I want to start by thanking Matt for his great videos on upgrading the battery pack, they were a tremendous help in planning my install. I had a pack of Headway cells going to waste in my VW bus conversion, so they were 'free' to me and I used them. If I had to pay for cells, I would have bought the CHL's and used Matt's incredibly detailed, well-thought out kit, it would have been much much simpler.
Yesterday I finished upgrading my Vectrix to a 50ah pack comprised of 45s/5p of Headway 38120s cells. I also installed a CycleAnalyst, it is so nice to be able to see performance data in the format I am used to, not to mention getting speed displayed in MPH. I'll be posting a build thread shortly, still cleaning up the carnage wrought in the process.
I did a test drive today around my area - terrain I typically ride anyhow - speeding suburban stop-and-go traffic, nailing the throttle at launch like I normally do, and a few looong steep hills. It pulls much harder than it used to, not so much at launch, but from 30mph up it is a ROCKET. I pulled 32ah from the pack and covered 32 miles.
Anyhow, the 45s I used is 3s more cells than Antiscab recommended, and it probably sounds odd: Peak charge on a 45s pack is 164.25v, far more than the 152v charger cutoff, and more than the 155v I read that the controller will shutdown at.
However, much of that voltage is 'fluff charge.' I only have to bleed a few dozen wh from the pack to drop it from 164v to 148v. Once there, the voltage is pretty stable - resting voltage only dropped from 148v to 145.1v after today's 32ah discharge. The higher voltage, at a given amp discharge, means I am getting more watts into the motor. In addition, not charging to a full 3.65v extends the cycle life of the cells.
The charger works (yay!) but as I feared it only put 8ah into the pack. Input from the charger raises the voltage on pack, so when the pack reaches about 148v, the charger sees 152v on the circuit and terminates the charge. It's still usesful for emergency charging, but I either drop a few cells to 43s/44s, or I charge externally.
What I would like to do is charge to 158v to get all the cells to the 'fluff charge' range, then bleed a few wh from the pack to drop it back under the 155v that the controller will recognize. When I occasionaly balance-charge the pack it could even see 170v before being bled down.
Which brings me to my question - With the ignition off, if I bring the pack voltage up to 170v, will I fry anything? The need for an ICL shows that something is in the circuit when the ignition switch is off.
Hey just checked the bike, I just noticed the charger turned back on, and went into the 3a charge phase. The CA indicated that 2ah more - 10ah total - were in the pack so far, but the red battery icon was flashing. I wonder which aspect of the cell-ular molestation it was complaining about.
-JD
Hi JD,
155v is likely where the controller prevents regen,
I did not experience any shutdown on 44 cells just off a fresh charge.
The charger I originally used charged to 165V, which appears to have been fine (it was meant for 45 cells).
Not sure about 170v, you may be the first to find out :)
Its the dc-dc that provides 12v that is always on (well, one of them)
What voltage does you BMS start shunting cells at?
I charge to 153v, and my BMS shunts cells starting at 3.6v
The cells themselves stay balanced (unless some have been overdischarged), its the BMS modules that cause un-even self discharge (the green LED's).
The difference is not great, and I have never needed to do a specific balance charge.
Unfortunately they are necessary for the kit as I don't trust the Vectrix charger to shutdown on its own (seen too many runaway chargers when running nimh)
The cells also don't always necessarily come balanced at 50% like they are supposed too
hows the acceleration above 50mph?
I found mine took off like a rocket as soon as you hit 50mph (~30kw from the battery)
You should get better with more volts :)
I now run 42 x 60Ah cells, as I thought the high voltage was causing my IGBT module to heat too quickly, however, that did not solved the problem.
I later found out it was no longer properly secured to the heatsink, so the higher voltage is bad idea is no longer quite so :)
I may go back to 44 cells when I get around to it.
have fun,
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Matt, you are putting a smile on my face today!
The IGTB problem was a loose heatsink, not hich voltage? That is good news!
You've run the MC at 165v? That is GREAT news!
I'm looking atthe Elcon TCCH-144-08 1500w charger, 144v-203v 8a, is that what you tried? Seems like a good enough fit, I can bulk charge externally and then swap it in for the factory charger when you come out with the mounting kit. I run a timer on the charger's outlet, so even if the Vectrix charger goes runaway, it gets cut off in 6 hours.
