Monday, September 30, 2024

Re: [electricboats] Cells (modules) are dying.

On Mon, Sep 30, 2024 at 06:17 PM, shredderf16 wrote:

The top balance works. About 3.6v in parallel with small DC power supply. Might take a week to 10 days.

I use this current-controlled power supply to speed up top balances (over 100 amps at 3.65V (voltage adjustable)):
 
 
Look for the charge current to stabilize at a tiny fraction of the total amp-hours you have in parallel.
Example: for my 10kWh, 48V-nominal pack, putting all sixteen cells in parallel comes to 3200Ah.
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Re: [electricboats] Cells (modules) are dying.

Peter,
Look at the charge/discharge chart for your batteries. There should be one. In addition to Will Prowse look up the Current Connected SOK rack battery manual. Very good discussion about charging, conclusion is to fully charge the bank every time.  You do need to top balance the bank. Our group of 3 guys have run solar off grid house banks exactly the same as yours for 4 years. Our biggest problem was BMS. Current favorite is Jackery, I personally made 3 Ant Bms from circuit boards from Taiwan. You can go without one if you top balance periodically with Lifepo4. All of us had cell failures like you did because of bad bms or because we manually over rid it. I recently went to server rack style because it's easier.

The top balance works. About 3.6v in parallel with small DC power supply. Might take a week to 10 days. Most exciting part is all that metal around exposed terminals. You drop a wrench once and you'll find out. Ditch the screws, get SS studs.
Jerry



On September 30, 2024, at 7:07 PM, bobkart <couch45@msn.com> wrote:


3.65V is 'full' for LFP cells.  By bringing all your cells to that voltage (usually in parallel), you're more sure they are at the same energy level (assuming capacity-balanced cells).  This approach is referred to as 'top-balancing'.
 
The problem with 3.2V is that's on the very flat part of the charge/discharge curve for LFP chemistry.  You could be at 20% SOC or 40% SOC, depending on very small voltage differences that would all read as 3.2V on a not-very-precise-or-accurate meter.
 
There is also an approach called bottom-balancing, which I've never used, that tries to achieve the same result by starting at 0% SOC (or some other very low number).  I don't like bringing cells down that low (it can be hard on them), and it's not as well-defined of a voltage (2.5V, 2.75V, ...?).  100% SOC is easy to know you're at, based on the cells not accepting further charge beyond just a trickle (C/100 say).
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Re: [electricboats] Cells (modules) are dying.

3.65V is 'full' for LFP cells.  By bringing all your cells to that voltage (usually in parallel), you're more sure they are at the same energy level (assuming capacity-balanced cells).  This approach is referred to as 'top-balancing'.
 
The problem with 3.2V is that's on the very flat part of the charge/discharge curve for LFP chemistry.  You could be at 20% SOC or 40% SOC, depending on very small voltage differences that would all read as 3.2V on a not-very-precise-or-accurate meter.
 
There is also an approach called bottom-balancing, which I've never used, that tries to achieve the same result by starting at 0% SOC (or some other very low number).  I don't like bringing cells down that low (it can be hard on them), and it's not as well-defined of a voltage (2.5V, 2.75V, ...?).  100% SOC is easy to know you're at, based on the cells not accepting further charge beyond just a trickle (C/100 say).
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Re: [electricboats] Cells (modules) are dying.

Thanks for all your suggestions and comments. I am following through with them all. However, I do have one fine question before I begin the balance. The specs on the Eve 280ah cells says nominal voltage 3.2v. However, I have seen others, Will Prowse among them and he seems like a reputable person, balance theirs at 3.6. Since I’ve never seen any of my batteries register more than 3.30 and ALL of them from the day I got them in the 3.28 to 3.29 range I am reluctant to put the current for balancing up to 3.6. I cannot find any other specs for these batteries other that that nominal 3.2v. Should I just balance at 3.2 or should I go higher? Since I screwed them up the first time I am being very cautious and before I plug anything in or hook anything on I’m making sure to know just what I need to do and what settings need to be to do a successful balance. Thanks so much.
 
peter
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Thursday, September 26, 2024

Re: [electricboats] Cells (modules) are dying.

Mark,
Agree very important to have bus bars and connections tight and clean. These Chinese cells have alu tapped terminals with iffy screws. I put SS studs in mine. Be very careful installing them, you can over torque them and break into battery cell easily. Bit once they are in a lot easier to change stuff later.
 
