77.2    91.9
60    75.6    90.0
50    74.0    88.1

So at 74V (50% charge) still 88% of the absolute possible torque (until overlean) is available.

Edited by Chriull

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Thank you Seba, Mono and Chriull...  That was great info.

I think my fast charger may be slightly defective.  Not enough for me to return it, but enough for me to keep an eye on it.  My wheel shipped with the fast charger, and I'm going to start looking around for the original...the fan noise is somewhere between Jet and Helicopter... ;)

As suggested I think I'll let my battery run down to 60 or 70% before charging up again.  At least see what happens with the wheel performance.  I have a friend who, like me, rides almost everyday and he advised I keep my charges up at 100% to ensure best performance...that said, nothing ventured nothing gained.  I'm on "team let the battery run down a bit" as of tonight!  :)

Again, appreciate all the help!

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3 hours ago, LZMutant said:

As suggested I think I'll let my battery run down to 60 or 70% before charging up again.  At least see what happens with the wheel performance.  I have a friend who, like me, rides almost everyday and he advised I keep my charges up at 100% to ensure best performance...that said, nothing ventured nothing gained.  I'm on "team let the battery run down a bit" as of tonight!  :)

Especially with a fast charger there should be no real problem to top the battery up just before driving - so no "stressing" of the batteries inbetween and full performance and safety margin for the ride... (1)

That's at least how i do it most of the time. But i have a medium sized battery (840Wh) and and an 8A charger (with reinforced wheel plug...) So some 1 to 1 1/2 hours are enough to get it fully charged again.

Efit: (1) although using li ion batteries directly after charging is not really the best, too... But that has hopefully not too much impact - as mostly one charges below something like 0.5C and don't really heat up the cells while charging (if this is the reason at all)

Edited by Chriull

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54 minutes ago, Chriull said:

Especially with a fast charger there should be no real problem to top the battery up just before driving - so no "stressing" of the batteries inbetween and full performance and safety margin for the ride... (1)

That's at least how i do it most of the time. But i have a medium sized battery (840Wh) and and an 8A charger (with reinforced wheel plug...) So some 1 to 1 1/2 hours are enough to get it fully charged again.

Efit: (1) although using li ion batteries directly after charging is not really the best, too... But that has hopefully not too much impact - as mostly one charges below something like 0.5C and don't really heat up the cells while charging (if this is the reason at all)

yes, cells heat up when charging, and swelling due to gas generation increases when cells are at 80% charge or more.

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