Scream Power LIFEPO4 Battery Won't Hold Above 14v Charge

[itsmattmp]

I've been using a 320 AH Scream Power LIFEPO4 battery for a few months now. Been fine until this past week. For some reason my chargers will quickly charge it up to 14.4-14.5 volts but the the chargers shut off and the battery voltage quickly falls to 13.1-13.2 volts. Is this normal, or should my battery maintain at least 14v at full charge?

I'm using two 60A Renogy charge controllers, and one 100A EPEVER charge controller to charge with solar, and an Inteli-Power PD9160AL to charge with a generator.

Using a Victron Multiplus 12/3000 inverter. It's been able to run our RV AC just fine in the past, but today it started shutting off from low voltage even though voltage should have been full. Voltage would sag from 13.0-13.5 volts to 12.0 volts during a short time running the AC, and then would jump back up to 13 something volts after shutting off.

I'm afraid my battery is failing. Scream Power advertises 1 C rates - that's why I went with their battery. But maybe it can't handle it?

 

[Forbisher]

I've been using a 320 AH Scream Power LIFEPO4 battery for a few months now. Been fine until this past week. For some reason my chargers will quickly charge it up to 14.4-14.5 volts but the the chargers shut off and the battery voltage quickly falls to 13.1-13.2 volts. Is this normal, or should my battery maintain at least 14v at full charge?

I'm using two 60A Renogy charge controllers, and one 100A EPEVER charge controller to charge with solar, and an Inteli-Power PD9160AL to charge with a generator.

Using a Victron Multiplus 12/3000 inverter. It's been able to run our RV AC just fine in the past, but today it started shutting off from low voltage even though voltage should have been full. Voltage would sag from 13.0-13.5 volts to 12.0 volts during a short time running the AC, and then would jump back up to 13 something volts after shutting off.

I'm afraid my battery is failing. Scream Power advertises 1 C rates - that's why I went with their battery. But maybe it can't handle it?

LFP battery voltage settles to 13.6V or less after a full charge.
LFP will never "maintain" an over 14V charge.
Look at the voltage chart on my avatar.

Even though LFP can be charged at 1C for longer life 0.5C is recommended.

 

[MisterSandals]

For some reason my chargers will quickly charge it up to 14.4-14.5 volts but the the chargers shut off and the battery voltage quickly falls

Are you sure the batteries are actually fully charged? If the current is not tapering you are likely measuring the charger/battery combined voltage (14.x).

Otherwise, measure the individual cells, that will provide more info at to what is going on with your battery. As Forbisher said, they will settle down. Some folks see 3.5v/cell while others (me!) see 3.35v/ cell.

 

[itsmattmp]

Are you sure the batteries are actually fully charged? If the current is not tapering you are likely measuring the charger/battery combined voltage (14.x).

Otherwise, measure the individual cells, that will provide more info at to what is going on with your battery. As Forbisher said, they will settle down. Some folks see 3.5v/cell while others (me!) see 3.35v/ cell.

My Inteli-Power charger starts at full amps (60 amps) and then tapers down to about 5 amps within about 1 minute of charging. So apparently it thinks the battery is fully charged. I have an Ammeter which I've programmed at 320AH, but I can't get it to read over 270AH now.

I used to be able to comfortably have enough power to last sun down to sun up, but now I lose power around 6 am.

I can't test the individual cells because the Scream Power battery is not "user serviceable". I understand I could cut it open, but I imagine it would void the warranty.

Is it possible that running my AC pulled too high a C rate from the battery? But shouldn't this battery have a BMS that would stop me from pulling a higher C rate than its rated for? And shouldn't a lithium battery be able to handle short surges from starting a compressor motor? What's the best way to test my battery to figure out if it's been damaged? Use a benchtop charger to fully charge, and then do a capacity test?

 

[MisterSandals]

I can't test the individual cells because the Scream Power battery is not "user serviceable". I understand I could cut it open, but I imagine it would void the warranty.

It sounds like a cell or two has given up. It sounds like a good time to put that warranty to use.

 

[itsmattmp]

I submitted a warranty claim and, to their credit, the seller promptly responded and offered to send me parts to fix it. The seller told me to open the battery and to check the cell voltages and BMS. Trying to figure out if the problem is with a cell, or with the BMS. The tops of the cells were inaccessible, so I tested the voltages from the BMS leads.

