RTLSHIP said:
I have an old cell phone charger that 5 v .7A, but it looks like I would have to cut of the USB plug to get 2 separate wires (plus and minus.)
If leaving the pack on the charger long enough doesn't fix the problem, then you can open up the pack and do the voltage tests first, and then if necessary go down that single-cell charger route. If you didn't want to cut the wires you could buy a USB extension cable for that same kind of plug, and cut taht cable in half, and use *it's* 5v and ground wire to make the connections for your cells. That makes it a little safer making the connections first, so you can be sure you have + and - in the right spots before hooking up the charger, too.
I have that old pack that gets a hot BMS when charging is finished. It never jumps back and forth from red to green like other packs.
That just means most of it's cells are close in voltage to each other, so the BMS has most of it's balancers turned on then, so they are shunting current away from the cells and dissipating this as heat. That's normal. If the current never drops below the minimum for the charger to turn off, or the BMS never shuts off the charge input port (or you are charging thru the discharge port) then the charger will never "turn off" so it never changes LED color. Some chargers also don't have the turn-off electronics, so they stay on all the time they are plugged in, and never change color.
So I'm wondering that this could be why my old pack is out of balance (among other reasons).
It's not the cause of the problem, it is a symptom of the problem.
And I would try to tamper with that one first before tinkering with this newer 48/12.
Well, tampering with it won't do you any good unless it's broken, and it wont' do anything at all to fix this one.
It might teach you how the packs are built inside, if they are both similar (there are a lot of ways to build packs, some of which are very different).
That old pack still runs and could be rejuvenated some. You have seen a few pics of it Fully charged the first pin(metal behind removed bms plug) reads 3.2,7.0, all the way to 53.
You should note voltages down not as a total from one end, but as the specific voltages between each pair of pins. Start from the most negative cell going up to the most positive. This is a lot easier to "read" and directly see where problems may lie.
For instance, if you had 3.2v on the first cell, and reading across it and the next one is 7.0v, then you have 3.8v on that second cell, which is a lot higher than it should be. Showing the actual individual voltages would help see what is really happening.
Curiously, there is a .3 or .4 volt difference between reading from charging negative spot and nedative discharge. It should be zero difference.
That depends on what is between those spots. If there is current flowing at all, then having electronics like shunt resistors and FETs and things between the two points will have a voltage drop across them. Not much, but some, and could account for what you see.
Connection problems can also account for that, if they are not directly crimped or soldered together and have any connectors in the path.