Do not order a ChargeDoctor for now!

[Chriull]

Quote

 

Update April 2020: There is a charge doctor alternative, now that the charge doctor guy seems to be missing in action. Get this instead of trying to order from any charge doctor-specific website. See here:

 

  

 

4 minutes ago, RagingGrandpa said:

For future reference, the user manual for the Charge Doctor V2 is archived permanently below:

https://web.archive.org/web/20210319012107/http://hobby16.neowp.fr/2016/11/07/charge-doctor-v2-firmware-v-2-03-2/

 

Original post follows.

-

On @hobby16's main site (http://hobby16.neowp.fr/buy/) it is not possible to order a CD anyhow, but there exists a second site (chargedoctor.fr) were the paypal links are not disabled! Doing some "research" on espritrue.fr (hobby16s "home" forum) this site could be legit but got somehow "forgotten" by him?!

From these posts it seems that @hobby16 is well, but for whatever reason he has no time/interest/possibility to make CDs right now. ... and it's about impossible to reach him ...

What to do if you already payed and did not receive a CD:

If you provided an address ("Warning!!! Please give me your address when or after ordering since Paypal does not always display the payer’s address. No address, no shipping") it could just arrive sometimes...

If your paypal payment went to "Sylvain Bouju" one can reach him on https://www.espritroue.fr/profile/10-sbouju/

If the payment went to some "ChristopheGardon" there could be a problem?:

https://www.espritroue.fr/topic/356-charge-doctor-v2/?do=findComment&comment=161801

Or maybe not?:

https://www.espritroue.fr/topic/356-charge-doctor-v2/?do=findComment&comment=161858

More topics regarding this:

 

Edited September 15, 2023 by RagingGrandpa
(added a quotation)

[Struck]

About chargedoctor.fr:

 

Quote

 if it's fake or fraud?

Two choices only...?

Anyway, the "good" adress for everything about the Charge Doctor is here:

http://hobby16.neowp.fr/fr/

https://www.espritroue.fr/topic/356-charge-doctor-v2/?do=findComment&comment=171938

and then:
 

Quote

I think it is an old, forgetted, obsolete page, and personnaly, I should not use such old Paypal links ! 🤡

https://www.espritroue.fr/topic/356-charge-doctor-v2/?do=findComment&comment=172000

 

Apparently the guy was making them a month ago. Hopefully will open the page again?

[AtlasP]

I ended up getting one of the eWheels rapid-chargers which appear to offer the same main functionality as ChargeDoctor (particularly the ability to stop charging at 80% or 90%).

Are there any notable differences in functionality or quality between them that someone would want specifically the ChargeDoctor instead?

Edited April 24, 2019 by AtlasP

[Chriull]

3 minutes ago, AtlasP said:

Are there any notable differences in functionality or quality between

One can afaik make the CD stop at any ?voltage/current? so one could charge up to for example ~40% charge for storage...

Wh are displayed, logging is available.

For details there is everthing described on his homepage...

5 minutes ago, AtlasP said:

Are there any notable differences in functionality or quality between them that someone would want specifically the ChargeDoctor instead?

Depends on your use case 😁 but most likely not.

 

[esaj]

16 minutes ago, AtlasP said:

I ended up getting one of the eWheels rapid-chargers which appear to offer the same functionality as ChargeDoctor (including the ability to stop charging at 80% or 90%).

Are there any notable differences in functionality or quality between them that someone would want specifically the ChargeDoctor instead?

The two main uses for Charge Doctor are measuring the amount of watthours you can charge into the battery and (possibly) stopping the charge before full if you don't want to charge to full all the time. Also, if you don't have a rapid charger, you can connect two "normal" chargers to the Charge Doctor to use them in parallel (I charge my KS16's with 2 x 2A chargers for faster charging), or at least some of the models (there are probably ones which have a connector only for a single charger).

The watthour-measurement is useful for checking battery health/remaining charge capacity (discharge them all the way to empty and measure how many watthours the batteries take in when charging all the way to full) and measuring consumption (start with a full battery, ride a trip where you know/can measure the exact length, recharge to full and you get the consumption by dividing the charged watthours with the distance, ie Wh/km or Wh/mile).

