# Elcon Charger Cut-Off Adjustment



## PeterH (Mar 20, 2009)

Hi there,

Have you ever changed charge curve selections on an Elcon charger? If so, maybe you can help me?

I am using a 2500 watt Elcon charger configured for 38 to 47 cells with a 3.5 volt per cell cutoff. Apparently you can't have more than one charge curver stored in the charger but you can have multiple cut off voltages based on cell count. So that is how I asked for this charger to be set up.

Presently it is set for 45 cells to match my pack. However, as half expected, it doesn't shut off the charge at the right time so I want to switch to a lower cell count. In theory, to do this, all I have to do is pull of the sticker on the side of the charger and hold in "the button" when power is applied and release it after 7 flashes of the green LED. This should select the 7th instead of the current 8th memory slot. Sounds SO easy...

BUT, when I removed that sticker, there isn't a button. I only see a piece of white plastic covering the red and green LEDs. I can tell the LEDs are there because they do flash as expected. I tried to depress the plastic thinking it might just be a cover over the button in addition to the LEDs but that doesn't seem to be the case.

So if you've done this before, can you offer some suggestions?

As I write this the timer on my cell phone is about to remind me to dash out to the garage to check the charge status... I've had to manually monitor each charge for the past several months because I don't trust the BMS after the vendor told me he expects the charger to cut off the charge, not the BMS... While the BMS will shut off the charge if I let it go long enough, I don't like how it will let my weakest cell exceed 3.65 volts during the end of charge... so I stand there and kill the power myself. This isn't a sustainable situation! 

Thanks
Peter


----------



## Weisheimer (May 11, 2009)

There are 2 sets of LED's...well actually one set of red/green, and one single red led.
The one with the white plastic around it is mounted on the main power board.
The other LED is a single red LED and it is mounted on the "logic" board right next to the S1 button that you are wanting to push.
It will be on the exact opposite side of the charger from the one that you are looking at now.
Do you know the profile number that is in the charger?


----------



## Elithion (Oct 6, 2009)

PeterH said:


> I don't trust the BMS after the vendor told me he expects the charger to cut off the charge, not the BMS


Which BMS, please?


----------



## EVfun (Mar 14, 2010)

PeterH said:


> As I write this the timer on my cell phone is about to remind me to dash out to the garage to check the charge status... I've had to manually monitor each charge for the past several months because I don't trust the BMS after the vendor told me he expects the charger to cut off the charge, not the BMS... While the BMS will shut off the charge if I let it go long enough, I don't like how it will let my weakest cell exceed 3.65 volts during the end of charge... so I stand there and kill the power myself. This isn't a sustainable situation!


Hopefully someone can help you get your charger set up right. I would have to agree, it is not a good idea to be dependent on the BMS shutting off your charger. The charger should be set up to take care of the pack and any BMS should only be a safety to back up a properly set up charger.


----------



## Elithion (Oct 6, 2009)

EVfun said:


> The charger should be set up to take care of the pack and any BMS should only be a safety to back up a properly set up charger.


Yes and no. 

Please check the 3 stages of charging (video, text).


While balancing, the BMS is what prevents overcharging (the charger can't, because the pack voltage is still too low)
Once balanced, the charger's Constant Voltage is what prevents overcharging (the BMS doesn't, because all cell voltages are within range)
While balancing, one may assume incorrectly that the CV of the charger is a back-up. It isn't really, but, still, it's better than nothing.

Once balanced, the BMS is indeed a back up for a charger whose CV is set incorrectly, as long as the BMS is wired correctly, to control the charger, directly.


----------



## PeterH (Mar 20, 2009)

Sorry, I really should have added a photo to this discussion to start with. This image illustrates the layout of the Elcon. My Elcon is programmed with the 501 charge curve.










According to the sticker on Side B of the charger, the area I've labeled should contain the button. Isn't that correct?

This charger is configured with the 501 charging curve. In its present configuration, the BMS will be indicating that it has started to shunt roughly the top 15 cells in my pack of 45, at just about the time the charger enters CV and the current is just starting to decrease from a max of 16.5 amps. The programmed shutoff value is supposed to be 157.5 VDC. However, according to my Fluke, the pack voltage is higher than that before the BMS will finally override and shut off the charge. By that time, my weakest two cells are at or above 3.65. 