I hit a committent point on my 12 foot cat dinghy last month. Gas or electric. I was making motor mount. Motor mount done for 8 hp gas yamaha. In my opinion, motors not there yet. Batteries are there or very close.

The submersible motors always leak or corrode. I think everything electric needs to live a very sheltered life. I've got ideas, but waiting for someone else to do it.

I do believe one day this will be way to go, but not now.

Jerry



On September 26, 2024, at 12:47 PM, Mark Stafford <mstafford@natca.net> wrote:


Peter,
Another possible failure point (there are many different types of failure points): each battery connection. Make sure each connection to each post of each battery has the same high amperage surface contact area, the same cleanliness, the same torque value on the nuts or bolts, the same operating temperature, the same washers, the same lug count, etc. The basic concept is that you are trying to drain and charge each battery identically. If one of the posts has a higher resistance to electricity flow (dirty, loose, wavy washer, different size washer, wavy lug, worse crimping of the battery cable to the lug...) that post will run hot, which changes the internal resistance of the battery, which further exacerbates the imbalance, which further drains that battery, which can quickly and permanently change the internal chemistry of the battery.
Most of the time, these slight imbalances amount to a hill of dry beans (dry beans self-level pretty well). But if you cook the beans, the hill of beans can be significant.
The BMS was telling you to stop, in a language that assumed you were an electrical engineer with deep knowledge of LiFePO4 battery chemistry. Sometimes safety requires us to kill the batteries to save the boat, so the nice thing about your BMS is that it let you kill some batteries to save yourselves.
One really helpful simple tool is a $30 temperature gun. A more expensive but automated option is to install calibrated temperature probes on each battery terminal, and feeding that information to a BMS that would alert you to temperature imbalances.
One gallon of diesel compares to roughly 40 kWh of energy. You have roughly 4 kWh in your fully charged healthy 16 battery pack (4,480 under perfect conditions, which they never are). But your e-propulsion is ideally about 5 times more efficient than diesel. This means your 4 kWh pack, times 5 for efficiency, equals 20 kWh diesel power equivalent. So going out with your (16) 280Ahr batteries fully charged is like leaving the dock with 1/2 gallon of diesel fuel. You could go really slow (~1 knot) for ~10 hours, or really fast for ~10 minutes, but then the batteries need charging. Your 2200EU generator allows you to travel at ~1 knot continuously if the generator is running continuously. These are very approximate water speed estimates, not GPS speeds, and are influenced by literally hundreds of variables about your sailboat, the sea state, the weather, people moving around on your boat, etc.
This is the ballpark you are playing in. It is not an argument for or against e-propulsion, just the current state of electricity storage and creation.
My arguments for e-propulsion are:
low operating cost
low maintenance
low stink
low sound
low space requirements
low emissions
high reliability
high precision of thrust
high thrust available
high longevity
high tech
high investment in a better tomorrow
The hard part: e-propulsion often comes with a high learning curve. Many of our ancestors died during the learning curve of gasoline, but they gifted us cultural wisdom about the dangers of gasoline. We are gifting our progeny with the cultural wisdom of clean energy use. Don't kill yourself in the process: each battery can be lethal.
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Re: [electricboats] Cells (modules) are dying.

