#151837  by Nut17
 Thu May 30, 2019 10:22 pm
Age and a little swelling is not a problem Neville. The cells in our last van had some swelling from the day we purchased them - They were three years old and over seven years old now with no measurable loss of capacity or performance. The photos show them still tightly packed with very little evidence of swelling.
 #151838  by davef
 Thu May 30, 2019 11:16 pm
Another forum dealing with batteries http://electrodacus.com/solarforum.html with some testing proposed on these cells
https://www.aliexpress.com/item/32949274207.html.
Found in a thread in the battery section.

I got confirmation from the seller that they really do ship to your door. Before I ordered any I would want to know the production date, that I would get consecutive serial numbers and the outcome of any tests. Evidently there can be "2nd-grade" cells and units not used in some big job that went under floating around.

I have my housebank Winston 8 * 200AH cells clamped and heated ... I want them to last as long as possible.
 #151841  by Nut17
 Fri May 31, 2019 2:25 am
My stumbling block was still the unknown cost of the New Zealand port handling fees. I tried a couple of customs clearance companies in Auckland and could not even get an estimate. That deal equates to around NZ$1100 plus GST plus port handling fees for 240 AH of unknown and unproven quality - Could be up to $1500 - $1600.
 #151855  by Nut17
 Fri May 31, 2019 4:53 pm
Completely different construction to the "Prismatic" LiFePO4 cells we are using Neville.
 #151856  by myles
 Fri May 31, 2019 6:58 pm
???

The construction of a pouch LiFePO4 and a prismatic LiFePO4 is pretty much identical (some pouch cells are refereed to as prismatic pouch cells). The only real difference is typically size and the surrounding package.

Heat is the 'killer' of LiFePO4 cells (any type). That is why high charge and discharge rates should be avoided if possible (improves the life of LiFePO4 batteries...).

Swelling is typically the result of over heated cells and typically has a detrimental effect on capacity. Having said that, some swelling is to be expected over time, but excess swelling is not something that should be ignored.
 #151857  by Neddy
 Fri May 31, 2019 8:55 pm
A good article on prismatic LiFePO4 battery failure can be found at
https://download.atlantis-press.com/art ... 846169.pdf

"Analysis of Lithium Iron Phosphate Battery Damage"
Their findings :-
Over-charge has a small negative effect on LiFePO4 battery capacity, but has a huge impact on their cycle life.
Over-discharge has a huge impact on both the capacity and the cycle life of LiFePO4 batteries.
Batteries damaged by over-discharge, bulged.
If the battery had been completely destroyed, the bulge was more pronounced.
 #151860  by scubadoo
 Fri May 31, 2019 10:20 pm
I have yet to to see any used free standing plastic housed unrestrained LiFePO4 prismatic cell more than a year old that does not exhibit some swelling. I have checked a few.
Mine are restrained by substantial stainless steel strapping and a steel ruler placed on any exterior long flat side surface reveals all. Concerned? Not at all. It is just evolution and expected except by a few doomsayers.
There is nothing and I repeat nothing in a typical RV charge/dishcharge setup that could ever raise lithium battery pack internals by more than a few degrees whether that pack is 100Ah or 500Ah under normal operating conditions. The tiny mΩ internal cell resistance dictates that.
A very serious and prolonged overcharge would have to occur without detection. We do all have some protection for that scenario don't we? :?

Significant swelling would be another matter regardless of battery chemistry. I have seen a few.

Those Trademe cells look perfect.

I will be placing my bid before lunch time tomorrow unless others get carried away.
Oops my $200 higher bid did not last long.
  • 1
  • 3
  • 4
  • 5
  • 6
  • 7
  • 9
Pay with Paymate Express