I've been monitoring the end of charge ever since I installed this charger and I've had to manually shut off the charge to prevent those two cells from exceeding 3.65.

Since I can't adjust the BMS my only option is to adjust the charger. Which is also the preferred remedy for this situation. But since I'm using an Elcon with its limited ability for adjustment, my only option is to tell the Elcon I have only 44 cells which should reduce the CV point by a few volts and hopefully, end the charge before any of my cells reach 3.65 volts. In reality the charger is set to end the charge based on a voltage of 3.5 volts per cell.

So basically, this is a bit of trial and error adjustment. But I'm stuck so far, on how to execute the change to the charger.

Thanks,
Pete


----------



## Elithion (Oct 6, 2009)

Pete,
You are blaming the charger and the BMS, but I am not sure that's the issue.
Any BMS worth its salt should be able to control your charger. 

Again, I ask you to please tell us: what BMS is it? 

If you could please answer that question, I may happen to know enough how to set up that particular BMS to control the charger, so you can keep on using both that BMS and that charger, without the need for your constant manual intervention.

Thanks


----------



## Weisheimer (May 11, 2009)

----------------This may be wrong--------------------------
No, the button access is on side A.
It will be directly opposite the one that you are looking at there.
The button is quite small and has a copper color. There is a very small red led next to it.
That is the LED that you will use to count your steps with.
-----------------------------------------------------------
so...start over here

Whoops...the above may be wrong.
Does Side B have a slot cut near the bottom of the picture?
If so, that is J2 of the logic board and that would mean that you are correct that the button is through the hole that you noted.
Does it have a plastic sheeting covering it?
Sorry for the confusion...


----------



## PeterH (Mar 20, 2009)

Hello,

Sorry, I forgot to mention the BMS... I'm using the centralized version of the Mini-BMS. Apparently since I bought and installed it, the designer/producer has decided to drop the centralized version. I haven't spoken with him directly but my local vendor simply said he was having too many problems with it.

I don't believe this BMS is adjustable. I think it is set for a voltage of 3.65 per cell. I was under the impression this BMS would shut off the charge as soon as any cell hit 3.65 but that isn't the case. At one time it seemed to do so. So perhaps it is damaged and should be replaced. However, at the moment, I don't have a job so I don't have a budget for replacing components.

Meanwhile, the BMS will shut off the charge but not until my weakest cells have gone past 3.65. I can't tell you exactly how far past because I try to monitor and shut off the charge before that happens. 

I know it is shutting off the charge because I have accidently let it go long enough to get to that point. However, I also expected it to shut off the charge and leave it switched off. But that isn't the case. It will shut off the charge by opening a small relay on the main BMS board with opens the control circuit in the charger. Then it closes the relay and the charge resumes. Upon resuming charge, the Elcon will start at a much lower current of 3 or 4 amps and slowly build up until the BMS shuts it off again. Each time the voltage on the weakest cells will rise above 3.65 and keep climbing until the BMS again opens the relay. I've never let that cycle continue through more than 2 restarts because if I understand the intended operation, that shouldn't be happening.

Below you can see the stack of 3 boards that make up the centralized version of the MiniBMS and my 'patch panel' of terminal strips contained in my "BMS Box" under the hood.



















You might wonder why I went with the centralized version of the MiniBMS rather than the distributed version. Mainly because my cells are within boxes beneath the driver's seat and the passenger seat and 15 more where the gas tank was. They are not easy to access if I want to manually check their voltage. So I build the box full of terminal strips you see above so I can check the individual cell voltage at any time. You know the story, the cells are the biggest expense in a project like this and they don't call me Paranoid Pete for nothing... I want these cells to last as long as possible. 

On a normal drive I don't use more than 50% of my capacity before I am home again and on the charger. Before I get out of the EV I calculate how many amp hours I've consumed and how long it will take to recharge at 16.5 amps from the charger and set a timer on my cell phone. Usually, right in the middle of dinner it goes off and I dash out to check the system. Wifie is getting tired of it and so am I but I'll continue to do it as long as it takes or until gas goes below 50 cents a gallon and stays there or until I have developed a trust in the charging system.