Peter,
Another possible failure point (there are many different types of failure points): each battery connection. Make sure each connection to each post of each battery has the same high amperage surface contact area, the same cleanliness, the same torque value on the nuts or bolts, the same operating temperature, the same washers, the same lug count, etc. The basic concept is that you are trying to drain and charge each battery identically. If one of the posts has a higher resistance to electricity flow (dirty, loose, wavy washer, different size washer, wavy lug, worse crimping of the battery cable to the lug...) that post will run hot, which changes the internal resistance of the battery, which further exacerbates the imbalance, which further drains that battery, which can quickly and permanently change the internal chemistry of the battery.
Most of the time, these slight imbalances amount to a hill of dry beans (dry beans self-level pretty well). But if you cook the beans, the hill of beans can be significant.
The BMS was telling you to stop, in a language that assumed you were an electrical engineer with deep knowledge of LiFePO4 battery chemistry. Sometimes safety requires us to kill the batteries to save the boat, so the nice thing about your BMS is that it let you kill some batteries to save yourselves.
One really helpful simple tool is a $30 temperature gun. A more expensive but automated option is to install calibrated temperature probes on each battery terminal, and feeding that information to a BMS that would alert you to temperature imbalances.
One gallon of diesel compares to roughly 40 kWh of energy. You have roughly 4 kWh in your fully charged healthy 16 battery pack (4,480 under perfect conditions, which they never are). But your e-propulsion is ideally about 5 times more efficient than diesel. This means your 4 kWh pack, times 5 for efficiency, equals 20 kWh diesel power equivalent. So going out with your (16) 280Ahr batteries fully charged is like leaving the dock with 1/2 gallon of diesel fuel. You could go really slow (~1 knot) for ~10 hours, or really fast for ~10 minutes, but then the batteries need charging. Your 2200EU generator allows you to travel at ~1 knot continuously if the generator is running continuously. These are very approximate water speed estimates, not GPS speeds, and are influenced by literally hundreds of variables about your sailboat, the sea state, the weather, people moving around on your boat, etc.
This is the ballpark you are playing in. It is not an argument for or against e-propulsion, just the current state of electricity storage and creation.
My arguments for e-propulsion are:
low operating cost
low maintenance
low stink
low sound
low space requirements
low emissions
high reliability
high precision of thrust
high thrust available
high longevity
high tech
high investment in a better tomorrow
The hard part: e-propulsion often comes with a high learning curve. Many of our ancestors died during the learning curve of gasoline, but they gifted us cultural wisdom about the dangers of gasoline. We are gifting our progeny with the cultural wisdom of clean energy use. Don't kill yourself in the process: each battery can be lethal.
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Wednesday, September 25, 2024

Re: [electricboats] Cells (modules) are dying.

Here's the one I have. I have 2 in different locations. Works well. Couldn't find share link, so paste in Amazon.
DC Power Supply Variable,0-30 V / 0-10 A LW-K3010D Adjustable Switching Regulated Power Supply Digital,with Alligator Leads US Power Cord Used for Spectrophotometer and lab Equipment Repair



On September 25, 2024, at 7:06 PM, Peter Knowlton <pqknowlton@gmail.com> wrote:


Thanks Jerry, Gives me hope. I just might try that. I have a couple that are below 2, as well. First it was the #6 module, then #5 went, and #12 went about the same time as #5. Do you have the link for that DC power supply you got?
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Re: [electricboats] Cells (modules) are dying.

Thanks Jerry, Gives me hope. I just might try that. I have a couple that are below 2, as well. First it was the #6 module, then #5 went, and #12 went about the same time as #5. Do you have the link for that DC power supply you got?
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Re: [electricboats] Cells (modules) are dying.

I will try to bring them back. I had thought from what I read, and what some have told me, that since the voltage for each battery was nearly identical there was no need to balance them. Looks like that was bad advice. I am going to try and bring the zero's back and will be balancing the bank. Thanks for that.
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Re: [electricboats] Cells (modules) are dying.

Peter,
   I had a bad bms on my house solar bank that resulted in something like you had. In my experience the ones on the positive end (number 15 and 16 go first. I had one at zero and another at around 1.5v. I have a small DC power supply (about $50) from Amazon. Put that on them individually at 3.2v and after about a week they were back up to 3.4v. The zero volt one made it another year before swelling and failing. The other is still working 4 years later.
Jerry



On September 25, 2024, at 1:57 PM, Peter Knowlton <pqknowlton@gmail.com> wrote:


So, I have an AC-34 HPEVS motor and a Curtis F6a controller. 48 volts. Eve LiFePo4 batteries. 3.2v and 280ah each. 16 of them. Have had them for three years in storage at 55-65 degrees. They were all 3.2v when I got them three years ago and 3.2 when I put them in the boat this spring. I have a JK BMS. Yesterday, for the first time, I put the boat in the water and they got their first true loads.  The power is crazy and I have a 28000 lb ketch sailboat with a full keel. Had really good power, which made controlling the boat so much better. However, after 1/2 an hour tooling around at fairly low rpms the app on the JK BMS said cell/module #6 voltage was dying and after another 10 minutes it was down to nothing/zero volts. Still had enough to motor. Docked the boat and tied it up for the night. Went back the next morning, with a spare cell/module I had, and measured the voltage on #6. Had no volts. Nothing. Took it out and replaced it with a spare, which was reading 3.2v.  We were all set. Headed back out to the mouth of the harbor humming along at about 1500 rpms. After 20 minutes the motor sounded like it was losing power and sure enough it was. Opened the App and now two more cells were down to zero on the app and the Curtis display said Fault Code L23 - low battery voltage. Battery bank was down to 36v total. A slight caveat. I have a Honda 2200eu generator for when the battery runs down and I'm motoring and the batteries needs additional juice. Plugged the generator into the shore power outlet fired it up - and noticed that when I did that the motor actually lost a little power. At least that's what it seemed like to us.  So, anyone have any experience losing cells/modules after they get put under loads and which showed 3.2v before.? Is it possible/likely that they simply are bad cells/modules? I originally bought 32 of them and it seems to me that losing 3 of them, when they've been in dry climate controlled storage, is not a good percentage of bad cells/modules. I have three more spares and will replace the ones that are reading zero voltage and see what happens. But I am, also, wondering if there is something I am doing, or not doing, to cause this? As I am new to this that is definitely a possibility but I don't know what I did, or didn't do to cause it. Seems like all the cells would be affected if I did something. Another thing to note is that I have a 24v battery bank for the house electronics that get their charge from the 48 volt bank, and I have a 12 volt battery bank that I use for the electric trolling motor for the dingy. All of theses cells/modules are, also, the same Eve cells that were bought at the same time as part of the same order.  I have used the 24 volt bank a little and used the trolling motor a few times. All of these cells are reading decent voltage and no cells/modules appear to be tanking in the 24v bank or the 12 volt bank. Any ideas would be greatly appreciated. My first time doing this so I am trying to figure this stuff out as I go along.
 
Peter Knowlton
South Dartmouth MA
 
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Re: [electricboats] Cells (modules) are dying.

Sounds like you didn't balance them or charge them after you received them? Voltage is almost meaningless with LFP. You can have one cell at 25% SOC and another at 85% and they with both read 3.2 volts. 

The cells were probably fine. The ones that hit 0 volts may now be toast. 


Matt Foley

Sunlight Conversions 
1-201-914-0466





On Sep 25, 2024, at 2:57 PM, Peter Knowlton <pqknowlton@gmail.com> wrote:


So, I have an AC-34 HPEVS motor and a Curtis F6a controller. 48 volts. Eve LiFePo4 batteries. 3.2v and 280ah each. 16 of them. Have had them for three years in storage at 55-65 degrees. They were all 3.2v when I got them three years ago and 3.2 when I put them in the boat this spring. I have a JK BMS. Yesterday, for the first time, I put the boat in the water and they got their first true loads.  The power is crazy and I have a 28000 lb ketch sailboat with a full keel. Had really good power, which made controlling the boat so much better. However, after 1/2 an hour tooling around at fairly low rpms the app on the JK BMS said cell/module #6 voltage was dying and after another 10 minutes it was down to nothing/zero volts. Still had enough to motor. Docked the boat and tied it up for the night. Went back the next morning, with a spare cell/module I had, and measured the voltage on #6. Had no volts. Nothing. Took it out and replaced it with a spare, which was reading 3.2v.  We were all set. Headed back out to the mouth of the harbor humming along at about 1500 rpms. After 20 minutes the motor sounded like it was losing power and sure enough it was. Opened the App and now two more cells were down to zero on the app and the Curtis display said Fault Code L23 - low battery voltage. Battery bank was down to 36v total. A slight caveat. I have a Honda 2200eu generator for when the battery runs down and I'm motoring and the batteries needs additional juice. Plugged the generator into the shore power outlet fired it up - and noticed that when I did that the motor actually lost a little power. At least that's what it seemed like to us.  So, anyone have any experience losing cells/modules after they get put under loads and which showed 3.2v before.? Is it possible/likely that they simply are bad cells/modules? I originally bought 32 of them and it seems to me that losing 3 of them, when they've been in dry climate controlled storage, is not a good percentage of bad cells/modules. I have three more spares and will replace the ones that are reading zero voltage and see what happens. But I am, also, wondering if there is something I am doing, or not doing, to cause this? As I am new to this that is definitely a possibility but I don't know what I did, or didn't do to cause it. Seems like all the cells would be affected if I did something. Another thing to note is that I have a 24v battery bank for the house electronics that get their charge from the 48 volt bank, and I have a 12 volt battery bank that I use for the electric trolling motor for the dingy. All of theses cells/modules are, also, the same Eve cells that were bought at the same time as part of the same order.  I have used the 24 volt bank a little and used the trolling motor a few times. All of these cells are reading decent voltage and no cells/modules appear to be tanking in the 24v bank or the 12 volt bank. Any ideas would be greatly appreciated. My first time doing this so I am trying to figure this stuff out as I go along.
 