If your charger already has the option to stop charging before full, and you don't care about the consumption / measuring total capacity of the batteries, then you have little use for a Charge Doctor. Also, Charge Doctor is not a charger on itself, but an extra device that sits between the charger(s) and the wheel:

Second-hand KS16B / 680Wh being charged from empty to full to see how much capacity the batteries still hold = 672.3Wh when the charging current has dropped to 20mA (0.02A)

There's also an option of recording data during the charging with a separate serial-connection, which allows you to draw charging graphs with Excel or whatever, not probably of much use to most people:

Old graph from charging a 264Wh Firewheel, the axes use a bit weird units (tens of watthours, tens of volts, hundredths of ampere) so I could fit them all on the same graph with "sane" scaling.

Edited April 24, 2019 by esaj

[Struck]

Great post @esaj

That is exactly what I want the ChargeDoctor for. I amb seeing strange behaviour in my batteries, and want to plot those graphs..

Also, I see you have a kingsong with the 840Wh battery pack, do you know if that is really 4 packs? or 2 twice as big compared to a ks14d?
 

thx!

[esaj]

2 hours ago, Struck said:

Also, I see you have a kingsong with the 840Wh battery pack, do you know if that is really 4 packs? or 2 twice as big compared to a ks14d?

There are 2 packs, one 16S2P on each side.

Image courtesy of Ecodrift's KS16S teardown:  https://ecodrift.ru/2017/03/24/kingsong-ks-16s-luchshaya-novinka-vesny-2017/

Edited April 29, 2019 by esaj

[svenomous]

OK so CD sits between charger and wheel, and provides partial charging cutoff support, as well as the ability to see how much power (in Wh) has been pumped in.  It also provides logging capability via serial port, and dual charger input capability to combine chargers.

I have a KS wheel with two charge ports, so don't need the dual port feature.  Also have an eWheels quick charger that can be set to different amperages up to 5A, and can be set to 80%, 90%, or 100% charge cutoff level, so don't need the cutoff feature.  However, I am interested in knowing how much power goes into the pack, to monitor consumption vs. charging, and also to compare over time and see how pack capacity is declining.  I don't need the more advanced logging feature, just a total of "how many watt-hours went in" per charging session.

It just so happens that I also play around with 12V battery systems for fun, including LiFePO4 packs, solar panels and charge controllers, AC-to-DC and DC-to-DC chargers, etc.  For an emergency/camping power supply I built, I put together a box that provides power distribution (cigarette lighter, PowerPole, and USB outlets), fusing, charge inputs, and battery monitoring.  It uses a couple of these:

http://www.amazon.com/gp/product/B013PKYILS

Even though the box was built for a 12V system, I found I could easily adapt it to the wheel charging situation, as the wiring and meters involved can handle the voltage and amperage involved, and I just have to remember to keep the USB adapters turned off (they would pop and fizzle instantly if I turned them on while 74-84V is flowing through the box!).  So, I just had to make a couple of adapters between Lenovo square connector and PowerPole, and I'm set!

I call this out because one of these meters costs less than $20, and it (and the shunt it comes with to measure amps/power) could easily be wired up in a small project box (or on a piece of wood or something) and placed into the charging circuit to provide some of the value-add features that CD provides.  I'll upload some details including photos of my setup tonight (need to take some photos after I get home).

[rinzler]

56 minutes ago, svenomous said:

I have a KS wheel with two charge ports, so don't need the dual port feature.  Also have an eWheels quick charger that can be set to different amperages up to 5A, and can be set to 80%, 90%, or 100% charge cutoff level, so don't need the cutoff feature. 

So is the ewheels unit a better catch all solution?

57 minutes ago, svenomous said:

http://www.amazon.com/gp/product/B013PKYILS

Thanks for posting this - I did not know there was loads of these types of devices...soooo

57 minutes ago, svenomous said:

Even though the box was built for a 12V system, I found I could easily adapt it to the wheel charging situation, as the wiring and meters involved can handle the voltage and amperage involved, and I just have to remember to keep the USB adapters turned off (they would pop and fizzle instantly if I turned them on while 74-84V is flowing through the box!).  So, I just had to make a couple of adapters between Lenovo square connector and PowerPole, and I'm set!

I call this out because one of these meters costs less than $20, and it (and the shunt it comes with to measure amps/power) could easily be wired up in a small project box (or on a piece of wood or something) and placed into the charging circuit to provide some of the value-add features that CD provides.  I'll upload some details including photos of my setup tonight (need to take some photos after I get home).

....it would be amazing to see what you have done an perhaps a layman explanation of why you prefer your execution over some of the other things.

Originally I was going to get a CD. Then considered the eWheels (or probs SpeedyFeet - due to taxes) solution even though I really don't need rapid charging given the range of the Tesla.

Before I've even done a mile on my wheel I'm already at the cost of a relatively new usable car car!

