I love my C124. One of the great things about it compared to my xm-3000 is that it comes with a built-in on-board charger. The plug for the charger is located under a door on the battery mound on the floor. To charge my xm-3000, I kept 5 small charging bricks under the seat that I connected to the 5 lead acid batteries. That worked fairly well except that I had a problem with the chargers burning out which could leave me with stranded at work with one uncharged battery. The only thing I miss about those chargers are the red and green LEDs that indicated when the batteries were charging and fully charged. On the C124 I use the fan noise on the charger to let me know the batteries are charging. When the fan goes off, I know the batteries are fully charged. The one issue I have with charging the C124 is that there is no way to turn the charger off so it is turned on and this causes the plug to arc when it is plugged in which is disconcerting. An on/off switch next to the plug would be nice. I work around this by feeding m extension cord through a power strip with an on/off switch. I plug the scooter in with the switch turned off and then use the switch to turn the power on thus avoiding the arcing.
I use a kill-a-watt device to measure how much power I'm using. It shows that I'm drawing 10.45 amps and over 900 watts while the batteries are charging. That drops to 65 watts and about 1 amps when the batteries are charged. I try to save electricity by turning the charger off as soon as charging is complete. This will become more important when I build my solar charging station and start using solar power to charge the bike. A nice feature would be a relay that turns the power off automatically when charging is complete. The relay then could be used to turn the charger on after it is plugged in to eliminate the arcing at the plug. Another cool feature to have would be to display the charging status on the upcoming LCD display on the dash. It could show the percent charge and the estimated times to 80 and 100 percent charge.
John D.
Hi John D,
Actually you can tell when the bike is charging as follows:
LONG DESCRIPTION (see below for a SHORT description)
1) When you open the charge door you will get a steady stream of short flashes on the LED on the dashboard. This is the same pattern you get when you apply either of the brakes or have the side stand down. This indicates that the BCU (Bike Control Unit) is powered up but that there is no power being supplied to the motor controller.
2) When you plug in the charger the first mode of charging starts up. This is called "Bulk charging" - you will see the LED on the dashboard switch to a steady stream of long flashes. At this point the bike is charging at around 10 amps. This charging continues until the BMS (Battery Management System) detects that the first cell is full. If your 60Ah bike is empty this stage will take around 5 hours (80% of 60 = 48 - so charging at 10amps takes 4.8 hours for 48 Ah).
3) When the BMS detects the first cell is full the second mode of charging begins. This is called "Balance charging" - you will see the LED on the dashboard switch to a stream of 1 short flash followed by 1 long flash. In this stage the BMS is bypassing the full cell and charging the remaining cells at around 0.5 amps. As each additional cell becomes full the BMS bypasses them - until the last cell registers full at which stage the charger is switched off. If there were 0.5Ah difference between the first and last cell then that would result in an additional hour of charging at this balance charging rate.
4) When the BMS finishes the charger is switched off and all the lights on the dashboard are off. At least that's what is supposed to happen. Unfortunately there is a difficult to trace bug in the BCU software and this isn't happening reliably - the charger is going down to 0 amps but the BCU is not always fully shutting it off.
SHORT DESCRIPTION
1) Stage One = Bulk Charging = Long Flash repeated on LED = Charger drawing around 10Amps
2) Stage Two = Balance Charging = Long Flash / Short Flash repeated on LED = Charger drawing around 0.5Amps
Stage One lasts for around 5 hours for an "empty" 60 Ah pack.
Stage Two lasts a varying amount of time depending on how much out of balance the pack is. Stage Two will timeout after 6 hours of balancing (approx. 3Ah difference between first and last cell)
IMPORTANT NOTE
So, to get the best range out of your pack you need to allow the pack to complete the stage two charging. Depending on how empty your pack is and how long balancing takes this could be as much as 11 hours. However, a more likely scenario is 4 to 6 hours total.
