Sunday, May 30, 2010

Now we're moving.


At long last, serious road testing begins. I lost several more cells before a proper commissioning charge was finished- the one block that I had prematurely watered had spewed so much electrolyte, that they didn't want to wash clean, and kept developing shorts against the stainless steel battery box, burning holes right through the side of the cell, right where the top had been sonic-welded onto the case. Methinks there were tiny flaws in those welds, because it only happened to a small percentage of the cells, but it's a killer flaw when it happens....


Anyway, with a fully-charged clean pack, my good friend Eric Gage rode along on some test drives, camera in hand. Here's the only clip small enough to post before editing.....

video

Saturday, May 29, 2010

If I'm not making progress, maybe these guys will!




Yes, all of you long-suffering readers know that the Karmann Eclectric is testing the claim that flooded nicad batteries have no "shelf life issues". But, that does not mean nothing has been going on... Thinking I'd channel Tom Sawyer and get a little work done, or at least share my pain, I invited the Tacoma Electric Vehicle Association over for a work party on March 6, 2010.




An excellent turnout, rare sunny spring weather, and fun without flareups was had by all. Plus, significant progress was made on the car thanks to Bill, Roger, Stan, Kyle, and the cool big guy with glasses who's name I have trouble with....




The big white box I'm pictured puzzling over is a surplus Uninterruptible Power Supply unit for server rooms (pure sine wave). Most 'small' UPS units run off of 12, 18, 36, or 48 volts, but this bad boy takes 240VDC input! That means that it can run off of the car's battery pack, powering the house (well, parts thereof) during a power failure. It also provides a backup battery charger for the EV pack, should some misfortune befall my precious PFC 20, and it will also serve as the core of a hi-po highly green off-grid EV charging station! That's right, a dump pack with manners.




Concept is, put a semi-retired 240V EV battery pack into my car trailer, and run it through the UPS to provide charging current to any EV that can take 240VAC input! That will come in handy at the races and car shows. Lastly, I intend to trickle-charge this pack during it's long periods of idleness through a solar array. But what say you? A 240VDC solar array could prove pricey? Not if one bridges the gap with a set of series/parallel switches to charge the pack in parallel. A stack of 40 amp 12V automotive relays should do the trick because each single relay will see no more than 12V potential, and if all legs are fuse-protected, if a relay sticks and shorts a battery, the whole circuit will get cut quickly...




But, i digressed, as I often do...back to the main event.




Here is one of the day's more important additions, a dc-rated circuit breaker on the input side of the PFC-20. The standard fused output of the charger only protects the battery pack and/or car, and could prevent a fire inside the charger, but does not really protect the charger. This way, with protection on both ends of the charger, there's a better chance that it could survive an onerous EVent. You noticed I wrote DC-rated? Yep, the PFC is capable of charging off of DC, simply acting as a DC-DC converter, up or down, making for the 'dump pack with manners'.. I could start off the aforementioned off-grid charging from DC input as low as 12V, but the 20 amp limitation would mean that not much practical power transfer is going on. 240 Watts is nothing to sneeze at, especially in the world of small-scale solar, but it's a huge waste of potential, when the charger is capable of shuttling 4800 Watts. Besides, Manzanita Micro doesn't recommend dc charging below 70V.

We also installed the Stage III pressure plate, which was of course complicated by a broken bolt, due entirely to miscommunication on my part. What Detroit-trained mechanic would believe that bolts on a flywheel would be spec'd to less than 20 foot-pounds! Thanks to Roger Wright's considerable talents in shadetree improvisation, the broken bolt was extracted with no ill effects.
> Next, we started fitting the uber-sturdy Gene Berg adaptor for a proper installation of the 091 Bus tranny. It's a weld-in mount, and required much more fitting than anticipated, so Roger was kind enough to return the following week to complete the installation. We also installed the truss bars, or "Kafer-Cup" traction bar set from V-Dub Engineering. Lanner Khan makes a beautifully machined, super-strong but ultra-light aluminum, and provides great service after the sale (even if if it's been a couple of years). The truss bar mounting points are also a custom weldment, so Roger and I had a lot of grinding and test-fitting to do. It was a full day's work, but the end result is a thing of beauty. I've been able to take one test drive since, and the clutch chatter seems to be a thing of the past- at least under moderate acceleration...












duty calls, more to come later....