[svenomous]

@rinzler, the eWheels charger is nice, and configurable.  The ability to charge to less than 100% is what sold me on it, although fast charging is also useful for wheels with larger battery packs.  This takes care of one of the CD features, although the eWheels charger isn't exactly cheap.  I wouldn't call it a better catch-all solution because the eWheels charger provides a display of volts and amps (instantaneous, no accumulated power reading) and adjustable charge completion level, and this covers only some of the CD capabilities.  It depends on what you're looking for, and if power accumulation (in watt-hours) is something you want, the eWheels charger alone won't give you that, much less logging.

Power accumulation reading is the one thing I was missing after getting the quick charger, so I rolled my own solution.  Will do another post this evening to show you what I have.  e-retailers like Amazon are full of battery monitors and voltmeters/ammeters/power-meters of all kinds, and I'm sure there's a cheap solution out there when it comes to monitoring the charge process to the desired degree.  Logging is of course much more involved, and that's one area where if I had to roll my own I'd be thinking in terms of an Arduino or Raspberry with some custom code from me and some appropriate add-on modules.  CD is probably the best plug and play solution if you want logging for charting/spreadsheet purposes. 

[svenomous]

Here's my setup (see photos at end).  In the first photo you can see the eWheels quick charger (black), the project box I mentioned (above the charger), and the wheel (at the left edge of the image).  The project box contains two of the meters I previously mentioned, a shunt, a fuse block with automotive fuses, and a bunch of inputs/outputs (all the ugly wiring is nicely tucked inside and invisible).  It is designed for battery monitoring and power distribution for a 12/14V battery system, and it's "standardized" around 30A Anderson PowerPole connectors (which is what I use for all of my projects of this type).  Since the cabling, fuses, meters, shunt, and connectors on this box can accommodate an 84V system like the one in my wheel just fine, as well as a 5A charge current, I decided to simply re-use it for charge monitoring of the wheel.  I just have to make sure the USB outlet on/off switch is off (see switch under the last two outlets at the top of the box, which are the two dual USB outlets).  If that switch were to be turned on while the box is energized with 84V, I'm guessing there'd be some loud pops and smoke, and two ruined USB adapters.

The design assumes connection directly to a battery to monitor not only charge, but also voltage and discharge (the right meter), but in this case that's not possible since the box is connected to the wheel via the charge connector, which has backflow prevention.  When the charger is not powered on, the box is dead because no power flows out through the wheel's connector.  That's fine for my needs, though, and when I hook up the box only the left meter shows anything useful, which is the voltage, amperage, and power (Wh).  The meter can be reset to 0 using the the button recessed in the right side of the bezel.

As I said, the box uses PowerPole connectors, so I needed a way to hook this up in series with the charging circuit.  This is a KingSong wheel which uses Lenovo-style square connectors.  It's easy to find cheap Lenovo square power adapters online.  I purchased one socket adapter and one plug adapter (each converting between Lenovo square and the older Lenovo 20V barrel connector standard).  Upon receiving these items I cut off the barrel sides, verified the wire gauge (each was 18AWG, which is plenty for 5A over short runs), and attached PowerPole connectors.  See photos 2 and 3 below.  The socket adapter receives the plug from the charger, and its PowerPole side goes into "the box" (into one of the input/output ports on the side).  The plug adapter attaches to the PowerPole battery pigtail on the project box, and goes into the wheel.

As soon as the charger power is turned on, the box comes alive and the left meter starts showing the charge stats.  Voltage and amperage closely follow the same numbers shown on the charger itself.  The watt-hour reading in the bottom right corner of the display is the one that interests me, and I reset that to zero before each charge session.  When the charge completes the charger shuts off and the box goes dark, but to see what the final Wh number was I can just unplug from the wheel and power-cycle the charger, which makes energize the output circuit and bring the meter displays to life so I can read the number.  This is good enough for me, and overall this setup gives me the Wh counting (my box), plus adjustable charge amperage and battery charge level (the quick charger), representing all the key features I require.

A simpler setup with a single meter and more customized cabling, and with no fusing, could be made by anyone with a few tools, some wood or a plastic project box, a crimper and/or soldering iron, the meter to be used, and a few supplies (wire, connectors).

  

Edited April 30, 2019 by svenomous
Initially I incorrectly provided image thumbnail links instead of direct links.

