Another Lithium Conversion, but with a different kind of cells...
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.