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Eco-Worthy 12.8V 150Ah (165Ah) Metal BT - Cell Divergence

AdriftAtlas

New Member
Joined
Jul 19, 2023
Messages
51
Location
Washington
I bought four Eco-Worthy 12.8V 150Ah (165Ah) Metal BT batteries. Three of them only diverge more than 10mv at less than 10% SoC, all manufactured Sep 26th. However, one of them manufactured Oct 30 begins to diverge by 15mv at 30%, 30mv at 15%, 43mv at 10%, 86mv at 7%. The biggest culprit appears to be cell 2.

I've let the BMS top balance the cells several times and they're within 10mv when the pack is 14.5V. I've cycled it several times and it always the same. I did a capacity test on it using a Victron Shunt and it counted 163Ah before cell undervolt at 2.5V. So it's close to 165Ah that the BMS reports, and 13Ah more than advertised on the tin.

However, I'm concerned that there is something wrong with the cell. I'm going to put these four batteries in series for a 51.2V nominal pack, so I really don't want one battery to fail on me.

What is going on here? Will it degrade faster or potentially cause early pack failure down the line? Do I request an exchange?

Pictures Attached.
 

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I’m guessing the other cells are just better than specified.
Not ideal but also no reason for return as the pack performs as promised.

Weakest cell is eventually the first one to die but you should still get the expected cycle life out of it.

Biggest problem this causes is low voltage setting on inverter. Weakest cell could trigger the BMS cut-off before total string voltage is anywhere near inverter low voltage setting.
 
Well, you’re not alone… but you’re actually doing better than I am…

I purchased 2 of the DC House versions of the same battery and have one battery that is testing at 162.5 Ah and has one weak cell (#3) that is over volting on charge and under volting on discharge. When the battery cuts off discharging due to cell 3 going under voltage, that cell is more than 900 millivolts lower than the other cells. It basically falls off a cliff at either end of the voltage range.

I’ve tried 24 hrs of low amperage charging to try and give the balancer a chance to bring this cell inline with the others but even at .5 amps it constantly went over voltage and no progress was made. I don’t see how this cell can be saved at this point.

I’m in contact with DC House via eBay to try and get a resolution. My 2nd battery looks good so far. I’m still cycling it and testing but so far it’s behaving as expected.
 
Well, you’re not alone… but you’re actually doing better than I am…

I purchased 2 of the DC House versions of the same battery and have one battery that is testing at 162.5 Ah and has one weak cell (#3) that is over volting on charge and under volting on discharge. When the battery cuts off discharging due to cell 3 going under voltage, that cell is more than 900 millivolts lower than the other cells. It basically falls off a cliff at either end of the voltage range.

I’ve tried 24 hrs of low amperage charging to try and give the balancer a chance to bring this cell inline with the others but even at .5 amps it constantly went over voltage and no progress was made. I don’t see how this cell can be saved at this point.

I’m in contact with DC House via eBay to try and get a resolution. My 2nd battery looks good so far. I’m still cycling it and testing but so far it’s behaving as expected.

Did they reply? What are they saying?
What is the date of manufacture of the good and bad one?
 
I tested another one that only output 160Ah. Technically, I have no grounds to say anything as they only advertise 150Ah. I think these batteries are just a bunch of mismatched cells. Likely why they are inexpensive.
 
Both of my batteries were built in October 2024. The battery with the weak cell is testing at 162-162.5Ah. But that is testing at the full range of the BMS limits which is 2200 LVC and 3750 HVC and letting the BMS cut off charging and discharging when the weak cell hits those limits.

These set points are far more aggressive than is recommended by the gurus here, but I wanted to use the full range of the factory BMS setting to show Eco-Worthy the extent of the capacity and how far out the runner cell is from the others. When the weak cell hits 2200mV, the remaining cells are still sitting at 3.17x volts.

EW has been responding with the typical delays of dealing with overseas support (24-48 hrs) and communication barriers. They have so far offered a modest discount to keep the battery. I’m still pushing for a replacement as this weak cell will only get worse over time and will drive down capacity further.
 
Both of my batteries were built in October 2024. The battery with the weak cell is testing at 162-162.5Ah. But that is testing at the full range of the BMS limits which is 2200 LVC and 3750 HVC and letting the BMS cut off charging and discharging when the weak cell hits those limits.

These set points are far more aggressive than is recommended by the gurus here, but I wanted to use the full range of the factory BMS setting to show Eco-Worthy the extent of the capacity and how far out the runner cell is from the others. When the weak cell hits 2200mV, the remaining cells are still sitting at 3.17x volts.

EW has been responding with the typical delays of dealing with overseas support (24-48 hrs) and communication barriers. They have so far offered a modest discount to keep the battery. I’m still pushing for a replacement as this weak cell will only get worse over time and will drive down capacity further.

I set my BMS to 2.5V and 3.65V. The stock settings are bad. The low temp charging cut off is -7C, which is a no-no.

The Eco-Worthy version is rated at 150Ah, so I don't think I have much recourse. I could try arguing that the cell should not diverge by 43mv at 10% but if the cells are actually rated at 150Ah, that somewhat makes sense. At worse they are not capacity matched. Thing is the one with the worse cell divergence actually has more capacity than two of the others 163Ah vs 160Ah.

Not sure whether to accept that these are inexpensive batteries or try to get Eco-Worthy to do something.