Peter Knowlton
South Dartmouth MA
 

[electricboats] Cells (modules) are dying.

So, I have an AC-34 HPEVS motor and a Curtis F6a controller. 48 volts. Eve LiFePo4 batteries. 3.2v and 280ah each. 16 of them. Have had them for three years in storage at 55-65 degrees. They were all 3.2v when I got them three years ago and 3.2 when I put them in the boat this spring. I have a JK BMS. Yesterday, for the first time, I put the boat in the water and they got their first true loads.  The power is crazy and I have a 28000 lb ketch sailboat with a full keel. Had really good power, which made controlling the boat so much better. However, after 1/2 an hour tooling around at fairly low rpms the app on the JK BMS said cell/module #6 voltage was dying and after another 10 minutes it was down to nothing/zero volts. Still had enough to motor. Docked the boat and tied it up for the night. Went back the next morning, with a spare cell/module I had, and measured the voltage on #6. Had no volts. Nothing. Took it out and replaced it with a spare, which was reading 3.2v.  We were all set. Headed back out to the mouth of the harbor humming along at about 1500 rpms. After 20 minutes the motor sounded like it was losing power and sure enough it was. Opened the App and now two more cells were down to zero on the app and the Curtis display said Fault Code L23 - low battery voltage. Battery bank was down to 36v total. A slight caveat. I have a Honda 2200eu generator for when the battery runs down and I'm motoring and the batteries needs additional juice. Plugged the generator into the shore power outlet fired it up - and noticed that when I did that the motor actually lost a little power. At least that's what it seemed like to us.  So, anyone have any experience losing cells/modules after they get put under loads and which showed 3.2v before.? Is it possible/likely that they simply are bad cells/modules? I originally bought 32 of them and it seems to me that losing 3 of them, when they've been in dry climate controlled storage, is not a good percentage of bad cells/modules. I have three more spares and will replace the ones that are reading zero voltage and see what happens. But I am, also, wondering if there is something I am doing, or not doing, to cause this? As I am new to this that is definitely a possibility but I don't know what I did, or didn't do to cause it. Seems like all the cells would be affected if I did something. Another thing to note is that I have a 24v battery bank for the house electronics that get their charge from the 48 volt bank, and I have a 12 volt battery bank that I use for the electric trolling motor for the dingy. All of theses cells/modules are, also, the same Eve cells that were bought at the same time as part of the same order.  I have used the 24 volt bank a little and used the trolling motor a few times. All of these cells are reading decent voltage and no cells/modules appear to be tanking in the 24v bank or the 12 volt bank. Any ideas would be greatly appreciated. My first time doing this so I am trying to figure this stuff out as I go along.
 
Peter Knowlton
South Dartmouth MA
 
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Monday, September 2, 2024

Re: [electricboats] Anyone with ME1616 experience? planning to run one at 48VDC, what is the actual kW available? 6kW continuous?

Hello Charlie,

On my catamaran, I went to 96vdc, not center tapped.

If you are still trying to decide whether to stay 48vdc or go to 96vdc, there is another important consideration to keep in mind: at 48dvc (limit of the "safe to touch" voltage range as discussed earlier in this thread), the availability of electronic equipments is plentiful (MPPT chargers, inverters, AC-DC chargers, etc.). At 96vdc, there are far fewer products. At 144vdc and over, that's crazy hard to find things. I wrote about my electric propulsion system decision process here https://www.catamaran-escargot.com/en/blog/20210126/ and I cover this point in the section "Electric Voltage of the Propulsion System" section.

One small benefit of having a 96vdc power bank is that most electronic equipment working with a switching power supply designed to work from 110 to 240vdc will work fine with your 100vdc. My navigation computer system, the networking equipment, my CCTV, etc. aboard Escargot (systems considered critical to have on) are connected directly to the 96vdc bus, i.e. they continue to work even if the inverter is off. Switching power supplies first create DC from the AC input, then create high frequency AC, to finally lower the voltage and make it DC. Feeding them DC or AC makes no difference as long as they do not have a built in protection against that. But, that is getting quite out of topic regarding your ME1616 initial topic, sorry. ;-)

Jerome


On Wed, Aug 28, 2024 at 6:11 AM Charlie via groups.io <cp3sail=gmail.com@groups.io> wrote:
For you guys building the 96vdc setups:
 
Is everyone considering doing a center tapped 96vdc/48vdc battery setup? Any other solution with a large 96v bank aboard seems difficult to charge with solar.
 
Thanks!

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