[Struck]

On 4/29/2019 at 9:08 PM, svenomous said:

  It uses a couple of these:

http://www.amazon.com/gp/product/B013PKYILS

Awesome, just discovered and bought this thanks to you:
https://www.ebay.es/itm/AC-DC-6-5-100V-20-50-100A-LCD-Combo-Panel-Display-Volt-Amp-Power-Watt-Meter/192537931397?&var=492637434832

Also, I wanted to share with you the following graph:

 

I measured the power used by the charger, so before the AC/DC conversion.

Theoretically I was charging the wheel from almost 0% battery (53.69V) to as much as I could (it reached 64.88V), I am having a problem, never goes past 90% :'( 

Theoretically the wheel is the 840Wh version... but does this look like it to you? Have I been scammed? I am still refusing to open the wheel, don't want to break anything.

Also.. There are two times when there is a drop from constant power, don't you find it weird?

Also, with that charge I could squeeze out of it 40km... Isn't that way too low for a 840Wh pack?

[Chriull]

1 hour ago, Struck said:

Awesome, just discovered and bought this thanks to you:
https://www.ebay.es/itm/AC-DC-6-5-100V-20-50-100A-LCD-Combo-Panel-Display-Volt-Amp-Power-Watt-Meter/192537931397?&var=492637434832

Imo one should not expect any precise measurements from such devices or that they come calibrated.

If one wants to use the absolute values one have to calibrate it oneself.

... but of course one can have good luck and get one not too far off...

Quote

Also, I wanted to share with you the following graph:

 

I measured the power used by the charger, so before the AC/DC conversion.

Theoretically I was charging the wheel from almost 0% battery (53.69V) to as much as I could (it reached 64.88V), I am having a problem, never goes past 90% :'( 

That's battery voltage reported from the wheel? Unfortionately these measurements can be off, too

Assuming they are about correct these values would lead to cell voltages (/16) of:

3.35V to 4,05V

3.3V is the normal "0% charge" stop of EUCs (just not the KS18(X)L which goes downto 3V)

At 3V a li ion cell has some ~5% capacity left. At 3.3V still some more (don't have this number).

4,05V is about 85% charge of a full li ion cell.

The 64.88V instead of 67.2V (4.2V full cell charge) come most likely from the charger not delivering the full max voltage. Its quite common that they are misadjusted. But could also be an unprecise measurement from the mainboard.

This one can check easily with a multimeter measuring the (no load) output voltage of the charger. This is normally some 0.3-0.6V higher than the max battery voltage can get (there is a diode inbetween)

This should also give a feeling of the quality of the values reported from the wheel.

Quote

Theoretically the wheel is the 840Wh version... but does this look like it to you? Have I been scammed? I am still refusing to open the wheel, don't want to break anything.

The capacity values are calculated with the max manufacturer numbers. They derive it from discharging a cell with ~0.2C from 4.2V downto ~2.5V.

So in your case (if the voltages from the mb are somewhat correct) you use from 4.05V to 3.35V just something around 70-75% of the capacity. And still some more losses by discharging them most likely with more than 0.2C.

This 70% of 840Wh are 588Wh.

The 600 Wh reported from the powermeter are including the losses of the charger (some 5-15%) and the charging losses of the li.ion cells.

So your numbers (and battery) backs seem perfectly fine! Just your charger seems to be heavily misadjusted.

And of course the capacity numbers on batteries are a bit marketing numbers - some "theoretic" perfect numbers from the manufacturer, never to be reached with real life use. Like fuel consumption numbers from cars...

Quote

Also.. There are two times when there is a drop from constant power, don't you find it weird?

The first drop is most probably the switching from constant current (power increase with increasing viltage) to constant voltage (power decrease with decreasing current).

The second drop is ähhh.. ?something?. Maybe some "internal" state change of the switching mode supply causing efficiency change?

Or the mains supply voltage changed? (Some nearby industries/plants started/stopped their working hours? 😀)

Quote

Also, with that charge I could squeeze out of it 40km... Isn't that way too low for a 840Wh pack?

Some 15-20 Wh/km are about "common". Strongly depending on speed and inclines.

With your cells just charged to 4.05V that's imho a good number.

Get a multimeter and check your charger!

Then you can (maybe) adjust it or get a new one!

 

Edited May 3, 2019 by Chriull

[Struck]

Wow, thanks so much for your post.

I'd buy you a beer, you know?

So... you were 100% right, my charger outputs 63.9V right now, measured from one voltmeter, 63.5 from another. It is even below the voltage the battery reached, I guess there must be a logical explanation but never mind, it makes sense.

So it looks like I have a chargedoctored charger. Unwantedly...

