Wednesday, September 25, 2024

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
 

No comments:

Post a Comment