If you don't let balance charge complete you won't damage your pack - however you will limit your distance to the "least full cell".
BTW, all this will become much clearer with the new LCD display currently in development!
Hope this helps,
John H.
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
Thank you for that information. I thought the blinking light meant the access door was open. I obviously didn't read the user manual. lol After reading your post I went to the manual and found the table of all the flash codes in the back. I'm glad you pointed this out since I have been unplugging the charger before the balancing was done. The LCD is a great idea. I want to upgrade to it as soon as it is ready.
I just plugged the charger in again and it is reading 10.66 amps on my kill a watt and about 910 watts. Since since I've not ridden the bike since the last charge it only stayed in phase one for a few minutes before going into phase two. Now that you pointed it our to me I can that the LED has switch to a long and short pattern instead of just blinking. My kill a watt reads exactly 1.00 amps however, not 0.5. I'll keep checking the LED and kill-a-watt meter through the balancing cycle to see what happens and post the result.
John D.
Good news. I just checked the charger and it went to just regular blinking again. I guess that means the batteries are balanced and it took less than an hour. My kill-a-watt meter is reading .16 amps and 6.5 watts. That means I don't have to worry about unplugging the charger to save electricity. I can just leave the bike plugged in whenever I'm not using it if I want to.
John D.
Just to make my "journal" complete I'm posting some pretty much useless details here. I left the charger plugged-in for another half hour and then turned it off using the switch on the power switch. The kill-a-watt meter was still reading 0.16 amps. After I turned it off, I heard what sounded to me like a clicking relay sound coming from the charger. It clicked 5 times and stopped.
John D.
Yeah, we really need that LCD! (I'm working on it today). That single LED falls into the category of "what were we thinking!?" - we try and communicate way too much info through different blink patterns. It's only slightly less complex than Morse Code...
A couple of notes:
1) In balancing mode the charger is supplying 0.5A to the pack. Your Kill-A-Watt will show more than that due to other parts of the system and inefficiencies.
2) Your pack balanced in a nice short time - so you have a healthy pack :-) You also saw the bug I mentioned :-( Your bike should have gone to off - not to a steady blink. However, I consider this a minor bug - because as you say it's only 0.16A in this state. It will get fixed in a later software release.
3) The clicking sound you're hearing is the charger shutting down.
Thanks for the post!
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
BTW - a shameless plug for our BMS - and why it's better than some others I could mention...
Our balance charging happens at 0.5A - it's designed with enough resistive load and big enough heat sinks to allow shunting this much energy. We time out the balance charge after 6 hours because we don't want to hold the cells at an artificially high voltage for too long a time. To put it another way - the voltage of the pack naturally relaxes after the charging voltage is removed. A relaxed pack is a happy pack! So, in 6 hours we can account for a 3Ah difference between cells.
Most other shunt-style BMS's restrict balance charging to 0.1A. I don't know if their systems time out or not. I suspect that they don't. That means that to achieve the same amount of balancing these other systems will run for 5 times as long - this will hold the cells in a "non-relaxed" state for longer. As well as that additional stress on the pack (which I confess, I don't know how much affect it has) - it also makes it much less likely that the rider will achieve a completely balanced pack. In 6 hours this system can only account for 0.6Ah of difference between cells.
Another one of those small details that us EV geeks care about! ;-)
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
Would it be possible to get rid of the ARC or "pop" when plugging in the charger by having the BCU keep the charger in Balance mode until a cord has been plugged in for longer than 10 seconds? The ARC should be much smaller if you're drawing .5A vs. the 10A during BULK charging?
I've noticed sometimes when I plug in (since I have the LCD display that shows me the codes coming from the BCU), that there is an initial Balance spit out for one second and the pop is smaller, but it only happens sometimes. Not sure what causes that condition, but if you could make it intentional, that might help the arcing issue.
