Speed Chargers

[Esper]

First of all, I'd like to hope that @esaj would know more. 

 

A lot of people are having issues with Speed Chargers, including myself. I'm hoping that this (hopefully mega thread) post will collect all the data we users need to know.

First, How to determine if it works.
If you plug in the charger and press the on switch on the back, the display will show it's current set 100% max capacity. It will vary from ~50v to ~90v or more.
IF THIS NUMBER DISPLAYED IS NOT YOUR BATTERY PACKS VOLTAGE IT IS NOT WORKING PROPERLY.
(I hope [desperately] that someone can explain how to change this voltage limiter)

Second, What do the knobs do?
The knob on the right adjusts what percentage of battery charge it will go to (if the max voltage setting is correct). The knob on the left adjust the amps going into the battery.

Third, how come my battery isn't charging?
There are several ways to diagnose the problem. The first of which is to simply, try a different outlet. The next would be to verify the voltage gage compared to your battery capacity. If the battery in your device is a 67v and the voltage on the display of the charger says 58v, it will only charge to 58v. THE OPPOSITE CAN HAPPEN TOO. If you have a battery at 67v and the charger says 95v it can overcharge your battery leading to a fire or explosion. 
If neither of those are your cause and you are getting the correct voltage display and power is going to the charger, the problem could either be the plug that goes into your device or your charging port on the device. First determine if it is the charger using a voltmeter and confirm its accuracy with the display. If that is not the issue, you may have to open up your device for further inspection. (I will not go into that detail because this thread is focusing on the chargers.)

 

If anyone would like to add information here, please feel free. You are not obligated to help provide any information but if you do, thank you.

Now, if someone smarter than me would like to explain. Please share what changing the AMP output does on these chargers. Anyone?

[Chriull]

@Esper: You are talking especially about the ewheels fast charger? https://www.ewheels.com/product/new-gen-v-5a67-2v-charger-king-song-electric-wheels/

 

Voltage can normally be adjusted with some trimer potentiometer inside the charger: (will look different in different chargers...)

@esaj also posted lately a description on how to adjust the voltage.

4 hours ago, Esper said:

IF THIS NUMBER DISPLAYED IS NOT YOUR BATTERY PACKS VOLTAGE IT IS NOT WORKING PROPERLY.
(I hope [desperately] that someone can explain how to change this voltage limiter)

I have no idea if this or other chargers can be adjusted within the full range (?50V-90V?) or one needs to buy a 67,2V or 84V charger and then just some fine adjustments can be made.

4 hours ago, Esper said:

Please share what changing the AMP output does on these chargers. Anyone?

First part of the charging process is a constant current pushed into the batteries - changing the amp setting changes how much amperes are used in this first phase.

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

[esaj]

11 hours ago, Esper said:

First of all, I'd like to hope that @esaj would know more. 

 

A lot of people are having issues with Speed Chargers, including myself. I'm hoping that this (hopefully mega thread) post will collect all the data we users need to know.

Is this Speed Charger some specific model called that or just "fast" (speed) chargers in general? I think there are many models going around...

 

Quote

First, How to determine if it works.
If you plug in the charger and press the on switch on the back, the display will show it's current set 100% max capacity. It will vary from ~50v to ~90v or more.
IF THIS NUMBER DISPLAYED IS NOT YOUR BATTERY PACKS VOLTAGE IT IS NOT WORKING PROPERLY.
(I hope [desperately] that someone can explain how to change this voltage limiter)

Second, What do the knobs do?
The knob on the right adjusts what percentage of battery charge it will go to (if the max voltage setting is correct). The knob on the left adjust the amps going into the battery.

I adjusted a friends' older fast charger last year, that he'd got from Jason in spring of 2016, as the output voltage was quite off (65.xx if memory serves, for a 67.2V wheel). In the case of that charger, there was just a switch for selecting 80%, 90% or 100% charge and no voltage or current adjustment outside the box. Inside I found four trimmers (small potentiometers), and after trial and error found the correct one for adjusting voltage (the three others were likely current limitation, fan turn-on/off -threshold and led red/green threshold). The trimmers usually look like this, although they might be different kind too:

 

If you want to / need to adjust the maximum voltage, you have to locate the correct trimmer/potentiometer. If and when you don't know which one it is, the way to check that is to put a multimeter in the charge connector of the charger in voltage measument (100V DC or more, often they go in steps like 2, 20, 200V, so probably 200V), turn the charger on (be careful not to short anything with the screwdriver or electrocute yourself, there are mains voltages there and the charger output isn't exactly low voltage either at around 67 or 84V) and start turning the potentiometers with a small screwdriver (if it's all plastic, all the better, can't short circuit anything on accident). Turn one trimmer half turn, if the voltage reading in the multimeter doesn't change, turn it back to where it was, it's not the correct one. When the voltage changes, you've located the correct potentiometer, now just turn it until you get the reading you want from the output. If the voltage goes in the "wrong direction" (Ie. you need higher voltage and the reading is dropping), turn it in the other direction.

