New lifepo4 280ah build was charging fine then rapidly charged and now show 0 charged with overkill solar 120a bms

[tsunami3775]

I got these instructions from overkill solar.. gonna try these steps now.

I have a couple comments /questions

• you can start by disconnecting the B- on the BMS from the cells and the balance line harness, let the BMS power down (10 seconds) and reconnect. May or may not be needed.
• I think you have a loose balance lead that's why the voltage is jumping all over. Take a look at the pic below, you should change the balance lead ring terminals they are too big for the bolts you are using (or maybe put them underneath like on cell 4)
• Also I would recommend changing out the terminal bolts you are using with a stud and nut pic below. (as long as you are going to the hardware store for smaller ring terminals) We find that the bolts can bottom out in the cell and even though it feels tight it is not. I do see you are using multiple nuts below the crew head so you may be ok but not great.
• did you top balance the cells?
• I see one screen shot where all the cells are at 3.307 ( I am guessing first reading from the factory?)
• the Dr meter is a bench power supply? I am guessing its ok, You could use this , once the connection issue is resolved, to get the battery near full, but you will want to top balance at the end .
• I would change the Cell minimal voltage from 3000 to 2500. these numbers are used by the BMS to calculate SOC nothing else. The protection #s will stop/start the BMS.
• I would also change the Cell % Cap. voltage #s to match your cells SOC chart. If one did not come with your cells I would start with a straight line 3350,3300,3250,3200.

 

[bgflyguy]

If you measure 3.3v at the cells even under load, the batteries are fine. The issue looks more likely to be a bms issues or wiring issue. I would trust a multi meter over the bms reading.

 

[Freep]

Plug the bms back in (make sure the bms is completely powered off), if the cell balance problem continues - contact the vendor - see if they have any other ideas . At that point I would guess a manufacturer error.

But also change the order of the cells and see if the problem stays with the cell.

 

[time2roll]

ok no resolve yet, I made some better crimps and connections. Fixed some kinks in balance cable but still get this reading. Multimeter on each cell read 3.302. All balanced. I did clean the terminals with alcohol also. I’ll read above to see if I missed any other suggestions. Any other ideas?

This picture in post #14 says the balance leads have an issue still. Check the sequence again and pull test the crimps.

 

[bgflyguy]

Yes, I agree with all of the things overkill recommended. The terminals and bolts looks sketchy, but if you can't get a similar reading with the mm it doesn't mean they are causing the issue.

 

[Freep]

• I think you have a loose balance lead that's why the voltage is jumping all over.

Also the crimp on the lead might not be great. I've had crappy leads result in the same symptom.

 

[tsunami3775]

Yes, I agree with all of the things overkill recommended. The terminals and bolts looks sketchy, but if you can't get a similar reading with the mm it doesn't mean they are causing the issue.

Where do u get your studs? Home Depot carry them? And how do u tighten them without having a head to them? Beginner questions here

 

[tsunami3775]

This picture in post #14 says the balance leads have an issue still. Check the sequence again and pull test the crimps.

Could be it. My crimper doesn’t go that tight. Just ordered one that does smaller wires

 

[bgflyguy]

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

There is a thread on how to install the grub screws. Use loctite on the screws and torque the nuts to spec.

 

[time2roll]

Could be it. My crimper doesn’t go that tight. Just ordered one that does smaller wires

I recommend non insulated ring terminals to get a better crimp on the tiny wires.

 

[Rocketman]

I got mine at McMaster too.

Batrium Watchmon Install

Tonight I finished my battery capacity test on the Fortune 25ah batteries. Success!!! I charged the battery up to 14.4v (3.6v each. Then I turned on anything I could. I had a small 150w 12v inverter - plugged a computer into it. Had a 12v fan and a 12v LED light - with all that stuff I was...

diysolarforum.com

Instead of using locktite, I used silver epoxy. There are several pictures on the above thread (page2). You hold the grub screw with an Allen wrench to tighten and while tightening the bolts down.

 

[tsunami3775]

I got mine at McMaster too.

Batrium Watchmon Install

Tonight I finished my battery capacity test on the Fortune 25ah batteries. Success!!! I charged the battery up to 14.4v (3.6v each. Then I turned on anything I could. I had a small 150w 12v inverter - plugged a computer into it. Had a 12v fan and a 12v LED light - with all that stuff I was...

diysolarforum.com

Instead of using locktite, I used silver epoxy. There are several pictures on the above thread (page2). You hold the grub screw with an Allen wrench to tighten and while tightening the bolts down.