Here is a video of my test results: https://www.dropbox.com/s/kp2opcn7j6ggkdg/20210506_225451.mp4?dl=0

Here is what I found:

I opened the case but not sure I could remove the cells without tearing the case apart, because of the spray foam and adhesive. But I was able to measure voltage of the cells across the BMS balance wires.

I found a 4s3p configuration with each parallel pack having roughly 13 volts.

The voltages in p1 were 3.31, 6.62, 9.94, 13.25; for p2 cells were 3.33, 6.66, 10.00, 13.33; for p3 cells were unstable, 6.61, 9.92, 13.23.

So the voltage of the first cell in P3 floats in value between 2.03 and 4.66 while its other cells were of fixed voltage.

Do you think this is the BMS? Or do you think it's the cell?

Here's the per cell voltages:

P1
3.31
3.31
3.32
3.31

P2
3.33
3.33
3.34
3.33

P3
X
(6.61 - X)
3.31
3.31

 

[itsmattmp]

The battery seems to be of decent build quality. Good solder connections, but probably uses grade B cells, and cheap BMSs.

One concern I have after opening it, is that the seller told me it is made up of 80AH cells. I count 12 cells total, with 3 12v packs in parallel. That would only equal 240AH. The seller does sell a 240AH version of this battery, so he may have been mistaken. BUT, is there any 3P configuration of available prismatic cells that would add up to 320AH? My math tells me that this would require 106.7AH cells, which I have never seen available anywhere. I was expecting to find a 4P scenario which would have added up perfectly. My only other thought is that they're over-rating 100 AH cells.

I will receive equipment early next week that will allow me to test capacity (although it may be too late now). I may be able to test the capacity of a single parallel set, as it appears only one of them is damaged. Or I can test after this is fixed. But it really appears to me that I was sold a 240AH battery labelled as 320AH. Thoughts?

 

[MisterSandals]

So the voltage of the first cell in P3 floats in value between 2.03 and 4.66 while its other cells were of fixed voltage.

Do you think this is the BMS? Or do you think it's the cell?

If you're getting this wild voltage fluctuation on the lead to the BMS, without the BMS, its not the BMS.
The wire going to cell 1 positive (wire #2) of P3 is an excellent candidate for the root of your problem.

But it really appears to me that I was sold a 240AH battery labelled as 320AH.

I just checked and 80ah x 3 is in fact 240ah. I don't see how its easy to accidentally label batteries incorrectly.
Sounds might suspicious to me.

But its great that they are interested in working with you.

 

[itsmattmp]

If you're getting this wild voltage fluctuation on the lead to the BMS, without the BMS, its not the BMS.
The wire going to cell 1 positive (wire #2) of P3 is an excellent candidate for the root of your problem.


I just checked and 80ah x 3 is in fact 240ah. I don't see how its easy to accidentally label batteries incorrectly.
Sounds might suspicious to me.

But its great that they are interested in working with you.

You think a bad cell could lead to fluctuating voltages?

The reason I think it could be the BMS is because the voltages on the other balance leads are constant and roughly what they should be. My thought is that the BMS is pushing a wild balance charge on that one wire. Perhaps my inverter is shutting off due to low voltage because the bad BMS is shutting off the battery when it perceives its own current to be out of wack?

 

[Darrenm01]

The battery seems to be of decent build quality. Good solder connections, but probably uses grade B cells, and cheap BMSs.

One concern I have after opening it, is that the seller told me it is made up of 80AH cells. I count 12 cells total, with 3 12v packs in parallel. That would only equal 240AH. The seller does sell a 240AH version of this battery, so he may have been mistaken. BUT, is there any 3P configuration of available prismatic cells that would add up to 320AH? My math tells me that this would require 106.7AH cells, which I have never seen available anywhere. I was expecting to find a 4P scenario which would have added up perfectly. My only other thought is that they're over-rating 100 AH cells.

I will receive equipment early next week that will allow me to test capacity (although it may be too late now). I may be able to test the capacity of a single parallel set, as it appears only one of them is damaged. Or I can test after this is fixed. But it really appears to me that I was sold a 240AH battery labelled as 320AH. Thoughts?

One way you can differentiate a 240 AH battery from one they put a sticker and marked as a 320 AH, is to measure and weigh the battery.

I will attach their specs from the Amazon.ca website. I will also attach a scanned version of the document they included with the second ScreamPower battery I bought. Nothing was included with the first.


