[kennybobby]

pdove had a similar incident which prompted the troubleshooting and repair of the TCCH/Elcon charger thread.

Did your pack ever get overdischarged down to a very low level, or hit any sort of low voltage limit?

i consider Full voltage as 3.33 volts per cell for that chemistry--and feel that there is no benefit to charge higher.

It sounds like your charger is set to charge to 156 for the pack, but the CV stage cutoff current limit was never reached to turn it off. This could happen in a pack with one damaged cell, and if held long enough will damage other cells, such as you have experienced.

You may be able to use the tiny push button on the control board to adjust for lower voltage, depends upon what table was used to program the button settings, and if this is listed on the charger label or tag.

 

[Joker1]

Yes my pack did get very low once and I lost one cell because of that and it seem like I also get an alarm for low voltage when ever I drive the truck and have replaced four more cell since then. I know right now that another cell is bad because the low voltage alarm goes off when I drive the truck but don't want to replace it until I fix the problem. I will try what you said and see what happens and I want to thank you for your help.

 

[kennybobby]

You may want to survey your pack by using a voltmeter to check each individual cell voltage and see how closely balanced they may be. Keep a log of this over time and you may see a trend. If one or more gets out of line with the others, then that can aggravate the UV alarms and OV charging situation.

 

[Joker1]

You may want to survey your pack by using a voltmeter to check each individual cell voltage and see how closely balanced they may be. Keep a log of this over time and you may see a trend. If one or more gets out of line with the others, then that can aggravate the UV alarms and OV charging situation.

I have been checking the pack voltage with a voltmeter since I first did the balancing charging and have even made up an excel spread sheet to keep track of the batteries voltage. I have done this many times and have spotted bad cells doing this, but what I don't understand is that the bad cell I have now shows the voltage well within the voltage range of the rest of the pack, but under a load the LED light on the BMS board on that battery goes out indicating a bad battery.

 

[pdove]

Sounds like a BMS problem to me. I never used a Mini-BMS but if you draw a picture of the way it is wired we might be able to solve this. You BMS should shut off the charger if a high voltage event is detected. It is definitely not a charger problem.

 

[Joker1]

I am sorry for the delay in getting back to you but I had a hard time uploading my diagram to the website. I am not much of a draftsman but I hope this will help you to see how I connected my BMS boards to the various components on my truck. If you have any questions and I am sure you will I will try and explain as best as I can what I did.

 

[kennybobby]

Looks like 2 copies of the same drawing?

Where is the charger?

What are the items on either side of the Hall Sensor, and the box above it?

 

[Joker1]

Looks like 2 copies of the same drawing?

Where is the charger?

What are the items on either side of the Hall Sensor, and the box above it?

You are right there are two copies of the same drawing I was having so much problems up loading the picture that I just wanted to make sure I got at least one picture uploaded. I didn't realize it until now that I didn't put the charger in the drawing I knew I would screw up something I will redraw the diagram with the charger and get back to you with that. The two items on either side of the Hall Sensor are battery cells connected with a copper bar that run through the Hall Sensor as all the cell are connected with copper bars. The box above the Hall Sensor is actually a circuit board that is connected to the Hall Sensor in other words it is all one piece of hardware.

 

[pdove]

Here is the diagram from the company literature.

 

[pdove]

The manual says that the high voltage cut off may or may not turn off your charger depending on the setting you use. HVC is selected at time of purchase..... so you need to find the value for yours.

You have 45 cells which can charge up to 3.65 volts per cell with a normal Elcon charger which would be 164.25 volts. You claim it reads 156V but that is only 3.47 volts per cell so that tells me that the charger if off at that point but hard to tell bu what you have said.... usually a CALB cell will read 3.38 volts after the charger shuts down and it has time to settle.

What voltage is your charger set to terminate and what HVC is your BMS set to? You appear to have a disconnect here.

 

[Joker1]

Here is the diagram from the company literature.