Having a high accuracy multimeter helps (I have a HP bench multimeter which has basic accuracy of 0.0035% for DC, although it hasn't been calibrated in years, but still measures 0.01% and 0.05% voltage references easily within tolerance), but I don't think it's that crucial here, a basic 20€ multimeter with 1% accuracy should be enough. The battery BMS should stop any overcharge and if it was off by the maximum 1%, at 84V that would mean up to 84.84V output voltage in the worst case, assuming it would go "evenly" to all the cells, the cells would be at 4,242V each, which of course isn't good for the cell longevity, but is still within the 50mV "tolerance" suggested by Battery University:  https://batteryuniversity.com/index.php/learn/article/charging_lithium_ion_batteries:

"Li-ion with the traditional cathode materials of cobalt, nickel, manganese and aluminum typically charge to 4.20V/cell. The tolerance is +/–50mV/cell. Some nickel-based varieties charge to 4.10V/cell; high capacity Li-ion may go to 4.30V/cell and higher. Boosting the voltage increases capacity, but going beyond specification stresses the battery and compromises safety. Protection circuits built into the pack do not allow exceeding the set voltage."

"Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V on a Li-ion designed for 4.20V/cell will plate metallic lithium on the anode. The cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2). The cell pressure rises and if the charge is allowed to continue, the current interrupt device (CID) responsible for cell safety disconnects at 1,000–1,380kPa (145–200psi). Should the pressure rise further, the safety membrane on some Li-ion bursts open at about 3,450kPa (500psi) and the cell might eventually vent with flame."

If you feel uncertain about the multimeters' accuracy, you could of course set the output to slightly under 4.2V per cell (like half or full volt under the maximum of 67.2V or 84V, for example), although I'm not sure how much under 4.2V per cell the BMS balancing will kick in.

 

Quote

Now, if someone smarter than me would like to explain. Please share what changing the AMP output does on these chargers. Anyone?

The chargers are CC/CV -power supplies, CC standing for Constant Current and CV standing for Constant Voltage. The charger circuitry outputs the set constant voltage (like 67.2V or 84V), followed by a constant current source. If the current tries to rise above the set value (like 2A or 4A for example), the current source will start limiting the current, usually through a mosfet or such to keep it at the set constant value, thus Constant Current. At this point, the "excess" voltage is dropped over the current source, and that's what causes the charger to heat up (you've probably noticed the charger gets hot until towards the end of the charge). Once less current than the set maximum is flowing, the voltage at the charge connector will be at the maximum voltage and the current source no longer needs to limit the current, and won't dissipate (as much) heat. A typical charge curve for the batteries looks like about this:

Using more amps will charge the batteries faster, but it will also heat up the charger and the pack more, and there are limits how much current the parts can withstand, usually the charge connector ("charge port") is the limiting factor. A single cell (or cells in series) shouldn't be charged above "1C" -speed, which means the same amount of amps as the amphours in the cell, so theoretically charging from empty to full in one hour (in practice it takes longer as the current starts to drop entering to the constant voltage phase). So for example a 3.4Ah cells should be charged at 3.4A maximum. Going above the maximum will degrade the cells faster, going way above the maximum can overheat them and cause a fire.

Most wheels have multiple cell-series in parallel and the charging current splits among them, so for example 4 packs in parallel with 3.4Ah (3400mAh) cells would mean a maximum current of 4 * 3.4A = 13.6A, for 2.4Ah (2400mAh) cells that would be 4 * 2.4A = 9.6A. The typical GX16-3's used as charge ports are rated for something like 5-7A max though, so unless there are multiple ports, going over the maximum might mean excessive heating of the port, possibly causing the plastic surrounding it to start to melt. For smaller amount of parallel packs, the cells themselves can be the limiting factor.

 

[Esper]

Thanks for everyone's feedback!!

These are particularly the answers I was looking for.

6 hours ago, Chriull said:

You are talking especially about the ewheels fast charger?

I was indeed talking about these chargers. They seem to have many faults with them that may be caused with the shipping or they just aren't put together properly. The first one I got in the mail wasn't set for the correct voltage and didn't charge my device enough. Set to 100% it would only go to 80%. But had I the knowledge and tools to fix it, I would have done so myself. Instead I sent it back and got a replacement that worked properly.

 

Another question arises though. My charger arrived set 67.2v and over the course of a week has gone down to settle at 67.0v. What causes these changes to happen in the charger without physically tampering with these trimmers?

[esaj]

37 minutes ago, Esper said:

Thanks for everyone's feedback!!

These are particularly the answers I was looking for.

I was indeed talking about these chargers. They seem to have many faults with them that may be caused with the shipping or they just aren't put together properly. The first one I got in the mail wasn't set for the correct voltage and didn't charge my device enough. Set to 100% it would only go to 80%. But had I the knowledge and tools to fix it, I would have done so myself. Instead I sent it back and got a replacement that worked properly.

 

Another question arises though. My charger arrived set 67.2v and over the course of a week has gone down to settle at 67.0v. What causes these changes to happen in the charger without physically tampering with these trimmers?

I'd hazard a guess that either temperature variances or there are some components requiring a certain "burn-in" -time in the charger, that settle after some use. These things are essentially fully analog when it comes to the charging circuitry (the displays etc. probably use some digital logic though) and analog things are... tricky when it comes to stability and such 

If it keeps wandering off still after some use (hard to say how much, at least a couple of full charge cycles?), then I'd start to suspect somethings "more" wrong in the charger itself.