You may be able to tell since you have yours partially opened, but it is my understanding that up until recently none of their batteries had low temp cutoff for charging (You mentioned an RV application).

They list two new Bluetooth models and specifically say those do - I expect they changed the BMS in those two batteries.

 

[MisterSandals]

The reason I think it could be the BMS is because the voltages on the other balance leads are constant and roughly what they should be. My thought is that the BMS is pushing a wild balance charge on that one wire.

Oh, i was thinking you disconnected the lead wire to the BMS. Can you disconnect it so you get a reading of just the battery (and wire(s))?

 

[itsmattmp]

One way you can differentiate a 240 AH battery from one they put a sticker and marked as a 320 AH, is to measure and weigh the battery.

I will attach their specs from the Amazon.ca website. I will also attach a scanned version of the document they included with the second ScreamPower battery I bought. Nothing was included with the first.


You may be able to tell since you have yours partially opened, but it is my understanding that up until recently none of their batteries had low temp cutoff for charging (You mentioned an RV application).

They list two new Bluetooth models and specifically say those do - I expect they changed the BMS in those two batteries.

Thanks for the documentation. It's a little confusing. The Amazon page advertised 1C capability, so I've assumed 1C charge and discharge. The Charge Mode says to charge at 0.2C5A, which to me means .2*5, or 1C. Am I interpreting that right? But then it goes on to say Maximum Charge Current 100A. So for the 320AH battery which is it?

I will try and find a scale to weigh it. Good idea.

I crafted my own low temperature cutoff using a 12v thermostat and relay. Works great.

 

[itsmattmp]

Oh, i was thinking you disconnected the lead wire to the BMS. Can you disconnect it so you get a reading of just the battery (and wire(s))?

Good idea. I'll try that tonight and see how it reads without the BMS connected. I tested the voltages direct from the PCB board on metal pieces coming out of the wiring harness of the lead wires. But I'll disconnect it and test the wires direct.

 

[itsmattmp]

I opened up the battery so I could see the posts and found that the main wires had been basically taped on. One of the positive wires was falling off. I soldered it to the terminal for a short term fix, but can solder handle Temps caused by up to 320 amps? Is there a better way to attach this to the terminal? The terminals aren't tapped. Can I use a self-tapping screw to screw a wire into the terminal? If so, how long a screw can I use?

 

[Substrate]

The Charge Mode says to charge at 0.2C5A, which to me means .2*5, or 1C. Am I interpreting that right? But then it goes on to say Maximum Charge Current 100A. So for the 320AH battery which is it?

Ah, they're playing the specification game. That funky 0.2C5A is the key.

Ok, so most battery capacities are determined by the old lead-acid C/20 rate (20 hour discharge). Some manufacturers may change that up a little, like some Enersys agm's that use C/10 to determine capacity. (more to be in line with a common day's work) And here with yours, they are using the C/5 hour rate causing some confusion.

C5A simple means "over the 5 hour rate".

WHOA - just checked them online, and see that they have a "solar panel configuration based on 4.5 hours per day"

This now makes sense. Your 240ah batteries are spec'ed at the 5 hour discharge rate, and can also be classified as 320ah at the more normal 20 hour discharge rate most of us are used to.

It would be a LOT easier if these guys would stick to one standard, but lets play with the math.

C/20 vs C/5 hourly rate - lets do some conversions

C20 / C5 = 4 (aka 0.25)

320 * 0.25 = 80

320 - 80 = 240

Sooooo their recommendation to charge at 0.2C5A is a reference to the 240ah 5-hour value.

That means 0.2 * 240 = 48. Seems like they are saying a normal charge should not exceed 48A.

AHA! Looks like their "new model" has a bms that is rated at 50ah max charge rate, but their older models had a BMS capable of 100ah. I think you have the "new model" with the lower-rated BMS.

Perhaps you are also just wearing them out quickly discharging at 1C. And which "C" do they mean if you are hammering them at 1C? The C/20 (320ah) or C/5 (240ah)?

Wow - what a detective story trying to suss out why they are mixing and matching specs. That was kinda fun I guess, but man they sure make the consumer work for it!

 

[itsmattmp]

I opened up the battery so I could see the posts and found that the main wires had been basically taped on. One of the positive wires was falling off. I soldered it to the terminal for a short term fix, but can solder handle Temps caused by up to 320 amps? Is there a better way to attach this to the terminal? The terminals aren't tapped. Can I use a self-tapping screw to screw a wire into the terminal? If so, how long a screw can I use?

