BMS problems (?)... please help! (edited)

[RyanNicholas]

Help! I'm not sure my bms is working right... I'm a newbie and recently put together a 12v life lifepo4 battery from 280ah eve cells... everything has been working fine for weeks, but today I woke up before sunrise and my charge controllers screen was completely blank and I was getting no power. When I volt test the cells they all read around 3.3, and the whole battery read around 13.2 *from the terminals* - BUT when I read from the external contacts (ie, with the bms involved), it was only reading 0.70. Why would it do that? My SmartBMS app was (and still is) showing a "0%" SOC - But that makes no sense because this is a fairly sizable battery bank and I haven't been using anywhere near enough power to fully discharge the battery. It was Sunny all day down here in Mexico yesterday, plus I did a fair amount of driving during the day and have an isolator routed from my vehicle battery.
Since the sun has risen, the direct volt readings on the battery/cells have stayed pretty much the same - but the reading from the outer contacts (with bms) has risen to just over 5v. (*also, as I've been typing this, the fan started running, weakly..) The charge controller has gone from a completely dead LCD screen to a Lit up low battery flashing mode. As far as I can tell this all seems to imply that the battery was actually dead and is beginning to charge up from the solar panels. But I just don't understand how that's possible. I really need to figure this out, because I'm not exactly in a familiar place. Please help!

 

[curiouscarbon]

Hello Ryan,

I’m sorry your bms isn’t working right.

Could you share the model of bms?

What’s the wiring like?

Any pictures or additional information is welcome too if you’re interested in sharing.

 

[RyanNicholas]

Yes, I accidentally hit the post button when I wasn't finished typing it all yet. It's a "Daly" bms (although it doesn't say Daly) from Alibaba. And what's even more puzzling is that just now, somehow after less than an hour of sunlight, the battery seems to suddenly be in full working order again and is reading at around 13.1 volts on the outer contacts. I'm totally confused at this point.

 

[RyanNicholas]

I do have the battery isolator setup with this thing, which does involve a grounding wire going from the battery to a metal spot on the wall of the van. Could that be draining the battery somehow? It's how the isolator was supposed to be set up with it, and it hasn't been giving me this problem for the last few weeks that I've been using the whole system.

 

[RyanNicholas]

These are the voltage parameters currently set in the BMS. It seems to me as if it was denying power flow to the external contact, as if it needed to because the cell voltages were low or something. But as I said before, they were all reading at around 3.3, or 13.2 in series. These are notably higher readings than the cell volt and sum volt low protect settings in the BMS. Also, although my fridge turned back on and things seem to be functioning in the van now, my BMS app is still showing a 0% state of charge.

 

[Just John]

All I can tell you is that the BMS seems to have turned off charging and discharge for no apparent reason. You may have a defective BMS.

 

[HRTKD]

On your app screen there is a message that there has been a temperature issue. Track that down.

 

[Kesa32]

I read somewhere you have to change the "sleep" settings too so it doesn't turn off after a certain amount of time of no use...……..I doubt this has anything to do with your problem, your settings are the same as mine , but im still setting up mine battery box wise so haven't really ran it much yet
Sounds like its working again ( bar the 0 v reading ) ….l guess check all your connections just in case , but yes a bit odd hey

 

[RyanNicholas]

On your app screen there is a message that there has been a temperature issue. Track that down.

There definitely has not been a temperature issue. I'm in Baja Mexico, and the temperature range down here has been very much in the ideal range for a lithium battery.

 

[RyanNicholas]

I read somewhere you have to change the "sleep" settings too so it doesn't turn off after a certain amount of time of no use...……..I doubt this has anything to do with your problem, your settings are the same as mine , but im still setting up mine battery box wise so haven't really ran it much yet
Sounds like its working again ( bar the 0 v reading ) ….l guess check all your connections just in case , but yes a bit odd hey

I've got the sleep timer set at 15300 which I'm told is the max setting for it. When I first put everything together I was having to reactivate the BMS every time I checked it because the sleep timer was set too low. But since I changed it to 15300 I haven't had to reactivate it. Although, 15300 seconds is only 4 hours and 15 minutes... So I'm not sure why it hasn't been timing out halfway through the night every night. Maybe 15300 tells it you don't want it to timeout at all? It was someone else here in the forums who told me to use that setting. I don't know where other people learn this stuff because none of the instructions I got mentioned details like this.

 

[MisterSandals]

What about the “diff volt protect = .26v”

Have you checked the individual cell voltages to see if there is (still) a cell that is divergent?

