I've accumulated many gp 3300's nd MEC tubes and plan on testing/re-arranging them so they are hopefully all matched up a lot closer. Nice thing about MEC tubes is that cells can be replaced/moved around without soldering. The packs are average packs.

Here's the plan so far:

First step is to see where the packs are in capacity and balance and match. This is done using a 500 ma charge or a fast charge PLUS 500 ma at the end. Both need to be done plenty long to ensure the cells (if mismatched/unbalanced) are all full.

Then the packs can be tested on CBA to see how they are. Evaluation will follow. Total of 100 cells or more will be involved.

To me this is the biggest benefit of using powerpole connectors, it allows multiple packs to be connected in series without any adapters/soldering/changeing connetors. The two halve simply slide apart.

Two tests on the CBA that are consistant would convince me that a cells are at thier best state of balance and cannot be helped any. They are simply mismatched a bit not unlike most packs. Using the CBA one can see clearly how many cells drop at a certain capacity and using a temp gun one can see which cells are first (during discharge or during charge) This is all done without measuring individual cells so far.

All packs overlayed , there are 2 - 6cell packs , 1 - 8 cell pack and the rest are 10 cell packs.

After seing the graphs the two 6 cell and the one 8 cell packs wil be left alone for now. I'm not into doing extra work.

The first graph shows mec1 pack that is the worst one that must've been imbalanced so a slow charge brings cells back into balance.

The second graph is a pack that was already in balance and was not helped at all (cells still mismatched.)

The packs that will be re-arranged. [:'(]

I decided to keep mec 5 and mec 6 as 10 cell packs for now and keep them the rainbow cells and here they both are overlayed with each other.

Looks like mec 5 has 1-2600,2-2700,1-28001-2900, 1-3200 the rest 3200+
Looks like mec 6 has 1-2500,1-2600,2-2700, the rest 3000+

For now I'll switch 4-6 cells between packs to see if they come out more balanced.

Here's mec5 and mec6 each with 3 tests overlayed before sorting. The last test on each one is pulled to 2.5 volts so I can see the better cells when they drop and because the worse cell are adding negative voltage to the pack.

Triton charger @ 90 watts is perfect for warming up a 10 cell pack.
Triton JR does a nice job at 63 watts.
Elite is used @ c/5 (650 ma) to ensure the cells are all full after re-arrangement.

First graph is old mec5 with new mec 5 Notice that the weak cells left and went to mec6.

Second graph is old mec6 wih new mec6 Notice that the strong cells went into mec5.

Third graph is the new mec5 and new mec6 overlayed. One pack is better than the other, but they are both better matched. Nice thing is with the tubes you can quickly and easily swap cells if screwed up.


Both packs are better matched. This may be as good as it gets with these two single packs.

CBA testing bench and "rc" computer

Here's a decently matched (and balanced) pack .

Plug for CBP

Excellent work can you actually tell any difference ? or just good to know you are getting the best out of the pack you can. Also on very low discharges thier is much less chance of cell reversal I would think.
BTW great way to pass the time during our North winds …an snow…[8D]
Rich

If one stops the run soon enough then it may never make a difference. Lots of us noobs "run it till it stops" and will always notice the dreaded gradual slow-down and if take the time to check the same cells will always be hotter after the run AND after the charge.

The weak cells in a sense "are getting it from both ends" during charge slightly overcharge and/or during discharge slight cell reversal. It may make the weakest cells get weaker at a faster rate than the strong ones and a lot of times it is the center cells in a pack.

I'm still not sure how much reversal hurts, but even at a tiny rate when the cell is empty it is empty and will be reversed. The key is how much the cells in a given pack are matched/balanced and the voltage cut-off point. All these tests are done at a cut-off that is much lower than the norm.

I'll break into the 4 spidery looking mec packs soon.