Lapwing wrote:Yep, anything over 48V needs careful attention. Rubber linemans gloves are not overkill.
I hear you Lapwing!
In the picture below, note the linesmans gloves on the right. Each of the rows of batteries is 10 cells, 30.00v/33.75v/36.50v (nominal/resting/fresh charged). Note the red 2/0 cable connecting rows 1 and 2, with 400a Silicon fuses on BOTH sides. Rows 2 and 3 are connected by a solid bus bar for 60.00v/67.50v/73.00v, which I am thinking about cutting so I can fuse between them. The wire for each single-cell charger is fused right at the battery terminus, and although the unterrminated ends are just floating around right now, there are no fuses in them.
I also have contactors on both the negative side and positive side, energized by discrete circuits.
I spent a LOT of time thinking about every exposed surface, and have taken great pains to cover every potential contact point possible. I don't have exposed terminals like an SLA battery, and I am pretty sure i could drop a wrench anywhere and not conduct current - but I don't want to test it out either.
When I put a sheet of plywood on top, this pack should be pretty well enclosed and maintenance free.
For the final mounting of the 180v pack, I am thinking of putting it between the front seats, 5 supercells per row, stacked 9 rows high (13.5"). Each row will rest in a tray that slides into a big steel box, each tray will be lined on all 6 sides with phenolic plastic, and each row will be connected by a silicon fuse. Cooling will become an issue at that point, and I have a lot of other vehicle-mechanical things to sort out first, so it will be a while before I go there.
ANYHOW, I busted my hump last night,
and got all of the new batteries installed.
I finished about 8:30pm and thought I would take it for a quick test. Clicked on the main contactor, clicked on the control contactor, pressed the pedal... and nothing happened.
So I tried to sort it out in the dark. I thought maybe I had popped a silicon fuse, but everything tested fine. Frustrated, I gave up for the night. I tested it again this morning, found continuity between the contactors, just no power! I ran a wire to test continuity of the negative 4/0 cable, which I had just been moving all over the place, and yep it was OK. Moved the wire to the positive 4/0 cable, which hasn't moved much - no continuity! I wiggled the battery side of the negative cable, and to my horror it came off in my hands, pulled right out of the lug.
So, power off, jammed the cable back into the lug, and viola! 108v. I could not resist taking it around the block to see how it rides. At 108v the bus now has at LEAST as much power as it did with the old ICE
- plus with electric torque it is a little faster off the line.
This means I have met one of my design goals;
I have successfully converted this bus to match ICE speed/accelleration, and because I used LIFEPO4, it is LIGHTER than when it started. There was no need to use 10c cells because the 80ah supercells will only be running around 2c continious, 40% of Headway's continous rating.
The Cycleanalyst, which is only rated to 100v, was flickering under load, and I could smell something burning, so I unhooked it. Until I can figure out how to get it working over 100v, or buy a new Custom version from Justin, I am not gonna have performance data
The cells were ice-cold immediately after the "ride."
Next, I need to fix/replace the 4/0 cable, wire the Vicor DC-DC single-cell charger system, and start dealing with mechanicals like the motor mount, brakes, fluids etc.
Then I am gonna try to soup it up - it will be a real screamer when I bump to 180v, even with the extra 80 or so lbs over stock that will take me to (I have hauled 1500lbs of slate in this bus, 80lbs is cake
-JD <----- Sporting the EV Permasmile!