ANT BMS does not want to charge after 0% battery

[nikto]

ANT BMS allowed the alarm to drain the battery up to 2.61V per cell (LifePO4 23S) even though the settings were 3.1V !!! damn that ANT BMS!

So ANT BMS still does not want to take a charge from charging.
What is ANT BMS waiting for? Some Kick? Maybe pressing a button of ANT BMS of some special duration?
Can't find ANT Bus manual.

Plese help!

 

[Hawaiiguy]

Go into protection settings and set your start charge lower than your lowest cell,it should then start charging

 

[nikto]

Go into protection settings and set your start charge lower than your lowest cell,it should then start charging

Is this logic of ANT BMS?! OMG! Battery really need charging! Why not open input?
Any cheap BMS will not block input. It's good logic I think.

 

[Hawaiiguy]

Also check last page and see if charge mosfet is turned on

 

[nikto]

Also check last page and see if charge mosfet is turned on

In "ANT BMS" app, right?

 

[Hawaiiguy]

Yes

 

[j bjork]

I dont recognize your app, but it clearly shows undervoltage protection and that both charging and discharging is turned off. That means the bms is doing what it should, protecting the pack from further discharge and protecting from charging overly discharged cells that might start a fire or something.
In both ant bms apps I have I can manually turn on and off charge and discharge for a temporary change. Or set the parameters as I want if I dont like the settings it comes with.

 

[nikto]

I dont recognize your app, but it clearly shows undervoltage protection and that both charging and discharging is turned off. That means the bms is doing what it should, protecting the pack from further discharge and protecting from charging overly discharged cells that might start a fire or something.
In both ant bms apps I have I can manually turn on and off charge and discharge for a temporary change. Or set the parameters as I want if I dont like the settings it comes with.

In general, I think this logic is bad.
Disabling the input in most cases is a pointless thing, since even in super cheap Chinese chargers have a diode is installed to protect against polarity reversal. Discharging from the BMS input is not possible through this diode. The developers of the ANT BMS could at least allow the charging input to be turned on with the button in such a situation.
Secondly, the situation is such that my motorbike is in a parking in another country (where I put it for 6 months).
And only because of my paranoia, I decided to ask a friend and go there just in case to recharge the battery. He had the task of only inserting the 220V plug into the socket.

Now I understand that maybe even ANT BMS not ignored my settings of 3.1V lower protection limit (which I set just in case before leaving, also because my paranoia), but in 2 months ANT BMS ate so much energy itself that only 2.61V remained.
What a shit! ANT BMS cannot sleep properly. And itself is capable of destroying the battery in a relatively short time.

That is, some cheap BMS board has much better logic and at least in this situation it would turn on immediately when voltage was applied from charging, and besides, cheap BMS (not Smart) itself would not eat up the battery so quickly.

My personal conclusion: Smart BMS in some cases can be even worse than a regular cheap BMS, you need to look for it. Now I will take a closer look at any Smart BMS technical specification and the logic of its operation. I personally will never buy ANT BMS for my projects. This one was included by manufacture.

 

[amberwolf]

If you have a low voltage protection set to a certain voltage, and the cell voltage is below that, then the BMS is *supposed* to prevent charging at that point. It's there as a safety feature, and is why those settings need to be correct for the specific cells being used in a pack.

Also, if you have cells that are more than about 0.1v difference from each other, many BMS disable charging (and usually discharging) because this kind of difference means the cells are not identical and the BMS is designed to assume this means there is a pack problem that needs to be fixed (because there is, since properly functioning packs that are correctly designed will used well-matched cells that won't become different in voltage, especially not to that degree).


Your screenshot of the app shows that you have both of these conditions in your pack, so the BMS is correct to not allow charge or discharge. (whether it's actually set to not allow for the 0.1v difference I can't tell, but that difference does exist in the pack).

You may be able to change the settings to allow charge and discharge anyway, but the fact that you have cells that are that different means there is a problem with the pack that should be fixed (by replacing the cells that are different from each other in characteristics with ones that all match each other as closely as possible).

Sometimes that's not practical...but in these cases you have to keep in mind that this is going to only get worse as the pack ages, especially if it's used harder.



Another thing about the BMS: It's supposed to be an emergency shutoff, so:

--if it didn't shut off at all even though it shows it's shut off, the discharge FETs have failed shorted, and would need to be replaced (but failing in the first place usually means the BMS is not correclty designed and it is going to happen again).

--if it did eventually shut off but not at the point it was set to, and no other settings override that, then the BMS is not correctly designed and should be replaced with a different kind (JBD, perhaps). If it's a sleep power consumption problem, that may also require replacement with a different design, but you'd have to test to find out what it's actual power consumption is in various conditions.

--The controller should have it's LVC set *above* what the BMS will protect at, because the controller should be doing the shutoff in all cases *except* where there is an actual battery failure (where a cell is dropped below LVC, or a thermal sensor shows cell overheating, or a current sensor shows pack current over the set limit, etc).

The BMS shouldn't have to shut the system off except in such emergency cases, and you don't want it to, because you don't want to suddenly simply be left without any power at all.

The controller often has ways of rolling back power as LVC approaches, so you aren't just left with a dead vehicle, but can baby it to somewhere you can recharge at least enough to get to a destination.

 

[nikto]

If you have a low voltage protection set to a certain voltage, and the cell voltage is below that, then the BMS is *supposed* to prevent charging at that point.

Please read your words one more time! Do you think it's normal for the SmartBMS,(I want to note: Smart!!!) block changing when battery is fully discharged? Discharged Li cells of battery will be happy with this?

you have cells that are that different means there is a problem with the pack that should be fixed (by replacing the cells that are different from each other in characteristics with ones that all match each other as closely as possible).