When I started with LiFePO4 in '07, I could depend on BMS's to be an early fail point, and I learned to get on without them. Learning a pack's characteristics, monitoring watt/hours and pack voltage with a CycleAnalyst, and not using a high DOD, I don't run into many balance issues. I use single-cell chargers to balance a pack periodically, or if I plan to do a full 80%DOD. I have killed a few cells with stupid mistakes a bms would have caught, but replacing those cells cost a lot less than I would have spent buying BMS's for every pack I've built. Your bit of BMS kit is pretty slick and inobtrusive, I would give that a go though.
I did feel the burst of speed come on like a freight train, swear it started at 30mph (50kph?). All the bike needed was a little more 'V' to really get jumping. It's like that zippy first half mile off a fresh charge on the old NiMh pack, but on steroids, and it lasts for the whole discharge.
I really like the throttle profile this MC uses, I was suprised to see amps starting quite modestly, then exploding the faster I went. On ebikes the amps spike at launch, and taper back as back-EMF comes into play. The Vectrix controller supplies 30-50a at launch, which keeps the motor/gearbox from heating up at low rpm, yet I got it up to 219a well on my way to top speed. And heck at 219amps, every extra volt adds a 219 watts. Glad the 200a replacement fuse doesn't blow, suprised the 125a fuse was ever used.
My pack is 225 cells that weigh .75lb each, so the pack is 30lbs/15% lighter than stock, that helps too. I ended up taking out the fans in the shroud out just to save 5.5lbs more. Now I wonder if I should fill that space with more cells, and see just what this MC can do
-JD
Yep, sure is.
When you order from Elcon/TC Charger you can tell them what your preferred max charge voltage is
I used one of those for 20'000km, so yes, they work fine
I now use a 2000W 15A charger (it actually only puts out 13.4A most of the time, as it goes into constant 2000W output)
I got the 165v one as I bought from a reseller that was nearby (I wanted my Vectrix back on the road quickly).
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
I configured (3) 48v/4.2a blades in series on a Vicor Megapack PSU, adjusted the trim pots, and ta-da, instant 160v charger. I had series'd (2) blades before, (3) is new to me, glad it worked. On 120v, it draws 900w, not the fastest charge, but that extends cycle life too. Charged the pack up the rest of the way nicely!
It was at 155.9v when I started today's ride. Instead of mimicing the hectic daily commute, I wanted to see what range I got from a touring ride. I wasn't nailing the throttle off the start line, but I wasn't shy about digging into it for passing either - the bike is SOOOO peppy at higher speeds it is hard not to. I hoped to burn off 40ah, a full 80%DOD on the 50ah pack, and to get to know what it was capable of.
I took a scenic route along the ocean that had long stretches without stops, speeds in the 40s/50s. Leaving this route has a looong, steep climb, I was pleased to be going uphill at 45-50mph on only 50-60a. I went So Far! By the time I discharged 40.15 ah, I had put 46.5 miles on the odometer, and it was still pulling strong. My CA reports 5,661.3wh, 122.0wh/m, 221.1 max amps, 64.1 max speed, 31.3 average speed, 1 hour 29 minutes.
Despite 80% DOD, resting voltage had only dropped to 144.7v, 3.21v/cell. I consider LVC for the headways to be 2.7v/cell, so there was a good bit more in the pack before it hit the 'cliff' on the discharge curve. For now, I'll use this as a baseline being able to take 5,700w from the pack and still have room for an out-of-balance condition. My work commute is only 16 miles/day, so having a 50 mile range despite my area's hilly terrian totally frees me from range anxiety. For commuting, I could get away with only charging every three days - though I'll top up daily to get maximum cycle life). For recreation, whole new vistas are opening up.
All I can say is wow, man. Wish I had done this sooner. 8^)
-JD
PS - For someone wanting a cheaper alternative, I am selling my old NiMh Vectrix pack, which had a few hot cells that need replacing. Also included are 14(?) replacement cells I bought on ebay. I used the battery harness on my rebuild, but boxes and all cabling are complete and intact. $1,100 pickup only/Los Angeles.
I posted a stop-motion video of the battery build I did for my Vectrix on my thread on Endless-sphere. As you can see the batteries are very different from the ones Matt's kit uses, so they present a unique set of problems and benefits. Removal of the pack would be very difficult, but I didn't have to cut my Plenum at all, and I have loads of extra space where the Plenum fans used to be. I got 46.5 miles on my 80%DOD test, but voltage was still pretty high, so I had a lot left in the pack.
http://www.endless-sphere.com/forums/viewtopic.php?f=12&t=17071&start=60#p493273
-JD
That's extraordinary.