Overkill Solar Problems Leave Me Stranded

[sshibly]

I think I saw that same symptom in other thread and it turns out to be bad crimping on the terminal of the balancing wire.

I HATE those squishy crimp connectors, I repeat, I hate them, I have worn finger joints and I don't like to over use them, but with these squishy ring terminals I can never get a good crimp,

OP, please cut off all the ring terminals off your balance wires and strip out an inch of bare wire and twist it around the screw and tighten.

For any system that sustains you, I would suggest having a backup item.

 

[JoeHam]

@Craig used to stock Chargery BMS and got a 16s to me in 3 days when I purchased one a year ago.

 

[moonlitsouls]

BTW, did you at one point disconnect the BMS sensing from the battery pack while the B- wire is still connected? Some BMS states that you must remove the BMS sensing cable plug from the BMS first before disconencting the B- cable otherwise the BMS can be damaged.

I am chatting with a guy on FB that may have an extra. Let me know if you don't get this one working.

I think I saw that same symptom in other thread and it turns out to be bad crimping on the terminal of the balancing wire.

The unit from LTT given in the above post should arrive quickly as they send air mail. Its the same as sold by Overkill but without the cable options that Overkill offer.
From,

4S or 3S 12V Li ion or Lifepo4 Battery smart BMS with Bluetooth function UART and RS485 communication with 60A to 120A constant current - LLT POWER ELECTRONIC

1) Application:this smart BMS can work for 3 to 4S Lithium ion or Lifepo4 Battery ,client can choose based on your battery chemistry features 2) Current : constant current of this version BMS can be made with 40A to 120A in accoridng to the different demand 3) Dimension: :Max 138*102*15mm for...

www.lithiumbatterypcb.com

You can pay with Paypal, shipping to the UK was 6 days.

Regarding the issues you are having, you may have already carried out the following but this is the method I used.
Withe the balance leads disconnected from the BMS connect to the cells taking care the white leads are in the correct order.
Connect the blue power cables to the battery negative, then connect the balance connector to the BMS.

If any work is carried out on the battery or leads to the BMS, the balance connector must be unplugged first.

If the sequence is not followed there is a possibility of damage to the BMS.

The voltage readings are way off for cells 1, too low, and 3, too high. Have you confirmed that these are the actual voltages with a meter?

If cell 3 actually has a voltage over 14 volts it may be damaged and needs discharging to a safe level.

Mike

2.646​	cell 1
3.020​	cell 2
4.263​	cell 3
3.310​	cell 4
13.239​	Battery total
3.310​	average per cell

Connector, crimp or whatever, we've seen this before. Something is so poor a connection, the input bias current of a chip pulls the voltage. Or it's just an open-circuit capacitance, floating.
You're almost there.

i appreciate the replies , the photo with the different ranges was taken prior to the photo below , it was believed that this varied range of voltage was due to bad crimping as i was having a problem getting the right sized terminal connectors

i purchased the correct size , recrimped , checked each cell and it read 3.4 volts , then i ran down the harness of the balance cable (without the harness attached to the BMS) and each individual wire on the harness of the balance leads matched the cells at 3.4 , does this not rule out the crimping completely? after that , i attached the balance lead harness to the BMS and this photo below is how i left off

pls confirm that i can rule out the crimping completely based on the verification done at the balance lead harness


if this does rule out the crimping , what do you suggest as the next step to troubleshoot? thanks
adam

 

[Hedges]

Good voltage at battery and at end of harness pretty much shows crimp, ring, wire are OK. Possible to have high resistance, still sufficient continuity for DMM to show voltage. Ohms reading from terminal to battery to connector pin would check that, but I wouldn't even bother at this point.

What I recall being another member's issue was connection between harness and BMS. Is that an unreasonably small connector? Could be flaky.
I'm not sure how to best deal with that; maybe another harness with new pins in the connectors. I forget of the other guy found the pins were loose and crimped new ones, or something else. Are you able to probe pins of connector on PCB (without shorting to metal plate of BMS) and check voltage & resistance of lead + connector?

 

[sshibly]

OP, you post is bit confusing for me:

1. Take the voltage of each cell at the cell terminals

2. take the resistance reading from the BMS ring terminals to the bms connector pin outs,

Did you cut off the rings?