My cell's are OK. Please believe me. My old battery had this problem and I have good experience about this. On fully discharged cells(or even fully charged) Delta Voltage almost always will be big for LifePO4.

--if it did eventually shut off but not at the point it was set to, and no other settings override that, then the BMS is not correctly designed and should be replaced with a different kind (JBD, perhaps).

This is where I was most likely wrong. Now I think AntBMS did her job, but the reason for the low voltage that I saw turned out to be even crazier - in 2.5 months AntBMS discharged the cells from 3.0V to 2.61V (total battery capacity of 2 kW). Motorbike is parked.

--The controller should have it's LVC set *above* what the BMS will protect at, because the controller should be doing the shutoff in all cases *except* where there is an actual battery failure (where a cell is dropped below LVC, or a thermal sensor shows cell overheating, or a current sensor shows pack current over the set limit, etc).

The BMS shouldn't have to shut the system off except in such emergency cases, and you don't want it to, because you don't want to suddenly simply be left without any power at all.

The controller often has ways of rolling back power as LVC approaches, so you aren't just left with a dead vehicle, but can baby it to somewhere you can recharge at least enough to get to a destination.

Yes, I knew it. Here I agree with you 100%. Now you are talking about practical smart solution.

And if Now we are talking about practical smart solution and you still think that in real life on your EV it's ok when SmartBMS block charging when battery is fully discharged?

 

[eee291]

3.0v is empty, doesn't help much if the battery is 2kwh. There is probably not even 100wh of energy in that range.
Is Bluetooth constantly enabled on your BMS or does it need to have the button pressed?

I would've been surprised at the drain if it had been at least 40% charged. In your case this is fairly normal.
Even with no BMS I don't let my batteries sit at 3.0v more like 3.5-3.7v.
There is something called a storage charge, just about every consumer electronic manufacturer recommends you check on your battery over the winter or when it sits for longer periods.

I've Seen worse, 30+ kWh worth of batteries destroyed because of improper winter storage by the customer. No smart BMS was used (cheap Daly BMS)
I can find even examples on my local marketplace app right now:
A Super soco TC for €1100 because the battery died over the winter. That thing cost over 4k new

I think you got away lightly, no damage etc.
Just a mild inconvenience in comparison.

 

[nikto]

3.0v is empty, doesn't help much if the battery is 2kwh. There is probably not even 100wh of energy in that range.
Is Bluetooth constantly enabled on your BMS or does it need to have the button pressed?

Constantly enabled buy like to go into sleep more. After for wake up Bluetooth some action is need. For example: turning on load(make little current) or start charging(good news is that Bluetooth woke up even if input(charger port) is switched off by AntBMS).

There is something called a storage charge

Yes I know, It's 40%-60%

A Super soco TC for €1100 because the battery died over the winter. That thing cost over 4k new

Li-Ion or LifePO4 ?

 

[nikto]

I think you got away lightly, no damage etc.
Just a mild inconvenience in comparison.

Thanks God and my new friend who came to help me!
Another 1 day and the battery would begin to degrade.
Now 43% charged.

 

[eee291]

Glad everything worked out in the end.
I work 99% with li-ion, but 3v is pretty much empty as well for lifepo4.

 

[nikto]

I came up with a solution - I will drill a hole in the battery case and will put a switch(that will break the power of BMS). And when I know that I park the bike for more than a month, I will turn off the power of Ant BMS (not smart BMS ). Ant company made wrong button

Also I found ShutdownVolt 2.4V in the settings
Logically, this is most likely when Ant BMS turns itself off and stop consume current.
But after that, the only way to charge the battery is to open it and apply voltage directly to internal terminals (before the BMS), which is very inconvenient.

I want to tell you that my battery is not a homemade product, it is a factory finished product.
And it's still under warranty. And her protection board (AntBMS) almost broke the battery.

 

[nikto]

How I saved my battery: AntBMS opened the input port and allowed charging only when settings of the lower minimum cell threshold was changed to below the current lowest cell voltage.

 

[amberwolf]

Please read your words one more time! Do you think it's normal for the SmartBMS,(I want to note: Smart!!!) block changing when battery is fully discharged? Discharged Li cells of battery will be happy with this?

Yes, if the cells are below the safe-low-voltage charging limit, it *has* to prevent charging, because they are below the limit that the manufacturer / builder has determined is safe to recharge those cells at.

This is because it's potentially unsafe to recharge overdischarged cells, that *could* be damaged in ways that could result in a fire, and it's not possible to tell if they are or aren't until the fire happens. :/ (or you destroy the cells to check them for damage with some form of microscopy)

If the limit has been set correctly, it will only prevent recharging cells that actually have a potential to have been damaged by the voltage they dropped to. The BMS can't know anything about this, it only does what it has been told to do.

If the cells are only below the regular LVC (to stop discharging when empty) and the BMS wont' allow recharge, *then* the BMS is defective or incorreclty designed.

A BMS should have at least two low limits (which may or may not have user-accessible settings to read or to change):
-- The first is the regular LVC, the voltage that if detected at any cell will cause it to turn off the discharge port.
-- The second is the safe-low-voltage limit (whatever the translation happens to be for that in non-technical Chinese/etc), the voltage that if detected at any cell will cause it to turn off *all* ports, to prevent recharge of an overdischarged (potentially hazardously damaged) cell.

Some BMS in OEM packs actually brick the pack if the second limit is detected, so that no user can accidentally start a fire by recharging a pack with damaged cells. (this is why unplugging the BMS from the balance/sense connector can brick it in some OEM bike battery packs, making them difficult to repair without knowing this and taking precautions against it).