So I'm willing to loose just a little capacity by telling the Elcon I have only 44 cells once I figure out how to do that.

Thanks,
Pete


----------



## PeterH (Mar 20, 2009)

Weisheimer;348725
Does it have a plastic sheeting covering it?
Sorry for the confusion...[/QUOTE said:


> Hi there!
> 
> Yes, side B has that slot along the bottom and there is a white plastic sheet blocking the hole where I expected a button of some sort.
> 
> ...


----------



## Weisheimer (May 11, 2009)

If there is a 5 hole female connector under the slot, then you are looking at the logic board.
The logic board contains the S1 push button.
That push button is quite small. The head is about 1/8" and copper colored.

On another similar charger the button is on the opposite side from where the red/green (and thus yellow) charge indicator is located.

Let me see if I can find a picture here to post, so back in a few if I can find it.

OK, here it is. Look familiar? :^>

The 5 pin female connector that I refer to is at the top of this picture, just to the right of center.
The button is at the far right, centered vis top to bottom and the red led is just below the button.


----------



## dladd (Jun 1, 2011)

PeterH said:


> I know it is shutting off the charge because I have accidently let it go long enough to get to that point. However, I also expected it to shut off the charge and leave it switched off. But that isn't the case. It will shut off the charge by opening a small relay on the main BMS board with opens the control circuit in the charger. Then it closes the relay and the charge resumes. Upon resuming charge, the Elcon will start at a much lower current of 3 or 4 amps and slowly build up until the BMS shuts it off again. Each time the voltage on the weakest cells will rise above 3.65 and keep climbing until the BMS again opens the relay. I've never let that cycle continue through more than 2 restarts because if I understand the intended operation, that shouldn't be happening.


i would definitely shoot an email to Dimitri if I were you, he has been quick to respond and helpful on questions I've had. Once the HVC trips the relay, it should not reset until the ignition key is cycled.


----------



## Elithion (Oct 6, 2009)

PeterH said:


> Mini-BMS..


Thanks.





PeterH said:


> I don't believe this BMS is adjustable..


It isn't. Which is one of the beauties of the MinBMS: anyone can figure it out.



PeterH said:


> I was under the impression this BMS would shut off the charge as soon as any cell hit 3.65


Yes.



PeterH said:


> but that isn't the case


Based on previous experiences with people's installations, my guess is that your have a wiring problem, and that the BMS is just fine.



PeterH said:


> perhaps it is damaged and should be replaced.


I doubt it.



PeterH said:


> I don't have a job so I don't have a budget for replacing components.


The good news is that you have the time to troubleshoot it. Let's do it together!



PeterH said:


> the BMS will shut off the charge but not until my weakest cells have gone past 3.65


Ah! So it DOES work! Why do you keep on saying that it doesn't work?




PeterH said:


> I know it is shutting off the charge because I have accidently let it go long enough to get to that point.


"Accidentally "? Why "accidentally"? That IS how it's supposed to work!




PeterH said:


> It will shut off the charge ... Then it closes the relay and the charge resumes.


PERFECT! That is EXACTLY how it should work.

You do not have a BMS problem, you may not have a charger problem. You have a explanation problem: no one bother to explain to you how charging a Li-ion battery works. It works exactly as you describe. 

I gave you a link to a video explaining the 3 stages of charging. Please watch it, and you'll see that you do not have a problem.

Your system is now in the middle of stage 2, and it's fine!



PeterH said:


> I've never let that cycle continue through more than 2 restarts because if I understand the intended operation, that shouldn't be happening.


On the contrary! That is exactly what should happen!

Here is a picture of what you're seeing:









It's perfectly normal.


