new Grade A vs new Grade B LiFePO4

[LiFer]

Hello folks,

I'm trying to learn what the pros/cons are between brand new Grade A and brand new Grade B batteries. Please chime in!
I've found a few articles about this and it seems that new batteries are differentiated between
a) internal resistance
b) charging capacity

If higher internal resistance was the only difference with Grade B cells, my intuition (ok, guess) is that I'd get the same life out of them, and I'd guess that it wouldn't affect charging as I'd be charging at a reasonably low current anyway.

Odd/disheartening: another diysolarforum post about this mentioned some suppliers are selling Grade B as Grade A: https://diysolarforum.com/threads/j...ered-grade-a-to-canada.3387/page-8#post-40695


Some data that might prove interesting:
1. (analysis shows Grade B cells have more capacity than Grade A cells) https://endless-sphere.com/forums/viewtopic.php?t=93488

Article that tries to make a case that Grade B cells are only differentiated between internal resistance and charging capacity:
1. http://www.batteryeducation.com/2008/09/battery-manuf-1.html

 

[LukeVader]

Here, watch this video. there's more to compare that makes a cell grade B

 

[LiFer]

Thanks. It's a little weird spending so much money for cells that are so hard to test to see if you got what you paid for (waiting x days to see if your 280Ah battery self-discharge time is within spec).

 

[LukeVader]

Yeah but the time waiting is kinda great cause you can see if your grade "A" cells hold up over the trip

 

[Bob B]

HERE IS ANOTHER VIDEO about cell grading.

Apparently there are also grade A+ and grade A- cells. Grade A- cells are grade A cells that have been stored longer ..... so, if you want the absolute best cells possible .... it may be good to not only insure they are grade A, but that they are grade A+.

 

[MullerEnergy-Australia]

Here, watch this video. there's more to compare that makes a cell grade B

I know it's a grave dig, but one of the comments in the video was just too silly not to comment on: Test the weight at a specific SOC. Now that's just silly!
While technically it's true, the change in mass is only ∆m=∆E/c^2, so assuming a 1kWh ∆E, the difference would be 0.00000000000004kg or 40pg (that's 40 picograms)!

If you have a scale that can measure that difference while weighing a 5kg cell, I want one!

 

[Sylwood2]

But, the big question is... Should I pay 50% more for a grade A? If I buy a 100ah cell and usually only use 40-50ahs, will a grade B cell diminish that much? Im wondering if I will even notice the difference.

 

[OnTheRoadAgain]

But, the big question is... Should I pay 50% more for a grade A? If I buy a 100ah cell and usually only use 40-50ahs, will a grade B cell diminish that much? Im wondering if I will even notice the difference.

THIS is THE question.

For example, you buy BattleBorn, is that $500 premium because you are indeed getting grade A cells?

And, is the difference in service life (all other things equal) of any real world significance ?

Will you REALLY get 10 years at 80%+ capacity with BattleBorn vs a LOT less from a $500 Budget LiFePO4 substitute?

BattleBorn has not been around 10 years, and the cells they warrant for 10 years most certainly have not so no one knows for certain.

 

[toms]

Thanks. It's a little weird spending so much money for cells that are so hard to test to see if you got what you paid for (waiting x days to see if your 280Ah battery self-discharge time is within spec).

You just need patience. I’ve been waiting over 8 years and counting to see if my LiFeTech @ 150% price of Winston are worth the extra dollars. Might have to wait another decade yet! Even the cheapest second hand cells i’ve used in an install are still performing well 3 years into service.

I think by the time we find out conclusively which type of LiFePO4 chemistry is best, it will be a redundant technology.