Is this one good?

MG Chemicals 8331D Silver Conductive Epoxy Adhesive, High Conductivity, 20 min Working time, 2-Part, 14 Gram Kit https://www.amazon.com/dp/B08K3TG5D9/ref=cm_sw_r_cp_api_glt_fabc_V1BSXQJC40P9TQQR0678

 

[Rocketman]

No idea… the one I used was from Atom adhesives. Remember you only get one chance when using epoxy.

 

[tsunami3775]

No idea… the one I used was from Atom adhesives. Remember you only get one chance when using epoxy.

Ok maybe I’m not ready for that yet

 

[tsunami3775]

Ok maybe I’m not ready for that yet

Overkill solar sent me this in depth guide to their BMS in. Case someone wants to reference it. I ordered all my new bolts, torque wrench, ring terminals. I’ll continue project this weekend when it arrives and update the thread. Thank you everyone

 

[tsunami3775]

I just put the batteries in parallel.. no terminals yet but realize one is bulging. Is it ok for me to use this or too dangerous?

 

[HRTKD]

Go back to the first post and look at the very first picture, focusing on the top cell and the positive terminal. The BMS balance lead is UNDER the fuse mount. That's not right. Also, I think there is a recommendation that the type of fuse you're using is NOT to be attached to a cell terminal.

Check all of your bus bars to make sure that the black insulation isn't extending onto the cell terminal surface.

Current is to flow through the horizontal disk portion of the cell terminal. Current doesn't flow through the terminal post, at least not much.

At least half the voltage issues seen on the forum are caused by a loose connection.

 

[tsunami3775]

Go back to the first post and look at the very first picture, focusing on the top cell and the positive terminal. The BMS balance lead is UNDER the fuse mount. That's not right. Also, I think there is a recommendation that the type of fuse you're using is NOT to be attached to a cell terminal.

Check all of your bus bars to make sure that the black insulation isn't extending onto the cell terminal surface.

Current is to flow through the horizontal disk portion of the cell terminal. Current doesn't flow through the terminal post, at least not much.

At least half the voltage issues seen on the forum are caused by a loose connection.

Noted thanks,

Go back to the first post and look at the very first picture, focusing on the top cell and the positive terminal. The BMS balance lead is UNDER the fuse mount. That's not right. Also, I think there is a recommendation that the type of fuse you're using is NOT to be attached to a cell terminal.

Check all of your bus bars to make sure that the black insulation isn't extending onto the cell terminal surface.

Current is to flow through the horizontal disk portion of the cell terminal. Current doesn't flow through the terminal post, at least not much.

At least half the voltage issues seen on the forum are caused by a loose connection.

yah I tried moving them around but didn’t change anything. Now I got a new problem.

 

[tsunami3775]

Measure the cells directly with a multimeter - how does that compare to the bms values? (I bet the cells are just fine).

You need to isolate the problems, and think through them logically. (Very hard to do on your own battery- that’s why we are here to help).

My guess… if you add up cells three and four on the bms - they total about what two cells should be. So I think your #3 or #4 lead is loose (either on the battery or wire loom or bms).

After verifying your cells are ok, maybe completely disconnect to bms and then reattach. Looking very carefully at the leads for #3 & #4. (Especially anything you did - crimps, etc).

If it continues try the wiggle test - while running and looking at the display- wiggle one wire (a little) to see if you have a bad connection there. Check all connections.

My guess is you have a bad connection somewhere… there is also a chance you have a bad bms. The challenge is figuring out the problem.

Hey Rocketman. I got a new problem. I stripped 2 of the terminals. I literally was being as careful as I could and set my torque wrench to 4. But it didn’t click and then it just got loose again. I really don’t know how to avoid that. I thought people were being wreckless to have this happen but truth is these things are fragile. Im going to read up on helicoil to fix this situation but if you or anyone had suggestions please advise. I don’t have access to any heavy duty tools. Thanks

 

[HRTKD]

I would certainly try the helicoil before going with more severe solutions.

Tou said you had your torque wrench set to 4. 4 what? 4 nm, 4 lb/in, 4 lb/ft?