I'm thoroughly impressed (and somewhat jealous. haha!). Great work
Don't be jealous, try it yourself, it is not as challanging as it seems
OTOH, I spent my ENTIRE weekend wiring up a Vicor PSU, the board of vicor dc-dc converters, and the rows ov batteries so I finally have a single-cell charge!
I paralleled (5) 48v4.2a sub-chargers into a Vicor Autoranging PSU, and ran a set of leads, with a 25a fuse in a waterproof ATC fuseholder, with Andersons on the end.
There are 10 (10) DC-DC converters (48v-3.7v) mounted on the aluminum charging plate, to match the 10 supercells in each of the (3) rows in the pack. I ran individual positive and negative 16ga leads to each of the converters, collected them into a 10gau wire, and terminated in andersons. Then I ran a 10ga wires to the output side, splittin each one between the positive of one vicor and the negative of the next vicor, and terminating them in a block of 11 anderson conectors. At the same time I wired trim pots between the '-' and the 'sense' of each converter.
Then I ran a 12gau wire to the fuse on each copper battery strip in the pack, soldered and double-shrinkwrapped, and terminated them in blocks of 11 andersons, matching the block on the aluminum charging plate. Once terminated, I put a 30a fuse in each waterproof ATC fuseholder - 50% headroom over the 20a/.25c load I anicipated. I can also use these connections for a future LVC/pack monitoring system.
I adjusted the trip pots from 3.7-3.75v down to 3.60v. A little low, I know, but I will not discharging this pack below 50% any time soon, and I want to take it easy on the batteries. I saw a recommendation that the t-skys not be taken below 70%DOD for their first 20 cycles, I have no idea whether it is logical but I will follow it supersitiously. Similarily, I will take it easy on the charging for a while, and take it to 3.65v when I start truly exercising the pack.
I then charged each row in turn. I figured that the 10 converters, each drawing 94w, would draw 940w. As you can see from the display on the Killawatt, the bulk of the charge was at 650w, occaisionally peaking up to 700-750w. I don't fully understand why it would increase, but OK. Still, this managed to put out a massive amount of heat; the massive aluminum plate was exteremely HOT, even though it was sitting directly on a cool concrete slab. I had intended to put (30) of these vicors on this plate, I am glad I did not get that far.
When not connected to the pack, the PSU and converters drew 94w. Because it was sitting on 116w for a long time, I charged each pack to 116w. When I have more time I might let a row sit a while and see what it goes down to. Each row took about 1.2 kw, although I have no idea how much of that was heat. The good news is, I am no longer running on chinese electricity - I have the means to power the pack again!
Oddly, (1) supercell charged up to 3.68v, even though the DC-DC was trimmed to 3.6v. This made me think about fetchers point about the string being charged in series, with current flowing through the balancing wires only when the the cells were out of balance... That 3.68v sure looks like a series charge, which makes me wonder about the efficacy of single-cell charging-which I have always sworn by before. OTOH maybe this is symptomatic of my 3.6v instead of 3.65v charge.
Anyhow, to pictures:
EDIT 12/14/12: replaced pictures lost when the forum crashed a few years ago.