That's what I Meant. I was looking at the pictures of his power supply, which shows less than 3.65V in Constant Voltage Mode... ??
Has anyone purchased/tested the lifepo4 310ah from aliexpress yet ?
- Thread starter Bobs RV 36'
- Start date
Let the cell rest for one hour then measure the cells voltage. The voltage should be be above 3.5 volts. You can then proceed to discharge the cell.
smithgeo
New Member
I upped the voltage from 3.60 to 3.65 on the PS. Battery hovering around 3.647 now.... ps still around around .28a going into the battery. Will let it hit 0.00 and report back.
Are you measuring the voltage at the cell with a DMM?
smithgeo
New Member
Yes. PS is set to C.V @ 3.65
Battery at the time of writing this @ the terminals is 3.647
Sounds like it's in the tail-end of the Absorption Stage, let it finish (0A) before letting it rest. Once it hits the Float Stage, I would disconnect, check voltage, wait 1 hour, check voltage again, wait 24 hours, check voltage again. Log all readings. If voltage drops noticeably, I might be concerned about Excessive Self-Discharge (Bad Cell, further testing required to verify). If voltage stabilizes, proceed with Capacity Testing.
All of my EVE cells were above 3.5 volts after sitting for a couple of days. It can't hurt to let the cell rest for 24 hours but if the cell voltage drops below 3.5 volts after resting for 1 hour would that not be concerning? And if the cell remains above 3.50 volts isn't that a good sign? To clarify this is with nothing connected to the cell....no loads.
smithgeo
New Member
It's done - both the PS and Cell @ the terminals sat at 3.650 - no current for a solid 15 minutes.
Will let it rest for an hour and check the voltage at the terminals. Nothing currently connected.
I've got a second cell charging up - I will get that one to 3.650 and do a 24h test to review discarge data. I'd like to get the capactiy test going on the first cell, as I am limited to about 20A with my tester... so expecting it to take roughly 15 hours.
Will let it rest for an hour and check the voltage at the terminals. Nothing currently connected.
I've got a second cell charging up - I will get that one to 3.650 and do a 24h test to review discarge data. I'd like to get the capactiy test going on the first cell, as I am limited to about 20A with my tester... so expecting it to take roughly 15 hours.
Yes. Personally my Biggest Concern with these cells from China (which seem to be mostly B-Grade, reason unknown) is Excessive Self-Discharge, which clearly indicates a fault/flaw in the manufacturing process. My second biggest concern is Internal Resistance, then Capacity and finally Cell Matching & Pack Balancing. Here are some good YouTube videos:
I recommend watching the videos I linked in my post above...
It's been awhile since I watched those videos. All of your concerns are valid. However after observing this forum for awhile I have noticed suppliers sending out electrically defective cells is rare, although it has happened. Most receive cells with physical defects and in some cases those could result in electrical defects....I am concerned about that as well.
I admire your passion for caution especially pertaining to the discussion of these cells. They are still "unknowns" as far as I am concerned and much more testing needs to be done as has been with the EVE and Lishens. Hoping for good results.
smithgeo
New Member
Thanks Guys - I really apprecate the feedback and advice from everyone. Very informative videos.
After 1hr, the cell is reading 3.595.
I will measure again over the next few hours before I start the discharge test and update with a small chart later this evening.
My other 4 cells arrived this afternoon as well. So fingers crossed we are in good shape. I knew there was risk buying from a new vendor from my readings on here. If I can get anything over 300 - I will be really happy. Starting to make some nice fresh cables now for my tests.
After 1hr, the cell is reading 3.595.
I will measure again over the next few hours before I start the discharge test and update with a small chart later this evening.
My other 4 cells arrived this afternoon as well. So fingers crossed we are in good shape. I knew there was risk buying from a new vendor from my readings on here. If I can get anything over 300 - I will be really happy. Starting to make some nice fresh cables now for my tests.
These are cheaper than the 280s, correct? personally, I would be happy with anything above the capacity of those. I am just looking for a new pack for my van. So my case might be a little different than some.
smithgeo
New Member
These were listed as 310AH. They were roughly 1200 usd all in (tax, duty, shipping to canada). so 150 a cell.
CATL 310Ah? How many did you order, who did you order from & what was the cost please?
smithgeo
New Member
8x
679.0US $ 30% OFF|NEW 3.2V 320Ah Lifepo4 Battery Grade A 48V 310AH Rechargeable Battery Pack for RV Solar Energy storage system EU US TAX FREE|Rechargeable Batteries| - AliExpress
Smarter Shopping, Better Living! Aliexpress.com
They were roughly 1200 usd all in (tax, duty, shipping to canada)
smithgeo
New Member
Here is what we have...
Not sure what to think at this point...
Not sure what to think at this point...
| Time | Voltage | v Drop |
| 2:42 | 3.650 | |
| 3:42 | 3.595 | 0.055 |
| 4:42 | 3.564 | 0.031 |
| 5:42 | 3.545 | 0.019 |
| 6:42 | 3.531 | 0.014 |
| 7:42 | 3.523 | 0.008 |
smithgeo
New Member
After it dropped even less over the next 30 minutes. I decided to start a discharge test.
I have also started another full charge on another cell. I will do a full 12hr chart like above, and 24h self discharge test on this cell once it hits 3.650.
As for the discharge test.. Will check in after a couple of hours.. while the screen on the tester seems to be hovering around 3.14v.. my DMM has been stable @ 3.310 since the test started.
20A draw. Resistance shows 00.15
I have also started another full charge on another cell. I will do a full 12hr chart like above, and 24h self discharge test on this cell once it hits 3.650.
As for the discharge test.. Will check in after a couple of hours.. while the screen on the tester seems to be hovering around 3.14v.. my DMM has been stable @ 3.310 since the test started.
20A draw. Resistance shows 00.15
Bud Martin
Solar Wizard
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- Aug 27, 2020
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What Voltage did you set your electronics load to cut off low Voltage at? You may have to compensate the low cutoff Voltage due to the tester meter is not showing true Battery Voltage reading because the Volt meter of the tester is not directly connected to the battery terminals. You can check the Voltage drops on the wires between the Battery terminals and the terminals of the tester to see what it is. I get about the same difference Voltage readings on my tester and the meter too.