I know we've talked a bit about the "pop" or arc before, just thowing out another idea on how to resolve it. (If the BCU can control the balance vs. bulk charging, that might be a way to resolve the issue).
Laters,
-d.
A micro switch sticking through the center of the socket could be used to detect when it's plugged in and used to turn the charger on. Or and on/off rocker switch mounted below the socket would be second best. The first option wouldn't require the user to do anything.
John D.
Another important charging feature would be a means to easily check the voltage of each cell at the end of charging - and at other times - or does the BCU do this already? The BMS's on my e-max have red LED for each cell that flashes when the shunting voltage is reached (the shunts also have 0.5 amp capacity). I also have a connector for easy voltmeter checking of each cell - to verify the operation of the BMS, plus finding the bad cell if a low-voltage cutoff condition is encountered. The per-cell BMS's can fail, and when they do, the affected cell can get ruined from overcharge.
I understand that the Current scooters don't currently have a means of checking individual cell voltages, so adding a check connector might be the one home-mod that I do.
Such mains-arcing from the charger (or other switchmode-power-supply devices) is probably due to inrush current into the large filter capacitor(s) used for the input rectifier. You will get such arcing even if the charger is not runningat all. The on board charger may simply need a more effective inrush suppressor.
Yes, you're right if you mean we don't have the means to display individual voltages.
The BCU (bike control unit) doesn't have a digital interface to the BMS (battery management system) so we don't have access to the individual cell voltages. The next revision of the BMS (already on the to-do list) will have a digital interface so the BCU will have access to much more data.
However, the BMS does monitor the voltage of each and every cell (wanted to make that clear in case it wasn't clear to some folks).
We have created our own tools that plug in to the BMS harness (disconnect the harness and re-connect these tools). One is a simple voltmeter with 30 push buttons - push a button to read that cell. The other is a "reverse BMS" that bottom-balances the pack and also tests individual cell health.
I'll see if Erik wants to publish the details of the voltmeter - although as you can imagine it's pretty straightforward.
In time these will become service tools that you'll be able to purchase.
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
The arc is probably not damaging, but a series MOV could tame the spark.
But, the BMS's low-voltage cutoff is based on the lowest individual cell voltage, not the total pack voltage, right?
Power supplies usually use a part called a NTC (negative temp. coefficient) thermistor. Higher resistance when cold, then lower resistance when heated by the mains current.
In the case of my e-max, inrush to the DC-DC converter caused arcing that shortened the life of the key switch, so I used an NTC in the DC-DC converter circuit to suppress it. I had a supply of them, because the e-max chargers were famous for their cheap Chinese NTC's failing and the charger going dead.
...
Correct. The BMS monitors each individual cell for under voltage, over voltage and performs balancing. The BMS communicates with the charger to request the amount of current supplied. The BCU controls switching on and off the charger and monitors the charging process.
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
I get a similar arc when I plugin my Kelly switch-mode charger. Since the capacitors in the charger are usually discharged prior to plugging it in, the input to the charger looks like a short at the instant you plug it in. You may have noticed that the intensity of the arc isn't always the same and sometimes you don't even get it because when you plugged it in the AC line just happened to be close to 0 volts. The resulting arc is a little disconcerting and it's hard on switch contacts. Even using a power strip, I suspect you often hear a little pop when when you turn on the switch. The big inrush current isn't particularly good for the caps in the charger but the input side of the charger is most likely designed to take the hit. If you really want to avoid it, you could add a NTC device in the line as previously suggested or make up your own precharge circuit similar to that used for many speed controllers. You could put a ~100Ω, 50 watt or so power resistor in series with the hot wire with a switch shunting the resistor. With the switch open, the resistor will limit the inrush current to the charger = no arc and then you close the the switch after a couple of seconds. The switch, resistor and receptacle should be mounted inside a 4x4 metal electrical box.
All said & done, I don't worry about it and live with the pop when I plug in my charger.
If your only tool is a hammer
everything looks like a nail.