Hard to see from this photo, but the red wires connection is peeling up. The wires are soldered to a small piece of sheet metal, and then that sheet metal is laser welded at the top and bottom edges to the terminal. Nothing connects the rest of the bottom of that sheet metal to the terminal, so the point of contact is small. In my case the top weld was insufficient and disconnected. I think that's what caused my voltage fluctuations.

 

[Rich585]

Great shots of the inside to see how it is constructed.

Before finding this site, I was leaning towards buying one off of Amazon but could not really find good reviews.

I hope it works out for you but it is a good info for community to see what the actual build quality of these batteries is considering you still paid fair amount for capacity you may have not received.

thanks for sharing.

 

[itsmattmp]

Ah, they're playing the specification game. That funky 0.2C5A is the key.

Ok, so most battery capacities are determined by the old lead-acid C/20 rate (20 hour discharge). Some manufacturers may change that up a little, like some Enersys agm's that use C/10 to determine capacity. (more to be in line with a common day's work) And here with yours, they are using the C/5 hour rate causing some confusion.

C5A simple means "over the 5 hour rate".

WHOA - just checked them online, and see that they have a "solar panel configuration based on 4.5 hours per day"

This now makes sense. Your 240ah batteries are spec'ed at the 5 hour discharge rate, and can also be classified as 320ah at the more normal 20 hour discharge rate most of us are used to.

It would be a LOT easier if these guys would stick to one standard, but lets play with the math.

C/20 vs C/5 hourly rate - lets do some conversions

C20 / C5 = 4 (aka 0.25)

320 * 0.25 = 80

320 - 80 = 240

Sooooo their recommendation to charge at 0.2C5A is a reference to the 240ah 5-hour value.

That means 0.2 * 240 = 48. Seems like they are saying a normal charge should not exceed 48A.

AHA! Looks like their "new model" has a bms that is rated at 50ah max charge rate, but their older models had a BMS capable of 100ah. I think you have the "new model" with the lower-rated BMS.

Perhaps you are also just wearing them out quickly discharging at 1C. And which "C" do they mean if you are hammering them at 1C? The C/20 (320ah) or C/5 (240ah)?

Wow - what a detective story trying to suss out why they are mixing and matching specs. That was kinda fun I guess, but man they sure make the consumer work for it!

Wow that's a mess and hard to understand. They need to start rating batteries by watt hours, and standardizing discharge rates.

 

[itsmattmp]

Great shots of the inside to see how it is constructed.

Before finding this site, I was leaning towards buying one off of Amazon but could not really find good reviews.

I hope it works out for you but it is a good info for community to see what the actual build quality of these batteries is considering you still paid fair amount for capacity you may have not received.

thanks for sharing.

Yeah, I wish I had all this information before I bought it. I may have actually still bought it, given its low price in comparison to some other brands, but great to be informed. I'm mostly disappointed with how they attach the wires to the terminals. That was my point of failure. Also disappointed with how much foam they use, so that you have to destroy the battery casing to get to the terminals and test the individual cells.

Now that I think I've fixed it, I'm going to do a capacity test. I will probably need to wait until my new 48v battery cells come in to capacity test this battery, because I rely on it right now for living off grid (and my capacity tester would take 24-48 hours to complete), but my cells should be here within 2-3 weeks and then I'll do a full capacity test on this battery to see if I was given a battery within spec. I will post the results here.

 

[Darrenm01]

Hard to see from this photo, but the red wires connection is peeling up. The wires are soldered to a small piece of sheet metal, and then that sheet metal is laser welded at the top and bottom edges to the terminal. Nothing connects the rest of the bottom of that sheet metal to the terminal, so the point of contact is small. In my case the top weld was insufficient and disconnected. I think that's what caused my voltage fluctuations.

I have two of these batteries (120 ah), and haven’t had them apart, so I’m likely more curious than most about your photos.

I have a different plastic case since my battery is much smaller, but what is the white plastic above the cells? Is it a glue to prevent anything from shifting during transport or in an RV or van location?

And how did you remove it to get to the batteries - it looks fairly thick.

Anyone know what the bar codes on the cells mean? I’ve heard Will talk about them in his videos, but I don’t know how to identify what I have based on those.

I’m glad I saw your photos even after buying the batteries. I didn’t expect they would be the best quality, but it looks like where the wires make connections could be improved.