cool stuff...... thanks for posting!
The protection PCB was shutting the pack down because the batteries were badly out of balance. Being out of balance was more than likely a symptom of the problem, but not the root cause. In the magicshine packs, this is typically caused by defective cells that have tiny internal shorts which causes them to run down over time. Be careful, because you're playing with fire (no pun intended). Because li-ion cells with these kinds of defects will have fairly normal capacity but can become unstable due to the internal shorts if you keep using them.
I've posted lot of details about this in the past, but unfortunately don't have the time to go find the old posts at the moment.
Thanks for the word of caution.
Honestly I feel way more comfortable using a smart charger then the OEM.
I still believe the problem was the OEM charger. In place of the failed charger I was using a Sony video camera charger that was probably tripping the PCB before it was full.
In the holders, I've carefully sequenced/paired the cells according to the factory orientation.
If the PCB trips prematurely then I know that at least on of the cells have gone bad.
just a Newbie
Did you had a chance to measure the voltage of each cell individually right after you tore apart the pack and before you charged them in your Intellicharger? That would have been the best time to see what the real issue for the 35 minute runtime. If you had a pair of cell being the same voltage but either much higher or lower than the other pair, than that pretty much sums it up as inbalance cells.
What I would do is to take these cell in your DIY holder and fully discharge the pack for several cycle and charge them back up with a standard MS or equivalent 8.4v charger instead of using the Intellicharger which charges them individually. Repeat this and check to see if you have different cell volatage by taking individual cell volt reading. It may take few or many charge/discharge cycle before you will see the effect. If you do get unbalance readings, I would toss the bad cell instead of taking a chance just to be safe.
If I am not mistaken, the protection board for the battery sense the battery voltage using the COM wire that is hook up to the center tap of the four cell. That allow the PCB to sense overcharging or over discharge between the the two half of the pack and not just the pack as a whole. Those who has better knowdlege of these PCB please correct me if I am wrong. So if the pack was unbalance, then the higher half of the pack reaching a charge voltage of >4.35 may cause the PCB to trip out before the pack was fully charge while the other half is lower than this volt, thus yeilding in a unfully charge pack. The 4.35 volt number I used is from one of my PCB instruction sheet for a 7.4v pack.
I thought the same thing you did but only in hindsight. I should have measured the individual cell Voltages immediately after the original discharge/dis-assembly.
I will need to get a hand on another OEM charger to test your method.
However I am carefully monitoring each cells after each cycle of discharge/recharge w the intellicharger.
R1: 4.20 v 4.19 v 4.20 v 4.19 v
D2: 3.47 v 3.47 v 3.46 v 3.46 v
R2: 4.20 v 4.19 v 4.20 v 4.20 v