Frist of all how in the heck did you upload those diagrams I had one hell of a time getting my diagram uploaded? I have been looking at the instructions I got with the charger and it say's that the round eight pin connection on the side of the charger need to be twisted together using a wire cap. Now looking at the diagram I can see that the way I wired mine up the charger is never in the wiring loop. I feel like an idiot if the charger is not hook-up in the loop somewhere there is no way for it to turn itself off. I will wire the charger according to the diagram you posted and see what happens.

 

[pdove]

First save your file to your computer.
Click on post reply.
Click on paperclip symbol.
Click on browse and locate you file.
Click upload.
Close that window
add any test you want in the message.
Click on submit reply

 

[Joker1]

First save your file to your computer.
Click on post reply.
Click on paperclip symbol.
Click on browse and locate you file.
Click upload.
Close that window
add any test you want in the message.
Click on submit reply

I wonder if my problem was that I was scanning the diagram then saving it to my computer. When I did as you described about and tried to upload the file it would also add a .tif extension to my document and then wouldn't upload it for me. The only work around I found was to take a picture of the diagram and then it uploaded perfectly.

 

[Joker1]

I wanted to get back to you and tell you I think the problem with the Elcon charger is fixed. I charged the battery pack last night and the Elcon charger shut itself off and I waited until this morning to check the voltage and it was 150v I then checked twenty batteries out of the pack and they where all within .008mv. Thanks so much for talking me through this problem now it seemed so obvious. If you would mind could we go on to the next issue I am having when I test drove the truck today and this has happened every time I drive the truck since the first time I test drove it. I get up around 200amps and the BMS system starts alarming the truck will still excel and runs normal. What is causing this to happen?

 

[kennybobby]

Re: BMS Problem

i would guess that the BMS is seeing a low pack voltage and sounding/setting the Under-Voltage alarm signal.

you could test this by putting a voltmeter across the pack and watch what happens to the voltage when you accelerate down into the 200 Amp region. Depending upon the age and condition of the cells, etc. it may be dropping 50 volts or more from the at-rest voltage, and this may be below the BMS setpoint.

 

[Joker1]

I got a digital fuel gauge in the truck and it monitors volts watts and amps. When I went on my test drive today I watched the voltage and amps on the gauge to see what is happening. When I first started the truck I had 150v on the gauge and I checked it with a voltmeter to make sure it was right. I then operated the battery pack under different conditions to see what happens. When I floored the truck the alarm went off at around 50amps but once I got going it wouldn't go off until around 200amps like I said. The total voltage would drop from 150v to around 142v to 146v once I got rolling and one time it went down to 138v but that is the lowest I ever saw it get. The battery pack is around five years old but most of that time the batteries were sitting in boxes they probably have been in use for about two years and that would be very minimal use at that. Just a thought I was always driving the truck in 2nd gear if that makes a difference.

 

[kennybobby]

If the sample rate of the digital fuel gauge is too slow, then you may not see the under-voltage during acceleration.

How are you measuring current--Is it the same digital gauge? What is the update or sample rate?

 

[pdove]

What Kennybobby said may be true but if I am not mistaken the BMS is looking at individual cell voltage so a single cell can cause the alarm which you may not see in the pack voltage. Can you set up a camera to watch the leds and see which cell is the culprit or do the leds latch on. I never used one of these Mini BMS before. Maybe have someone else watch the less while you drive if that is possible

 

[Joker1]

What Kennybobby said may be true but if I am not mistaken the BMS is looking at individual cell voltage so a single cell can cause the alarm which you may not see in the pack voltage. Can you set up a camera to watch the leds and see which cell is the culprit or do the leds latch on. I never used one of these Mini BMS before. Maybe have someone else watch the less while you drive if that is possible

Here is what I came up with to find the problem I first checked the cells voltages. I jacked up the rear wheels and put them on jack stands then I put the truck in 5th gear and had someone run the accelerator peddle until the BMS alarm started buzzing I was watching the BMS boards on the battery cells to see if one would go out. One did go out and I checked the voltage while it was out and it sagged down to 2.51v before the test it was 3.34v. I checked an hour after the test and the voltage was back up to 3.34v so I am assuming that battery cell is bad but why? This will be the 5th battery I have had to replace.