 

Still no idea about the second transition from constant voltage to constant current, maybe yes, the mains voltage, went up?

 

Thanks!!

[svenomous]

On 5/3/2019 at 2:02 AM, Chriull said:

Imo one should not expect any precise measurements from such devices or that they come calibrated.

Sorry for the delay in replying, but I was gone on a trip and then had a crazy time at work since Tuesday.  I agree that these can be very poorly calibrated, but mine have been cross-checked against each other (there are two of the same model), against a separate stand-alone voltmeter display I have, and most importantly against my calibrated Fluke voltmeter.  I don't have a way to test amperage (and therefore power) accuracy with my current equipment, but the two displays are consistent with each other and with my expectations of the batteries and loads I apply the meters to.  Anyone who gets this type of display should verify readings, or should accept that readings will be approximate and better suited for determining consistency and trends than to know whether something is at 83.6 or 83.9V, precisely, or whether 1520Wh or 1483Wh was pumped into a batter pack.

[Pinkalsky]

I found this link: http://chargedoctor.fr/en/buy/
Does anyone know if it's safe?

[Chriull]

1 hour ago, Pinkalsky said:

I found this link: http://chargedoctor.fr/en/buy/
Does anyone know if it's safe?

As writte in the first post this is presumably an "old" site from @hobby16 at which he forgot to disable the buying links.

 

[rinzler]

Do you know of any EU partner sellers?

I know @Jason McNeil has them in the US. I'd order if it wasn't the case rhat shipping and import taxes add to higher than the unit itself.

I don't think i need a fast charger.  Only something to manage the charge amount which this does. 

[Struck]

On 5/3/2019 at 11:02 AM, Chriull said:

On 5/3/2019 at 10:00 AM, Struck said:

Awesome, just discovered and bought this thanks to you:
https://www.ebay.es/itm/AC-DC-6-5-100V-20-50-100A-LCD-Combo-Panel-Display-Volt-Amp-Power-Watt-Meter/192537931397?&var=492637434832

Imo one should not expect any precise measurements from such devices or that they come calibrated.

If one wants to use the absolute values one have to calibrate it oneself.

... but of course one can have good luck and get one not too far off...

Well, it arrived y-day, I think I had not soldered anything for 15 years:

 

I know, I know, those two ends are live, and there is a high change of making a short there. I'll fix it with some electrical tape

 

 

Update:
The charger is definitely the culprit:

 

 

Edited May 24, 2019 by Struck

[Ben Kim]

Don't mean to revive an old thread, but I have a Charge Doctor V2 with 2x GX16-3 ports for dual charger usage.  I used it on my Dualtron (sold) to cut the charge at a certain voltage, found it works as-is on my 18S, but looking to see if I could repurpose this into working with a 100.8V (24S) wheel.  I'm aware I'd have to solder in some GX16-5 ports to it, but willing to do the work if it can go beyond.  

[esaj]

7 hours ago, Ben Kim said:

Don't mean to revive an old thread, but I have a Charge Doctor V2 with 2x GX16-3 ports for dual charger usage.  I used it on my Dualtron (sold) to cut the charge at a certain voltage, found it works as-is on my 18S, but looking to see if I could repurpose this into working with a 100.8V (24S) wheel.  I'm aware I'd have to solder in some GX16-5 ports to it, but willing to do the work if it can go beyond.  

The low-side mosfet stopping the charging seems to be an IRF540, which has an absolute maximum Vds of 100V, so at least that would need to be changed to a higher voltage variety. Similar looking current/voltage-meters as what is used in Charge Doctor come in 100V and 200V -varieties, I don't know which hobby16 used (if it even is the same), but it's possible the meter cannot handle 100V and change, if it's the absolute maximum rating, but I don't know. Usually the absolute maximums are something to stay away from, ie. I wouldn't use a 100V max Vds mosfet for 100V input voltage, but maybe up to 90-95V max to leave some "headroom". Running something right at the limit at least drops the lifetime of the component, if not cause an outright failure.

Still, it's also possible that the 100V & 200V -models are the same device, but just use a different voltage divider and software-values for measuring the voltage, and the circuitry otherwise works just fine with higher voltages (might need a protection diode in the measurement divider to prevent overvoltage at the MCU ADC-input). It could work, but the risk is that you'll burn your CD and/or damage your charger if it gets shorted over the failing CD. I don't want to test on mine 

I started polling for interest in a CD-like device some time ago, currently looking into going to open-source hardware/software-route, and maybe selling kits/pre-built devices at some point, but unfortunately the price (even just for the components + board + encasing, if building by yourself) is going to be much higher than the original CD. The current idea is to support voltages up to (around) 105V, so it can work with the 24S-wheels, OLED-display, BT-communication so a mobile app could be used and separate adapter-cables, so the same device can be used with wheels having different connectors.