----------



## tomofreno (Mar 3, 2009)

I agree with dladd, contact Dimitri. From the minibms manual under cleanpowerauto product support for minibms:




> 1. During charging Ignition key is off, which tells BMS to expect HVC event. When first cell reaches HVC voltage BMS will interrupt NC loop and cause charger AC relay to interrupt power to the charger. HVC event will latch on, so charger will not come back on when resting voltage goes below HVC. NOTE: In ideal world HVC function may not even interfere with the charger, allowing it to finish CC/CV charging phases as intended by charger’s manufacturer. However, in case there enough misbalance across multiple cells such that one cell gets to HVC much sooner than others, HVC will protect the cell by cutting off charging process prematurely. It is up to you what action to take depending on how prematurely HVC cutoff occurs. If charger is interrupted only a few minutes before the end of CV phase, at which point charging current is very low, then you are not losing much and you can simply let this happen every day. If you have BMS with shunting option, then shunting process will over time pull backthis pesky cell and equalize it with others. Or, you can manually attempt to discharge that cell a little bit, to bring it down in line with others. You have many choices and MiniBMS is here to protect your battery investment, even at the cost of somewhat incomplete charge. You may soon realize that small amounts of charge at the end of the charge cycle are not all that important and not worth risking overcharge of individual cell.
> 
> 2. You must disconnect the charger before turning Ignition on. Once ignition key is on, BMS will reset HVC circuit to prepare it for the next charging cycle.


 
The relay is supposed to latch so the charger remains off, not come back on as Davide shows. That is how his and the Manzanita (Edit: Rudman Regulators) bms work, but not the minbms.


----------



## PeterH (Mar 20, 2009)

Thank you Davide, I actually ran across your videos last night and watched the same one you linked me to in this thread. 

What you are saying in the video makes sense but as I understand the MiniBMS, it shouldn't be doing what I've observed. This is the source of my current distrust of my setup.

You suggested a wiring problem. Do you have any thoughts on what that might be? I think later today, after a trip to town, I'll set up a video camera and my meters to visually capture the behavior at the end of the charge. I'm not a trained/educated electrical engineer, just a Instructional Designer/Computer Programmer with too much time on his hands. 


On some of your other responses to my thread:

I said "accidently" in one of my comments because I had intended to be present to manually end the charge. I either didn't hear my timer go off or hadn't set it. I think this happened just after I installed the replacement charger. I had switched from a 4KW TCCH charger to a 2.5KW Elcon. As you know, basically, the same charger but with the Elcon, I got much better information from the source in Sacramento that I did from TCCH in China. The factory wouldn't provide any information about the charging program they installed. The Elcon came with that information neatly attached to the side of the charger.

I also say it isn't working because it does let my weakest cell exceed the cut-off voltage of 3.65. While it is certainly working in some manner, it isn't behaving as expected which leads me to question the entire setup. By now, after roughly 180 charge cycles, shouldn't the BMS have top-balanced those two weak cells? I honestly don't know, but I would think so.

Yes, recalling watching your video, the BMS does seem to be controlling the charger as you suggest it should in order to properly charge these cells. But since that wasn't the designer's intention (at least not as far as I know based on his documentation (thanks tomofreno)) it suggests a problem with something within the BMS.

So here is my plan. I'll set up another charge this afternoon and keep very careful records of what happens. I'll try not to panic as my weak cells exceed 3.65 and record what happens. I'll post those observations and a video link here and see what everyone thinks. This will do two things. First it will ensure I'm relating facts about my setup and secondly, it will give me solid data to send to Dimitri to see what he thinks.

I probably won't be able to get all that information posted till this evening after I've edited the video.

Thanks,
Pete


----------



## PeterH (Mar 20, 2009)

Weisheimer said:


> OK, here it is. Look familiar? :^>
> 
> The 5 pin female connector that I refer to is at the top of this picture, just to the right of center.
> The button is at the far right, centered vis top to bottom and the red led is just below the button.


 Yes, this looks familiar if mentally flip the image and imagine the case in the image. I haven't cracked the case on this charger and hope to avoid doing so. 

I'm guessing there isn't an easy way to access that button behind that plastic shield, is there.... ?

Pete


----------



## racunniff (Jan 14, 2009)

PeterH said:


> You suggested a wiring problem. Do you have any thoughts on what that might be?