In your case they specifically advertise 165Ah, so you can argue that it does not meet advertised capacity. Though 2.2V vs 3.17V is ridiculously mismatched capacity. It's like they mixed much higher capacity (180Ah) cells with a much lower capacity cell (165Ah).
 
Top balancing and only expecting the artificially low 150ah rating would probably be just fine from all the opinions that I have read. If I expect perfectly matched cells, I would also expect to pay a premium price. Even then, there will always be a first cell to hit the limit. As long as none die before 150ah, and they all go back to full together from that level, why worry. The case where a slightly smaller cell is run between its limits, just means the others are "overperforming". Are the dc-house versions actually rated 165ah? If so, nevermind and carry on.
 
I’ve been hesitant to update the BMS LVC/HVC set points as I don’t want to give DCHouse any reason to deny warranty/return. I roughly estimate that the capacity would be around 160Ah (vs the advertised 165Ah) if I imposed a range of 2.5-3.65v.

At the factory defaults of 2.2-3.7, I know that weak cell is getting abused. I also realize that it is not contributing much capacity at the edges of the range but it is really just buying time so the healthy cells can continue to discharge. It’s probably doing the BMS no favors to keep hitting the hard limits as well.

There does seem to be a big cell mismatch in my problem battery. My second battery still tests right at 165Ah and the cells stay in pretty tight balance throughout the range. So at least we know they are capable of assembling a well matched set of cells or I got lucky on my second battery.

And this experience has reinforced the value of having a Bluetooth BMS. Without it I wouldn’t be able to spot this cell anomaly and the crazy wide voltage set points.
 
I’ve been hesitant to update the BMS LVC/HVC set points as I don’t want to give DCHouse any reason to deny warranty/return. I roughly estimate that the capacity would be around 160Ah (vs the advertised 165Ah) if I imposed a range of 2.5-3.65v.

At the factory defaults of 2.2-3.7, I know that weak cell is getting abused. I also realize that it is not contributing much capacity at the edges of the range but it is really just buying time so the healthy cells can continue to discharge. It’s probably doing the BMS no favors to keep hitting the hard limits as well.

There does seem to be a big cell mismatch in my problem battery. My second battery still tests right at 165Ah and the cells stay in pretty tight balance throughout the range. So at least we know they are capable of assembling a well matched set of cells or I got lucky on my second battery.

And this experience has reinforced the value of having a Bluetooth BMS. Without it I wouldn’t be able to spot this cell anomaly and the crazy wide voltage set points.
Yep, after what I saw there is no way I'm buying anything without a BMS that I can adjust. I saved the default values in the Overkill Solar app, so if I need to restore it's very simple.
 
I’ve been hesitant to update the BMS LVC/HVC set points as I don’t want to give DCHouse any reason to deny warranty/return. I roughly estimate that the capacity would be around 160Ah (vs the advertised 165Ah) if I imposed a range of 2.5-3.65v.

At the factory defaults of 2.2-3.7, I know that weak cell is getting abused. I also realize that it is not contributing much capacity at the edges of the range but it is really just buying time so the healthy cells can continue to discharge. It’s probably doing the BMS no favors to keep hitting the hard limits as well.

There does seem to be a big cell mismatch in my problem battery. My second battery still tests right at 165Ah and the cells stay in pretty tight balance throughout the range. So at least we know they are capable of assembling a well matched set of cells or I got lucky on my second battery.

And this experience has reinforced the value of having a Bluetooth BMS. Without it I wouldn’t be able to spot this cell anomaly and the crazy wide voltage set points.
So they are claiming 165ah on the ones you have. In that case, you do have reason to complain.
 
I’ve been hesitant to update the BMS LVC/HVC set points as I don’t want to give DCHouse any reason to deny warranty/return. I roughly estimate that the capacity would be around 160Ah (vs the advertised 165Ah) if I imposed a range of 2.5-3.65v.

At the factory defaults of 2.2-3.7, I know that weak cell is getting abused. I also realize that it is not contributing much capacity at the edges of the range but it is really just buying time so the healthy cells can continue to discharge. It’s probably doing the BMS no favors to keep hitting the hard limits as well.

There does seem to be a big cell mismatch in my problem battery. My second battery still tests right at 165Ah and the cells stay in pretty tight balance throughout the range. So at least we know they are capable of assembling a well matched set of cells or I got lucky on my second battery.

And this experience has reinforced the value of having a Bluetooth BMS. Without it I wouldn’t be able to spot this cell anomaly and the crazy wide voltage set points.
What did you end up doing with your battery?
 
My guess is that the cells are actually rated at 150Ah. It's common for cells to be 10% higher than rated though. They seem to be charging to 57.6V (14.4V per battery) in series without hitting a high cell voltage disconnect so it will do.

Capacity, resistance, and voltage matched cells are much more expensive. These are likely the cheapest cells one can find.
 
What did you end up doing with your battery?

I returned it and ordered a replacement. Cycling it now to see how it performs. My 2nd battery (of my two original batteries) is working hard and staying balanced and full capacity so far. The 3rd battery (replacing the 1st one with the weak cell) is not as balanced but it’s still early yet and I haven’t had time to focus on it yet.
 
Ordered a fifth one from Amazon to keep as a spare. And this one has a 260mv divergence and cannot be charged beyond 13.8V. Not sure if it will ever balance.
 

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