[Boogieman]

I just charged my Tesla 1KWh battery from around 30% to 100% (green light on charger).

When i disconnected I placed my hand on each side of the wheel/battery pack cover.

One side was warm to the touch, the other one not. Not burning hot but defentiely warmer than my body.

Should i be worried? Is there any way to check if batteries are about to reach their life time or worse "go poof"?

I've ridden for a year, around 3'000 km's

[Boogieman]

On 5/4/2019 at 6:23 PM, Struck said:

Wow, thanks so much for your post.

I'd buy you a beer, you know?

So... you were 100% right, my charger outputs 63.9V right now, measured from one voltmeter, 63.5 from another. It is even below the voltage the battery reached, I guess there must be a logical explanation but never mind, it makes sense.

So it looks like I have a chargedoctored charger. Unwantedly...

 

Still no idea about the second transition from constant voltage to constant current, maybe yes, the mains voltage, went up?

 

Thanks!!

How did you measure the charger.
With no load (wheel not connected) directly on the charger pins on the contact?

[esaj]

On 8/2/2019 at 4:22 AM, Boogieman said:

How did you measure the charger.
With no load (wheel not connected) directly on the charger pins on the contact?

Yes, directly on the charger pins, make sure you have the multimeter wired correctly (for voltage measurement, if there are separate jacks for current measurement ) and use a high enough DC voltage range (Usually they're something like 2, 20, 200V for the basic meters, so use the 200V DC area). Unloaded charger should output the maximum voltage, 4.2V per cell, ie. 67.2V for 16S, 84V for 20S, 100.8V for 24S (assuming there are no actual diodes for reverse protection in the BMS).

If it's slightly higher (like 0.01V per cell), it shouldn't usually be very dangerous, on a pack with healthy cells, the voltage is divided pretty much equally across all the cells in series, so for example 84.2V / 20S = 4.21V / cell, but going much above starts to stress the cells and in the worst case can damage them, so the safest bet is to stay around 4.2V per cell (some chemistries can handle overvoltage better than others). On some another topic, I think it was mentioned that KS uses 4.24V as the cell overvoltage protection threshold. The passive bleed-balancing should take care of slight overvoltage above 4.2V, albeit slowly.

I found out that the Firewheel charger I was using with it was putting out 67.8V (for 67.2V packs) after I had already been using if for quite some time, that's 4.2375V per cell, and I know the pack didn't have any kind of reverse protection (so no diodes dropping the voltage) because I could power things directly from the charge port    Apparently it didn't have any overvoltage protections either, because I'd often take the wheel "hot off the charger" and my rides start with a short straight bit and then a couple of hundred meters of downhill without issues, where the regenerative braking was likely pushing the voltage up even more...

If the charger voltage's below the maximum battery voltages, the cells will never be fully charged (or some will and others wont, if they're out of balance enough), and depending how high the balancing voltage per cell is in the BMS, the cells might never get balanced and you won't get the full range out of the pack.

[Boogieman]

15 hours ago, esaj said:

Unloaded charger should output the maximum voltage, 4.2V per cell, ie. 67.2V for 16S, 84V for 20S, 100.8V for 24S (assuming there are no actual diodes for reverse protection in the BMS).

Ok, so i measure

1) with wheel NOT connected to charger

2) directly on + and - on the charger plug from the charger (godda figure out which those pins are on my gotway tesla charger)

But the BMS comment i dont understand? The BMS is in the battery pack and since battery pack is not connected when meassuring the voltage (as described ABOVE), the BMS has nothing to do with the charger output voltage?

Or am i missing something here?

Thanks a lot for the QUICK reply :-) Hope you can clarify above. My father allways tought me to measure with load when doimg charger measurements back im the days when we were charging ni-cd batteries, but that was basically to check the batteries (charge and life). But to check the charger, it still fells like there should be some kind of load (except only the fluke internal resistor or maybe thats enough? I mean normaly voltage drops tremendeously as load is applied = charging, so even if 84 with "no load"(except internal resistor to get voltage measurement) looks ok, it might not be able to output 84V even at 0.25A, depends on how robust the china charger is...and i Guess not that robust LOL)

Boogie

Edited August 4, 2019 by Boogieman