I see you have multiple centralized boards. You should check the jumpers on your BMS board stack. Per the documentation:



> Each board has 3 jumpers, which set the role of each board. Bottom board in each stack must have a “Bottom” jumper installed. If entire system is in one stack and there are no remote stacks, then “No Slave” jumper must be installed on Master Board only. “Top Slave” jumper is only installed on top board of remote stack. Middle boards have no jumpers at all. Each board has board-to-board connections in 4 corners, so one board plugs into the next board. Two adjacent boards must be shifted 0.1” to match connections. When mating more than 2 boards, shift them in a zigzag pattern to make vertical column.


----------



## PeterH (Mar 20, 2009)

As planned, I recorded on video the final stages of my charge cycle. I used 3 cameras. It took longer to render and post than expected so by 11 PM last night I'd had enough and finished it this morning.

I captured the BMS cell status lights so we can see what was shunting and what wasn't, the pack voltage on one meter face and the weakest cell's voltage on another meter, and finally, the amp hours accumulated and amps being pused into the pack. I added timecode to the final video to make referencing easier.

I let the BMS switch off the charger 5 times before I manually disconnected the power.

Each period of charge, after the first, was shorter and the peak voltage on my weakest cell higher. The max it reached was 3.7902vdc at the fifth termination of the charge. Between the first cut off and the fifth, I gained only.8 amp hours of capacity. Which is hardly worth the effort and certainly not worth the wear on my weakest cells. The BMS was clearly swiching the charger off and then on again when it should just switch it off and keep it off until the next time.

I've posted this oh-so-exciting video at this URL. I rendered the video at twice the normal speed but the timecode embedded in the video will help identify the important spots. No audio other than the alarm sounding when the BMS shuts off the charger.

http://www.petehoyt.com/download/Elcon/chargeSequence.html

As the video starts, the charge has been underway for over 3 hours and is nearly finished. The charger has started reducing current because it has entered the CV stage. Normal output is 16.5 amps with this charger and the video picks up as it goes down through 16.2 to 16 amps when the first BMS charger shut down occurs.

You can jump to the point where the BMS shuts of the charger at the times shown below. The first number is the time code of the video and the second number is the pack voltage at that point, followed by the peak voltage of my weakest cell.

First: 05:31:10 157.2vdc 3.6389vdc
Second: 08:37:29 157.1vdc 3.6849vdc
Third: 11:23:01 157.1vdc 3.7503vdc 
Fourth: 13:38:04 156.9vdc 3.7708vdc
Fifth: 15:37:04 156.7vdc 3.7902vdc

Immediately after the charge, I drove 1.9 miles to 'burn off' some of the charge because this exercise had charged these cells higher than they have been in a long time. After that drive, I measured the voltages on all of the cells. The lowest voltage was 3.3297 vdc and the highest was 3.3388 vdc with the average voltage on the cells of 3.3357 vdc.

I think this confirms that the BMS isn't behaving as I expected. Had it not re-engergized the charger after the first shut down, I'd be happy. Right after installing this charger, I watched the weakest cell exceed 3.75 on the first (main) cycle. Ever since, I've watched it and shut down the charger manually.

So, I still want to back down the Elcon one cell.

Thanks,
Pete


----------



## racunniff (Jan 14, 2009)

PeterH said:


> The BMS was clearly swiching the charger off and then on again when it should just switch it off and keep it off until the next time.


Do you have *keyed/switched* +12V going to the IGN pin on the head-end board, or is it always on? If it is always on, that *might* explain it:


----------



## dladd (Jun 1, 2011)

PeterH said:


> First: 05:31:10 157.2vdc 3.6389vdc
> Second: 08:37:29 157.1vdc 3.6849vdc
> Third: 11:23:01 157.1vdc 3.7503vdc
> Fourth: 13:38:04 156.9vdc 3.7708vdc
> Fifth: 15:37:04 156.7vdc 3.7902vdc


Seems like the charger is doing just fine, 45 cells x 3.5vpc = 157.5v, you are pretty close to that! I think the issue may just be that your cells aren't balanced. Did you balance them upon initial install, or are you relying on the MiniBMS to do it? Not a good idea to let the MiniBMS do it, cause it's sooooo slow to balance. It's pretty easy to knock down/pull up a few cells one at a time, it's been pretty well documented around the forums here.