 

[HRTKD]

There definitely has not been a temperature issue. I'm in Baja Mexico, and the temperature range down here has been very much in the ideal range for a lithium battery.

What does "Num of temp: 1" on your app screen mean?

 

[Just John]

What does "Num of temp: 1" on your app screen mean?

It means there is one external temperature sensor, it is capable of two. If you have a temperature disconnect value defined, it won't even turn on until you plug one in.

 

[RyanNicholas]

What does "Num of temp: 1" on your app screen mean?

I'm not sure, but it didn't read as a fault alarm.

What about the “diff volt protect = .26v”

Have you checked the individual cell voltages to see if there is (still) a cell that is divergent?

That might actually be the issue. I noticed there was more of a difference than usual in the individual cell voltages when I checked this morning. I'm not sure what's causing that. I charged them all up as fully as the BMS would allow after assembling the battery, then we connected in parallel to sit overnight. I was told buy some professional dude that would be enough to balance the cells. But I also recently saw a reply to a different thread I posted on that topic where someone said they need an active current in order to properly balance. This might be the issue. It's just that I'm in Mexico and I'm operating fully out of the van so I'm not sure where to plug-in, plus I don't have a bench power supply with me. Maybe an auto parts store...

 

[HRTKD]

It means there is one external temperature sensor, it is capable of two. If you have a temperature disconnect value defined, it won't even turn on until you plug one in.

OK. Seems like a strange thing to present on the dashboard screen.

 

[HRTKD]

I do have the battery isolator setup with this thing, which does involve a grounding wire going from the battery to a metal spot on the wall of the van. Could that be draining the battery somehow? It's how the isolator was supposed to be set up with it, and it hasn't been giving me this problem for the last few weeks that I've been using the whole system.

Can you go into more details on the isolator?

Rereading your original post, it sounds like the BMS went into total shutdown of the discharge circuit. That's strange because it was displaying a battery voltage of 13.2v. On your BMS app screen, when things are working correctly, do the sliders in the middle of the screen (Chg MOS on the left side) show to the right instead of to the left?

Given the 13.2v reading, I doubt the isolator is the problem. But it wouldn't hurt to verify that setup.

 

[Just John]

OK. Seems like a strange thing to present on the dashboard screen.

Yes, sort of like their gauge that is the biggest thing on the display that is so totally inaccurate as to be totally useless!

Biggest thing I noticed was his charge and discharge were both off, but that might be the BMS just went to sleep/power save mode. Oddly enough, even if you are in a triggered low temperature disconnect, it will show as charge enabled until you actually try and charge, then it will show as off. Daly is a mess, but so far everything that is important works reliably (i.e. low and high cell voltage disconnect, low temp disconnect).

My readings for amps in or out are ALWAYS off, even after doing the "calibrate with zero current" dance.

 

[Just John]

I've got the sleep timer set at 15300 which I'm told is the max setting for it. When I first put everything together I was having to reactivate the BMS every time I checked it because the sleep timer was set too low. But since I changed it to 15300 I haven't had to reactivate it. Although, 15300 seconds is only 4 hours and 15 minutes... So I'm not sure why it hasn't been timing out halfway through the night every night. Maybe 15300 tells it you don't want it to timeout at all? It was someone else here in the forums who told me to use that setting. I don't know where other people learn this stuff because none of the instructions I got mentioned details like this.

BTW, there are two different values you can put in there to disable "sleep", you might try the other one. It seems to be random which value yours might require.

As for top balancing, I did try to warn you, what the expert told you is not what I've experienced. But internet experts are a dime a dozen, including me!

 

[RyanNicholas]

BTW, there are two different values you can put in there to disable "sleep", you might try the other one. It seems to be random which value yours might require.

As for top balancing, I did try to warn you, what the expert told you is not what I've experienced. But internet experts are a dime a dozen, including me!

I hear you man, and thanks for your perspective. Looks like you were right. The guy who told me that was actually a guy who works at a solar supplier place in a town I was in, so I figured he was worth listening to. But I guess I need to balance these things again.

 

[RyanNicholas]

Can you go into more details on the isolator?

Rereading your original post, it sounds like the BMS went into total shutdown of the discharge circuit. That's strange because it was displaying a battery voltage of 13.2v. On your BMS app screen, when things are working correctly, do the sliders in the middle of the screen (Chg MOS on the left side) show to the right instead of to the left?

Given the 13.2v reading, I doubt the isolator is the problem. But it wouldn't hurt to verify that setup.

When everything is working the first two sliders are green. I still hardly ever see the third balance slider green, and it doesn't turn green when I press it. I think mr. Sandals nailed it with the charge difference issue in the cells...