 

[moonlitsouls]

OP, you post is bit confusing for me:

1. Take the voltage of each cell at the cell terminals

2. take the resistance reading from the BMS ring terminals to the bms connector pin outs,

Did you cut off the rings?

i checked the voltage of each cell of the battery , 3.4

then i attached all the balance lead cables and checked the voltage of each individual pin shown here and it matched 3.4 for balance lead 1 , 2 , 3 and 4 , it seems this would rule out any crimping issue

then i plugged in the Balance lead harness end into the BMS and it showed the reading above .1 .1 .1 .1 , and the error message

 

[moonlitsouls]

The unit from LTT given in the above post should arrive quickly as they send air mail. Its the same as sold by Overkill but without the cable options that Overkill offer.
From,

4S or 3S 12V Li ion or Lifepo4 Battery smart BMS with Bluetooth function UART and RS485 communication with 60A to 120A constant current - LLT POWER ELECTRONIC

1) Application:this smart BMS can work for 3 to 4S Lithium ion or Lifepo4 Battery ,client can choose based on your battery chemistry features 2) Current : constant current of this version BMS can be made with 40A to 120A in accoridng to the different demand 3) Dimension: :Max 138*102*15mm for...

www.lithiumbatterypcb.com

i found a guy on ebay with this exact unit, he quoted me $30 USD to use DHL expedited shipping about 7 days from China , if i cant get my bms to work within the next couple of days im going to go with that

 

[Hedges]

View attachment 43592

i checked the voltage of each cell of the battery , 3.4

then i attached all the balance lead cables and checked the voltage of each individual pin shown here and it matched 3.4 for balance lead 1 , 2 , 3 and 4 , it seems this would rule out any crimping issue

then i plugged in the Balance lead harness end into the BMS and it showed the reading above .1 .1 .1 .1 , and the error message

We don't know for sure pins of that plug makes contact with pins of connector on BMS.
Are you able to connect it and then probe pins on BMS?

i appreciate the replies , the photo with the different ranges was taken prior to the photo below , it was believed that this varied range of voltage was due to bad crimping as i was having a problem getting the right sized terminal connectors

I thought your first photo showed all 0.1, then you connected another battery wire to BMS and got the varied voltages which were almost correct. Now you're back to all 0.1; was anything left disconnected this time?

 

[moonlitsouls]

We don't know for sure pins of that plug makes contact with pins of connector on BMS.
Are you able to connect it and then probe pins on BMS?




I thought your first photo showed all 0.1, then you connected another battery wire to BMS and got the varied voltages which were almost correct. Now you're back to all 0.1; was anything left disconnected this time?

no no i just showed the varied photo because thats what it was showing prior to me fitting the last crimps , i am sure its confusing , it is for me too. When we saw the varied voltages everyone assumed it was the crimps so i fixed them and now the .1

but confusing because people told me if you're able to verify the voltage matches the pins in the harnesss then it cant be the crimps , so why no voltage in the BMS app?

I am going to attempt to reassemble tomorrow and check the pins after connecting the harness into the bms, do i just repeat the same process of putting the negative lead of my multimeter to the black wire and running down the harness? im not sure what to do once the harness is connected to the bms to do your test

 

[Hedges]

The BMS has a metal plate. Make sure you don't tilt the probe and short between pin and plate:



You can check between adjacent pins on the connector. That should show cell voltages.
You can check voltage from pin on connector to corresponding cell terminal. That should be zero.
You can check resistance from pin to terminal. That should be low (a few ohms at the most.)

If you can get back to the state of having varied voltages between 2.x and 4.x, averaging 3.3V or 3.4V, then the problem is bad connection in test leads, somewhere between cell terminal and BMS. Building the harness involved crimping pins on wires and inserting them in the plug. For a lot of connectors, the crimp tool is $500 to $1000 (manual tool), and without the right tool it is hard to assemble well.

What causes all 0.1V readings, I'm not sure. That means it has power to display something, but apparently no data.

 

[sshibly]

op, what is your max amp draw?
4s1p?

how are you charging it? max charge amps?

next thing to try if you have not:
1. RESET the bms - look up steps in the manual.

 

[nwillitts]

batteryhookup.com has that bms.well,its rated at 100AH.same BMS Manufacturer.works the same.
i bought one 2 weeks ago when i discovered the problems overkill was having.
i have one back ordered from them now for a month.

Li-ion/Lifepo4 3s-20s 100a BMS W/ LOW TEMP CUTOFF

--------------------Here are 100a BMS units. We carry 3s-20s and both Lithium Ion (Li-Ion) and Lithium Iron Phosphate (Lifepo4). The lithium ion version also works with Lithium Polymer (Li-Po) since they both have the same parameters. (WIRING DIAGRAM BELOW!) Some of the BMSs arrived without the...

batteryhookup.com

 

[moonlitsouls]

For the record overkill solar sent me another BMS and it’s working , thanks @OverkillSolar

 

[nwillitts]

got mine today.

 

[time2roll]

My order from Mar 20 arrived today.