You still have an issue with the BMS letting the charger restart off I think, but in terms of adjusting your charger... if you want to be charging to 3.5vpc, it's already there.

Weird also that as you go down your list of data points there, the termination voltage goes down, but the cell voltage goes up. Seems counterintuitive to me, since it should be shunting that high cell a little bit each time.


----------



## Elithion (Oct 6, 2009)

Hello Peter,
Very nice job! Thanks for sharing, and I compliment you on the care you are showing towards your pack.



PeterH said:


> I think this confirms that the BMS isn't behaving as I expected.


OK.

But is it misbehaving?
No.
It's behaving exactly how most of us BMS designers believe a BMS should behave.

Is it behaving in a way that is different from what we are told that the MiniBMS is supposed to behave?
Yes. 
It's behaving better than the way the MiniBMS is supposed to behave.

The difference is:


Go off once: it takes 10 days to balance
Go on and off: it takes 10 cycles to balance on the first day
In the long run, it makes little difference, because, once the battery is top balanced, it tends to stay top balanced.



PeterH said:


> ... 3.6389vdc ... 3.7902vdc


Those are the voltages when the charger goes off. But those voltages will quickly settle down ( end of IR drop due to charging current, and brought down by the balancing loads) so those voltages are fine.

Please find comfort in knowing that the damage resulting from higher cell voltage is gradual:


there is no "wall" that, once you cross it, the cells are suddenly damaged: it's a gently sloping curve of increased damage vs cell voltage
the damage / time is very small; it is only when kept at high voltage for a long time that the damage starts getting apparent


----------



## dimitri (May 16, 2008)

PeterH said:


> I think this confirms that the BMS isn't behaving as I expected. Had it not re-engergized the charger after the first shut down, I'd be happy. Right after installing this charger, I watched the weakest cell exceed 3.75 on the first (main) cycle. Ever since, I've watched it and shut down the charger manually.
> 
> So, I still want to back down the Elcon one cell.
> 
> ...


Pete, you are correct, miniBMS is not supposed to allow the charger to restart, since HVC behavior should be latching. I suspect you did not wire BMS correctly. IGN terminal controls latching behavior, it should not have any voltage on it during charge, please check that. Also, check that you wired charger control to HVC terminals , not LVC terminals on the top board. Otherwise your BMS is working well, but you should have manually done initial pack balance, we have a PDF paper published on this subject at our Web store, in Product Support section.

The reason HVC trips a little higher than 3.6V is due to voltage drop across cell wires during shunting. This is perfectly normal and as Davide mentioned, this does not damage anything since this voltage is only there for a brief time and settles back as soon as charge is terminated.

However, if your charger is programmed with 10 steps, you should be able to step it down one notch, to minimize shunting at the end of charge. The button is recessed inside the hole, you must use a pencil to reach it and press it.

If I were you I would do all 3 things, balance the pack, fix the HVC latch and step down the charger.


----------



## PeterH (Mar 20, 2009)

Hello Dimitri,

I appreciate your advice and I'll try to follow it. 

I have my EV on a charge cycle presently and I attempted to measure voltage between the ground connection on the BMS top board terminal and the ingnition connection. At the most, during a charge, I am measuring .0074 volts. I am measuring this with my Fluke meter which of all my instruments, I think is the most accurate. Is that small amount of voltage enough to cause the problem I am having?

I have also verified that the red and black wires from the Elcon are correctly attached to the H-Com and H-NC terminals on the top board. I don't have anything else connected to the top board other than the +12V, GND, and IGN connections.

I've printed the pack balancing PDF file you mentioned and I'll review the instructions again.

I still haven't been able to step down the Elcon to indicate I'm only charging 44 cells. But I'll get a little more agressive with my effort. I'm sure my son has a stubby pencil around here somewhere I can borrow. 

I'll post a report detailing progress on this issue soon as I have anything new to report.

Thanks,
Pete


----------



## PStechPaul (May 1, 2012)

You might consider using a power rectifier bridge in series with the pack, so it would be two diode drops in series, or about 1.5 to 2 volts. The voltage drop will decrease with higher temperature and also with lower current, which may help with tapering off the end of charge. You can get a 25 amp bridge for about $1.00.


----------

